* [PATCH 5.17 001/111] HID: amd_sfh: Add support for sensor discovery
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 002/111] KVM: x86/mmu: fix NULL pointer dereference on guest INVPCID Greg Kroah-Hartman
` (115 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Mario Limonciello, Basavaraj Natikar,
Jiri Kosina, Mario Limonciello
From: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
commit b5d7f43e97dabfa04a4be5ff027ce7da119332be upstream.
Sensor discovery status fails in case of broken sensors or
platform not supported. Hence disable driver on failure
of sensor discovery.
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Mario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hid/amd-sfh-hid/amd_sfh_client.c | 11 +++++++++++
drivers/hid/amd-sfh-hid/amd_sfh_pcie.c | 7 +++++++
drivers/hid/amd-sfh-hid/amd_sfh_pcie.h | 4 ++++
3 files changed, 22 insertions(+)
--- a/drivers/hid/amd-sfh-hid/amd_sfh_client.c
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_client.c
@@ -227,6 +227,17 @@ int amd_sfh_hid_client_init(struct amd_m
dev_dbg(dev, "sid 0x%x status 0x%x\n",
cl_data->sensor_idx[i], cl_data->sensor_sts[i]);
}
+ if (privdata->mp2_ops->discovery_status &&
+ privdata->mp2_ops->discovery_status(privdata) == 0) {
+ amd_sfh_hid_client_deinit(privdata);
+ for (i = 0; i < cl_data->num_hid_devices; i++) {
+ devm_kfree(dev, cl_data->feature_report[i]);
+ devm_kfree(dev, in_data->input_report[i]);
+ devm_kfree(dev, cl_data->report_descr[i]);
+ }
+ dev_warn(dev, "Failed to discover, sensors not enabled\n");
+ return -EOPNOTSUPP;
+ }
schedule_delayed_work(&cl_data->work_buffer, msecs_to_jiffies(AMD_SFH_IDLE_LOOP));
return 0;
--- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
@@ -130,6 +130,12 @@ static int amd_sfh_irq_init_v2(struct am
return 0;
}
+static int amd_sfh_dis_sts_v2(struct amd_mp2_dev *privdata)
+{
+ return (readl(privdata->mmio + AMD_P2C_MSG(1)) &
+ SENSOR_DISCOVERY_STATUS_MASK) >> SENSOR_DISCOVERY_STATUS_SHIFT;
+}
+
void amd_start_sensor(struct amd_mp2_dev *privdata, struct amd_mp2_sensor_info info)
{
union sfh_cmd_param cmd_param;
@@ -245,6 +251,7 @@ static const struct amd_mp2_ops amd_sfh_
.response = amd_sfh_wait_response_v2,
.clear_intr = amd_sfh_clear_intr_v2,
.init_intr = amd_sfh_irq_init_v2,
+ .discovery_status = amd_sfh_dis_sts_v2,
};
static const struct amd_mp2_ops amd_sfh_ops = {
--- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.h
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.h
@@ -39,6 +39,9 @@
#define AMD_SFH_IDLE_LOOP 200
+#define SENSOR_DISCOVERY_STATUS_MASK GENMASK(5, 3)
+#define SENSOR_DISCOVERY_STATUS_SHIFT 3
+
/* SFH Command register */
union sfh_cmd_base {
u32 ul;
@@ -143,5 +146,6 @@ struct amd_mp2_ops {
int (*response)(struct amd_mp2_dev *mp2, u8 sid, u32 sensor_sts);
void (*clear_intr)(struct amd_mp2_dev *privdata);
int (*init_intr)(struct amd_mp2_dev *privdata);
+ int (*discovery_status)(struct amd_mp2_dev *privdata);
};
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 002/111] KVM: x86/mmu: fix NULL pointer dereference on guest INVPCID
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 001/111] HID: amd_sfh: Add support for sensor discovery Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 003/111] random: use computational hash for entropy extraction Greg Kroah-Hartman
` (114 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Yongkang Jia, Paolo Bonzini, Vegard Nossum
From: Paolo Bonzini <pbonzini@redhat.com>
commit 9f46c187e2e680ecd9de7983e4d081c3391acc76 upstream.
With shadow paging enabled, the INVPCID instruction results in a call
to kvm_mmu_invpcid_gva. If INVPCID is executed with CR0.PG=0, the
invlpg callback is not set and the result is a NULL pointer dereference.
Fix it trivially by checking for mmu->invlpg before every call.
There are other possibilities:
- check for CR0.PG, because KVM (like all Intel processors after P5)
flushes guest TLB on CR0.PG changes so that INVPCID/INVLPG are a
nop with paging disabled
- check for EFER.LMA, because KVM syncs and flushes when switching
MMU contexts outside of 64-bit mode
All of these are tricky, go for the simple solution. This is CVE-2022-1789.
Reported-by: Yongkang Jia <kangel@zju.edu.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[fix conflict due to missing b9e5603c2a3accbadfec570ac501a54431a6bdba]
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/mmu/mmu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5416,14 +5416,16 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu
uint i;
if (pcid == kvm_get_active_pcid(vcpu)) {
- mmu->invlpg(vcpu, gva, mmu->root_hpa);
+ if (mmu->invlpg)
+ mmu->invlpg(vcpu, gva, mmu->root_hpa);
tlb_flush = true;
}
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
if (VALID_PAGE(mmu->prev_roots[i].hpa) &&
pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) {
- mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
+ if (mmu->invlpg)
+ mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
tlb_flush = true;
}
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 003/111] random: use computational hash for entropy extraction
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 001/111] HID: amd_sfh: Add support for sensor discovery Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 002/111] KVM: x86/mmu: fix NULL pointer dereference on guest INVPCID Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 004/111] random: simplify entropy debiting Greg Kroah-Hartman
` (113 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jean-Philippe Aumasson, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 6e8ec2552c7d13991148e551e3325a624d73fac6 upstream.
The current 4096-bit LFSR used for entropy collection had a few
desirable attributes for the context in which it was created. For
example, the state was huge, which meant that /dev/random would be able
to output quite a bit of accumulated entropy before blocking. It was
also, in its time, quite fast at accumulating entropy byte-by-byte,
which matters given the varying contexts in which mix_pool_bytes() is
called. And its diffusion was relatively high, which meant that changes
would ripple across several words of state rather quickly.
However, it also suffers from a few security vulnerabilities. In
particular, inputs learned by an attacker can be undone, but moreover,
if the state of the pool leaks, its contents can be controlled and
entirely zeroed out. I've demonstrated this attack with this SMT2
script, <https://xn--4db.cc/5o9xO8pb>, which Boolector/CaDiCal solves in
a matter of seconds on a single core of my laptop, resulting in little
proof of concept C demonstrators such as <https://xn--4db.cc/jCkvvIaH/c>.
For basically all recent formal models of RNGs, these attacks represent
a significant cryptographic flaw. But how does this manifest
practically? If an attacker has access to the system to such a degree
that he can learn the internal state of the RNG, arguably there are
other lower hanging vulnerabilities -- side-channel, infoleak, or
otherwise -- that might have higher priority. On the other hand, seed
files are frequently used on systems that have a hard time generating
much entropy on their own, and these seed files, being files, often leak
or are duplicated and distributed accidentally, or are even seeded over
the Internet intentionally, where their contents might be recorded or
tampered with. Seen this way, an otherwise quasi-implausible
vulnerability is a bit more practical than initially thought.
Another aspect of the current mix_pool_bytes() function is that, while
its performance was arguably competitive for the time in which it was
created, it's no longer considered so. This patch improves performance
significantly: on a high-end CPU, an i7-11850H, it improves performance
of mix_pool_bytes() by 225%, and on a low-end CPU, a Cortex-A7, it
improves performance by 103%.
This commit replaces the LFSR of mix_pool_bytes() with a straight-
forward cryptographic hash function, BLAKE2s, which is already in use
for pool extraction. Universal hashing with a secret seed was considered
too, something along the lines of <https://eprint.iacr.org/2013/338>,
but the requirement for a secret seed makes for a chicken & egg problem.
Instead we go with a formally proven scheme using a computational hash
function, described in sections 5.1, 6.4, and B.1.8 of
<https://eprint.iacr.org/2019/198>.
BLAKE2s outputs 256 bits, which should give us an appropriate amount of
min-entropy accumulation, and a wide enough margin of collision
resistance against active attacks. mix_pool_bytes() becomes a simple
call to blake2s_update(), for accumulation, while the extraction step
becomes a blake2s_final() to generate a seed, with which we can then do
a HKDF-like or BLAKE2X-like expansion, the first part of which we fold
back as an init key for subsequent blake2s_update()s, and the rest we
produce to the caller. This then is provided to our CRNG like usual. In
that expansion step, we make opportunistic use of 32 bytes of RDRAND
output, just as before. We also always reseed the crng with 32 bytes,
unconditionally, or not at all, rather than sometimes with 16 as before,
as we don't win anything by limiting beyond the 16 byte threshold.
Going for a hash function as an entropy collector is a conservative,
proven approach. The result of all this is a much simpler and much less
bespoke construction than what's there now, which not only plugs a
vulnerability but also improves performance considerably.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 304 +++++++++-----------------------------------------
1 file changed, 55 insertions(+), 249 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -42,61 +42,6 @@
*/
/*
- * (now, with legal B.S. out of the way.....)
- *
- * This routine gathers environmental noise from device drivers, etc.,
- * and returns good random numbers, suitable for cryptographic use.
- * Besides the obvious cryptographic uses, these numbers are also good
- * for seeding TCP sequence numbers, and other places where it is
- * desirable to have numbers which are not only random, but hard to
- * predict by an attacker.
- *
- * Theory of operation
- * ===================
- *
- * Computers are very predictable devices. Hence it is extremely hard
- * to produce truly random numbers on a computer --- as opposed to
- * pseudo-random numbers, which can easily generated by using a
- * algorithm. Unfortunately, it is very easy for attackers to guess
- * the sequence of pseudo-random number generators, and for some
- * applications this is not acceptable. So instead, we must try to
- * gather "environmental noise" from the computer's environment, which
- * must be hard for outside attackers to observe, and use that to
- * generate random numbers. In a Unix environment, this is best done
- * from inside the kernel.
- *
- * Sources of randomness from the environment include inter-keyboard
- * timings, inter-interrupt timings from some interrupts, and other
- * events which are both (a) non-deterministic and (b) hard for an
- * outside observer to measure. Randomness from these sources are
- * added to an "entropy pool", which is mixed using a CRC-like function.
- * This is not cryptographically strong, but it is adequate assuming
- * the randomness is not chosen maliciously, and it is fast enough that
- * the overhead of doing it on every interrupt is very reasonable.
- * As random bytes are mixed into the entropy pool, the routines keep
- * an *estimate* of how many bits of randomness have been stored into
- * the random number generator's internal state.
- *
- * When random bytes are desired, they are obtained by taking the BLAKE2s
- * hash of the contents of the "entropy pool". The BLAKE2s hash avoids
- * exposing the internal state of the entropy pool. It is believed to
- * be computationally infeasible to derive any useful information
- * about the input of BLAKE2s from its output. Even if it is possible to
- * analyze BLAKE2s in some clever way, as long as the amount of data
- * returned from the generator is less than the inherent entropy in
- * the pool, the output data is totally unpredictable. For this
- * reason, the routine decreases its internal estimate of how many
- * bits of "true randomness" are contained in the entropy pool as it
- * outputs random numbers.
- *
- * If this estimate goes to zero, the routine can still generate
- * random numbers; however, an attacker may (at least in theory) be
- * able to infer the future output of the generator from prior
- * outputs. This requires successful cryptanalysis of BLAKE2s, which is
- * not believed to be feasible, but there is a remote possibility.
- * Nonetheless, these numbers should be useful for the vast majority
- * of purposes.
- *
* Exported interfaces ---- output
* ===============================
*
@@ -298,23 +243,6 @@
*
* mknod /dev/random c 1 8
* mknod /dev/urandom c 1 9
- *
- * Acknowledgements:
- * =================
- *
- * Ideas for constructing this random number generator were derived
- * from Pretty Good Privacy's random number generator, and from private
- * discussions with Phil Karn. Colin Plumb provided a faster random
- * number generator, which speed up the mixing function of the entropy
- * pool, taken from PGPfone. Dale Worley has also contributed many
- * useful ideas and suggestions to improve this driver.
- *
- * Any flaws in the design are solely my responsibility, and should
- * not be attributed to the Phil, Colin, or any of authors of PGP.
- *
- * Further background information on this topic may be obtained from
- * RFC 1750, "Randomness Recommendations for Security", by Donald
- * Eastlake, Steve Crocker, and Jeff Schiller.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -358,79 +286,15 @@
/* #define ADD_INTERRUPT_BENCH */
-/*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
-static int random_write_wakeup_bits = 28 * (1 << 5);
-
-/*
- * Originally, we used a primitive polynomial of degree .poolwords
- * over GF(2). The taps for various sizes are defined below. They
- * were chosen to be evenly spaced except for the last tap, which is 1
- * to get the twisting happening as fast as possible.
- *
- * For the purposes of better mixing, we use the CRC-32 polynomial as
- * well to make a (modified) twisted Generalized Feedback Shift
- * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
- * generators. ACM Transactions on Modeling and Computer Simulation
- * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
- * GFSR generators II. ACM Transactions on Modeling and Computer
- * Simulation 4:254-266)
- *
- * Thanks to Colin Plumb for suggesting this.
- *
- * The mixing operation is much less sensitive than the output hash,
- * where we use BLAKE2s. All that we want of mixing operation is that
- * it be a good non-cryptographic hash; i.e. it not produce collisions
- * when fed "random" data of the sort we expect to see. As long as
- * the pool state differs for different inputs, we have preserved the
- * input entropy and done a good job. The fact that an intelligent
- * attacker can construct inputs that will produce controlled
- * alterations to the pool's state is not important because we don't
- * consider such inputs to contribute any randomness. The only
- * property we need with respect to them is that the attacker can't
- * increase his/her knowledge of the pool's state. Since all
- * additions are reversible (knowing the final state and the input,
- * you can reconstruct the initial state), if an attacker has any
- * uncertainty about the initial state, he/she can only shuffle that
- * uncertainty about, but never cause any collisions (which would
- * decrease the uncertainty).
- *
- * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
- * Videau in their paper, "The Linux Pseudorandom Number Generator
- * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
- * paper, they point out that we are not using a true Twisted GFSR,
- * since Matsumoto & Kurita used a trinomial feedback polynomial (that
- * is, with only three taps, instead of the six that we are using).
- * As a result, the resulting polynomial is neither primitive nor
- * irreducible, and hence does not have a maximal period over
- * GF(2**32). They suggest a slight change to the generator
- * polynomial which improves the resulting TGFSR polynomial to be
- * irreducible, which we have made here.
- */
enum poolinfo {
- POOL_WORDS = 128,
- POOL_WORDMASK = POOL_WORDS - 1,
- POOL_BYTES = POOL_WORDS * sizeof(u32),
- POOL_BITS = POOL_BYTES * 8,
+ POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_BITSHIFT = ilog2(POOL_BITS),
/* To allow fractional bits to be tracked, the entropy_count field is
* denominated in units of 1/8th bits. */
POOL_ENTROPY_SHIFT = 3,
#define POOL_ENTROPY_BITS() (input_pool.entropy_count >> POOL_ENTROPY_SHIFT)
- POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT,
-
- /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
- POOL_TAP1 = 104,
- POOL_TAP2 = 76,
- POOL_TAP3 = 51,
- POOL_TAP4 = 25,
- POOL_TAP5 = 1,
-
- EXTRACT_SIZE = BLAKE2S_HASH_SIZE / 2
+ POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT
};
/*
@@ -438,6 +302,12 @@ enum poolinfo {
*/
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
static struct fasync_struct *fasync;
+/*
+ * If the entropy count falls under this number of bits, then we
+ * should wake up processes which are selecting or polling on write
+ * access to /dev/random.
+ */
+static int random_write_wakeup_bits = POOL_BITS * 3 / 4;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);
@@ -493,73 +363,31 @@ MODULE_PARM_DESC(ratelimit_disable, "Dis
*
**********************************************************************/
-static u32 input_pool_data[POOL_WORDS] __latent_entropy;
-
static struct {
+ struct blake2s_state hash;
spinlock_t lock;
- u16 add_ptr;
- u16 input_rotate;
int entropy_count;
} input_pool = {
+ .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
+ BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
+ BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 },
+ .hash.outlen = BLAKE2S_HASH_SIZE,
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
};
-static ssize_t extract_entropy(void *buf, size_t nbytes, int min);
-static ssize_t _extract_entropy(void *buf, size_t nbytes);
+static bool extract_entropy(void *buf, size_t nbytes, int min);
+static void _extract_entropy(void *buf, size_t nbytes);
static void crng_reseed(struct crng_state *crng, bool use_input_pool);
-static const u32 twist_table[8] = {
- 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
- 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
-
/*
* This function adds bytes into the entropy "pool". It does not
* update the entropy estimate. The caller should call
* credit_entropy_bits if this is appropriate.
- *
- * The pool is stirred with a primitive polynomial of the appropriate
- * degree, and then twisted. We twist by three bits at a time because
- * it's cheap to do so and helps slightly in the expected case where
- * the entropy is concentrated in the low-order bits.
*/
static void _mix_pool_bytes(const void *in, int nbytes)
{
- unsigned long i;
- int input_rotate;
- const u8 *bytes = in;
- u32 w;
-
- input_rotate = input_pool.input_rotate;
- i = input_pool.add_ptr;
-
- /* mix one byte at a time to simplify size handling and churn faster */
- while (nbytes--) {
- w = rol32(*bytes++, input_rotate);
- i = (i - 1) & POOL_WORDMASK;
-
- /* XOR in the various taps */
- w ^= input_pool_data[i];
- w ^= input_pool_data[(i + POOL_TAP1) & POOL_WORDMASK];
- w ^= input_pool_data[(i + POOL_TAP2) & POOL_WORDMASK];
- w ^= input_pool_data[(i + POOL_TAP3) & POOL_WORDMASK];
- w ^= input_pool_data[(i + POOL_TAP4) & POOL_WORDMASK];
- w ^= input_pool_data[(i + POOL_TAP5) & POOL_WORDMASK];
-
- /* Mix the result back in with a twist */
- input_pool_data[i] = (w >> 3) ^ twist_table[w & 7];
-
- /*
- * Normally, we add 7 bits of rotation to the pool.
- * At the beginning of the pool, add an extra 7 bits
- * rotation, so that successive passes spread the
- * input bits across the pool evenly.
- */
- input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
- }
-
- input_pool.input_rotate = input_rotate;
- input_pool.add_ptr = i;
+ blake2s_update(&input_pool.hash, in, nbytes);
}
static void __mix_pool_bytes(const void *in, int nbytes)
@@ -953,15 +781,14 @@ static int crng_slow_load(const u8 *cp,
static void crng_reseed(struct crng_state *crng, bool use_input_pool)
{
unsigned long flags;
- int i, num;
+ int i;
union {
u8 block[CHACHA_BLOCK_SIZE];
u32 key[8];
} buf;
if (use_input_pool) {
- num = extract_entropy(&buf, 32, 16);
- if (num == 0)
+ if (!extract_entropy(&buf, 32, 16))
return;
} else {
_extract_crng(&primary_crng, buf.block);
@@ -1329,74 +1156,48 @@ retry:
}
/*
- * This function does the actual extraction for extract_entropy.
- *
- * Note: we assume that .poolwords is a multiple of 16 words.
+ * This is an HKDF-like construction for using the hashed collected entropy
+ * as a PRF key, that's then expanded block-by-block.
*/
-static void extract_buf(u8 *out)
+static void _extract_entropy(void *buf, size_t nbytes)
{
- struct blake2s_state state __aligned(__alignof__(unsigned long));
- u8 hash[BLAKE2S_HASH_SIZE];
- unsigned long *salt;
unsigned long flags;
-
- blake2s_init(&state, sizeof(hash));
-
- /*
- * If we have an architectural hardware random number
- * generator, use it for BLAKE2's salt & personal fields.
- */
- for (salt = (unsigned long *)&state.h[4];
- salt < (unsigned long *)&state.h[8]; ++salt) {
- unsigned long v;
- if (!arch_get_random_long(&v))
- break;
- *salt ^= v;
+ u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
+ struct {
+ unsigned long rdrand[32 / sizeof(long)];
+ size_t counter;
+ } block;
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) {
+ if (!arch_get_random_long(&block.rdrand[i]))
+ block.rdrand[i] = random_get_entropy();
}
- /* Generate a hash across the pool */
spin_lock_irqsave(&input_pool.lock, flags);
- blake2s_update(&state, (const u8 *)input_pool_data, POOL_BYTES);
- blake2s_final(&state, hash); /* final zeros out state */
- /*
- * We mix the hash back into the pool to prevent backtracking
- * attacks (where the attacker knows the state of the pool
- * plus the current outputs, and attempts to find previous
- * outputs), unless the hash function can be inverted. By
- * mixing at least a hash worth of hash data back, we make
- * brute-forcing the feedback as hard as brute-forcing the
- * hash.
- */
- __mix_pool_bytes(hash, sizeof(hash));
- spin_unlock_irqrestore(&input_pool.lock, flags);
+ /* seed = HASHPRF(last_key, entropy_input) */
+ blake2s_final(&input_pool.hash, seed);
- /* Note that EXTRACT_SIZE is half of hash size here, because above
- * we've dumped the full length back into mixer. By reducing the
- * amount that we emit, we retain a level of forward secrecy.
- */
- memcpy(out, hash, EXTRACT_SIZE);
- memzero_explicit(hash, sizeof(hash));
-}
+ /* next_key = HASHPRF(seed, RDRAND || 0) */
+ block.counter = 0;
+ blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
+ blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
-static ssize_t _extract_entropy(void *buf, size_t nbytes)
-{
- ssize_t ret = 0, i;
- u8 tmp[EXTRACT_SIZE];
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+ memzero_explicit(next_key, sizeof(next_key));
while (nbytes) {
- extract_buf(tmp);
- i = min_t(int, nbytes, EXTRACT_SIZE);
- memcpy(buf, tmp, i);
+ i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
+ /* output = HASHPRF(seed, RDRAND || ++counter) */
+ ++block.counter;
+ blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
nbytes -= i;
buf += i;
- ret += i;
}
- /* Wipe data just returned from memory */
- memzero_explicit(tmp, sizeof(tmp));
-
- return ret;
+ memzero_explicit(seed, sizeof(seed));
+ memzero_explicit(&block, sizeof(block));
}
/*
@@ -1404,13 +1205,18 @@ static ssize_t _extract_entropy(void *bu
* returns it in a buffer.
*
* The min parameter specifies the minimum amount we can pull before
- * failing to avoid races that defeat catastrophic reseeding.
+ * failing to avoid races that defeat catastrophic reseeding. If we
+ * have less than min entropy available, we return false and buf is
+ * not filled.
*/
-static ssize_t extract_entropy(void *buf, size_t nbytes, int min)
+static bool extract_entropy(void *buf, size_t nbytes, int min)
{
trace_extract_entropy(nbytes, POOL_ENTROPY_BITS(), _RET_IP_);
- nbytes = account(nbytes, min);
- return _extract_entropy(buf, nbytes);
+ if (account(nbytes, min)) {
+ _extract_entropy(buf, nbytes);
+ return true;
+ }
+ return false;
}
#define warn_unseeded_randomness(previous) \
@@ -1674,7 +1480,7 @@ static void __init init_std_data(void)
unsigned long rv;
mix_pool_bytes(&now, sizeof(now));
- for (i = POOL_BYTES; i > 0; i -= sizeof(rv)) {
+ for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_seed_long(&rv) &&
!arch_get_random_long(&rv))
rv = random_get_entropy();
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 004/111] random: simplify entropy debiting
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (2 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 003/111] random: use computational hash for entropy extraction Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 005/111] random: use linear min-entropy accumulation crediting Greg Kroah-Hartman
` (112 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 9c07f57869e90140080cfc282cc628d123e27704 upstream.
Our pool is 256 bits, and we only ever use all of it or don't use it at
all, which is decided by whether or not it has at least 128 bits in it.
So we can drastically simplify the accounting and cmpxchg loop to do
exactly this. While we're at it, we move the minimum bit size into a
constant so it can be shared between the two places where it matters.
The reason we want any of this is for the case in which an attacker has
compromised the current state, and then bruteforces small amounts of
entropy added to it. By demanding a particular minimum amount of entropy
be present before reseeding, we make that bruteforcing difficult.
Note that this rationale no longer includes anything about /dev/random
blocking at the right moment, since /dev/random no longer blocks (except
for at ~boot), but rather uses the crng. In a former life, /dev/random
was different and therefore required a more nuanced account(), but this
is no longer.
Behaviorally, nothing changes here. This is just a simplification of
the code.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 91 +++++++++---------------------------------
include/trace/events/random.h | 30 ++-----------
2 files changed, 27 insertions(+), 94 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -289,12 +289,14 @@
enum poolinfo {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_BITSHIFT = ilog2(POOL_BITS),
+ POOL_MIN_BITS = POOL_BITS / 2,
/* To allow fractional bits to be tracked, the entropy_count field is
* denominated in units of 1/8th bits. */
POOL_ENTROPY_SHIFT = 3,
#define POOL_ENTROPY_BITS() (input_pool.entropy_count >> POOL_ENTROPY_SHIFT)
- POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT
+ POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT,
+ POOL_MIN_FRACBITS = POOL_MIN_BITS << POOL_ENTROPY_SHIFT
};
/*
@@ -375,8 +377,7 @@ static struct {
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
};
-static bool extract_entropy(void *buf, size_t nbytes, int min);
-static void _extract_entropy(void *buf, size_t nbytes);
+static void extract_entropy(void *buf, size_t nbytes);
static void crng_reseed(struct crng_state *crng, bool use_input_pool);
@@ -467,7 +468,7 @@ static void process_random_ready_list(vo
*/
static void credit_entropy_bits(int nbits)
{
- int entropy_count, entropy_bits, orig;
+ int entropy_count, orig;
int nfrac = nbits << POOL_ENTROPY_SHIFT;
/* Ensure that the multiplication can avoid being 64 bits wide. */
@@ -527,8 +528,7 @@ retry:
trace_credit_entropy_bits(nbits, entropy_count >> POOL_ENTROPY_SHIFT, _RET_IP_);
- entropy_bits = entropy_count >> POOL_ENTROPY_SHIFT;
- if (crng_init < 2 && entropy_bits >= 128)
+ if (crng_init < 2 && entropy_count >= POOL_MIN_FRACBITS)
crng_reseed(&primary_crng, true);
}
@@ -618,7 +618,7 @@ static void crng_initialize_secondary(st
static void __init crng_initialize_primary(void)
{
- _extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
+ extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
if (crng_init_try_arch_early() && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();
numa_crng_init();
@@ -788,8 +788,17 @@ static void crng_reseed(struct crng_stat
} buf;
if (use_input_pool) {
- if (!extract_entropy(&buf, 32, 16))
- return;
+ int entropy_count;
+ do {
+ entropy_count = READ_ONCE(input_pool.entropy_count);
+ if (entropy_count < POOL_MIN_FRACBITS)
+ return;
+ } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
+ extract_entropy(buf.key, sizeof(buf.key));
+ if (random_write_wakeup_bits) {
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ }
} else {
_extract_crng(&primary_crng, buf.block);
_crng_backtrack_protect(&primary_crng, buf.block,
@@ -1115,51 +1124,10 @@ EXPORT_SYMBOL_GPL(add_disk_randomness);
*********************************************************************/
/*
- * This function decides how many bytes to actually take from the
- * given pool, and also debits the entropy count accordingly.
- */
-static size_t account(size_t nbytes, int min)
-{
- int entropy_count, orig;
- size_t ibytes, nfrac;
-
- BUG_ON(input_pool.entropy_count > POOL_FRACBITS);
-
- /* Can we pull enough? */
-retry:
- entropy_count = orig = READ_ONCE(input_pool.entropy_count);
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy count: count %d\n", entropy_count);
- entropy_count = 0;
- }
-
- /* never pull more than available */
- ibytes = min_t(size_t, nbytes, entropy_count >> (POOL_ENTROPY_SHIFT + 3));
- if (ibytes < min)
- ibytes = 0;
- nfrac = ibytes << (POOL_ENTROPY_SHIFT + 3);
- if ((size_t)entropy_count > nfrac)
- entropy_count -= nfrac;
- else
- entropy_count = 0;
-
- if (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig)
- goto retry;
-
- trace_debit_entropy(8 * ibytes);
- if (ibytes && POOL_ENTROPY_BITS() < random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
-
- return ibytes;
-}
-
-/*
* This is an HKDF-like construction for using the hashed collected entropy
* as a PRF key, that's then expanded block-by-block.
*/
-static void _extract_entropy(void *buf, size_t nbytes)
+static void extract_entropy(void *buf, size_t nbytes)
{
unsigned long flags;
u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
@@ -1169,6 +1137,8 @@ static void _extract_entropy(void *buf,
} block;
size_t i;
+ trace_extract_entropy(nbytes, POOL_ENTROPY_BITS());
+
for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) {
if (!arch_get_random_long(&block.rdrand[i]))
block.rdrand[i] = random_get_entropy();
@@ -1200,25 +1170,6 @@ static void _extract_entropy(void *buf,
memzero_explicit(&block, sizeof(block));
}
-/*
- * This function extracts randomness from the "entropy pool", and
- * returns it in a buffer.
- *
- * The min parameter specifies the minimum amount we can pull before
- * failing to avoid races that defeat catastrophic reseeding. If we
- * have less than min entropy available, we return false and buf is
- * not filled.
- */
-static bool extract_entropy(void *buf, size_t nbytes, int min)
-{
- trace_extract_entropy(nbytes, POOL_ENTROPY_BITS(), _RET_IP_);
- if (account(nbytes, min)) {
- _extract_entropy(buf, nbytes);
- return true;
- }
- return false;
-}
-
#define warn_unseeded_randomness(previous) \
_warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -79,22 +79,6 @@ TRACE_EVENT(credit_entropy_bits,
__entry->bits, __entry->entropy_count, (void *)__entry->IP)
);
-TRACE_EVENT(debit_entropy,
- TP_PROTO(int debit_bits),
-
- TP_ARGS( debit_bits),
-
- TP_STRUCT__entry(
- __field( int, debit_bits )
- ),
-
- TP_fast_assign(
- __entry->debit_bits = debit_bits;
- ),
-
- TP_printk("input pool: debit_bits %d", __entry->debit_bits)
-);
-
TRACE_EVENT(add_input_randomness,
TP_PROTO(int input_bits),
@@ -161,31 +145,29 @@ DEFINE_EVENT(random__get_random_bytes, g
);
DECLARE_EVENT_CLASS(random__extract_entropy,
- TP_PROTO(int nbytes, int entropy_count, unsigned long IP),
+ TP_PROTO(int nbytes, int entropy_count),
- TP_ARGS(nbytes, entropy_count, IP),
+ TP_ARGS(nbytes, entropy_count),
TP_STRUCT__entry(
__field( int, nbytes )
__field( int, entropy_count )
- __field(unsigned long, IP )
),
TP_fast_assign(
__entry->nbytes = nbytes;
__entry->entropy_count = entropy_count;
- __entry->IP = IP;
),
- TP_printk("input pool: nbytes %d entropy_count %d caller %pS",
- __entry->nbytes, __entry->entropy_count, (void *)__entry->IP)
+ TP_printk("input pool: nbytes %d entropy_count %d",
+ __entry->nbytes, __entry->entropy_count)
);
DEFINE_EVENT(random__extract_entropy, extract_entropy,
- TP_PROTO(int nbytes, int entropy_count, unsigned long IP),
+ TP_PROTO(int nbytes, int entropy_count),
- TP_ARGS(nbytes, entropy_count, IP)
+ TP_ARGS(nbytes, entropy_count)
);
TRACE_EVENT(urandom_read,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 005/111] random: use linear min-entropy accumulation crediting
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (3 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 004/111] random: simplify entropy debiting Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 006/111] random: always wake up entropy writers after extraction Greg Kroah-Hartman
` (111 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jean-Philippe Aumasson, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit c570449094844527577c5c914140222cb1893e3f upstream.
30e37ec516ae ("random: account for entropy loss due to overwrites")
assumed that adding new entropy to the LFSR pool probabilistically
cancelled out old entropy there, so entropy was credited asymptotically,
approximating Shannon entropy of independent sources (rather than a
stronger min-entropy notion) using 1/8th fractional bits and replacing
a constant 2-2/√𝑒 term (~0.786938) with 3/4 (0.75) to slightly
underestimate it. This wasn't superb, but it was perhaps better than
nothing, so that's what was done. Which entropy specifically was being
cancelled out and how much precisely each time is hard to tell, though
as I showed with the attack code in my previous commit, a motivated
adversary with sufficient information can actually cancel out
everything.
Since we're no longer using an LFSR for entropy accumulation, this
probabilistic cancellation is no longer relevant. Rather, we're now
using a computational hash function as the accumulator and we've
switched to working in the random oracle model, from which we can now
revisit the question of min-entropy accumulation, which is done in
detail in <https://eprint.iacr.org/2019/198>.
Consider a long input bit string that is built by concatenating various
smaller independent input bit strings. Each one of these inputs has a
designated min-entropy, which is what we're passing to
credit_entropy_bits(h). When we pass the concatenation of these to a
random oracle, it means that an adversary trying to receive back the
same reply as us would need to become certain about each part of the
concatenated bit string we passed in, which means becoming certain about
all of those h values. That means we can estimate the accumulation by
simply adding up the h values in calls to credit_entropy_bits(h);
there's no probabilistic cancellation at play like there was said to be
for the LFSR. Incidentally, this is also what other entropy accumulators
based on computational hash functions do as well.
So this commit replaces credit_entropy_bits(h) with essentially `total =
min(POOL_BITS, total + h)`, done with a cmpxchg loop as before.
What if we're wrong and the above is nonsense? It's not, but let's
assume we don't want the actual _behavior_ of the code to change much.
Currently that behavior is not extracting from the input pool until it
has 128 bits of entropy in it. With the old algorithm, we'd hit that
magic 128 number after roughly 256 calls to credit_entropy_bits(1). So,
we can retain more or less the old behavior by waiting to extract from
the input pool until it hits 256 bits of entropy using the new code. For
people concerned about this change, it means that there's not that much
practical behavioral change. And for folks actually trying to model
the behavior rigorously, it means that we have an even higher margin
against attacks.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 114 ++++++++------------------------------------------
1 file changed, 20 insertions(+), 94 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -286,17 +286,9 @@
/* #define ADD_INTERRUPT_BENCH */
-enum poolinfo {
+enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_BITSHIFT = ilog2(POOL_BITS),
- POOL_MIN_BITS = POOL_BITS / 2,
-
- /* To allow fractional bits to be tracked, the entropy_count field is
- * denominated in units of 1/8th bits. */
- POOL_ENTROPY_SHIFT = 3,
-#define POOL_ENTROPY_BITS() (input_pool.entropy_count >> POOL_ENTROPY_SHIFT)
- POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT,
- POOL_MIN_FRACBITS = POOL_MIN_BITS << POOL_ENTROPY_SHIFT
+ POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
};
/*
@@ -309,7 +301,7 @@ static struct fasync_struct *fasync;
* should wake up processes which are selecting or polling on write
* access to /dev/random.
*/
-static int random_write_wakeup_bits = POOL_BITS * 3 / 4;
+static int random_write_wakeup_bits = POOL_MIN_BITS;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);
@@ -469,66 +461,18 @@ static void process_random_ready_list(vo
static void credit_entropy_bits(int nbits)
{
int entropy_count, orig;
- int nfrac = nbits << POOL_ENTROPY_SHIFT;
-
- /* Ensure that the multiplication can avoid being 64 bits wide. */
- BUILD_BUG_ON(2 * (POOL_ENTROPY_SHIFT + POOL_BITSHIFT) > 31);
if (!nbits)
return;
-retry:
- entropy_count = orig = READ_ONCE(input_pool.entropy_count);
- if (nfrac < 0) {
- /* Debit */
- entropy_count += nfrac;
- } else {
- /*
- * Credit: we have to account for the possibility of
- * overwriting already present entropy. Even in the
- * ideal case of pure Shannon entropy, new contributions
- * approach the full value asymptotically:
- *
- * entropy <- entropy + (pool_size - entropy) *
- * (1 - exp(-add_entropy/pool_size))
- *
- * For add_entropy <= pool_size/2 then
- * (1 - exp(-add_entropy/pool_size)) >=
- * (add_entropy/pool_size)*0.7869...
- * so we can approximate the exponential with
- * 3/4*add_entropy/pool_size and still be on the
- * safe side by adding at most pool_size/2 at a time.
- *
- * The use of pool_size-2 in the while statement is to
- * prevent rounding artifacts from making the loop
- * arbitrarily long; this limits the loop to log2(pool_size)*2
- * turns no matter how large nbits is.
- */
- int pnfrac = nfrac;
- const int s = POOL_BITSHIFT + POOL_ENTROPY_SHIFT + 2;
- /* The +2 corresponds to the /4 in the denominator */
-
- do {
- unsigned int anfrac = min(pnfrac, POOL_FRACBITS / 2);
- unsigned int add =
- ((POOL_FRACBITS - entropy_count) * anfrac * 3) >> s;
-
- entropy_count += add;
- pnfrac -= anfrac;
- } while (unlikely(entropy_count < POOL_FRACBITS - 2 && pnfrac));
- }
-
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy/overflow: count %d\n", entropy_count);
- entropy_count = 0;
- } else if (entropy_count > POOL_FRACBITS)
- entropy_count = POOL_FRACBITS;
- if (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig)
- goto retry;
+ do {
+ orig = READ_ONCE(input_pool.entropy_count);
+ entropy_count = min(POOL_BITS, orig + nbits);
+ } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
- trace_credit_entropy_bits(nbits, entropy_count >> POOL_ENTROPY_SHIFT, _RET_IP_);
+ trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_);
- if (crng_init < 2 && entropy_count >= POOL_MIN_FRACBITS)
+ if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
crng_reseed(&primary_crng, true);
}
@@ -791,7 +735,7 @@ static void crng_reseed(struct crng_stat
int entropy_count;
do {
entropy_count = READ_ONCE(input_pool.entropy_count);
- if (entropy_count < POOL_MIN_FRACBITS)
+ if (entropy_count < POOL_MIN_BITS)
return;
} while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
extract_entropy(buf.key, sizeof(buf.key));
@@ -1014,7 +958,7 @@ void add_input_randomness(unsigned int t
last_value = value;
add_timer_randomness(&input_timer_state,
(type << 4) ^ code ^ (code >> 4) ^ value);
- trace_add_input_randomness(POOL_ENTROPY_BITS());
+ trace_add_input_randomness(input_pool.entropy_count);
}
EXPORT_SYMBOL_GPL(add_input_randomness);
@@ -1112,7 +1056,7 @@ void add_disk_randomness(struct gendisk
return;
/* first major is 1, so we get >= 0x200 here */
add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
- trace_add_disk_randomness(disk_devt(disk), POOL_ENTROPY_BITS());
+ trace_add_disk_randomness(disk_devt(disk), input_pool.entropy_count);
}
EXPORT_SYMBOL_GPL(add_disk_randomness);
#endif
@@ -1137,7 +1081,7 @@ static void extract_entropy(void *buf, s
} block;
size_t i;
- trace_extract_entropy(nbytes, POOL_ENTROPY_BITS());
+ trace_extract_entropy(nbytes, input_pool.entropy_count);
for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) {
if (!arch_get_random_long(&block.rdrand[i]))
@@ -1486,9 +1430,9 @@ static ssize_t urandom_read_nowarn(struc
{
int ret;
- nbytes = min_t(size_t, nbytes, INT_MAX >> (POOL_ENTROPY_SHIFT + 3));
+ nbytes = min_t(size_t, nbytes, INT_MAX >> 6);
ret = extract_crng_user(buf, nbytes);
- trace_urandom_read(8 * nbytes, 0, POOL_ENTROPY_BITS());
+ trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count);
return ret;
}
@@ -1527,7 +1471,7 @@ static __poll_t random_poll(struct file
mask = 0;
if (crng_ready())
mask |= EPOLLIN | EPOLLRDNORM;
- if (POOL_ENTROPY_BITS() < random_write_wakeup_bits)
+ if (input_pool.entropy_count < random_write_wakeup_bits)
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;
}
@@ -1582,8 +1526,7 @@ static long random_ioctl(struct file *f,
switch (cmd) {
case RNDGETENTCNT:
/* inherently racy, no point locking */
- ent_count = POOL_ENTROPY_BITS();
- if (put_user(ent_count, p))
+ if (put_user(input_pool.entropy_count, p))
return -EFAULT;
return 0;
case RNDADDTOENTCNT:
@@ -1734,23 +1677,6 @@ static int proc_do_uuid(struct ctl_table
return proc_dostring(&fake_table, write, buffer, lenp, ppos);
}
-/*
- * Return entropy available scaled to integral bits
- */
-static int proc_do_entropy(struct ctl_table *table, int write, void *buffer,
- size_t *lenp, loff_t *ppos)
-{
- struct ctl_table fake_table;
- int entropy_count;
-
- entropy_count = *(int *)table->data >> POOL_ENTROPY_SHIFT;
-
- fake_table.data = &entropy_count;
- fake_table.maxlen = sizeof(entropy_count);
-
- return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
-}
-
static int sysctl_poolsize = POOL_BITS;
static struct ctl_table random_table[] = {
{
@@ -1762,10 +1688,10 @@ static struct ctl_table random_table[] =
},
{
.procname = "entropy_avail",
+ .data = &input_pool.entropy_count,
.maxlen = sizeof(int),
.mode = 0444,
- .proc_handler = proc_do_entropy,
- .data = &input_pool.entropy_count,
+ .proc_handler = proc_dointvec,
},
{
.procname = "write_wakeup_threshold",
@@ -1972,7 +1898,7 @@ void add_hwgenerator_randomness(const ch
*/
wait_event_interruptible_timeout(random_write_wait,
!system_wq || kthread_should_stop() ||
- POOL_ENTROPY_BITS() <= random_write_wakeup_bits,
+ input_pool.entropy_count <= random_write_wakeup_bits,
CRNG_RESEED_INTERVAL);
mix_pool_bytes(buffer, count);
credit_entropy_bits(entropy);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 006/111] random: always wake up entropy writers after extraction
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (4 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 005/111] random: use linear min-entropy accumulation crediting Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 007/111] random: make credit_entropy_bits() always safe Greg Kroah-Hartman
` (110 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Eric Biggers, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 489c7fc44b5740d377e8cfdbf0851036e493af00 upstream.
Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up
entropy writers after every extraction. Therefore there's no point of
write_wakeup_threshold, so we can move it to the dustbin of unused
compatibility sysctls. While we're at it, we can fix a small comparison
where we were waking up after <= min rather than < min.
Cc: Theodore Ts'o <tytso@mit.edu>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/admin-guide/sysctl/kernel.rst | 7 ++++-
drivers/char/random.c | 33 +++++++++-------------------
2 files changed, 16 insertions(+), 24 deletions(-)
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1030,14 +1030,17 @@ This is a directory, with the following
* ``poolsize``: the entropy pool size, in bits;
* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum
- number of seconds between urandom pool reseeding).
+ number of seconds between urandom pool reseeding). This file is
+ writable for compatibility purposes, but writing to it has no effect
+ on any RNG behavior.
* ``uuid``: a UUID generated every time this is retrieved (this can
thus be used to generate UUIDs at will);
* ``write_wakeup_threshold``: when the entropy count drops below this
(as a number of bits), processes waiting to write to ``/dev/random``
- are woken up.
+ are woken up. This file is writable for compatibility purposes, but
+ writing to it has no effect on any RNG behavior.
If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH``
defined, these additional entries are present:
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -296,12 +296,6 @@ enum {
*/
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
static struct fasync_struct *fasync;
-/*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
-static int random_write_wakeup_bits = POOL_MIN_BITS;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);
@@ -739,10 +733,8 @@ static void crng_reseed(struct crng_stat
return;
} while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
extract_entropy(buf.key, sizeof(buf.key));
- if (random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
} else {
_extract_crng(&primary_crng, buf.block);
_crng_backtrack_protect(&primary_crng, buf.block,
@@ -1471,7 +1463,7 @@ static __poll_t random_poll(struct file
mask = 0;
if (crng_ready())
mask |= EPOLLIN | EPOLLRDNORM;
- if (input_pool.entropy_count < random_write_wakeup_bits)
+ if (input_pool.entropy_count < POOL_MIN_BITS)
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;
}
@@ -1556,7 +1548,7 @@ static long random_ioctl(struct file *f,
*/
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) {
+ if (xchg(&input_pool.entropy_count, 0)) {
wake_up_interruptible(&random_write_wait);
kill_fasync(&fasync, SIGIO, POLL_OUT);
}
@@ -1636,9 +1628,9 @@ SYSCALL_DEFINE3(getrandom, char __user *
#include <linux/sysctl.h>
-static int min_write_thresh;
-static int max_write_thresh = POOL_BITS;
static int random_min_urandom_seed = 60;
+static int random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_poolsize = POOL_BITS;
static char sysctl_bootid[16];
/*
@@ -1677,7 +1669,6 @@ static int proc_do_uuid(struct ctl_table
return proc_dostring(&fake_table, write, buffer, lenp, ppos);
}
-static int sysctl_poolsize = POOL_BITS;
static struct ctl_table random_table[] = {
{
.procname = "poolsize",
@@ -1698,9 +1689,7 @@ static struct ctl_table random_table[] =
.data = &random_write_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &min_write_thresh,
- .extra2 = &max_write_thresh,
+ .proc_handler = proc_dointvec,
},
{
.procname = "urandom_min_reseed_secs",
@@ -1892,13 +1881,13 @@ void add_hwgenerator_randomness(const ch
}
/* Throttle writing if we're above the trickle threshold.
- * We'll be woken up again once below random_write_wakeup_thresh,
- * when the calling thread is about to terminate, or once
- * CRNG_RESEED_INTERVAL has lapsed.
+ * We'll be woken up again once below POOL_MIN_BITS, when
+ * the calling thread is about to terminate, or once
+ * CRNG_RESEED_INTERVAL has elapsed.
*/
wait_event_interruptible_timeout(random_write_wait,
!system_wq || kthread_should_stop() ||
- input_pool.entropy_count <= random_write_wakeup_bits,
+ input_pool.entropy_count < POOL_MIN_BITS,
CRNG_RESEED_INTERVAL);
mix_pool_bytes(buffer, count);
credit_entropy_bits(entropy);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 007/111] random: make credit_entropy_bits() always safe
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (5 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 006/111] random: always wake up entropy writers after extraction Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 008/111] random: remove use_input_pool parameter from crng_reseed() Greg Kroah-Hartman
` (109 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Sultan Alsawaf, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a49c010e61e1938be851f5e49ac219d49b704103 upstream.
This is called from various hwgenerator drivers, so rather than having
one "safe" version for userspace and one "unsafe" version for the
kernel, just make everything safe; the checks are cheap and sensible to
have anyway.
Reported-by: Sultan Alsawaf <sultan@kerneltoast.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 29 +++++++++--------------------
1 file changed, 9 insertions(+), 20 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -447,18 +447,15 @@ static void process_random_ready_list(vo
spin_unlock_irqrestore(&random_ready_list_lock, flags);
}
-/*
- * Credit (or debit) the entropy store with n bits of entropy.
- * Use credit_entropy_bits_safe() if the value comes from userspace
- * or otherwise should be checked for extreme values.
- */
static void credit_entropy_bits(int nbits)
{
int entropy_count, orig;
- if (!nbits)
+ if (nbits <= 0)
return;
+ nbits = min(nbits, POOL_BITS);
+
do {
orig = READ_ONCE(input_pool.entropy_count);
entropy_count = min(POOL_BITS, orig + nbits);
@@ -470,18 +467,6 @@ static void credit_entropy_bits(int nbit
crng_reseed(&primary_crng, true);
}
-static int credit_entropy_bits_safe(int nbits)
-{
- if (nbits < 0)
- return -EINVAL;
-
- /* Cap the value to avoid overflows */
- nbits = min(nbits, POOL_BITS);
-
- credit_entropy_bits(nbits);
- return 0;
-}
-
/*********************************************************************
*
* CRNG using CHACHA20
@@ -1526,7 +1511,10 @@ static long random_ioctl(struct file *f,
return -EPERM;
if (get_user(ent_count, p))
return -EFAULT;
- return credit_entropy_bits_safe(ent_count);
+ if (ent_count < 0)
+ return -EINVAL;
+ credit_entropy_bits(ent_count);
+ return 0;
case RNDADDENTROPY:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -1539,7 +1527,8 @@ static long random_ioctl(struct file *f,
retval = write_pool((const char __user *)p, size);
if (retval < 0)
return retval;
- return credit_entropy_bits_safe(ent_count);
+ credit_entropy_bits(ent_count);
+ return 0;
case RNDZAPENTCNT:
case RNDCLEARPOOL:
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 008/111] random: remove use_input_pool parameter from crng_reseed()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (6 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 007/111] random: make credit_entropy_bits() always safe Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 009/111] random: remove batched entropy locking Greg Kroah-Hartman
` (108 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Eric Biggers, Jason A. Donenfeld
From: Eric Biggers <ebiggers@google.com>
commit 5d58ea3a31cc98b9fa563f6921d3d043bf0103d1 upstream.
The primary_crng is always reseeded from the input_pool, while the NUMA
crngs are always reseeded from the primary_crng. Remove the redundant
'use_input_pool' parameter from crng_reseed() and just directly check
whether the crng is the primary_crng.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -365,7 +365,7 @@ static struct {
static void extract_entropy(void *buf, size_t nbytes);
-static void crng_reseed(struct crng_state *crng, bool use_input_pool);
+static void crng_reseed(struct crng_state *crng);
/*
* This function adds bytes into the entropy "pool". It does not
@@ -464,7 +464,7 @@ static void credit_entropy_bits(int nbit
trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_);
if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
- crng_reseed(&primary_crng, true);
+ crng_reseed(&primary_crng);
}
/*********************************************************************
@@ -701,7 +701,7 @@ static int crng_slow_load(const u8 *cp,
return 1;
}
-static void crng_reseed(struct crng_state *crng, bool use_input_pool)
+static void crng_reseed(struct crng_state *crng)
{
unsigned long flags;
int i;
@@ -710,7 +710,7 @@ static void crng_reseed(struct crng_stat
u32 key[8];
} buf;
- if (use_input_pool) {
+ if (crng == &primary_crng) {
int entropy_count;
do {
entropy_count = READ_ONCE(input_pool.entropy_count);
@@ -748,7 +748,7 @@ static void _extract_crng(struct crng_st
init_time = READ_ONCE(crng->init_time);
if (time_after(READ_ONCE(crng_global_init_time), init_time) ||
time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
- crng_reseed(crng, crng == &primary_crng);
+ crng_reseed(crng);
}
spin_lock_irqsave(&crng->lock, flags);
chacha20_block(&crng->state[0], out);
@@ -1547,7 +1547,7 @@ static long random_ioctl(struct file *f,
return -EPERM;
if (crng_init < 2)
return -ENODATA;
- crng_reseed(&primary_crng, true);
+ crng_reseed(&primary_crng);
WRITE_ONCE(crng_global_init_time, jiffies - 1);
return 0;
default:
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 009/111] random: remove batched entropy locking
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (7 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 008/111] random: remove use_input_pool parameter from crng_reseed() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 010/111] random: fix locking in crng_fast_load() Greg Kroah-Hartman
` (107 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Sebastian Andrzej Siewior,
Dominik Brodowski, Eric Biggers, Andy Lutomirski,
Jonathan Neuschäfer, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 77760fd7f7ae3dfd03668204e708d1568d75447d upstream.
Rather than use spinlocks to protect batched entropy, we can instead
disable interrupts locally, since we're dealing with per-cpu data, and
manage resets with a basic generation counter. At the same time, we
can't quite do this on PREEMPT_RT, where we still want spinlocks-as-
mutexes semantics. So we use a local_lock_t, which provides the right
behavior for each. Because this is a per-cpu lock, that generation
counter is still doing the necessary CPU-to-CPU communication.
This should improve performance a bit. It will also fix the linked splat
that Jonathan received with a PROVE_RAW_LOCK_NESTING=y.
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Reported-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Tested-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/lkml/YfMa0QgsjCVdRAvJ@latitude/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 55 +++++++++++++++++++++++++-------------------------
1 file changed, 28 insertions(+), 27 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1731,13 +1731,16 @@ static int __init random_sysctls_init(vo
device_initcall(random_sysctls_init);
#endif /* CONFIG_SYSCTL */
+static atomic_t batch_generation = ATOMIC_INIT(0);
+
struct batched_entropy {
union {
u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
};
+ local_lock_t lock;
unsigned int position;
- spinlock_t batch_lock;
+ int generation;
};
/*
@@ -1749,7 +1752,7 @@ struct batched_entropy {
* point prior.
*/
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock),
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock)
};
u64 get_random_u64(void)
@@ -1758,67 +1761,65 @@ u64 get_random_u64(void)
unsigned long flags;
struct batched_entropy *batch;
static void *previous;
+ int next_gen;
warn_unseeded_randomness(&previous);
+ local_lock_irqsave(&batched_entropy_u64.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u64);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
+
+ next_gen = atomic_read(&batch_generation);
+ if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0 ||
+ next_gen != batch->generation) {
extract_crng((u8 *)batch->entropy_u64);
batch->position = 0;
+ batch->generation = next_gen;
}
+
ret = batch->entropy_u64[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
+ local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
return ret;
}
EXPORT_SYMBOL(get_random_u64);
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock),
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock)
};
+
u32 get_random_u32(void)
{
u32 ret;
unsigned long flags;
struct batched_entropy *batch;
static void *previous;
+ int next_gen;
warn_unseeded_randomness(&previous);
+ local_lock_irqsave(&batched_entropy_u32.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u32);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
+
+ next_gen = atomic_read(&batch_generation);
+ if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0 ||
+ next_gen != batch->generation) {
extract_crng((u8 *)batch->entropy_u32);
batch->position = 0;
+ batch->generation = next_gen;
}
+
ret = batch->entropy_u32[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
+ local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
return ret;
}
EXPORT_SYMBOL(get_random_u32);
/* It's important to invalidate all potential batched entropy that might
* be stored before the crng is initialized, which we can do lazily by
- * simply resetting the counter to zero so that it's re-extracted on the
- * next usage. */
+ * bumping the generation counter.
+ */
static void invalidate_batched_entropy(void)
{
- int cpu;
- unsigned long flags;
-
- for_each_possible_cpu(cpu) {
- struct batched_entropy *batched_entropy;
-
- batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu);
- spin_lock_irqsave(&batched_entropy->batch_lock, flags);
- batched_entropy->position = 0;
- spin_unlock(&batched_entropy->batch_lock);
-
- batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu);
- spin_lock(&batched_entropy->batch_lock);
- batched_entropy->position = 0;
- spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
- }
+ atomic_inc(&batch_generation);
}
/**
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 010/111] random: fix locking in crng_fast_load()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (8 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 009/111] random: remove batched entropy locking Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 011/111] random: use RDSEED instead of RDRAND in entropy extraction Greg Kroah-Hartman
` (106 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Eric Biggers,
Jason A. Donenfeld
From: Dominik Brodowski <linux@dominikbrodowski.net>
commit 7c2fe2b32bf76441ff5b7a425b384e5f75aa530a upstream.
crng_init is protected by primary_crng->lock, so keep holding that lock
when incrementing crng_init from 0 to 1 in crng_fast_load(). The call to
pr_notice() can wait until the lock is released; this code path cannot
be reached twice, as crng_fast_load() aborts early if crng_init > 0.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -647,12 +647,13 @@ static size_t crng_fast_load(const u8 *c
p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
cp++; crng_init_cnt++; len--; ret++;
}
- spin_unlock_irqrestore(&primary_crng.lock, flags);
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
invalidate_batched_entropy();
crng_init = 1;
- pr_notice("fast init done\n");
}
+ spin_unlock_irqrestore(&primary_crng.lock, flags);
+ if (crng_init == 1)
+ pr_notice("fast init done\n");
return ret;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 011/111] random: use RDSEED instead of RDRAND in entropy extraction
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (9 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 010/111] random: fix locking in crng_fast_load() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 012/111] random: get rid of secondary crngs Greg Kroah-Hartman
` (105 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 28f425e573e906a4c15f8392cc2b1561ef448595 upstream.
When /dev/random was directly connected with entropy extraction, without
any expansion stage, extract_buf() was called for every 10 bytes of data
read from /dev/random. For that reason, RDRAND was used rather than
RDSEED. At the same time, crng_reseed() was still only called every 5
minutes, so there RDSEED made sense.
Those olden days were also a time when the entropy collector did not use
a cryptographic hash function, which meant most bets were off in terms
of real preimage resistance. For that reason too it didn't matter
_that_ much whether RDSEED was mixed in before or after entropy
extraction; both choices were sort of bad.
But now we have a cryptographic hash function at work, and with that we
get real preimage resistance. We also now only call extract_entropy()
every 5 minutes, rather than every 10 bytes. This allows us to do two
important things.
First, we can switch to using RDSEED in extract_entropy(), as Dominik
suggested. Second, we can ensure that RDSEED input always goes into the
cryptographic hash function with other things before being used
directly. This eliminates a category of attacks in which the CPU knows
the current state of the crng and knows that we're going to xor RDSEED
into it, and so it computes a malicious RDSEED. By going through our
hash function, it would require the CPU to compute a preimage on the
fly, which isn't going to happen.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Suggested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -727,13 +727,8 @@ static void crng_reseed(struct crng_stat
CHACHA_KEY_SIZE);
}
spin_lock_irqsave(&crng->lock, flags);
- for (i = 0; i < 8; i++) {
- unsigned long rv;
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- crng->state[i + 4] ^= buf.key[i] ^ rv;
- }
+ for (i = 0; i < 8; i++)
+ crng->state[i + 4] ^= buf.key[i];
memzero_explicit(&buf, sizeof(buf));
WRITE_ONCE(crng->init_time, jiffies);
spin_unlock_irqrestore(&crng->lock, flags);
@@ -1054,16 +1049,17 @@ static void extract_entropy(void *buf, s
unsigned long flags;
u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
struct {
- unsigned long rdrand[32 / sizeof(long)];
+ unsigned long rdseed[32 / sizeof(long)];
size_t counter;
} block;
size_t i;
trace_extract_entropy(nbytes, input_pool.entropy_count);
- for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) {
- if (!arch_get_random_long(&block.rdrand[i]))
- block.rdrand[i] = random_get_entropy();
+ for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
+ if (!arch_get_random_seed_long(&block.rdseed[i]) &&
+ !arch_get_random_long(&block.rdseed[i]))
+ block.rdseed[i] = random_get_entropy();
}
spin_lock_irqsave(&input_pool.lock, flags);
@@ -1071,7 +1067,7 @@ static void extract_entropy(void *buf, s
/* seed = HASHPRF(last_key, entropy_input) */
blake2s_final(&input_pool.hash, seed);
- /* next_key = HASHPRF(seed, RDRAND || 0) */
+ /* next_key = HASHPRF(seed, RDSEED || 0) */
block.counter = 0;
blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
@@ -1081,7 +1077,7 @@ static void extract_entropy(void *buf, s
while (nbytes) {
i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
- /* output = HASHPRF(seed, RDRAND || ++counter) */
+ /* output = HASHPRF(seed, RDSEED || ++counter) */
++block.counter;
blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
nbytes -= i;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 012/111] random: get rid of secondary crngs
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (10 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 011/111] random: use RDSEED instead of RDRAND in entropy extraction Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 013/111] random: inline leaves of rand_initialize() Greg Kroah-Hartman
` (104 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a9412d510ab9a9ba411fea612903631d2e1f1601 upstream.
As the comment said, this is indeed a "hack". Since it was introduced,
it's been a constant state machine nightmare, with lots of subtle early
boot issues and a wildly complex set of machinery to keep everything in
sync. Rather than continuing to play whack-a-mole with this approach,
this commit simply removes it entirely. This commit is preparation for
"random: use simpler fast key erasure flow on per-cpu keys" in this
series, which introduces a simpler (and faster) mechanism to accomplish
the same thing.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 227 +++++++++++---------------------------------------
1 file changed, 54 insertions(+), 173 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -323,14 +323,11 @@ static struct crng_state primary_crng =
* its value (from 0->1->2).
*/
static int crng_init = 0;
-static bool crng_need_final_init = false;
#define crng_ready() (likely(crng_init > 1))
static int crng_init_cnt = 0;
-static unsigned long crng_global_init_time = 0;
#define CRNG_INIT_CNT_THRESH (2 * CHACHA_KEY_SIZE)
-static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE]);
-static void _crng_backtrack_protect(struct crng_state *crng,
- u8 tmp[CHACHA_BLOCK_SIZE], int used);
+static void extract_crng(u8 out[CHACHA_BLOCK_SIZE]);
+static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used);
static void process_random_ready_list(void);
static void _get_random_bytes(void *buf, int nbytes);
@@ -365,7 +362,7 @@ static struct {
static void extract_entropy(void *buf, size_t nbytes);
-static void crng_reseed(struct crng_state *crng);
+static void crng_reseed(void);
/*
* This function adds bytes into the entropy "pool". It does not
@@ -464,7 +461,7 @@ static void credit_entropy_bits(int nbit
trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_);
if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
- crng_reseed(&primary_crng);
+ crng_reseed();
}
/*********************************************************************
@@ -477,16 +474,7 @@ static void credit_entropy_bits(int nbit
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
-/*
- * Hack to deal with crazy userspace progams when they are all trying
- * to access /dev/urandom in parallel. The programs are almost
- * certainly doing something terribly wrong, but we'll work around
- * their brain damage.
- */
-static struct crng_state **crng_node_pool __read_mostly;
-
static void invalidate_batched_entropy(void);
-static void numa_crng_init(void);
static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
static int __init parse_trust_cpu(char *arg)
@@ -495,24 +483,6 @@ static int __init parse_trust_cpu(char *
}
early_param("random.trust_cpu", parse_trust_cpu);
-static bool crng_init_try_arch(struct crng_state *crng)
-{
- int i;
- bool arch_init = true;
- unsigned long rv;
-
- for (i = 4; i < 16; i++) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv)) {
- rv = random_get_entropy();
- arch_init = false;
- }
- crng->state[i] ^= rv;
- }
-
- return arch_init;
-}
-
static bool __init crng_init_try_arch_early(void)
{
int i;
@@ -531,100 +501,17 @@ static bool __init crng_init_try_arch_ea
return arch_init;
}
-static void crng_initialize_secondary(struct crng_state *crng)
-{
- chacha_init_consts(crng->state);
- _get_random_bytes(&crng->state[4], sizeof(u32) * 12);
- crng_init_try_arch(crng);
- crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
-}
-
-static void __init crng_initialize_primary(void)
+static void __init crng_initialize(void)
{
extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
if (crng_init_try_arch_early() && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();
- numa_crng_init();
crng_init = 2;
pr_notice("crng init done (trusting CPU's manufacturer)\n");
}
primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
}
-static void crng_finalize_init(void)
-{
- if (!system_wq) {
- /* We can't call numa_crng_init until we have workqueues,
- * so mark this for processing later. */
- crng_need_final_init = true;
- return;
- }
-
- invalidate_batched_entropy();
- numa_crng_init();
- crng_init = 2;
- crng_need_final_init = false;
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
-}
-
-static void do_numa_crng_init(struct work_struct *work)
-{
- int i;
- struct crng_state *crng;
- struct crng_state **pool;
-
- pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL | __GFP_NOFAIL);
- for_each_online_node(i) {
- crng = kmalloc_node(sizeof(struct crng_state),
- GFP_KERNEL | __GFP_NOFAIL, i);
- spin_lock_init(&crng->lock);
- crng_initialize_secondary(crng);
- pool[i] = crng;
- }
- /* pairs with READ_ONCE() in select_crng() */
- if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) {
- for_each_node(i)
- kfree(pool[i]);
- kfree(pool);
- }
-}
-
-static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
-
-static void numa_crng_init(void)
-{
- if (IS_ENABLED(CONFIG_NUMA))
- schedule_work(&numa_crng_init_work);
-}
-
-static struct crng_state *select_crng(void)
-{
- if (IS_ENABLED(CONFIG_NUMA)) {
- struct crng_state **pool;
- int nid = numa_node_id();
-
- /* pairs with cmpxchg_release() in do_numa_crng_init() */
- pool = READ_ONCE(crng_node_pool);
- if (pool && pool[nid])
- return pool[nid];
- }
-
- return &primary_crng;
-}
-
/*
* crng_fast_load() can be called by code in the interrupt service
* path. So we can't afford to dilly-dally. Returns the number of
@@ -702,68 +589,71 @@ static int crng_slow_load(const u8 *cp,
return 1;
}
-static void crng_reseed(struct crng_state *crng)
+static void crng_reseed(void)
{
unsigned long flags;
- int i;
+ int i, entropy_count;
union {
u8 block[CHACHA_BLOCK_SIZE];
u32 key[8];
} buf;
- if (crng == &primary_crng) {
- int entropy_count;
- do {
- entropy_count = READ_ONCE(input_pool.entropy_count);
- if (entropy_count < POOL_MIN_BITS)
- return;
- } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
- extract_entropy(buf.key, sizeof(buf.key));
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- } else {
- _extract_crng(&primary_crng, buf.block);
- _crng_backtrack_protect(&primary_crng, buf.block,
- CHACHA_KEY_SIZE);
- }
- spin_lock_irqsave(&crng->lock, flags);
+ do {
+ entropy_count = READ_ONCE(input_pool.entropy_count);
+ if (entropy_count < POOL_MIN_BITS)
+ return;
+ } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
+ extract_entropy(buf.key, sizeof(buf.key));
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+
+ spin_lock_irqsave(&primary_crng.lock, flags);
for (i = 0; i < 8; i++)
- crng->state[i + 4] ^= buf.key[i];
+ primary_crng.state[i + 4] ^= buf.key[i];
memzero_explicit(&buf, sizeof(buf));
- WRITE_ONCE(crng->init_time, jiffies);
- spin_unlock_irqrestore(&crng->lock, flags);
- if (crng == &primary_crng && crng_init < 2)
- crng_finalize_init();
+ WRITE_ONCE(primary_crng.init_time, jiffies);
+ spin_unlock_irqrestore(&primary_crng.lock, flags);
+ if (crng_init < 2) {
+ invalidate_batched_entropy();
+ crng_init = 2;
+ process_random_ready_list();
+ wake_up_interruptible(&crng_init_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ pr_notice("crng init done\n");
+ if (unseeded_warning.missed) {
+ pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
+ unseeded_warning.missed);
+ unseeded_warning.missed = 0;
+ }
+ if (urandom_warning.missed) {
+ pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+ urandom_warning.missed);
+ urandom_warning.missed = 0;
+ }
+ }
}
-static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE])
+static void extract_crng(u8 out[CHACHA_BLOCK_SIZE])
{
unsigned long flags, init_time;
if (crng_ready()) {
- init_time = READ_ONCE(crng->init_time);
- if (time_after(READ_ONCE(crng_global_init_time), init_time) ||
- time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
- crng_reseed(crng);
- }
- spin_lock_irqsave(&crng->lock, flags);
- chacha20_block(&crng->state[0], out);
- if (crng->state[12] == 0)
- crng->state[13]++;
- spin_unlock_irqrestore(&crng->lock, flags);
-}
-
-static void extract_crng(u8 out[CHACHA_BLOCK_SIZE])
-{
- _extract_crng(select_crng(), out);
+ init_time = READ_ONCE(primary_crng.init_time);
+ if (time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
+ crng_reseed();
+ }
+ spin_lock_irqsave(&primary_crng.lock, flags);
+ chacha20_block(&primary_crng.state[0], out);
+ if (primary_crng.state[12] == 0)
+ primary_crng.state[13]++;
+ spin_unlock_irqrestore(&primary_crng.lock, flags);
}
/*
* Use the leftover bytes from the CRNG block output (if there is
* enough) to mutate the CRNG key to provide backtracking protection.
*/
-static void _crng_backtrack_protect(struct crng_state *crng,
- u8 tmp[CHACHA_BLOCK_SIZE], int used)
+static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used)
{
unsigned long flags;
u32 *s, *d;
@@ -774,17 +664,12 @@ static void _crng_backtrack_protect(stru
extract_crng(tmp);
used = 0;
}
- spin_lock_irqsave(&crng->lock, flags);
+ spin_lock_irqsave(&primary_crng.lock, flags);
s = (u32 *)&tmp[used];
- d = &crng->state[4];
+ d = &primary_crng.state[4];
for (i = 0; i < 8; i++)
*d++ ^= *s++;
- spin_unlock_irqrestore(&crng->lock, flags);
-}
-
-static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used)
-{
- _crng_backtrack_protect(select_crng(), tmp, used);
+ spin_unlock_irqrestore(&primary_crng.lock, flags);
}
static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
@@ -1371,10 +1256,7 @@ static void __init init_std_data(void)
int __init rand_initialize(void)
{
init_std_data();
- if (crng_need_final_init)
- crng_finalize_init();
- crng_initialize_primary();
- crng_global_init_time = jiffies;
+ crng_initialize();
if (ratelimit_disable) {
urandom_warning.interval = 0;
unseeded_warning.interval = 0;
@@ -1544,8 +1426,7 @@ static long random_ioctl(struct file *f,
return -EPERM;
if (crng_init < 2)
return -ENODATA;
- crng_reseed(&primary_crng);
- WRITE_ONCE(crng_global_init_time, jiffies - 1);
+ crng_reseed();
return 0;
default:
return -EINVAL;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 013/111] random: inline leaves of rand_initialize()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (11 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 012/111] random: get rid of secondary crngs Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 014/111] random: ensure early RDSEED goes through mixer on init Greg Kroah-Hartman
` (103 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 8566417221fcec51346ec164e920dacb979c6b5f upstream.
This is a preparatory commit for the following one. We simply inline the
various functions that rand_initialize() calls that have no other
callers. The compiler was doing this anyway before. Doing this will
allow us to reorganize this after. We can then move the trust_cpu and
parse_trust_cpu definitions a bit closer to where they're actually used,
which makes the code easier to read.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 90 ++++++++++++++++++--------------------------------
1 file changed, 33 insertions(+), 57 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -476,42 +476,6 @@ static DECLARE_WAIT_QUEUE_HEAD(crng_init
static void invalidate_batched_entropy(void);
-static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
-static int __init parse_trust_cpu(char *arg)
-{
- return kstrtobool(arg, &trust_cpu);
-}
-early_param("random.trust_cpu", parse_trust_cpu);
-
-static bool __init crng_init_try_arch_early(void)
-{
- int i;
- bool arch_init = true;
- unsigned long rv;
-
- for (i = 4; i < 16; i++) {
- if (!arch_get_random_seed_long_early(&rv) &&
- !arch_get_random_long_early(&rv)) {
- rv = random_get_entropy();
- arch_init = false;
- }
- primary_crng.state[i] ^= rv;
- }
-
- return arch_init;
-}
-
-static void __init crng_initialize(void)
-{
- extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
- if (crng_init_try_arch_early() && trust_cpu && crng_init < 2) {
- invalidate_batched_entropy();
- crng_init = 2;
- pr_notice("crng init done (trusting CPU's manufacturer)\n");
- }
- primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
-}
-
/*
* crng_fast_load() can be called by code in the interrupt service
* path. So we can't afford to dilly-dally. Returns the number of
@@ -1220,17 +1184,28 @@ int __must_check get_random_bytes_arch(v
}
EXPORT_SYMBOL(get_random_bytes_arch);
+static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
+static int __init parse_trust_cpu(char *arg)
+{
+ return kstrtobool(arg, &trust_cpu);
+}
+early_param("random.trust_cpu", parse_trust_cpu);
+
/*
- * init_std_data - initialize pool with system data
- *
- * This function clears the pool's entropy count and mixes some system
- * data into the pool to prepare it for use. The pool is not cleared
- * as that can only decrease the entropy in the pool.
+ * Note that setup_arch() may call add_device_randomness()
+ * long before we get here. This allows seeding of the pools
+ * with some platform dependent data very early in the boot
+ * process. But it limits our options here. We must use
+ * statically allocated structures that already have all
+ * initializations complete at compile time. We should also
+ * take care not to overwrite the precious per platform data
+ * we were given.
*/
-static void __init init_std_data(void)
+int __init rand_initialize(void)
{
int i;
ktime_t now = ktime_get_real();
+ bool arch_init = true;
unsigned long rv;
mix_pool_bytes(&now, sizeof(now));
@@ -1241,22 +1216,23 @@ static void __init init_std_data(void)
mix_pool_bytes(&rv, sizeof(rv));
}
mix_pool_bytes(utsname(), sizeof(*(utsname())));
-}
-/*
- * Note that setup_arch() may call add_device_randomness()
- * long before we get here. This allows seeding of the pools
- * with some platform dependent data very early in the boot
- * process. But it limits our options here. We must use
- * statically allocated structures that already have all
- * initializations complete at compile time. We should also
- * take care not to overwrite the precious per platform data
- * we were given.
- */
-int __init rand_initialize(void)
-{
- init_std_data();
- crng_initialize();
+ extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
+ for (i = 4; i < 16; i++) {
+ if (!arch_get_random_seed_long_early(&rv) &&
+ !arch_get_random_long_early(&rv)) {
+ rv = random_get_entropy();
+ arch_init = false;
+ }
+ primary_crng.state[i] ^= rv;
+ }
+ if (arch_init && trust_cpu && crng_init < 2) {
+ invalidate_batched_entropy();
+ crng_init = 2;
+ pr_notice("crng init done (trusting CPU's manufacturer)\n");
+ }
+ primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
+
if (ratelimit_disable) {
urandom_warning.interval = 0;
unseeded_warning.interval = 0;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 014/111] random: ensure early RDSEED goes through mixer on init
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (12 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 013/111] random: inline leaves of rand_initialize() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 015/111] random: do not xor RDRAND when writing into /dev/random Greg Kroah-Hartman
` (102 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a02cf3d0dd77244fd5333ac48d78871de459ae6d upstream.
Continuing the reasoning of "random: use RDSEED instead of RDRAND in
entropy extraction" from this series, at init time we also don't want to
be xoring RDSEED directly into the crng. Instead it's safer to put it
into our entropy collector and then re-extract it, so that it goes
through a hash function with preimage resistance. As a matter of hygiene,
we also order these now so that the RDSEED byte are hashed in first,
followed by the bytes that are likely more predictable (e.g. utsname()).
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1208,24 +1208,18 @@ int __init rand_initialize(void)
bool arch_init = true;
unsigned long rv;
- mix_pool_bytes(&now, sizeof(now));
for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- mix_pool_bytes(&rv, sizeof(rv));
- }
- mix_pool_bytes(utsname(), sizeof(*(utsname())));
-
- extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
- for (i = 4; i < 16; i++) {
if (!arch_get_random_seed_long_early(&rv) &&
!arch_get_random_long_early(&rv)) {
rv = random_get_entropy();
arch_init = false;
}
- primary_crng.state[i] ^= rv;
+ mix_pool_bytes(&rv, sizeof(rv));
}
+ mix_pool_bytes(&now, sizeof(now));
+ mix_pool_bytes(utsname(), sizeof(*(utsname())));
+
+ extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
if (arch_init && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();
crng_init = 2;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 015/111] random: do not xor RDRAND when writing into /dev/random
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (13 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 014/111] random: ensure early RDSEED goes through mixer on init Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 016/111] random: absorb fast pool into input pool after fast load Greg Kroah-Hartman
` (101 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 91c2afca290ed3034841c8c8532e69ed9e16cf34 upstream.
Continuing the reasoning of "random: ensure early RDSEED goes through
mixer on init", we don't want RDRAND interacting with anything without
going through the mixer function, as a backdoored CPU could presumably
cancel out data during an xor, which it'd have a harder time doing when
being forced through a cryptographic hash function. There's actually no
need at all to be calling RDRAND in write_pool(), because before we
extract from the pool, we always do so with 32 bytes of RDSEED hashed in
at that stage. Xoring at this stage is needless and introduces a minor
liability.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1305,25 +1305,15 @@ static __poll_t random_poll(struct file
static int write_pool(const char __user *buffer, size_t count)
{
size_t bytes;
- u32 t, buf[16];
+ u8 buf[BLAKE2S_BLOCK_SIZE];
const char __user *p = buffer;
while (count > 0) {
- int b, i = 0;
-
bytes = min(count, sizeof(buf));
- if (copy_from_user(&buf, p, bytes))
+ if (copy_from_user(buf, p, bytes))
return -EFAULT;
-
- for (b = bytes; b > 0; b -= sizeof(u32), i++) {
- if (!arch_get_random_int(&t))
- break;
- buf[i] ^= t;
- }
-
count -= bytes;
p += bytes;
-
mix_pool_bytes(buf, bytes);
cond_resched();
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 016/111] random: absorb fast pool into input pool after fast load
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (14 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 015/111] random: do not xor RDRAND when writing into /dev/random Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 017/111] random: use simpler fast key erasure flow on per-cpu keys Greg Kroah-Hartman
` (100 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit c30c575db4858f0bbe5e315ff2e529c782f33a1f upstream.
During crng_init == 0, we never credit entropy in add_interrupt_
randomness(), but instead dump it directly into the primary_crng. That's
fine, except for the fact that we then wind up throwing away that
entropy later when we switch to extracting from the input pool and
xoring into (and later in this series overwriting) the primary_crng key.
The two other early init sites -- add_hwgenerator_randomness()'s use
crng_fast_load() and add_device_ randomness()'s use of crng_slow_load()
-- always additionally give their inputs to the input pool. But not
add_interrupt_randomness().
This commit fixes that shortcoming by calling mix_pool_bytes() after
crng_fast_load() in add_interrupt_randomness(). That's partially
verboten on PREEMPT_RT, where it implies taking spinlock_t from an IRQ
handler. But this also only happens during early boot and then never
again after that. Plus it's a trylock so it has the same considerations
as calling crng_fast_load(), which we're already using.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Suggested-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -850,6 +850,10 @@ void add_interrupt_randomness(int irq)
crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) {
fast_pool->count = 0;
fast_pool->last = now;
+ if (spin_trylock(&input_pool.lock)) {
+ _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
+ spin_unlock(&input_pool.lock);
+ }
}
return;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 017/111] random: use simpler fast key erasure flow on per-cpu keys
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (15 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 016/111] random: absorb fast pool into input pool after fast load Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 018/111] random: use hash function for crng_slow_load() Greg Kroah-Hartman
` (99 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Sebastian Andrzej Siewior, Jann Horn, Eric Biggers,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 186873c549df11b63e17062f863654e1501e1524 upstream.
Rather than the clunky NUMA full ChaCha state system we had prior, this
commit is closer to the original "fast key erasure RNG" proposal from
<https://blog.cr.yp.to/20170723-random.html>, by simply treating ChaCha
keys on a per-cpu basis.
All entropy is extracted to a base crng key of 32 bytes. This base crng
has a birthdate and a generation counter. When we go to take bytes from
the crng, we first check if the birthdate is too old; if it is, we
reseed per usual. Then we start working on a per-cpu crng.
This per-cpu crng makes sure that it has the same generation counter as
the base crng. If it doesn't, it does fast key erasure with the base
crng key and uses the output as its new per-cpu key, and then updates
its local generation counter. Then, using this per-cpu state, we do
ordinary fast key erasure. Half of this first block is used to overwrite
the per-cpu crng key for the next call -- this is the fast key erasure
RNG idea -- and the other half, along with the ChaCha state, is returned
to the caller. If the caller desires more than this remaining half, it
can generate more ChaCha blocks, unlocked, using the now detached ChaCha
state that was just returned. Crypto-wise, this is more or less what we
were doing before, but this simply makes it more explicit and ensures
that we always have backtrack protection by not playing games with a
shared block counter.
The flow looks like this:
──extract()──► base_crng.key ◄──memcpy()───┐
│ │
└──chacha()──────┬─► new_base_key
└─► crngs[n].key ◄──memcpy()───┐
│ │
└──chacha()───┬─► new_key
└─► random_bytes
│
└────►
There are a few hairy details around early init. Just as was done
before, prior to having gathered enough entropy, crng_fast_load() and
crng_slow_load() dump bytes directly into the base crng, and when we go
to take bytes from the crng, in that case, we're doing fast key erasure
with the base crng rather than the fast unlocked per-cpu crngs. This is
fine as that's only the state of affairs during very early boot; once
the crng initializes we never use these paths again.
In the process of all this, the APIs into the crng become a bit simpler:
we have get_random_bytes(buf, len) and get_random_bytes_user(buf, len),
which both do what you'd expect. All of the details of fast key erasure
and per-cpu selection happen only in a very short critical section of
crng_make_state(), which selects the right per-cpu key, does the fast
key erasure, and returns a local state to the caller's stack. So, we no
longer have a need for a separate backtrack function, as this happens
all at once here. The API then allows us to extend backtrack protection
to batched entropy without really having to do much at all.
The result is a bit simpler than before and has fewer foot guns. The
init time state machine also gets a lot simpler as we don't need to wait
for workqueues to come online and do deferred work. And the multi-core
performance should be increased significantly, by virtue of having hardly
any locking on the fast path.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 403 ++++++++++++++++++++++++++++----------------------
1 file changed, 233 insertions(+), 170 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -67,63 +67,19 @@
* Exported interfaces ---- kernel output
* --------------------------------------
*
- * The primary kernel interface is
+ * The primary kernel interfaces are:
*
* void get_random_bytes(void *buf, int nbytes);
- *
- * This interface will return the requested number of random bytes,
- * and place it in the requested buffer. This is equivalent to a
- * read from /dev/urandom.
- *
- * For less critical applications, there are the functions:
- *
* u32 get_random_u32()
* u64 get_random_u64()
* unsigned int get_random_int()
* unsigned long get_random_long()
*
- * These are produced by a cryptographic RNG seeded from get_random_bytes,
- * and so do not deplete the entropy pool as much. These are recommended
- * for most in-kernel operations *if the result is going to be stored in
- * the kernel*.
- *
- * Specifically, the get_random_int() family do not attempt to do
- * "anti-backtracking". If you capture the state of the kernel (e.g.
- * by snapshotting the VM), you can figure out previous get_random_int()
- * return values. But if the value is stored in the kernel anyway,
- * this is not a problem.
- *
- * It *is* safe to expose get_random_int() output to attackers (e.g. as
- * network cookies); given outputs 1..n, it's not feasible to predict
- * outputs 0 or n+1. The only concern is an attacker who breaks into
- * the kernel later; the get_random_int() engine is not reseeded as
- * often as the get_random_bytes() one.
- *
- * get_random_bytes() is needed for keys that need to stay secret after
- * they are erased from the kernel. For example, any key that will
- * be wrapped and stored encrypted. And session encryption keys: we'd
- * like to know that after the session is closed and the keys erased,
- * the plaintext is unrecoverable to someone who recorded the ciphertext.
- *
- * But for network ports/cookies, stack canaries, PRNG seeds, address
- * space layout randomization, session *authentication* keys, or other
- * applications where the sensitive data is stored in the kernel in
- * plaintext for as long as it's sensitive, the get_random_int() family
- * is just fine.
- *
- * Consider ASLR. We want to keep the address space secret from an
- * outside attacker while the process is running, but once the address
- * space is torn down, it's of no use to an attacker any more. And it's
- * stored in kernel data structures as long as it's alive, so worrying
- * about an attacker's ability to extrapolate it from the get_random_int()
- * CRNG is silly.
- *
- * Even some cryptographic keys are safe to generate with get_random_int().
- * In particular, keys for SipHash are generally fine. Here, knowledge
- * of the key authorizes you to do something to a kernel object (inject
- * packets to a network connection, or flood a hash table), and the
- * key is stored with the object being protected. Once it goes away,
- * we no longer care if anyone knows the key.
+ * These interfaces will return the requested number of random bytes
+ * into the given buffer or as a return value. This is equivalent to a
+ * read from /dev/urandom. The get_random_{u32,u64,int,long}() family
+ * of functions may be higher performance for one-off random integers,
+ * because they do a bit of buffering.
*
* prandom_u32()
* -------------
@@ -300,20 +256,6 @@ static struct fasync_struct *fasync;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);
-struct crng_state {
- u32 state[16];
- unsigned long init_time;
- spinlock_t lock;
-};
-
-static struct crng_state primary_crng = {
- .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
- .state[0] = CHACHA_CONSTANT_EXPA,
- .state[1] = CHACHA_CONSTANT_ND_3,
- .state[2] = CHACHA_CONSTANT_2_BY,
- .state[3] = CHACHA_CONSTANT_TE_K,
-};
-
/*
* crng_init = 0 --> Uninitialized
* 1 --> Initialized
@@ -325,9 +267,6 @@ static struct crng_state primary_crng =
static int crng_init = 0;
#define crng_ready() (likely(crng_init > 1))
static int crng_init_cnt = 0;
-#define CRNG_INIT_CNT_THRESH (2 * CHACHA_KEY_SIZE)
-static void extract_crng(u8 out[CHACHA_BLOCK_SIZE]);
-static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used);
static void process_random_ready_list(void);
static void _get_random_bytes(void *buf, int nbytes);
@@ -470,7 +409,30 @@ static void credit_entropy_bits(int nbit
*
*********************************************************************/
-#define CRNG_RESEED_INTERVAL (300 * HZ)
+enum {
+ CRNG_RESEED_INTERVAL = 300 * HZ,
+ CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE
+};
+
+static struct {
+ u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long));
+ unsigned long birth;
+ unsigned long generation;
+ spinlock_t lock;
+} base_crng = {
+ .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock)
+};
+
+struct crng {
+ u8 key[CHACHA_KEY_SIZE];
+ unsigned long generation;
+ local_lock_t lock;
+};
+
+static DEFINE_PER_CPU(struct crng, crngs) = {
+ .generation = ULONG_MAX,
+ .lock = INIT_LOCAL_LOCK(crngs.lock),
+};
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
@@ -487,22 +449,22 @@ static size_t crng_fast_load(const u8 *c
u8 *p;
size_t ret = 0;
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
+ if (!spin_trylock_irqsave(&base_crng.lock, flags))
return 0;
if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
return 0;
}
- p = (u8 *)&primary_crng.state[4];
+ p = base_crng.key;
while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
+ p[crng_init_cnt % sizeof(base_crng.key)] ^= *cp;
cp++; crng_init_cnt++; len--; ret++;
}
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
invalidate_batched_entropy();
crng_init = 1;
}
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
if (crng_init == 1)
pr_notice("fast init done\n");
return ret;
@@ -527,14 +489,14 @@ static int crng_slow_load(const u8 *cp,
unsigned long flags;
static u8 lfsr = 1;
u8 tmp;
- unsigned int i, max = CHACHA_KEY_SIZE;
+ unsigned int i, max = sizeof(base_crng.key);
const u8 *src_buf = cp;
- u8 *dest_buf = (u8 *)&primary_crng.state[4];
+ u8 *dest_buf = base_crng.key;
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
+ if (!spin_trylock_irqsave(&base_crng.lock, flags))
return 0;
if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
return 0;
}
if (len > max)
@@ -545,38 +507,50 @@ static int crng_slow_load(const u8 *cp,
lfsr >>= 1;
if (tmp & 1)
lfsr ^= 0xE1;
- tmp = dest_buf[i % CHACHA_KEY_SIZE];
- dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
+ tmp = dest_buf[i % sizeof(base_crng.key)];
+ dest_buf[i % sizeof(base_crng.key)] ^= src_buf[i % len] ^ lfsr;
lfsr += (tmp << 3) | (tmp >> 5);
}
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
return 1;
}
static void crng_reseed(void)
{
unsigned long flags;
- int i, entropy_count;
- union {
- u8 block[CHACHA_BLOCK_SIZE];
- u32 key[8];
- } buf;
+ int entropy_count;
+ unsigned long next_gen;
+ u8 key[CHACHA_KEY_SIZE];
+ /*
+ * First we make sure we have POOL_MIN_BITS of entropy in the pool,
+ * and then we drain all of it. Only then can we extract a new key.
+ */
do {
entropy_count = READ_ONCE(input_pool.entropy_count);
if (entropy_count < POOL_MIN_BITS)
return;
} while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
- extract_entropy(buf.key, sizeof(buf.key));
+ extract_entropy(key, sizeof(key));
wake_up_interruptible(&random_write_wait);
kill_fasync(&fasync, SIGIO, POLL_OUT);
- spin_lock_irqsave(&primary_crng.lock, flags);
- for (i = 0; i < 8; i++)
- primary_crng.state[i + 4] ^= buf.key[i];
- memzero_explicit(&buf, sizeof(buf));
- WRITE_ONCE(primary_crng.init_time, jiffies);
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ /*
+ * We copy the new key into the base_crng, overwriting the old one,
+ * and update the generation counter. We avoid hitting ULONG_MAX,
+ * because the per-cpu crngs are initialized to ULONG_MAX, so this
+ * forces new CPUs that come online to always initialize.
+ */
+ spin_lock_irqsave(&base_crng.lock, flags);
+ memcpy(base_crng.key, key, sizeof(base_crng.key));
+ next_gen = base_crng.generation + 1;
+ if (next_gen == ULONG_MAX)
+ ++next_gen;
+ WRITE_ONCE(base_crng.generation, next_gen);
+ WRITE_ONCE(base_crng.birth, jiffies);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ memzero_explicit(key, sizeof(key));
+
if (crng_init < 2) {
invalidate_batched_entropy();
crng_init = 2;
@@ -597,77 +571,143 @@ static void crng_reseed(void)
}
}
-static void extract_crng(u8 out[CHACHA_BLOCK_SIZE])
+/*
+ * The general form here is based on a "fast key erasure RNG" from
+ * <https://blog.cr.yp.to/20170723-random.html>. It generates a ChaCha
+ * block using the provided key, and then immediately overwites that
+ * key with half the block. It returns the resultant ChaCha state to the
+ * user, along with the second half of the block containing 32 bytes of
+ * random data that may be used; random_data_len may not be greater than
+ * 32.
+ */
+static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
+ u32 chacha_state[CHACHA_STATE_WORDS],
+ u8 *random_data, size_t random_data_len)
{
- unsigned long flags, init_time;
+ u8 first_block[CHACHA_BLOCK_SIZE];
- if (crng_ready()) {
- init_time = READ_ONCE(primary_crng.init_time);
- if (time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
- crng_reseed();
- }
- spin_lock_irqsave(&primary_crng.lock, flags);
- chacha20_block(&primary_crng.state[0], out);
- if (primary_crng.state[12] == 0)
- primary_crng.state[13]++;
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ BUG_ON(random_data_len > 32);
+
+ chacha_init_consts(chacha_state);
+ memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE);
+ memset(&chacha_state[12], 0, sizeof(u32) * 4);
+ chacha20_block(chacha_state, first_block);
+
+ memcpy(key, first_block, CHACHA_KEY_SIZE);
+ memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len);
+ memzero_explicit(first_block, sizeof(first_block));
}
/*
- * Use the leftover bytes from the CRNG block output (if there is
- * enough) to mutate the CRNG key to provide backtracking protection.
+ * This function returns a ChaCha state that you may use for generating
+ * random data. It also returns up to 32 bytes on its own of random data
+ * that may be used; random_data_len may not be greater than 32.
*/
-static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used)
+static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
+ u8 *random_data, size_t random_data_len)
{
unsigned long flags;
- u32 *s, *d;
- int i;
+ struct crng *crng;
+
+ BUG_ON(random_data_len > 32);
+
+ /*
+ * For the fast path, we check whether we're ready, unlocked first, and
+ * then re-check once locked later. In the case where we're really not
+ * ready, we do fast key erasure with the base_crng directly, because
+ * this is what crng_{fast,slow}_load mutate during early init.
+ */
+ if (unlikely(!crng_ready())) {
+ bool ready;
+
+ spin_lock_irqsave(&base_crng.lock, flags);
+ ready = crng_ready();
+ if (!ready)
+ crng_fast_key_erasure(base_crng.key, chacha_state,
+ random_data, random_data_len);
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ if (!ready)
+ return;
+ }
+
+ /*
+ * If the base_crng is more than 5 minutes old, we reseed, which
+ * in turn bumps the generation counter that we check below.
+ */
+ if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL)))
+ crng_reseed();
+
+ local_lock_irqsave(&crngs.lock, flags);
+ crng = raw_cpu_ptr(&crngs);
+
+ /*
+ * If our per-cpu crng is older than the base_crng, then it means
+ * somebody reseeded the base_crng. In that case, we do fast key
+ * erasure on the base_crng, and use its output as the new key
+ * for our per-cpu crng. This brings us up to date with base_crng.
+ */
+ if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) {
+ spin_lock(&base_crng.lock);
+ crng_fast_key_erasure(base_crng.key, chacha_state,
+ crng->key, sizeof(crng->key));
+ crng->generation = base_crng.generation;
+ spin_unlock(&base_crng.lock);
+ }
+
+ /*
+ * Finally, when we've made it this far, our per-cpu crng has an up
+ * to date key, and we can do fast key erasure with it to produce
+ * some random data and a ChaCha state for the caller. All other
+ * branches of this function are "unlikely", so most of the time we
+ * should wind up here immediately.
+ */
+ crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len);
+ local_unlock_irqrestore(&crngs.lock, flags);
+}
+
+static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
+{
+ bool large_request = nbytes > 256;
+ ssize_t ret = 0, len;
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ u8 output[CHACHA_BLOCK_SIZE];
+
+ if (!nbytes)
+ return 0;
- used = round_up(used, sizeof(u32));
- if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) {
- extract_crng(tmp);
- used = 0;
- }
- spin_lock_irqsave(&primary_crng.lock, flags);
- s = (u32 *)&tmp[used];
- d = &primary_crng.state[4];
- for (i = 0; i < 8; i++)
- *d++ ^= *s++;
- spin_unlock_irqrestore(&primary_crng.lock, flags);
-}
-
-static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
-{
- ssize_t ret = 0, i = CHACHA_BLOCK_SIZE;
- u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
- int large_request = (nbytes > 256);
+ len = min_t(ssize_t, 32, nbytes);
+ crng_make_state(chacha_state, output, len);
+
+ if (copy_to_user(buf, output, len))
+ return -EFAULT;
+ nbytes -= len;
+ buf += len;
+ ret += len;
while (nbytes) {
if (large_request && need_resched()) {
- if (signal_pending(current)) {
- if (ret == 0)
- ret = -ERESTARTSYS;
+ if (signal_pending(current))
break;
- }
schedule();
}
- extract_crng(tmp);
- i = min_t(int, nbytes, CHACHA_BLOCK_SIZE);
- if (copy_to_user(buf, tmp, i)) {
+ chacha20_block(chacha_state, output);
+ if (unlikely(chacha_state[12] == 0))
+ ++chacha_state[13];
+
+ len = min_t(ssize_t, nbytes, CHACHA_BLOCK_SIZE);
+ if (copy_to_user(buf, output, len)) {
ret = -EFAULT;
break;
}
- nbytes -= i;
- buf += i;
- ret += i;
+ nbytes -= len;
+ buf += len;
+ ret += len;
}
- crng_backtrack_protect(tmp, i);
-
- /* Wipe data just written to memory */
- memzero_explicit(tmp, sizeof(tmp));
+ memzero_explicit(chacha_state, sizeof(chacha_state));
+ memzero_explicit(output, sizeof(output));
return ret;
}
@@ -976,23 +1016,36 @@ static void _warn_unseeded_randomness(co
*/
static void _get_random_bytes(void *buf, int nbytes)
{
- u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ u8 tmp[CHACHA_BLOCK_SIZE];
+ ssize_t len;
trace_get_random_bytes(nbytes, _RET_IP_);
- while (nbytes >= CHACHA_BLOCK_SIZE) {
- extract_crng(buf);
- buf += CHACHA_BLOCK_SIZE;
+ if (!nbytes)
+ return;
+
+ len = min_t(ssize_t, 32, nbytes);
+ crng_make_state(chacha_state, buf, len);
+ nbytes -= len;
+ buf += len;
+
+ while (nbytes) {
+ if (nbytes < CHACHA_BLOCK_SIZE) {
+ chacha20_block(chacha_state, tmp);
+ memcpy(buf, tmp, nbytes);
+ memzero_explicit(tmp, sizeof(tmp));
+ break;
+ }
+
+ chacha20_block(chacha_state, buf);
+ if (unlikely(chacha_state[12] == 0))
+ ++chacha_state[13];
nbytes -= CHACHA_BLOCK_SIZE;
+ buf += CHACHA_BLOCK_SIZE;
}
- if (nbytes > 0) {
- extract_crng(tmp);
- memcpy(buf, tmp, nbytes);
- crng_backtrack_protect(tmp, nbytes);
- } else
- crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE);
- memzero_explicit(tmp, sizeof(tmp));
+ memzero_explicit(chacha_state, sizeof(chacha_state));
}
void get_random_bytes(void *buf, int nbytes)
@@ -1223,13 +1276,12 @@ int __init rand_initialize(void)
mix_pool_bytes(&now, sizeof(now));
mix_pool_bytes(utsname(), sizeof(*(utsname())));
- extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
if (arch_init && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();
crng_init = 2;
pr_notice("crng init done (trusting CPU's manufacturer)\n");
}
- primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
if (ratelimit_disable) {
urandom_warning.interval = 0;
@@ -1261,7 +1313,7 @@ static ssize_t urandom_read_nowarn(struc
int ret;
nbytes = min_t(size_t, nbytes, INT_MAX >> 6);
- ret = extract_crng_user(buf, nbytes);
+ ret = get_random_bytes_user(buf, nbytes);
trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count);
return ret;
}
@@ -1577,8 +1629,15 @@ static atomic_t batch_generation = ATOMI
struct batched_entropy {
union {
- u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
- u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
+ /*
+ * We make this 1.5x a ChaCha block, so that we get the
+ * remaining 32 bytes from fast key erasure, plus one full
+ * block from the detached ChaCha state. We can increase
+ * the size of this later if needed so long as we keep the
+ * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.
+ */
+ u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))];
+ u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
};
local_lock_t lock;
unsigned int position;
@@ -1587,14 +1646,13 @@ struct batched_entropy {
/*
* Get a random word for internal kernel use only. The quality of the random
- * number is good as /dev/urandom, but there is no backtrack protection, with
- * the goal of being quite fast and not depleting entropy. In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once at any
- * point prior.
+ * number is good as /dev/urandom. In order to ensure that the randomness
+ * provided by this function is okay, the function wait_for_random_bytes()
+ * should be called and return 0 at least once at any point prior.
*/
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock)
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock),
+ .position = UINT_MAX
};
u64 get_random_u64(void)
@@ -1611,21 +1669,24 @@ u64 get_random_u64(void)
batch = raw_cpu_ptr(&batched_entropy_u64);
next_gen = atomic_read(&batch_generation);
- if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0 ||
+ if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
next_gen != batch->generation) {
- extract_crng((u8 *)batch->entropy_u64);
+ _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
batch->position = 0;
batch->generation = next_gen;
}
- ret = batch->entropy_u64[batch->position++];
+ ret = batch->entropy_u64[batch->position];
+ batch->entropy_u64[batch->position] = 0;
+ ++batch->position;
local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
return ret;
}
EXPORT_SYMBOL(get_random_u64);
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock)
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock),
+ .position = UINT_MAX
};
u32 get_random_u32(void)
@@ -1642,14 +1703,16 @@ u32 get_random_u32(void)
batch = raw_cpu_ptr(&batched_entropy_u32);
next_gen = atomic_read(&batch_generation);
- if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0 ||
+ if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
next_gen != batch->generation) {
- extract_crng((u8 *)batch->entropy_u32);
+ _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
batch->position = 0;
batch->generation = next_gen;
}
- ret = batch->entropy_u32[batch->position++];
+ ret = batch->entropy_u32[batch->position];
+ batch->entropy_u32[batch->position] = 0;
+ ++batch->position;
local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
return ret;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 018/111] random: use hash function for crng_slow_load()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (16 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 017/111] random: use simpler fast key erasure flow on per-cpu keys Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 019/111] random: make more consistent use of integer types Greg Kroah-Hartman
` (98 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 66e4c2b9541503d721e936cc3898c9f25f4591ff upstream.
Since we have a hash function that's really fast, and the goal of
crng_slow_load() is reportedly to "touch all of the crng's state", we
can just hash the old state together with the new state and call it a
day. This way we dont need to reason about another LFSR or worry about
various attacks there. This code is only ever used at early boot and
then never again.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 40 ++++++++++++++--------------------------
1 file changed, 14 insertions(+), 26 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -477,42 +477,30 @@ static size_t crng_fast_load(const u8 *c
* all), and (2) it doesn't have the performance constraints of
* crng_fast_load().
*
- * So we do something more comprehensive which is guaranteed to touch
- * all of the primary_crng's state, and which uses a LFSR with a
- * period of 255 as part of the mixing algorithm. Finally, we do
- * *not* advance crng_init_cnt since buffer we may get may be something
- * like a fixed DMI table (for example), which might very well be
- * unique to the machine, but is otherwise unvarying.
+ * So, we simply hash the contents in with the current key. Finally,
+ * we do *not* advance crng_init_cnt since buffer we may get may be
+ * something like a fixed DMI table (for example), which might very
+ * well be unique to the machine, but is otherwise unvarying.
*/
-static int crng_slow_load(const u8 *cp, size_t len)
+static void crng_slow_load(const u8 *cp, size_t len)
{
unsigned long flags;
- static u8 lfsr = 1;
- u8 tmp;
- unsigned int i, max = sizeof(base_crng.key);
- const u8 *src_buf = cp;
- u8 *dest_buf = base_crng.key;
+ struct blake2s_state hash;
+
+ blake2s_init(&hash, sizeof(base_crng.key));
if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return 0;
+ return;
if (crng_init != 0) {
spin_unlock_irqrestore(&base_crng.lock, flags);
- return 0;
+ return;
}
- if (len > max)
- max = len;
- for (i = 0; i < max; i++) {
- tmp = lfsr;
- lfsr >>= 1;
- if (tmp & 1)
- lfsr ^= 0xE1;
- tmp = dest_buf[i % sizeof(base_crng.key)];
- dest_buf[i % sizeof(base_crng.key)] ^= src_buf[i % len] ^ lfsr;
- lfsr += (tmp << 3) | (tmp >> 5);
- }
+ blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
+ blake2s_update(&hash, cp, len);
+ blake2s_final(&hash, base_crng.key);
+
spin_unlock_irqrestore(&base_crng.lock, flags);
- return 1;
}
static void crng_reseed(void)
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 019/111] random: make more consistent use of integer types
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (17 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 018/111] random: use hash function for crng_slow_load() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 020/111] random: remove outdated INT_MAX >> 6 check in urandom_read() Greg Kroah-Hartman
` (97 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jann Horn, Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 04ec96b768c9dd43946b047c3da60dcc66431370 upstream.
We've been using a flurry of int, unsigned int, size_t, and ssize_t.
Let's unify all of this into size_t where it makes sense, as it does in
most places, and leave ssize_t for return values with possible errors.
In addition, keeping with the convention of other functions in this
file, functions that are dealing with raw bytes now take void *
consistently instead of a mix of that and u8 *, because much of the time
we're actually passing some other structure that is then interpreted as
bytes by the function.
We also take the opportunity to fix the outdated and incorrect comment
in get_random_bytes_arch().
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 125 ++++++++++++++++++------------------------
include/linux/hw_random.h | 2
include/linux/random.h | 10 +--
include/trace/events/random.h | 79 ++++++++++++--------------
4 files changed, 100 insertions(+), 116 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -69,7 +69,7 @@
*
* The primary kernel interfaces are:
*
- * void get_random_bytes(void *buf, int nbytes);
+ * void get_random_bytes(void *buf, size_t nbytes);
* u32 get_random_u32()
* u64 get_random_u64()
* unsigned int get_random_int()
@@ -97,14 +97,14 @@
* The current exported interfaces for gathering environmental noise
* from the devices are:
*
- * void add_device_randomness(const void *buf, unsigned int size);
+ * void add_device_randomness(const void *buf, size_t size);
* void add_input_randomness(unsigned int type, unsigned int code,
* unsigned int value);
* void add_interrupt_randomness(int irq);
* void add_disk_randomness(struct gendisk *disk);
- * void add_hwgenerator_randomness(const char *buffer, size_t count,
+ * void add_hwgenerator_randomness(const void *buffer, size_t count,
* size_t entropy);
- * void add_bootloader_randomness(const void *buf, unsigned int size);
+ * void add_bootloader_randomness(const void *buf, size_t size);
*
* add_device_randomness() is for adding data to the random pool that
* is likely to differ between two devices (or possibly even per boot).
@@ -268,7 +268,7 @@ static int crng_init = 0;
#define crng_ready() (likely(crng_init > 1))
static int crng_init_cnt = 0;
static void process_random_ready_list(void);
-static void _get_random_bytes(void *buf, int nbytes);
+static void _get_random_bytes(void *buf, size_t nbytes);
static struct ratelimit_state unseeded_warning =
RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
@@ -290,7 +290,7 @@ MODULE_PARM_DESC(ratelimit_disable, "Dis
static struct {
struct blake2s_state hash;
spinlock_t lock;
- int entropy_count;
+ unsigned int entropy_count;
} input_pool = {
.hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
@@ -308,18 +308,12 @@ static void crng_reseed(void);
* update the entropy estimate. The caller should call
* credit_entropy_bits if this is appropriate.
*/
-static void _mix_pool_bytes(const void *in, int nbytes)
+static void _mix_pool_bytes(const void *in, size_t nbytes)
{
blake2s_update(&input_pool.hash, in, nbytes);
}
-static void __mix_pool_bytes(const void *in, int nbytes)
-{
- trace_mix_pool_bytes_nolock(nbytes, _RET_IP_);
- _mix_pool_bytes(in, nbytes);
-}
-
-static void mix_pool_bytes(const void *in, int nbytes)
+static void mix_pool_bytes(const void *in, size_t nbytes)
{
unsigned long flags;
@@ -383,18 +377,18 @@ static void process_random_ready_list(vo
spin_unlock_irqrestore(&random_ready_list_lock, flags);
}
-static void credit_entropy_bits(int nbits)
+static void credit_entropy_bits(size_t nbits)
{
- int entropy_count, orig;
+ unsigned int entropy_count, orig, add;
- if (nbits <= 0)
+ if (!nbits)
return;
- nbits = min(nbits, POOL_BITS);
+ add = min_t(size_t, nbits, POOL_BITS);
do {
orig = READ_ONCE(input_pool.entropy_count);
- entropy_count = min(POOL_BITS, orig + nbits);
+ entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_);
@@ -443,10 +437,10 @@ static void invalidate_batched_entropy(v
* path. So we can't afford to dilly-dally. Returns the number of
* bytes processed from cp.
*/
-static size_t crng_fast_load(const u8 *cp, size_t len)
+static size_t crng_fast_load(const void *cp, size_t len)
{
unsigned long flags;
- u8 *p;
+ const u8 *src = (const u8 *)cp;
size_t ret = 0;
if (!spin_trylock_irqsave(&base_crng.lock, flags))
@@ -455,10 +449,9 @@ static size_t crng_fast_load(const u8 *c
spin_unlock_irqrestore(&base_crng.lock, flags);
return 0;
}
- p = base_crng.key;
while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- p[crng_init_cnt % sizeof(base_crng.key)] ^= *cp;
- cp++; crng_init_cnt++; len--; ret++;
+ base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src;
+ src++; crng_init_cnt++; len--; ret++;
}
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
invalidate_batched_entropy();
@@ -482,7 +475,7 @@ static size_t crng_fast_load(const u8 *c
* something like a fixed DMI table (for example), which might very
* well be unique to the machine, but is otherwise unvarying.
*/
-static void crng_slow_load(const u8 *cp, size_t len)
+static void crng_slow_load(const void *cp, size_t len)
{
unsigned long flags;
struct blake2s_state hash;
@@ -656,14 +649,15 @@ static void crng_make_state(u32 chacha_s
static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
{
bool large_request = nbytes > 256;
- ssize_t ret = 0, len;
+ ssize_t ret = 0;
+ size_t len;
u32 chacha_state[CHACHA_STATE_WORDS];
u8 output[CHACHA_BLOCK_SIZE];
if (!nbytes)
return 0;
- len = min_t(ssize_t, 32, nbytes);
+ len = min_t(size_t, 32, nbytes);
crng_make_state(chacha_state, output, len);
if (copy_to_user(buf, output, len))
@@ -683,7 +677,7 @@ static ssize_t get_random_bytes_user(voi
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
- len = min_t(ssize_t, nbytes, CHACHA_BLOCK_SIZE);
+ len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE);
if (copy_to_user(buf, output, len)) {
ret = -EFAULT;
break;
@@ -721,7 +715,7 @@ struct timer_rand_state {
* the entropy pool having similar initial state across largely
* identical devices.
*/
-void add_device_randomness(const void *buf, unsigned int size)
+void add_device_randomness(const void *buf, size_t size)
{
unsigned long time = random_get_entropy() ^ jiffies;
unsigned long flags;
@@ -749,7 +743,7 @@ static struct timer_rand_state input_tim
* keyboard scan codes, and 256 upwards for interrupts.
*
*/
-static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
+static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
struct {
long jiffies;
@@ -793,7 +787,7 @@ static void add_timer_randomness(struct
* Round down by 1 bit on general principles,
* and limit entropy estimate to 12 bits.
*/
- credit_entropy_bits(min_t(int, fls(delta >> 1), 11));
+ credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11));
}
void add_input_randomness(unsigned int type, unsigned int code,
@@ -874,8 +868,8 @@ void add_interrupt_randomness(int irq)
add_interrupt_bench(cycles);
if (unlikely(crng_init == 0)) {
- if ((fast_pool->count >= 64) &&
- crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) {
+ if (fast_pool->count >= 64 &&
+ crng_fast_load(fast_pool->pool, sizeof(fast_pool->pool)) > 0) {
fast_pool->count = 0;
fast_pool->last = now;
if (spin_trylock(&input_pool.lock)) {
@@ -893,7 +887,7 @@ void add_interrupt_randomness(int irq)
return;
fast_pool->last = now;
- __mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
+ _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
spin_unlock(&input_pool.lock);
fast_pool->count = 0;
@@ -1002,18 +996,18 @@ static void _warn_unseeded_randomness(co
* wait_for_random_bytes() should be called and return 0 at least once
* at any point prior.
*/
-static void _get_random_bytes(void *buf, int nbytes)
+static void _get_random_bytes(void *buf, size_t nbytes)
{
u32 chacha_state[CHACHA_STATE_WORDS];
u8 tmp[CHACHA_BLOCK_SIZE];
- ssize_t len;
+ size_t len;
trace_get_random_bytes(nbytes, _RET_IP_);
if (!nbytes)
return;
- len = min_t(ssize_t, 32, nbytes);
+ len = min_t(size_t, 32, nbytes);
crng_make_state(chacha_state, buf, len);
nbytes -= len;
buf += len;
@@ -1036,7 +1030,7 @@ static void _get_random_bytes(void *buf,
memzero_explicit(chacha_state, sizeof(chacha_state));
}
-void get_random_bytes(void *buf, int nbytes)
+void get_random_bytes(void *buf, size_t nbytes)
{
static void *previous;
@@ -1197,25 +1191,19 @@ EXPORT_SYMBOL(del_random_ready_callback)
/*
* This function will use the architecture-specific hardware random
- * number generator if it is available. The arch-specific hw RNG will
- * almost certainly be faster than what we can do in software, but it
- * is impossible to verify that it is implemented securely (as
- * opposed, to, say, the AES encryption of a sequence number using a
- * key known by the NSA). So it's useful if we need the speed, but
- * only if we're willing to trust the hardware manufacturer not to
- * have put in a back door.
- *
- * Return number of bytes filled in.
+ * number generator if it is available. It is not recommended for
+ * use. Use get_random_bytes() instead. It returns the number of
+ * bytes filled in.
*/
-int __must_check get_random_bytes_arch(void *buf, int nbytes)
+size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes)
{
- int left = nbytes;
+ size_t left = nbytes;
u8 *p = buf;
trace_get_random_bytes_arch(left, _RET_IP_);
while (left) {
unsigned long v;
- int chunk = min_t(int, left, sizeof(unsigned long));
+ size_t chunk = min_t(size_t, left, sizeof(unsigned long));
if (!arch_get_random_long(&v))
break;
@@ -1248,12 +1236,12 @@ early_param("random.trust_cpu", parse_tr
*/
int __init rand_initialize(void)
{
- int i;
+ size_t i;
ktime_t now = ktime_get_real();
bool arch_init = true;
unsigned long rv;
- for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) {
+ for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
if (!arch_get_random_seed_long_early(&rv) &&
!arch_get_random_long_early(&rv)) {
rv = random_get_entropy();
@@ -1302,7 +1290,7 @@ static ssize_t urandom_read_nowarn(struc
nbytes = min_t(size_t, nbytes, INT_MAX >> 6);
ret = get_random_bytes_user(buf, nbytes);
- trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count);
+ trace_urandom_read(nbytes, input_pool.entropy_count);
return ret;
}
@@ -1346,19 +1334,18 @@ static __poll_t random_poll(struct file
return mask;
}
-static int write_pool(const char __user *buffer, size_t count)
+static int write_pool(const char __user *ubuf, size_t count)
{
- size_t bytes;
- u8 buf[BLAKE2S_BLOCK_SIZE];
- const char __user *p = buffer;
-
- while (count > 0) {
- bytes = min(count, sizeof(buf));
- if (copy_from_user(buf, p, bytes))
+ size_t len;
+ u8 block[BLAKE2S_BLOCK_SIZE];
+
+ while (count) {
+ len = min(count, sizeof(block));
+ if (copy_from_user(block, ubuf, len))
return -EFAULT;
- count -= bytes;
- p += bytes;
- mix_pool_bytes(buf, bytes);
+ count -= len;
+ ubuf += len;
+ mix_pool_bytes(block, len);
cond_resched();
}
@@ -1368,7 +1355,7 @@ static int write_pool(const char __user
static ssize_t random_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
- size_t ret;
+ int ret;
ret = write_pool(buffer, count);
if (ret)
@@ -1464,8 +1451,6 @@ const struct file_operations urandom_fop
SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
flags)
{
- int ret;
-
if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
return -EINVAL;
@@ -1480,6 +1465,8 @@ SYSCALL_DEFINE3(getrandom, char __user *
count = INT_MAX;
if (!(flags & GRND_INSECURE) && !crng_ready()) {
+ int ret;
+
if (flags & GRND_NONBLOCK)
return -EAGAIN;
ret = wait_for_random_bytes();
@@ -1751,7 +1738,7 @@ unsigned long randomize_page(unsigned lo
* Those devices may produce endless random bits and will be throttled
* when our pool is full.
*/
-void add_hwgenerator_randomness(const char *buffer, size_t count,
+void add_hwgenerator_randomness(const void *buffer, size_t count,
size_t entropy)
{
if (unlikely(crng_init == 0)) {
@@ -1782,7 +1769,7 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_random
* it would be regarded as device data.
* The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
*/
-void add_bootloader_randomness(const void *buf, unsigned int size)
+void add_bootloader_randomness(const void *buf, size_t size)
{
if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
add_hwgenerator_randomness(buf, size, size * 8);
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -61,6 +61,6 @@ extern int devm_hwrng_register(struct de
extern void hwrng_unregister(struct hwrng *rng);
extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng);
/** Feed random bits into the pool. */
-extern void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy);
+extern void add_hwgenerator_randomness(const void *buffer, size_t count, size_t entropy);
#endif /* LINUX_HWRANDOM_H_ */
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -20,8 +20,8 @@ struct random_ready_callback {
struct module *owner;
};
-extern void add_device_randomness(const void *, unsigned int);
-extern void add_bootloader_randomness(const void *, unsigned int);
+extern void add_device_randomness(const void *, size_t);
+extern void add_bootloader_randomness(const void *, size_t);
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
static inline void add_latent_entropy(void)
@@ -37,13 +37,13 @@ extern void add_input_randomness(unsigne
unsigned int value) __latent_entropy;
extern void add_interrupt_randomness(int irq) __latent_entropy;
-extern void get_random_bytes(void *buf, int nbytes);
+extern void get_random_bytes(void *buf, size_t nbytes);
extern int wait_for_random_bytes(void);
extern int __init rand_initialize(void);
extern bool rng_is_initialized(void);
extern int add_random_ready_callback(struct random_ready_callback *rdy);
extern void del_random_ready_callback(struct random_ready_callback *rdy);
-extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
+extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
#ifndef MODULE
extern const struct file_operations random_fops, urandom_fops;
@@ -87,7 +87,7 @@ static inline unsigned long get_random_c
/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
* Returns the result of the call to wait_for_random_bytes. */
-static inline int get_random_bytes_wait(void *buf, int nbytes)
+static inline int get_random_bytes_wait(void *buf, size_t nbytes)
{
int ret = wait_for_random_bytes();
get_random_bytes(buf, nbytes);
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -9,13 +9,13 @@
#include <linux/tracepoint.h>
TRACE_EVENT(add_device_randomness,
- TP_PROTO(int bytes, unsigned long IP),
+ TP_PROTO(size_t bytes, unsigned long IP),
TP_ARGS(bytes, IP),
TP_STRUCT__entry(
- __field( int, bytes )
- __field(unsigned long, IP )
+ __field(size_t, bytes )
+ __field(unsigned long, IP )
),
TP_fast_assign(
@@ -23,18 +23,18 @@ TRACE_EVENT(add_device_randomness,
__entry->IP = IP;
),
- TP_printk("bytes %d caller %pS",
+ TP_printk("bytes %zu caller %pS",
__entry->bytes, (void *)__entry->IP)
);
DECLARE_EVENT_CLASS(random__mix_pool_bytes,
- TP_PROTO(int bytes, unsigned long IP),
+ TP_PROTO(size_t bytes, unsigned long IP),
TP_ARGS(bytes, IP),
TP_STRUCT__entry(
- __field( int, bytes )
- __field(unsigned long, IP )
+ __field(size_t, bytes )
+ __field(unsigned long, IP )
),
TP_fast_assign(
@@ -42,12 +42,12 @@ DECLARE_EVENT_CLASS(random__mix_pool_byt
__entry->IP = IP;
),
- TP_printk("input pool: bytes %d caller %pS",
+ TP_printk("input pool: bytes %zu caller %pS",
__entry->bytes, (void *)__entry->IP)
);
DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
- TP_PROTO(int bytes, unsigned long IP),
+ TP_PROTO(size_t bytes, unsigned long IP),
TP_ARGS(bytes, IP)
);
@@ -59,13 +59,13 @@ DEFINE_EVENT(random__mix_pool_bytes, mix
);
TRACE_EVENT(credit_entropy_bits,
- TP_PROTO(int bits, int entropy_count, unsigned long IP),
+ TP_PROTO(size_t bits, size_t entropy_count, unsigned long IP),
TP_ARGS(bits, entropy_count, IP),
TP_STRUCT__entry(
- __field( int, bits )
- __field( int, entropy_count )
+ __field(size_t, bits )
+ __field(size_t, entropy_count )
__field(unsigned long, IP )
),
@@ -75,34 +75,34 @@ TRACE_EVENT(credit_entropy_bits,
__entry->IP = IP;
),
- TP_printk("input pool: bits %d entropy_count %d caller %pS",
+ TP_printk("input pool: bits %zu entropy_count %zu caller %pS",
__entry->bits, __entry->entropy_count, (void *)__entry->IP)
);
TRACE_EVENT(add_input_randomness,
- TP_PROTO(int input_bits),
+ TP_PROTO(size_t input_bits),
TP_ARGS(input_bits),
TP_STRUCT__entry(
- __field( int, input_bits )
+ __field(size_t, input_bits )
),
TP_fast_assign(
__entry->input_bits = input_bits;
),
- TP_printk("input_pool_bits %d", __entry->input_bits)
+ TP_printk("input_pool_bits %zu", __entry->input_bits)
);
TRACE_EVENT(add_disk_randomness,
- TP_PROTO(dev_t dev, int input_bits),
+ TP_PROTO(dev_t dev, size_t input_bits),
TP_ARGS(dev, input_bits),
TP_STRUCT__entry(
- __field( dev_t, dev )
- __field( int, input_bits )
+ __field(dev_t, dev )
+ __field(size_t, input_bits )
),
TP_fast_assign(
@@ -110,17 +110,17 @@ TRACE_EVENT(add_disk_randomness,
__entry->input_bits = input_bits;
),
- TP_printk("dev %d,%d input_pool_bits %d", MAJOR(__entry->dev),
+ TP_printk("dev %d,%d input_pool_bits %zu", MAJOR(__entry->dev),
MINOR(__entry->dev), __entry->input_bits)
);
DECLARE_EVENT_CLASS(random__get_random_bytes,
- TP_PROTO(int nbytes, unsigned long IP),
+ TP_PROTO(size_t nbytes, unsigned long IP),
TP_ARGS(nbytes, IP),
TP_STRUCT__entry(
- __field( int, nbytes )
+ __field(size_t, nbytes )
__field(unsigned long, IP )
),
@@ -129,29 +129,29 @@ DECLARE_EVENT_CLASS(random__get_random_b
__entry->IP = IP;
),
- TP_printk("nbytes %d caller %pS", __entry->nbytes, (void *)__entry->IP)
+ TP_printk("nbytes %zu caller %pS", __entry->nbytes, (void *)__entry->IP)
);
DEFINE_EVENT(random__get_random_bytes, get_random_bytes,
- TP_PROTO(int nbytes, unsigned long IP),
+ TP_PROTO(size_t nbytes, unsigned long IP),
TP_ARGS(nbytes, IP)
);
DEFINE_EVENT(random__get_random_bytes, get_random_bytes_arch,
- TP_PROTO(int nbytes, unsigned long IP),
+ TP_PROTO(size_t nbytes, unsigned long IP),
TP_ARGS(nbytes, IP)
);
DECLARE_EVENT_CLASS(random__extract_entropy,
- TP_PROTO(int nbytes, int entropy_count),
+ TP_PROTO(size_t nbytes, size_t entropy_count),
TP_ARGS(nbytes, entropy_count),
TP_STRUCT__entry(
- __field( int, nbytes )
- __field( int, entropy_count )
+ __field( size_t, nbytes )
+ __field( size_t, entropy_count )
),
TP_fast_assign(
@@ -159,37 +159,34 @@ DECLARE_EVENT_CLASS(random__extract_entr
__entry->entropy_count = entropy_count;
),
- TP_printk("input pool: nbytes %d entropy_count %d",
+ TP_printk("input pool: nbytes %zu entropy_count %zu",
__entry->nbytes, __entry->entropy_count)
);
DEFINE_EVENT(random__extract_entropy, extract_entropy,
- TP_PROTO(int nbytes, int entropy_count),
+ TP_PROTO(size_t nbytes, size_t entropy_count),
TP_ARGS(nbytes, entropy_count)
);
TRACE_EVENT(urandom_read,
- TP_PROTO(int got_bits, int pool_left, int input_left),
+ TP_PROTO(size_t nbytes, size_t entropy_count),
- TP_ARGS(got_bits, pool_left, input_left),
+ TP_ARGS(nbytes, entropy_count),
TP_STRUCT__entry(
- __field( int, got_bits )
- __field( int, pool_left )
- __field( int, input_left )
+ __field( size_t, nbytes )
+ __field( size_t, entropy_count )
),
TP_fast_assign(
- __entry->got_bits = got_bits;
- __entry->pool_left = pool_left;
- __entry->input_left = input_left;
+ __entry->nbytes = nbytes;
+ __entry->entropy_count = entropy_count;
),
- TP_printk("got_bits %d nonblocking_pool_entropy_left %d "
- "input_entropy_left %d", __entry->got_bits,
- __entry->pool_left, __entry->input_left)
+ TP_printk("reading: nbytes %zu entropy_count %zu",
+ __entry->nbytes, __entry->entropy_count)
);
TRACE_EVENT(prandom_u32,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 020/111] random: remove outdated INT_MAX >> 6 check in urandom_read()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (18 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 019/111] random: make more consistent use of integer types Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 021/111] random: zero buffer after reading entropy from userspace Greg Kroah-Hartman
` (96 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jann Horn, Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 434537ae54ad37e93555de21b6ac8133d6d773a9 upstream.
In 79a8468747c5 ("random: check for increase of entropy_count because of
signed conversion"), a number of checks were added around what values
were passed to account(), because account() was doing fancy fixed point
fractional arithmetic, and a user had some ability to pass large values
directly into it. One of things in that commit was limiting those values
to INT_MAX >> 6. The first >> 3 was for bytes to bits, and the next >> 3
was for bits to 1/8 fractional bits.
However, for several years now, urandom reads no longer touch entropy
accounting, and so this check serves no purpose. The current flow is:
urandom_read_nowarn()-->get_random_bytes_user()-->chacha20_block()
Of course, we don't want that size_t to be truncated when adding it into
the ssize_t. But we arrive at urandom_read_nowarn() in the first place
either via ordinary fops, which limits reads to MAX_RW_COUNT, or via
getrandom() which limits reads to INT_MAX.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1286,9 +1286,8 @@ void rand_initialize_disk(struct gendisk
static ssize_t urandom_read_nowarn(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
- int ret;
+ ssize_t ret;
- nbytes = min_t(size_t, nbytes, INT_MAX >> 6);
ret = get_random_bytes_user(buf, nbytes);
trace_urandom_read(nbytes, input_pool.entropy_count);
return ret;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 021/111] random: zero buffer after reading entropy from userspace
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (19 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 020/111] random: remove outdated INT_MAX >> 6 check in urandom_read() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 022/111] random: fix locking for crng_init in crng_reseed() Greg Kroah-Hartman
` (95 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jann Horn,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 7b5164fb1279bf0251371848e40bae646b59b3a8 upstream.
This buffer may contain entropic data that shouldn't stick around longer
than needed, so zero out the temporary buffer at the end of write_pool().
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1336,19 +1336,24 @@ static __poll_t random_poll(struct file
static int write_pool(const char __user *ubuf, size_t count)
{
size_t len;
+ int ret = 0;
u8 block[BLAKE2S_BLOCK_SIZE];
while (count) {
len = min(count, sizeof(block));
- if (copy_from_user(block, ubuf, len))
- return -EFAULT;
+ if (copy_from_user(block, ubuf, len)) {
+ ret = -EFAULT;
+ goto out;
+ }
count -= len;
ubuf += len;
mix_pool_bytes(block, len);
cond_resched();
}
- return 0;
+out:
+ memzero_explicit(block, sizeof(block));
+ return ret;
}
static ssize_t random_write(struct file *file, const char __user *buffer,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 022/111] random: fix locking for crng_init in crng_reseed()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (20 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 021/111] random: zero buffer after reading entropy from userspace Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 023/111] random: tie batched entropy generation to base_crng generation Greg Kroah-Hartman
` (94 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Eric Biggers,
Jason A. Donenfeld
From: Dominik Brodowski <linux@dominikbrodowski.net>
commit 7191c628fe07b70d3f37de736d173d1b115396ed upstream.
crng_init is protected by primary_crng->lock. Therefore, we need
to hold this lock when increasing crng_init to 2. As we shouldn't
hold this lock for too long, only hold it for those parts which
require protection.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -502,6 +502,7 @@ static void crng_reseed(void)
int entropy_count;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
+ bool finalize_init = false;
/*
* First we make sure we have POOL_MIN_BITS of entropy in the pool,
@@ -529,12 +530,14 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- spin_unlock_irqrestore(&base_crng.lock, flags);
- memzero_explicit(key, sizeof(key));
-
if (crng_init < 2) {
invalidate_batched_entropy();
crng_init = 2;
+ finalize_init = true;
+ }
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ memzero_explicit(key, sizeof(key));
+ if (finalize_init) {
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 023/111] random: tie batched entropy generation to base_crng generation
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (21 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 022/111] random: fix locking for crng_init in crng_reseed() Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 024/111] random: remove ifdefd out interrupt bench Greg Kroah-Hartman
` (93 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 0791e8b655cc373718f0f58800fdc625a3447ac5 upstream.
Now that we have an explicit base_crng generation counter, we don't need
a separate one for batched entropy. Rather, we can just move the
generation forward every time we change crng_init state or update the
base_crng key.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 29 ++++++++---------------------
1 file changed, 8 insertions(+), 21 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -430,8 +430,6 @@ static DEFINE_PER_CPU(struct crng, crngs
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
-static void invalidate_batched_entropy(void);
-
/*
* crng_fast_load() can be called by code in the interrupt service
* path. So we can't afford to dilly-dally. Returns the number of
@@ -454,7 +452,7 @@ static size_t crng_fast_load(const void
src++; crng_init_cnt++; len--; ret++;
}
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- invalidate_batched_entropy();
+ ++base_crng.generation;
crng_init = 1;
}
spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -531,7 +529,6 @@ static void crng_reseed(void)
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
if (crng_init < 2) {
- invalidate_batched_entropy();
crng_init = 2;
finalize_init = true;
}
@@ -1256,8 +1253,9 @@ int __init rand_initialize(void)
mix_pool_bytes(utsname(), sizeof(*(utsname())));
extract_entropy(base_crng.key, sizeof(base_crng.key));
+ ++base_crng.generation;
+
if (arch_init && trust_cpu && crng_init < 2) {
- invalidate_batched_entropy();
crng_init = 2;
pr_notice("crng init done (trusting CPU's manufacturer)\n");
}
@@ -1607,8 +1605,6 @@ static int __init random_sysctls_init(vo
device_initcall(random_sysctls_init);
#endif /* CONFIG_SYSCTL */
-static atomic_t batch_generation = ATOMIC_INIT(0);
-
struct batched_entropy {
union {
/*
@@ -1622,8 +1618,8 @@ struct batched_entropy {
u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
};
local_lock_t lock;
+ unsigned long generation;
unsigned int position;
- int generation;
};
/*
@@ -1643,14 +1639,14 @@ u64 get_random_u64(void)
unsigned long flags;
struct batched_entropy *batch;
static void *previous;
- int next_gen;
+ unsigned long next_gen;
warn_unseeded_randomness(&previous);
local_lock_irqsave(&batched_entropy_u64.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u64);
- next_gen = atomic_read(&batch_generation);
+ next_gen = READ_ONCE(base_crng.generation);
if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
next_gen != batch->generation) {
_get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
@@ -1677,14 +1673,14 @@ u32 get_random_u32(void)
unsigned long flags;
struct batched_entropy *batch;
static void *previous;
- int next_gen;
+ unsigned long next_gen;
warn_unseeded_randomness(&previous);
local_lock_irqsave(&batched_entropy_u32.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u32);
- next_gen = atomic_read(&batch_generation);
+ next_gen = READ_ONCE(base_crng.generation);
if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
next_gen != batch->generation) {
_get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
@@ -1700,15 +1696,6 @@ u32 get_random_u32(void)
}
EXPORT_SYMBOL(get_random_u32);
-/* It's important to invalidate all potential batched entropy that might
- * be stored before the crng is initialized, which we can do lazily by
- * bumping the generation counter.
- */
-static void invalidate_batched_entropy(void)
-{
- atomic_inc(&batch_generation);
-}
-
/**
* randomize_page - Generate a random, page aligned address
* @start: The smallest acceptable address the caller will take.
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 024/111] random: remove ifdefd out interrupt bench
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (22 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 023/111] random: tie batched entropy generation to base_crng generation Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 025/111] random: remove unused tracepoints Greg Kroah-Hartman
` (92 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 95e6060c20a7f5db60163274c5222a725ac118f9 upstream.
With tools like kbench9000 giving more finegrained responses, and this
basically never having been used ever since it was initially added,
let's just get rid of this. There *is* still work to be done on the
interrupt handler, but this really isn't the way it's being developed.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/admin-guide/sysctl/kernel.rst | 9 ------
drivers/char/random.c | 40 ----------------------------
2 files changed, 49 deletions(-)
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1042,15 +1042,6 @@ This is a directory, with the following
are woken up. This file is writable for compatibility purposes, but
writing to it has no effect on any RNG behavior.
-If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH``
-defined, these additional entries are present:
-
-* ``add_interrupt_avg_cycles``: the average number of cycles between
- interrupts used to feed the pool;
-
-* ``add_interrupt_avg_deviation``: the standard deviation seen on the
- number of cycles between interrupts used to feed the pool.
-
randomize_va_space
==================
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -240,8 +240,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/random.h>
-/* #define ADD_INTERRUPT_BENCH */
-
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
@@ -808,27 +806,6 @@ EXPORT_SYMBOL_GPL(add_input_randomness);
static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
-#ifdef ADD_INTERRUPT_BENCH
-static unsigned long avg_cycles, avg_deviation;
-
-#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
-#define FIXED_1_2 (1 << (AVG_SHIFT - 1))
-
-static void add_interrupt_bench(cycles_t start)
-{
- long delta = random_get_entropy() - start;
-
- /* Use a weighted moving average */
- delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
- avg_cycles += delta;
- /* And average deviation */
- delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
- avg_deviation += delta;
-}
-#else
-#define add_interrupt_bench(x)
-#endif
-
static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
{
u32 *ptr = (u32 *)regs;
@@ -865,7 +842,6 @@ void add_interrupt_randomness(int irq)
(sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs);
fast_mix(fast_pool);
- add_interrupt_bench(cycles);
if (unlikely(crng_init == 0)) {
if (fast_pool->count >= 64 &&
@@ -1574,22 +1550,6 @@ static struct ctl_table random_table[] =
.mode = 0444,
.proc_handler = proc_do_uuid,
},
-#ifdef ADD_INTERRUPT_BENCH
- {
- .procname = "add_interrupt_avg_cycles",
- .data = &avg_cycles,
- .maxlen = sizeof(avg_cycles),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
- {
- .procname = "add_interrupt_avg_deviation",
- .data = &avg_deviation,
- .maxlen = sizeof(avg_deviation),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
-#endif
{ }
};
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 025/111] random: remove unused tracepoints
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (23 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 024/111] random: remove ifdefd out interrupt bench Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 026/111] random: add proper SPDX header Greg Kroah-Hartman
` (91 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 14c174633f349cb41ea90c2c0aaddac157012f74 upstream.
These explicit tracepoints aren't really used and show sign of aging.
It's work to keep these up to date, and before I attempted to keep them
up to date, they weren't up to date, which indicates that they're not
really used. These days there are better ways of introspecting anyway.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 30 -----
include/trace/events/random.h | 212 ------------------------------------------
lib/random32.c | 2
3 files changed, 3 insertions(+), 241 deletions(-)
delete mode 100644 include/trace/events/random.h
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -237,9 +237,6 @@
#include <asm/irq_regs.h>
#include <asm/io.h>
-#define CREATE_TRACE_POINTS
-#include <trace/events/random.h>
-
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
@@ -315,7 +312,6 @@ static void mix_pool_bytes(const void *i
{
unsigned long flags;
- trace_mix_pool_bytes(nbytes, _RET_IP_);
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(in, nbytes);
spin_unlock_irqrestore(&input_pool.lock, flags);
@@ -389,8 +385,6 @@ static void credit_entropy_bits(size_t n
entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
- trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_);
-
if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
crng_reseed();
}
@@ -721,7 +715,6 @@ void add_device_randomness(const void *b
if (!crng_ready() && size)
crng_slow_load(buf, size);
- trace_add_device_randomness(size, _RET_IP_);
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(buf, size);
_mix_pool_bytes(&time, sizeof(time));
@@ -800,7 +793,6 @@ void add_input_randomness(unsigned int t
last_value = value;
add_timer_randomness(&input_timer_state,
(type << 4) ^ code ^ (code >> 4) ^ value);
- trace_add_input_randomness(input_pool.entropy_count);
}
EXPORT_SYMBOL_GPL(add_input_randomness);
@@ -880,7 +872,6 @@ void add_disk_randomness(struct gendisk
return;
/* first major is 1, so we get >= 0x200 here */
add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
- trace_add_disk_randomness(disk_devt(disk), input_pool.entropy_count);
}
EXPORT_SYMBOL_GPL(add_disk_randomness);
#endif
@@ -905,8 +896,6 @@ static void extract_entropy(void *buf, s
} block;
size_t i;
- trace_extract_entropy(nbytes, input_pool.entropy_count);
-
for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
if (!arch_get_random_seed_long(&block.rdseed[i]) &&
!arch_get_random_long(&block.rdseed[i]))
@@ -978,8 +967,6 @@ static void _get_random_bytes(void *buf,
u8 tmp[CHACHA_BLOCK_SIZE];
size_t len;
- trace_get_random_bytes(nbytes, _RET_IP_);
-
if (!nbytes)
return;
@@ -1176,7 +1163,6 @@ size_t __must_check get_random_bytes_arc
size_t left = nbytes;
u8 *p = buf;
- trace_get_random_bytes_arch(left, _RET_IP_);
while (left) {
unsigned long v;
size_t chunk = min_t(size_t, left, sizeof(unsigned long));
@@ -1260,16 +1246,6 @@ void rand_initialize_disk(struct gendisk
}
#endif
-static ssize_t urandom_read_nowarn(struct file *file, char __user *buf,
- size_t nbytes, loff_t *ppos)
-{
- ssize_t ret;
-
- ret = get_random_bytes_user(buf, nbytes);
- trace_urandom_read(nbytes, input_pool.entropy_count);
- return ret;
-}
-
static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
loff_t *ppos)
{
@@ -1282,7 +1258,7 @@ static ssize_t urandom_read(struct file
current->comm, nbytes);
}
- return urandom_read_nowarn(file, buf, nbytes, ppos);
+ return get_random_bytes_user(buf, nbytes);
}
static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,
@@ -1293,7 +1269,7 @@ static ssize_t random_read(struct file *
ret = wait_for_random_bytes();
if (ret != 0)
return ret;
- return urandom_read_nowarn(file, buf, nbytes, ppos);
+ return get_random_bytes_user(buf, nbytes);
}
static __poll_t random_poll(struct file *file, poll_table *wait)
@@ -1454,7 +1430,7 @@ SYSCALL_DEFINE3(getrandom, char __user *
if (unlikely(ret))
return ret;
}
- return urandom_read_nowarn(NULL, buf, count, NULL);
+ return get_random_bytes_user(buf, count);
}
/********************************************************************
--- a/include/trace/events/random.h
+++ /dev/null
@@ -1,212 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#undef TRACE_SYSTEM
-#define TRACE_SYSTEM random
-
-#if !defined(_TRACE_RANDOM_H) || defined(TRACE_HEADER_MULTI_READ)
-#define _TRACE_RANDOM_H
-
-#include <linux/writeback.h>
-#include <linux/tracepoint.h>
-
-TRACE_EVENT(add_device_randomness,
- TP_PROTO(size_t bytes, unsigned long IP),
-
- TP_ARGS(bytes, IP),
-
- TP_STRUCT__entry(
- __field(size_t, bytes )
- __field(unsigned long, IP )
- ),
-
- TP_fast_assign(
- __entry->bytes = bytes;
- __entry->IP = IP;
- ),
-
- TP_printk("bytes %zu caller %pS",
- __entry->bytes, (void *)__entry->IP)
-);
-
-DECLARE_EVENT_CLASS(random__mix_pool_bytes,
- TP_PROTO(size_t bytes, unsigned long IP),
-
- TP_ARGS(bytes, IP),
-
- TP_STRUCT__entry(
- __field(size_t, bytes )
- __field(unsigned long, IP )
- ),
-
- TP_fast_assign(
- __entry->bytes = bytes;
- __entry->IP = IP;
- ),
-
- TP_printk("input pool: bytes %zu caller %pS",
- __entry->bytes, (void *)__entry->IP)
-);
-
-DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
- TP_PROTO(size_t bytes, unsigned long IP),
-
- TP_ARGS(bytes, IP)
-);
-
-DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock,
- TP_PROTO(int bytes, unsigned long IP),
-
- TP_ARGS(bytes, IP)
-);
-
-TRACE_EVENT(credit_entropy_bits,
- TP_PROTO(size_t bits, size_t entropy_count, unsigned long IP),
-
- TP_ARGS(bits, entropy_count, IP),
-
- TP_STRUCT__entry(
- __field(size_t, bits )
- __field(size_t, entropy_count )
- __field(unsigned long, IP )
- ),
-
- TP_fast_assign(
- __entry->bits = bits;
- __entry->entropy_count = entropy_count;
- __entry->IP = IP;
- ),
-
- TP_printk("input pool: bits %zu entropy_count %zu caller %pS",
- __entry->bits, __entry->entropy_count, (void *)__entry->IP)
-);
-
-TRACE_EVENT(add_input_randomness,
- TP_PROTO(size_t input_bits),
-
- TP_ARGS(input_bits),
-
- TP_STRUCT__entry(
- __field(size_t, input_bits )
- ),
-
- TP_fast_assign(
- __entry->input_bits = input_bits;
- ),
-
- TP_printk("input_pool_bits %zu", __entry->input_bits)
-);
-
-TRACE_EVENT(add_disk_randomness,
- TP_PROTO(dev_t dev, size_t input_bits),
-
- TP_ARGS(dev, input_bits),
-
- TP_STRUCT__entry(
- __field(dev_t, dev )
- __field(size_t, input_bits )
- ),
-
- TP_fast_assign(
- __entry->dev = dev;
- __entry->input_bits = input_bits;
- ),
-
- TP_printk("dev %d,%d input_pool_bits %zu", MAJOR(__entry->dev),
- MINOR(__entry->dev), __entry->input_bits)
-);
-
-DECLARE_EVENT_CLASS(random__get_random_bytes,
- TP_PROTO(size_t nbytes, unsigned long IP),
-
- TP_ARGS(nbytes, IP),
-
- TP_STRUCT__entry(
- __field(size_t, nbytes )
- __field(unsigned long, IP )
- ),
-
- TP_fast_assign(
- __entry->nbytes = nbytes;
- __entry->IP = IP;
- ),
-
- TP_printk("nbytes %zu caller %pS", __entry->nbytes, (void *)__entry->IP)
-);
-
-DEFINE_EVENT(random__get_random_bytes, get_random_bytes,
- TP_PROTO(size_t nbytes, unsigned long IP),
-
- TP_ARGS(nbytes, IP)
-);
-
-DEFINE_EVENT(random__get_random_bytes, get_random_bytes_arch,
- TP_PROTO(size_t nbytes, unsigned long IP),
-
- TP_ARGS(nbytes, IP)
-);
-
-DECLARE_EVENT_CLASS(random__extract_entropy,
- TP_PROTO(size_t nbytes, size_t entropy_count),
-
- TP_ARGS(nbytes, entropy_count),
-
- TP_STRUCT__entry(
- __field( size_t, nbytes )
- __field( size_t, entropy_count )
- ),
-
- TP_fast_assign(
- __entry->nbytes = nbytes;
- __entry->entropy_count = entropy_count;
- ),
-
- TP_printk("input pool: nbytes %zu entropy_count %zu",
- __entry->nbytes, __entry->entropy_count)
-);
-
-
-DEFINE_EVENT(random__extract_entropy, extract_entropy,
- TP_PROTO(size_t nbytes, size_t entropy_count),
-
- TP_ARGS(nbytes, entropy_count)
-);
-
-TRACE_EVENT(urandom_read,
- TP_PROTO(size_t nbytes, size_t entropy_count),
-
- TP_ARGS(nbytes, entropy_count),
-
- TP_STRUCT__entry(
- __field( size_t, nbytes )
- __field( size_t, entropy_count )
- ),
-
- TP_fast_assign(
- __entry->nbytes = nbytes;
- __entry->entropy_count = entropy_count;
- ),
-
- TP_printk("reading: nbytes %zu entropy_count %zu",
- __entry->nbytes, __entry->entropy_count)
-);
-
-TRACE_EVENT(prandom_u32,
-
- TP_PROTO(unsigned int ret),
-
- TP_ARGS(ret),
-
- TP_STRUCT__entry(
- __field( unsigned int, ret)
- ),
-
- TP_fast_assign(
- __entry->ret = ret;
- ),
-
- TP_printk("ret=%u" , __entry->ret)
-);
-
-#endif /* _TRACE_RANDOM_H */
-
-/* This part must be outside protection */
-#include <trace/define_trace.h>
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -41,7 +41,6 @@
#include <linux/bitops.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
-#include <trace/events/random.h>
/**
* prandom_u32_state - seeded pseudo-random number generator.
@@ -387,7 +386,6 @@ u32 prandom_u32(void)
struct siprand_state *state = get_cpu_ptr(&net_rand_state);
u32 res = siprand_u32(state);
- trace_prandom_u32(res);
put_cpu_ptr(&net_rand_state);
return res;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 026/111] random: add proper SPDX header
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (24 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 025/111] random: remove unused tracepoints Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:48 ` [PATCH 5.17 027/111] random: deobfuscate irq u32/u64 contributions Greg Kroah-Hartman
` (90 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Theodore Tso,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a07fdae346c35c6ba286af1c88e0effcfa330bf9 upstream.
Convert the current license into the SPDX notation of "(GPL-2.0 OR
BSD-3-Clause)". This infers GPL-2.0 from the text "ALTERNATIVELY, this
product may be distributed under the terms of the GNU General Public
License, in which case the provisions of the GPL are required INSTEAD OF
the above restrictions" and it infers BSD-3-Clause from the verbatim
BSD 3 clause license in the file.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 37 +------------------------------------
1 file changed, 1 insertion(+), 36 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1,44 +1,9 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/*
- * random.c -- A strong random number generator
- *
* Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
- *
* Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
- *
* Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
* rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, and the entire permission notice in its entirety,
- * including the disclaimer of warranties.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * ALTERNATIVELY, this product may be distributed under the terms of
- * the GNU General Public License, in which case the provisions of the GPL are
- * required INSTEAD OF the above restrictions. (This clause is
- * necessary due to a potential bad interaction between the GPL and
- * the restrictions contained in a BSD-style copyright.)
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
- * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
- * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
- * DAMAGE.
*/
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 027/111] random: deobfuscate irq u32/u64 contributions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (25 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 026/111] random: add proper SPDX header Greg Kroah-Hartman
@ 2022-05-27 8:48 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 028/111] random: introduce drain_entropy() helper to declutter crng_reseed() Greg Kroah-Hartman
` (89 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:48 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit b2f408fe403800c91a49f6589d95b6759ce1b30b upstream.
In the irq handler, we fill out 16 bytes differently on 32-bit and
64-bit platforms, and for 32-bit vs 64-bit cycle counters, which doesn't
always correspond with the bitness of the platform. Whether or not you
like this strangeness, it is a matter of fact. But it might not be a
fact you well realized until now, because the code that loaded the irq
info into 4 32-bit words was quite confusing. Instead, this commit
makes everything explicit by having separate (compile-time) branches for
32-bit and 64-bit types.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 49 ++++++++++++++++++++++++++++---------------------
1 file changed, 28 insertions(+), 21 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -283,7 +283,10 @@ static void mix_pool_bytes(const void *i
}
struct fast_pool {
- u32 pool[4];
+ union {
+ u32 pool32[4];
+ u64 pool64[2];
+ };
unsigned long last;
u16 reg_idx;
u8 count;
@@ -294,10 +297,10 @@ struct fast_pool {
* collector. It's hardcoded for an 128 bit pool and assumes that any
* locks that might be needed are taken by the caller.
*/
-static void fast_mix(struct fast_pool *f)
+static void fast_mix(u32 pool[4])
{
- u32 a = f->pool[0], b = f->pool[1];
- u32 c = f->pool[2], d = f->pool[3];
+ u32 a = pool[0], b = pool[1];
+ u32 c = pool[2], d = pool[3];
a += b; c += d;
b = rol32(b, 6); d = rol32(d, 27);
@@ -315,9 +318,8 @@ static void fast_mix(struct fast_pool *f
b = rol32(b, 16); d = rol32(d, 14);
d ^= a; b ^= c;
- f->pool[0] = a; f->pool[1] = b;
- f->pool[2] = c; f->pool[3] = d;
- f->count++;
+ pool[0] = a; pool[1] = b;
+ pool[2] = c; pool[3] = d;
}
static void process_random_ready_list(void)
@@ -784,29 +786,34 @@ void add_interrupt_randomness(int irq)
struct pt_regs *regs = get_irq_regs();
unsigned long now = jiffies;
cycles_t cycles = random_get_entropy();
- u32 c_high, j_high;
- u64 ip;
if (cycles == 0)
cycles = get_reg(fast_pool, regs);
- c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
- j_high = (sizeof(now) > 4) ? now >> 32 : 0;
- fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
- fast_pool->pool[1] ^= now ^ c_high;
- ip = regs ? instruction_pointer(regs) : _RET_IP_;
- fast_pool->pool[2] ^= ip;
- fast_pool->pool[3] ^=
- (sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs);
- fast_mix(fast_pool);
+ if (sizeof(cycles) == 8)
+ fast_pool->pool64[0] ^= cycles ^ rol64(now, 32) ^ irq;
+ else {
+ fast_pool->pool32[0] ^= cycles ^ irq;
+ fast_pool->pool32[1] ^= now;
+ }
+
+ if (sizeof(unsigned long) == 8)
+ fast_pool->pool64[1] ^= regs ? instruction_pointer(regs) : _RET_IP_;
+ else {
+ fast_pool->pool32[2] ^= regs ? instruction_pointer(regs) : _RET_IP_;
+ fast_pool->pool32[3] ^= get_reg(fast_pool, regs);
+ }
+
+ fast_mix(fast_pool->pool32);
+ ++fast_pool->count;
if (unlikely(crng_init == 0)) {
if (fast_pool->count >= 64 &&
- crng_fast_load(fast_pool->pool, sizeof(fast_pool->pool)) > 0) {
+ crng_fast_load(fast_pool->pool32, sizeof(fast_pool->pool32)) > 0) {
fast_pool->count = 0;
fast_pool->last = now;
if (spin_trylock(&input_pool.lock)) {
- _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
+ _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
spin_unlock(&input_pool.lock);
}
}
@@ -820,7 +827,7 @@ void add_interrupt_randomness(int irq)
return;
fast_pool->last = now;
- _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
+ _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
spin_unlock(&input_pool.lock);
fast_pool->count = 0;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 028/111] random: introduce drain_entropy() helper to declutter crng_reseed()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (26 preceding siblings ...)
2022-05-27 8:48 ` [PATCH 5.17 027/111] random: deobfuscate irq u32/u64 contributions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 029/111] random: remove useless header comment Greg Kroah-Hartman
` (88 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 246c03dd899164d0186b6d685d6387f228c28d93 upstream.
In preparation for separating responsibilities, break out the entropy
count management part of crng_reseed() into its own function.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 36 +++++++++++++++++++++++-------------
1 file changed, 23 insertions(+), 13 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -260,6 +260,7 @@ static struct {
};
static void extract_entropy(void *buf, size_t nbytes);
+static bool drain_entropy(void *buf, size_t nbytes);
static void crng_reseed(void);
@@ -456,23 +457,13 @@ static void crng_slow_load(const void *c
static void crng_reseed(void)
{
unsigned long flags;
- int entropy_count;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
bool finalize_init = false;
- /*
- * First we make sure we have POOL_MIN_BITS of entropy in the pool,
- * and then we drain all of it. Only then can we extract a new key.
- */
- do {
- entropy_count = READ_ONCE(input_pool.entropy_count);
- if (entropy_count < POOL_MIN_BITS)
- return;
- } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
- extract_entropy(key, sizeof(key));
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
+ /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */
+ if (!drain_entropy(key, sizeof(key)))
+ return;
/*
* We copy the new key into the base_crng, overwriting the old one,
@@ -900,6 +891,25 @@ static void extract_entropy(void *buf, s
memzero_explicit(&block, sizeof(block));
}
+/*
+ * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we
+ * set the entropy count to zero (but don't actually touch any data). Only then
+ * can we extract a new key with extract_entropy().
+ */
+static bool drain_entropy(void *buf, size_t nbytes)
+{
+ unsigned int entropy_count;
+ do {
+ entropy_count = READ_ONCE(input_pool.entropy_count);
+ if (entropy_count < POOL_MIN_BITS)
+ return false;
+ } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
+ extract_entropy(buf, nbytes);
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ return true;
+}
+
#define warn_unseeded_randomness(previous) \
_warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 029/111] random: remove useless header comment
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (27 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 028/111] random: introduce drain_entropy() helper to declutter crng_reseed() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 030/111] random: remove whitespace and reorder includes Greg Kroah-Hartman
` (87 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 6071a6c0fba2d747742cadcbb3ba26ed756ed73b upstream.
This really adds nothing at all useful.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/random.h | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -1,9 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * include/linux/random.h
- *
- * Include file for the random number generator.
- */
+
#ifndef _LINUX_RANDOM_H
#define _LINUX_RANDOM_H
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 030/111] random: remove whitespace and reorder includes
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (28 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 029/111] random: remove useless header comment Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 031/111] random: group initialization wait functions Greg Kroah-Hartman
` (86 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Eric Biggers,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 87e7d5abad0cbc9312dea7f889a57d294c1a5fcc upstream.
This is purely cosmetic. Future work involves figuring out which of
these headers we need and which we don't.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -193,11 +193,10 @@
#include <linux/syscalls.h>
#include <linux/completion.h>
#include <linux/uuid.h>
+#include <linux/uaccess.h>
#include <crypto/chacha.h>
#include <crypto/blake2s.h>
-
#include <asm/processor.h>
-#include <linux/uaccess.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/io.h>
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 031/111] random: group initialization wait functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (29 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 030/111] random: remove whitespace and reorder includes Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 032/111] random: group crng functions Greg Kroah-Hartman
` (85 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5f1bb112006b104b3e2a1e1b39bbb9b2617581e6 upstream.
This pulls all of the readiness waiting-focused functions into the first
labeled section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 333 +++++++++++++++++++++++++-------------------------
1 file changed, 172 insertions(+), 161 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -201,44 +201,197 @@
#include <asm/irq_regs.h>
#include <asm/io.h>
-enum {
- POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
-};
-
-/*
- * Static global variables
- */
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-static struct fasync_struct *fasync;
-
-static DEFINE_SPINLOCK(random_ready_list_lock);
-static LIST_HEAD(random_ready_list);
+/*********************************************************************
+ *
+ * Initialization and readiness waiting.
+ *
+ * Much of the RNG infrastructure is devoted to various dependencies
+ * being able to wait until the RNG has collected enough entropy and
+ * is ready for safe consumption.
+ *
+ *********************************************************************/
/*
* crng_init = 0 --> Uninitialized
* 1 --> Initialized
* 2 --> Initialized from input_pool
*
- * crng_init is protected by primary_crng->lock, and only increases
+ * crng_init is protected by base_crng->lock, and only increases
* its value (from 0->1->2).
*/
static int crng_init = 0;
#define crng_ready() (likely(crng_init > 1))
-static int crng_init_cnt = 0;
-static void process_random_ready_list(void);
-static void _get_random_bytes(void *buf, size_t nbytes);
+/* Various types of waiters for crng_init->2 transition. */
+static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
+static struct fasync_struct *fasync;
+static DEFINE_SPINLOCK(random_ready_list_lock);
+static LIST_HEAD(random_ready_list);
+/* Control how we warn userspace. */
static struct ratelimit_state unseeded_warning =
RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
static struct ratelimit_state urandom_warning =
RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
-
static int ratelimit_disable __read_mostly;
-
module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
+/*
+ * Returns whether or not the input pool has been seeded and thus guaranteed
+ * to supply cryptographically secure random numbers. This applies to: the
+ * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
+ * ,u64,int,long} family of functions.
+ *
+ * Returns: true if the input pool has been seeded.
+ * false if the input pool has not been seeded.
+ */
+bool rng_is_initialized(void)
+{
+ return crng_ready();
+}
+EXPORT_SYMBOL(rng_is_initialized);
+
+/* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
+static void try_to_generate_entropy(void);
+
+/*
+ * Wait for the input pool to be seeded and thus guaranteed to supply
+ * cryptographically secure random numbers. This applies to: the /dev/urandom
+ * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
+ * family of functions. Using any of these functions without first calling
+ * this function forfeits the guarantee of security.
+ *
+ * Returns: 0 if the input pool has been seeded.
+ * -ERESTARTSYS if the function was interrupted by a signal.
+ */
+int wait_for_random_bytes(void)
+{
+ if (likely(crng_ready()))
+ return 0;
+
+ do {
+ int ret;
+ ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
+ if (ret)
+ return ret > 0 ? 0 : ret;
+
+ try_to_generate_entropy();
+ } while (!crng_ready());
+
+ return 0;
+}
+EXPORT_SYMBOL(wait_for_random_bytes);
+
+/*
+ * Add a callback function that will be invoked when the input
+ * pool is initialised.
+ *
+ * returns: 0 if callback is successfully added
+ * -EALREADY if pool is already initialised (callback not called)
+ * -ENOENT if module for callback is not alive
+ */
+int add_random_ready_callback(struct random_ready_callback *rdy)
+{
+ struct module *owner;
+ unsigned long flags;
+ int err = -EALREADY;
+
+ if (crng_ready())
+ return err;
+
+ owner = rdy->owner;
+ if (!try_module_get(owner))
+ return -ENOENT;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ if (crng_ready())
+ goto out;
+
+ owner = NULL;
+
+ list_add(&rdy->list, &random_ready_list);
+ err = 0;
+
+out:
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+
+ module_put(owner);
+
+ return err;
+}
+EXPORT_SYMBOL(add_random_ready_callback);
+
+/*
+ * Delete a previously registered readiness callback function.
+ */
+void del_random_ready_callback(struct random_ready_callback *rdy)
+{
+ unsigned long flags;
+ struct module *owner = NULL;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ if (!list_empty(&rdy->list)) {
+ list_del_init(&rdy->list);
+ owner = rdy->owner;
+ }
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+
+ module_put(owner);
+}
+EXPORT_SYMBOL(del_random_ready_callback);
+
+static void process_random_ready_list(void)
+{
+ unsigned long flags;
+ struct random_ready_callback *rdy, *tmp;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
+ struct module *owner = rdy->owner;
+
+ list_del_init(&rdy->list);
+ rdy->func(rdy);
+ module_put(owner);
+ }
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+}
+
+#define warn_unseeded_randomness(previous) \
+ _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
+
+static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
+{
+#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
+ const bool print_once = false;
+#else
+ static bool print_once __read_mostly;
+#endif
+
+ if (print_once || crng_ready() ||
+ (previous && (caller == READ_ONCE(*previous))))
+ return;
+ WRITE_ONCE(*previous, caller);
+#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
+ print_once = true;
+#endif
+ if (__ratelimit(&unseeded_warning))
+ printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
+ func_name, caller, crng_init);
+}
+
+
+enum {
+ POOL_BITS = BLAKE2S_HASH_SIZE * 8,
+ POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
+};
+
+/*
+ * Static global variables
+ */
+static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+
+static int crng_init_cnt = 0;
+
/**********************************************************************
*
* OS independent entropy store. Here are the functions which handle
@@ -322,22 +475,6 @@ static void fast_mix(u32 pool[4])
pool[2] = c; pool[3] = d;
}
-static void process_random_ready_list(void)
-{
- unsigned long flags;
- struct random_ready_callback *rdy, *tmp;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
- struct module *owner = rdy->owner;
-
- list_del_init(&rdy->list);
- rdy->func(rdy);
- module_put(owner);
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
-}
-
static void credit_entropy_bits(size_t nbits)
{
unsigned int entropy_count, orig, add;
@@ -387,8 +524,6 @@ static DEFINE_PER_CPU(struct crng, crngs
.lock = INIT_LOCAL_LOCK(crngs.lock),
};
-static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
-
/*
* crng_fast_load() can be called by code in the interrupt service
* path. So we can't afford to dilly-dally. Returns the number of
@@ -909,29 +1044,6 @@ static bool drain_entropy(void *buf, siz
return true;
}
-#define warn_unseeded_randomness(previous) \
- _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
-
-static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
-{
-#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- const bool print_once = false;
-#else
- static bool print_once __read_mostly;
-#endif
-
- if (print_once || crng_ready() ||
- (previous && (caller == READ_ONCE(*previous))))
- return;
- WRITE_ONCE(*previous, caller);
-#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- print_once = true;
-#endif
- if (__ratelimit(&unseeded_warning))
- printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
- func_name, caller, crng_init);
-}
-
/*
* This function is the exported kernel interface. It returns some
* number of good random numbers, suitable for key generation, seeding
@@ -1033,107 +1145,6 @@ static void try_to_generate_entropy(void
}
/*
- * Wait for the urandom pool to be seeded and thus guaranteed to supply
- * cryptographically secure random numbers. This applies to: the /dev/urandom
- * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
- * family of functions. Using any of these functions without first calling
- * this function forfeits the guarantee of security.
- *
- * Returns: 0 if the urandom pool has been seeded.
- * -ERESTARTSYS if the function was interrupted by a signal.
- */
-int wait_for_random_bytes(void)
-{
- if (likely(crng_ready()))
- return 0;
-
- do {
- int ret;
- ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
- if (ret)
- return ret > 0 ? 0 : ret;
-
- try_to_generate_entropy();
- } while (!crng_ready());
-
- return 0;
-}
-EXPORT_SYMBOL(wait_for_random_bytes);
-
-/*
- * Returns whether or not the urandom pool has been seeded and thus guaranteed
- * to supply cryptographically secure random numbers. This applies to: the
- * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
- * ,u64,int,long} family of functions.
- *
- * Returns: true if the urandom pool has been seeded.
- * false if the urandom pool has not been seeded.
- */
-bool rng_is_initialized(void)
-{
- return crng_ready();
-}
-EXPORT_SYMBOL(rng_is_initialized);
-
-/*
- * Add a callback function that will be invoked when the nonblocking
- * pool is initialised.
- *
- * returns: 0 if callback is successfully added
- * -EALREADY if pool is already initialised (callback not called)
- * -ENOENT if module for callback is not alive
- */
-int add_random_ready_callback(struct random_ready_callback *rdy)
-{
- struct module *owner;
- unsigned long flags;
- int err = -EALREADY;
-
- if (crng_ready())
- return err;
-
- owner = rdy->owner;
- if (!try_module_get(owner))
- return -ENOENT;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (crng_ready())
- goto out;
-
- owner = NULL;
-
- list_add(&rdy->list, &random_ready_list);
- err = 0;
-
-out:
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
-
- module_put(owner);
-
- return err;
-}
-EXPORT_SYMBOL(add_random_ready_callback);
-
-/*
- * Delete a previously registered readiness callback function.
- */
-void del_random_ready_callback(struct random_ready_callback *rdy)
-{
- unsigned long flags;
- struct module *owner = NULL;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (!list_empty(&rdy->list)) {
- list_del_init(&rdy->list);
- owner = rdy->owner;
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
-
- module_put(owner);
-}
-EXPORT_SYMBOL(del_random_ready_callback);
-
-/*
* This function will use the architecture-specific hardware random
* number generator if it is available. It is not recommended for
* use. Use get_random_bytes() instead. It returns the number of
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 032/111] random: group crng functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (30 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 031/111] random: group initialization wait functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 033/111] random: group entropy extraction functions Greg Kroah-Hartman
` (84 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 3655adc7089da4f8ca74cec8fcef73ea5101430e upstream.
This pulls all of the crng-focused functions into the second labeled
section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 792 +++++++++++++++++++++++++-------------------------
1 file changed, 410 insertions(+), 382 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -380,122 +380,27 @@ static void _warn_unseeded_randomness(co
}
-enum {
- POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
-};
-
-/*
- * Static global variables
- */
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-
-static int crng_init_cnt = 0;
-
-/**********************************************************************
+/*********************************************************************
*
- * OS independent entropy store. Here are the functions which handle
- * storing entropy in an entropy pool.
+ * Fast key erasure RNG, the "crng".
*
- **********************************************************************/
-
-static struct {
- struct blake2s_state hash;
- spinlock_t lock;
- unsigned int entropy_count;
-} input_pool = {
- .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
- BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
- BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 },
- .hash.outlen = BLAKE2S_HASH_SIZE,
- .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
-};
-
-static void extract_entropy(void *buf, size_t nbytes);
-static bool drain_entropy(void *buf, size_t nbytes);
-
-static void crng_reseed(void);
-
-/*
- * This function adds bytes into the entropy "pool". It does not
- * update the entropy estimate. The caller should call
- * credit_entropy_bits if this is appropriate.
- */
-static void _mix_pool_bytes(const void *in, size_t nbytes)
-{
- blake2s_update(&input_pool.hash, in, nbytes);
-}
-
-static void mix_pool_bytes(const void *in, size_t nbytes)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(in, nbytes);
- spin_unlock_irqrestore(&input_pool.lock, flags);
-}
-
-struct fast_pool {
- union {
- u32 pool32[4];
- u64 pool64[2];
- };
- unsigned long last;
- u16 reg_idx;
- u8 count;
-};
-
-/*
- * This is a fast mixing routine used by the interrupt randomness
- * collector. It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
- */
-static void fast_mix(u32 pool[4])
-{
- u32 a = pool[0], b = pool[1];
- u32 c = pool[2], d = pool[3];
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
-
- pool[0] = a; pool[1] = b;
- pool[2] = c; pool[3] = d;
-}
-
-static void credit_entropy_bits(size_t nbits)
-{
- unsigned int entropy_count, orig, add;
-
- if (!nbits)
- return;
-
- add = min_t(size_t, nbits, POOL_BITS);
-
- do {
- orig = READ_ONCE(input_pool.entropy_count);
- entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
- } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
-
- if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
- crng_reseed();
-}
-
-/*********************************************************************
+ * These functions expand entropy from the entropy extractor into
+ * long streams for external consumption using the "fast key erasure"
+ * RNG described at <https://blog.cr.yp.to/20170723-random.html>.
+ *
+ * There are a few exported interfaces for use by other drivers:
*
- * CRNG using CHACHA20
+ * void get_random_bytes(void *buf, size_t nbytes)
+ * u32 get_random_u32()
+ * u64 get_random_u64()
+ * unsigned int get_random_int()
+ * unsigned long get_random_long()
+ *
+ * These interfaces will return the requested number of random bytes
+ * into the given buffer or as a return value. This is equivalent to
+ * a read from /dev/urandom. The integer family of functions may be
+ * higher performance for one-off random integers, because they do a
+ * bit of buffering.
*
*********************************************************************/
@@ -524,70 +429,14 @@ static DEFINE_PER_CPU(struct crng, crngs
.lock = INIT_LOCAL_LOCK(crngs.lock),
};
-/*
- * crng_fast_load() can be called by code in the interrupt service
- * path. So we can't afford to dilly-dally. Returns the number of
- * bytes processed from cp.
- */
-static size_t crng_fast_load(const void *cp, size_t len)
-{
- unsigned long flags;
- const u8 *src = (const u8 *)cp;
- size_t ret = 0;
-
- if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return 0;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&base_crng.lock, flags);
- return 0;
- }
- while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src;
- src++; crng_init_cnt++; len--; ret++;
- }
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- ++base_crng.generation;
- crng_init = 1;
- }
- spin_unlock_irqrestore(&base_crng.lock, flags);
- if (crng_init == 1)
- pr_notice("fast init done\n");
- return ret;
-}
+/* Used by crng_reseed() to extract a new seed from the input pool. */
+static bool drain_entropy(void *buf, size_t nbytes);
/*
- * crng_slow_load() is called by add_device_randomness, which has two
- * attributes. (1) We can't trust the buffer passed to it is
- * guaranteed to be unpredictable (so it might not have any entropy at
- * all), and (2) it doesn't have the performance constraints of
- * crng_fast_load().
- *
- * So, we simply hash the contents in with the current key. Finally,
- * we do *not* advance crng_init_cnt since buffer we may get may be
- * something like a fixed DMI table (for example), which might very
- * well be unique to the machine, but is otherwise unvarying.
+ * This extracts a new crng key from the input pool, but only if there is a
+ * sufficient amount of entropy available, in order to mitigate bruteforcing
+ * of newly added bits.
*/
-static void crng_slow_load(const void *cp, size_t len)
-{
- unsigned long flags;
- struct blake2s_state hash;
-
- blake2s_init(&hash, sizeof(base_crng.key));
-
- if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&base_crng.lock, flags);
- return;
- }
-
- blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
- blake2s_update(&hash, cp, len);
- blake2s_final(&hash, base_crng.key);
-
- spin_unlock_irqrestore(&base_crng.lock, flags);
-}
-
static void crng_reseed(void)
{
unsigned long flags;
@@ -637,13 +486,11 @@ static void crng_reseed(void)
}
/*
- * The general form here is based on a "fast key erasure RNG" from
- * <https://blog.cr.yp.to/20170723-random.html>. It generates a ChaCha
- * block using the provided key, and then immediately overwites that
- * key with half the block. It returns the resultant ChaCha state to the
- * user, along with the second half of the block containing 32 bytes of
- * random data that may be used; random_data_len may not be greater than
- * 32.
+ * This generates a ChaCha block using the provided key, and then
+ * immediately overwites that key with half the block. It returns
+ * the resultant ChaCha state to the user, along with the second
+ * half of the block containing 32 bytes of random data that may
+ * be used; random_data_len may not be greater than 32.
*/
static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
u32 chacha_state[CHACHA_STATE_WORDS],
@@ -730,6 +577,126 @@ static void crng_make_state(u32 chacha_s
local_unlock_irqrestore(&crngs.lock, flags);
}
+/*
+ * This function is for crng_init == 0 only.
+ *
+ * crng_fast_load() can be called by code in the interrupt service
+ * path. So we can't afford to dilly-dally. Returns the number of
+ * bytes processed from cp.
+ */
+static size_t crng_fast_load(const void *cp, size_t len)
+{
+ static int crng_init_cnt = 0;
+ unsigned long flags;
+ const u8 *src = (const u8 *)cp;
+ size_t ret = 0;
+
+ if (!spin_trylock_irqsave(&base_crng.lock, flags))
+ return 0;
+ if (crng_init != 0) {
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ return 0;
+ }
+ while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
+ base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src;
+ src++; crng_init_cnt++; len--; ret++;
+ }
+ if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
+ ++base_crng.generation;
+ crng_init = 1;
+ }
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ if (crng_init == 1)
+ pr_notice("fast init done\n");
+ return ret;
+}
+
+/*
+ * This function is for crng_init == 0 only.
+ *
+ * crng_slow_load() is called by add_device_randomness, which has two
+ * attributes. (1) We can't trust the buffer passed to it is
+ * guaranteed to be unpredictable (so it might not have any entropy at
+ * all), and (2) it doesn't have the performance constraints of
+ * crng_fast_load().
+ *
+ * So, we simply hash the contents in with the current key. Finally,
+ * we do *not* advance crng_init_cnt since buffer we may get may be
+ * something like a fixed DMI table (for example), which might very
+ * well be unique to the machine, but is otherwise unvarying.
+ */
+static void crng_slow_load(const void *cp, size_t len)
+{
+ unsigned long flags;
+ struct blake2s_state hash;
+
+ blake2s_init(&hash, sizeof(base_crng.key));
+
+ if (!spin_trylock_irqsave(&base_crng.lock, flags))
+ return;
+ if (crng_init != 0) {
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ return;
+ }
+
+ blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
+ blake2s_update(&hash, cp, len);
+ blake2s_final(&hash, base_crng.key);
+
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+}
+
+static void _get_random_bytes(void *buf, size_t nbytes)
+{
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ u8 tmp[CHACHA_BLOCK_SIZE];
+ size_t len;
+
+ if (!nbytes)
+ return;
+
+ len = min_t(size_t, 32, nbytes);
+ crng_make_state(chacha_state, buf, len);
+ nbytes -= len;
+ buf += len;
+
+ while (nbytes) {
+ if (nbytes < CHACHA_BLOCK_SIZE) {
+ chacha20_block(chacha_state, tmp);
+ memcpy(buf, tmp, nbytes);
+ memzero_explicit(tmp, sizeof(tmp));
+ break;
+ }
+
+ chacha20_block(chacha_state, buf);
+ if (unlikely(chacha_state[12] == 0))
+ ++chacha_state[13];
+ nbytes -= CHACHA_BLOCK_SIZE;
+ buf += CHACHA_BLOCK_SIZE;
+ }
+
+ memzero_explicit(chacha_state, sizeof(chacha_state));
+}
+
+/*
+ * This function is the exported kernel interface. It returns some
+ * number of good random numbers, suitable for key generation, seeding
+ * TCP sequence numbers, etc. It does not rely on the hardware random
+ * number generator. For random bytes direct from the hardware RNG
+ * (when available), use get_random_bytes_arch(). In order to ensure
+ * that the randomness provided by this function is okay, the function
+ * wait_for_random_bytes() should be called and return 0 at least once
+ * at any point prior.
+ */
+void get_random_bytes(void *buf, size_t nbytes)
+{
+ static void *previous;
+
+ warn_unseeded_randomness(&previous);
+ _get_random_bytes(buf, nbytes);
+}
+EXPORT_SYMBOL(get_random_bytes);
+
static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
{
bool large_request = nbytes > 256;
@@ -777,6 +744,268 @@ static ssize_t get_random_bytes_user(voi
return ret;
}
+/*
+ * Batched entropy returns random integers. The quality of the random
+ * number is good as /dev/urandom. In order to ensure that the randomness
+ * provided by this function is okay, the function wait_for_random_bytes()
+ * should be called and return 0 at least once at any point prior.
+ */
+struct batched_entropy {
+ union {
+ /*
+ * We make this 1.5x a ChaCha block, so that we get the
+ * remaining 32 bytes from fast key erasure, plus one full
+ * block from the detached ChaCha state. We can increase
+ * the size of this later if needed so long as we keep the
+ * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.
+ */
+ u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))];
+ u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
+ };
+ local_lock_t lock;
+ unsigned long generation;
+ unsigned int position;
+};
+
+
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock),
+ .position = UINT_MAX
+};
+
+u64 get_random_u64(void)
+{
+ u64 ret;
+ unsigned long flags;
+ struct batched_entropy *batch;
+ static void *previous;
+ unsigned long next_gen;
+
+ warn_unseeded_randomness(&previous);
+
+ local_lock_irqsave(&batched_entropy_u64.lock, flags);
+ batch = raw_cpu_ptr(&batched_entropy_u64);
+
+ next_gen = READ_ONCE(base_crng.generation);
+ if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
+ next_gen != batch->generation) {
+ _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
+ batch->position = 0;
+ batch->generation = next_gen;
+ }
+
+ ret = batch->entropy_u64[batch->position];
+ batch->entropy_u64[batch->position] = 0;
+ ++batch->position;
+ local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(get_random_u64);
+
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
+ .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock),
+ .position = UINT_MAX
+};
+
+u32 get_random_u32(void)
+{
+ u32 ret;
+ unsigned long flags;
+ struct batched_entropy *batch;
+ static void *previous;
+ unsigned long next_gen;
+
+ warn_unseeded_randomness(&previous);
+
+ local_lock_irqsave(&batched_entropy_u32.lock, flags);
+ batch = raw_cpu_ptr(&batched_entropy_u32);
+
+ next_gen = READ_ONCE(base_crng.generation);
+ if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
+ next_gen != batch->generation) {
+ _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
+ batch->position = 0;
+ batch->generation = next_gen;
+ }
+
+ ret = batch->entropy_u32[batch->position];
+ batch->entropy_u32[batch->position] = 0;
+ ++batch->position;
+ local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(get_random_u32);
+
+/**
+ * randomize_page - Generate a random, page aligned address
+ * @start: The smallest acceptable address the caller will take.
+ * @range: The size of the area, starting at @start, within which the
+ * random address must fall.
+ *
+ * If @start + @range would overflow, @range is capped.
+ *
+ * NOTE: Historical use of randomize_range, which this replaces, presumed that
+ * @start was already page aligned. We now align it regardless.
+ *
+ * Return: A page aligned address within [start, start + range). On error,
+ * @start is returned.
+ */
+unsigned long randomize_page(unsigned long start, unsigned long range)
+{
+ if (!PAGE_ALIGNED(start)) {
+ range -= PAGE_ALIGN(start) - start;
+ start = PAGE_ALIGN(start);
+ }
+
+ if (start > ULONG_MAX - range)
+ range = ULONG_MAX - start;
+
+ range >>= PAGE_SHIFT;
+
+ if (range == 0)
+ return start;
+
+ return start + (get_random_long() % range << PAGE_SHIFT);
+}
+
+/*
+ * This function will use the architecture-specific hardware random
+ * number generator if it is available. It is not recommended for
+ * use. Use get_random_bytes() instead. It returns the number of
+ * bytes filled in.
+ */
+size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes)
+{
+ size_t left = nbytes;
+ u8 *p = buf;
+
+ while (left) {
+ unsigned long v;
+ size_t chunk = min_t(size_t, left, sizeof(unsigned long));
+
+ if (!arch_get_random_long(&v))
+ break;
+
+ memcpy(p, &v, chunk);
+ p += chunk;
+ left -= chunk;
+ }
+
+ return nbytes - left;
+}
+EXPORT_SYMBOL(get_random_bytes_arch);
+
+enum {
+ POOL_BITS = BLAKE2S_HASH_SIZE * 8,
+ POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
+};
+
+/*
+ * Static global variables
+ */
+static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+
+/**********************************************************************
+ *
+ * OS independent entropy store. Here are the functions which handle
+ * storing entropy in an entropy pool.
+ *
+ **********************************************************************/
+
+static struct {
+ struct blake2s_state hash;
+ spinlock_t lock;
+ unsigned int entropy_count;
+} input_pool = {
+ .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
+ BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
+ BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 },
+ .hash.outlen = BLAKE2S_HASH_SIZE,
+ .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
+};
+
+static void extract_entropy(void *buf, size_t nbytes);
+static bool drain_entropy(void *buf, size_t nbytes);
+
+static void crng_reseed(void);
+
+/*
+ * This function adds bytes into the entropy "pool". It does not
+ * update the entropy estimate. The caller should call
+ * credit_entropy_bits if this is appropriate.
+ */
+static void _mix_pool_bytes(const void *in, size_t nbytes)
+{
+ blake2s_update(&input_pool.hash, in, nbytes);
+}
+
+static void mix_pool_bytes(const void *in, size_t nbytes)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(in, nbytes);
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+}
+
+struct fast_pool {
+ union {
+ u32 pool32[4];
+ u64 pool64[2];
+ };
+ unsigned long last;
+ u16 reg_idx;
+ u8 count;
+};
+
+/*
+ * This is a fast mixing routine used by the interrupt randomness
+ * collector. It's hardcoded for an 128 bit pool and assumes that any
+ * locks that might be needed are taken by the caller.
+ */
+static void fast_mix(u32 pool[4])
+{
+ u32 a = pool[0], b = pool[1];
+ u32 c = pool[2], d = pool[3];
+
+ a += b; c += d;
+ b = rol32(b, 6); d = rol32(d, 27);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 16); d = rol32(d, 14);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 6); d = rol32(d, 27);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 16); d = rol32(d, 14);
+ d ^= a; b ^= c;
+
+ pool[0] = a; pool[1] = b;
+ pool[2] = c; pool[3] = d;
+}
+
+static void credit_entropy_bits(size_t nbits)
+{
+ unsigned int entropy_count, orig, add;
+
+ if (!nbits)
+ return;
+
+ add = min_t(size_t, nbits, POOL_BITS);
+
+ do {
+ orig = READ_ONCE(input_pool.entropy_count);
+ entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
+
+ if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
+ crng_reseed();
+}
+
/*********************************************************************
*
* Entropy input management
@@ -1045,57 +1274,6 @@ static bool drain_entropy(void *buf, siz
}
/*
- * This function is the exported kernel interface. It returns some
- * number of good random numbers, suitable for key generation, seeding
- * TCP sequence numbers, etc. It does not rely on the hardware random
- * number generator. For random bytes direct from the hardware RNG
- * (when available), use get_random_bytes_arch(). In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once
- * at any point prior.
- */
-static void _get_random_bytes(void *buf, size_t nbytes)
-{
- u32 chacha_state[CHACHA_STATE_WORDS];
- u8 tmp[CHACHA_BLOCK_SIZE];
- size_t len;
-
- if (!nbytes)
- return;
-
- len = min_t(size_t, 32, nbytes);
- crng_make_state(chacha_state, buf, len);
- nbytes -= len;
- buf += len;
-
- while (nbytes) {
- if (nbytes < CHACHA_BLOCK_SIZE) {
- chacha20_block(chacha_state, tmp);
- memcpy(buf, tmp, nbytes);
- memzero_explicit(tmp, sizeof(tmp));
- break;
- }
-
- chacha20_block(chacha_state, buf);
- if (unlikely(chacha_state[12] == 0))
- ++chacha_state[13];
- nbytes -= CHACHA_BLOCK_SIZE;
- buf += CHACHA_BLOCK_SIZE;
- }
-
- memzero_explicit(chacha_state, sizeof(chacha_state));
-}
-
-void get_random_bytes(void *buf, size_t nbytes)
-{
- static void *previous;
-
- warn_unseeded_randomness(&previous);
- _get_random_bytes(buf, nbytes);
-}
-EXPORT_SYMBOL(get_random_bytes);
-
-/*
* Each time the timer fires, we expect that we got an unpredictable
* jump in the cycle counter. Even if the timer is running on another
* CPU, the timer activity will be touching the stack of the CPU that is
@@ -1144,33 +1322,6 @@ static void try_to_generate_entropy(void
mix_pool_bytes(&stack.now, sizeof(stack.now));
}
-/*
- * This function will use the architecture-specific hardware random
- * number generator if it is available. It is not recommended for
- * use. Use get_random_bytes() instead. It returns the number of
- * bytes filled in.
- */
-size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes)
-{
- size_t left = nbytes;
- u8 *p = buf;
-
- while (left) {
- unsigned long v;
- size_t chunk = min_t(size_t, left, sizeof(unsigned long));
-
- if (!arch_get_random_long(&v))
- break;
-
- memcpy(p, &v, chunk);
- p += chunk;
- left -= chunk;
- }
-
- return nbytes - left;
-}
-EXPORT_SYMBOL(get_random_bytes_arch);
-
static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
static int __init parse_trust_cpu(char *arg)
{
@@ -1533,129 +1684,6 @@ static int __init random_sysctls_init(vo
device_initcall(random_sysctls_init);
#endif /* CONFIG_SYSCTL */
-struct batched_entropy {
- union {
- /*
- * We make this 1.5x a ChaCha block, so that we get the
- * remaining 32 bytes from fast key erasure, plus one full
- * block from the detached ChaCha state. We can increase
- * the size of this later if needed so long as we keep the
- * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.
- */
- u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))];
- u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
- };
- local_lock_t lock;
- unsigned long generation;
- unsigned int position;
-};
-
-/*
- * Get a random word for internal kernel use only. The quality of the random
- * number is good as /dev/urandom. In order to ensure that the randomness
- * provided by this function is okay, the function wait_for_random_bytes()
- * should be called and return 0 at least once at any point prior.
- */
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock),
- .position = UINT_MAX
-};
-
-u64 get_random_u64(void)
-{
- u64 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
- unsigned long next_gen;
-
- warn_unseeded_randomness(&previous);
-
- local_lock_irqsave(&batched_entropy_u64.lock, flags);
- batch = raw_cpu_ptr(&batched_entropy_u64);
-
- next_gen = READ_ONCE(base_crng.generation);
- if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
- next_gen != batch->generation) {
- _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
- batch->position = 0;
- batch->generation = next_gen;
- }
-
- ret = batch->entropy_u64[batch->position];
- batch->entropy_u64[batch->position] = 0;
- ++batch->position;
- local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u64);
-
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock),
- .position = UINT_MAX
-};
-
-u32 get_random_u32(void)
-{
- u32 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
- unsigned long next_gen;
-
- warn_unseeded_randomness(&previous);
-
- local_lock_irqsave(&batched_entropy_u32.lock, flags);
- batch = raw_cpu_ptr(&batched_entropy_u32);
-
- next_gen = READ_ONCE(base_crng.generation);
- if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
- next_gen != batch->generation) {
- _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
- batch->position = 0;
- batch->generation = next_gen;
- }
-
- ret = batch->entropy_u32[batch->position];
- batch->entropy_u32[batch->position] = 0;
- ++batch->position;
- local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u32);
-
-/**
- * randomize_page - Generate a random, page aligned address
- * @start: The smallest acceptable address the caller will take.
- * @range: The size of the area, starting at @start, within which the
- * random address must fall.
- *
- * If @start + @range would overflow, @range is capped.
- *
- * NOTE: Historical use of randomize_range, which this replaces, presumed that
- * @start was already page aligned. We now align it regardless.
- *
- * Return: A page aligned address within [start, start + range). On error,
- * @start is returned.
- */
-unsigned long randomize_page(unsigned long start, unsigned long range)
-{
- if (!PAGE_ALIGNED(start)) {
- range -= PAGE_ALIGN(start) - start;
- start = PAGE_ALIGN(start);
- }
-
- if (start > ULONG_MAX - range)
- range = ULONG_MAX - start;
-
- range >>= PAGE_SHIFT;
-
- if (range == 0)
- return start;
-
- return start + (get_random_long() % range << PAGE_SHIFT);
-}
-
/* Interface for in-kernel drivers of true hardware RNGs.
* Those devices may produce endless random bits and will be throttled
* when our pool is full.
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 033/111] random: group entropy extraction functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (31 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 032/111] random: group crng functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 034/111] random: group entropy collection functions Greg Kroah-Hartman
` (83 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a5ed7cb1a7732ef11959332d507889fbc39ebbb4 upstream.
This pulls all of the entropy extraction-focused functions into the
third labeled section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 216 +++++++++++++++++++++++++-------------------------
1 file changed, 109 insertions(+), 107 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -895,23 +895,36 @@ size_t __must_check get_random_bytes_arc
}
EXPORT_SYMBOL(get_random_bytes_arch);
+
+/**********************************************************************
+ *
+ * Entropy accumulation and extraction routines.
+ *
+ * Callers may add entropy via:
+ *
+ * static void mix_pool_bytes(const void *in, size_t nbytes)
+ *
+ * After which, if added entropy should be credited:
+ *
+ * static void credit_entropy_bits(size_t nbits)
+ *
+ * Finally, extract entropy via these two, with the latter one
+ * setting the entropy count to zero and extracting only if there
+ * is POOL_MIN_BITS entropy credited prior:
+ *
+ * static void extract_entropy(void *buf, size_t nbytes)
+ * static bool drain_entropy(void *buf, size_t nbytes)
+ *
+ **********************************************************************/
+
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
};
-/*
- * Static global variables
- */
+/* For notifying userspace should write into /dev/random. */
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-/**********************************************************************
- *
- * OS independent entropy store. Here are the functions which handle
- * storing entropy in an entropy pool.
- *
- **********************************************************************/
-
static struct {
struct blake2s_state hash;
spinlock_t lock;
@@ -924,28 +937,106 @@ static struct {
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
};
-static void extract_entropy(void *buf, size_t nbytes);
-static bool drain_entropy(void *buf, size_t nbytes);
-
-static void crng_reseed(void);
+static void _mix_pool_bytes(const void *in, size_t nbytes)
+{
+ blake2s_update(&input_pool.hash, in, nbytes);
+}
/*
* This function adds bytes into the entropy "pool". It does not
* update the entropy estimate. The caller should call
* credit_entropy_bits if this is appropriate.
*/
-static void _mix_pool_bytes(const void *in, size_t nbytes)
+static void mix_pool_bytes(const void *in, size_t nbytes)
{
- blake2s_update(&input_pool.hash, in, nbytes);
+ unsigned long flags;
+
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(in, nbytes);
+ spin_unlock_irqrestore(&input_pool.lock, flags);
}
-static void mix_pool_bytes(const void *in, size_t nbytes)
+static void credit_entropy_bits(size_t nbits)
+{
+ unsigned int entropy_count, orig, add;
+
+ if (!nbits)
+ return;
+
+ add = min_t(size_t, nbits, POOL_BITS);
+
+ do {
+ orig = READ_ONCE(input_pool.entropy_count);
+ entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
+
+ if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
+ crng_reseed();
+}
+
+/*
+ * This is an HKDF-like construction for using the hashed collected entropy
+ * as a PRF key, that's then expanded block-by-block.
+ */
+static void extract_entropy(void *buf, size_t nbytes)
{
unsigned long flags;
+ u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
+ struct {
+ unsigned long rdseed[32 / sizeof(long)];
+ size_t counter;
+ } block;
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
+ if (!arch_get_random_seed_long(&block.rdseed[i]) &&
+ !arch_get_random_long(&block.rdseed[i]))
+ block.rdseed[i] = random_get_entropy();
+ }
spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(in, nbytes);
+
+ /* seed = HASHPRF(last_key, entropy_input) */
+ blake2s_final(&input_pool.hash, seed);
+
+ /* next_key = HASHPRF(seed, RDSEED || 0) */
+ block.counter = 0;
+ blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
+ blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
+
spin_unlock_irqrestore(&input_pool.lock, flags);
+ memzero_explicit(next_key, sizeof(next_key));
+
+ while (nbytes) {
+ i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
+ /* output = HASHPRF(seed, RDSEED || ++counter) */
+ ++block.counter;
+ blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
+ nbytes -= i;
+ buf += i;
+ }
+
+ memzero_explicit(seed, sizeof(seed));
+ memzero_explicit(&block, sizeof(block));
+}
+
+/*
+ * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we
+ * set the entropy count to zero (but don't actually touch any data). Only then
+ * can we extract a new key with extract_entropy().
+ */
+static bool drain_entropy(void *buf, size_t nbytes)
+{
+ unsigned int entropy_count;
+ do {
+ entropy_count = READ_ONCE(input_pool.entropy_count);
+ if (entropy_count < POOL_MIN_BITS)
+ return false;
+ } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
+ extract_entropy(buf, nbytes);
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ return true;
}
struct fast_pool {
@@ -988,24 +1079,6 @@ static void fast_mix(u32 pool[4])
pool[2] = c; pool[3] = d;
}
-static void credit_entropy_bits(size_t nbits)
-{
- unsigned int entropy_count, orig, add;
-
- if (!nbits)
- return;
-
- add = min_t(size_t, nbits, POOL_BITS);
-
- do {
- orig = READ_ONCE(input_pool.entropy_count);
- entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
- } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
-
- if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
- crng_reseed();
-}
-
/*********************************************************************
*
* Entropy input management
@@ -1202,77 +1275,6 @@ void add_disk_randomness(struct gendisk
EXPORT_SYMBOL_GPL(add_disk_randomness);
#endif
-/*********************************************************************
- *
- * Entropy extraction routines
- *
- *********************************************************************/
-
-/*
- * This is an HKDF-like construction for using the hashed collected entropy
- * as a PRF key, that's then expanded block-by-block.
- */
-static void extract_entropy(void *buf, size_t nbytes)
-{
- unsigned long flags;
- u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
- struct {
- unsigned long rdseed[32 / sizeof(long)];
- size_t counter;
- } block;
- size_t i;
-
- for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
- if (!arch_get_random_seed_long(&block.rdseed[i]) &&
- !arch_get_random_long(&block.rdseed[i]))
- block.rdseed[i] = random_get_entropy();
- }
-
- spin_lock_irqsave(&input_pool.lock, flags);
-
- /* seed = HASHPRF(last_key, entropy_input) */
- blake2s_final(&input_pool.hash, seed);
-
- /* next_key = HASHPRF(seed, RDSEED || 0) */
- block.counter = 0;
- blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
- blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
-
- spin_unlock_irqrestore(&input_pool.lock, flags);
- memzero_explicit(next_key, sizeof(next_key));
-
- while (nbytes) {
- i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
- /* output = HASHPRF(seed, RDSEED || ++counter) */
- ++block.counter;
- blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
- nbytes -= i;
- buf += i;
- }
-
- memzero_explicit(seed, sizeof(seed));
- memzero_explicit(&block, sizeof(block));
-}
-
-/*
- * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we
- * set the entropy count to zero (but don't actually touch any data). Only then
- * can we extract a new key with extract_entropy().
- */
-static bool drain_entropy(void *buf, size_t nbytes)
-{
- unsigned int entropy_count;
- do {
- entropy_count = READ_ONCE(input_pool.entropy_count);
- if (entropy_count < POOL_MIN_BITS)
- return false;
- } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
- extract_entropy(buf, nbytes);
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- return true;
-}
-
/*
* Each time the timer fires, we expect that we got an unpredictable
* jump in the cycle counter. Even if the timer is running on another
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 034/111] random: group entropy collection functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (32 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 033/111] random: group entropy extraction functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 035/111] random: group userspace read/write functions Greg Kroah-Hartman
` (82 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 92c653cf14400946f376a29b828d6af7e01f38dd upstream.
This pulls all of the entropy collection-focused functions into the
fourth labeled section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 370 +++++++++++++++++++++++++++-----------------------
1 file changed, 206 insertions(+), 164 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1039,60 +1039,112 @@ static bool drain_entropy(void *buf, siz
return true;
}
-struct fast_pool {
- union {
- u32 pool32[4];
- u64 pool64[2];
- };
- unsigned long last;
- u16 reg_idx;
- u8 count;
-};
+
+/**********************************************************************
+ *
+ * Entropy collection routines.
+ *
+ * The following exported functions are used for pushing entropy into
+ * the above entropy accumulation routines:
+ *
+ * void add_device_randomness(const void *buf, size_t size);
+ * void add_input_randomness(unsigned int type, unsigned int code,
+ * unsigned int value);
+ * void add_disk_randomness(struct gendisk *disk);
+ * void add_hwgenerator_randomness(const void *buffer, size_t count,
+ * size_t entropy);
+ * void add_bootloader_randomness(const void *buf, size_t size);
+ * void add_interrupt_randomness(int irq);
+ *
+ * add_device_randomness() adds data to the input pool that
+ * is likely to differ between two devices (or possibly even per boot).
+ * This would be things like MAC addresses or serial numbers, or the
+ * read-out of the RTC. This does *not* credit any actual entropy to
+ * the pool, but it initializes the pool to different values for devices
+ * that might otherwise be identical and have very little entropy
+ * available to them (particularly common in the embedded world).
+ *
+ * add_input_randomness() uses the input layer interrupt timing, as well
+ * as the event type information from the hardware.
+ *
+ * add_disk_randomness() uses what amounts to the seek time of block
+ * layer request events, on a per-disk_devt basis, as input to the
+ * entropy pool. Note that high-speed solid state drives with very low
+ * seek times do not make for good sources of entropy, as their seek
+ * times are usually fairly consistent.
+ *
+ * The above two routines try to estimate how many bits of entropy
+ * to credit. They do this by keeping track of the first and second
+ * order deltas of the event timings.
+ *
+ * add_hwgenerator_randomness() is for true hardware RNGs, and will credit
+ * entropy as specified by the caller. If the entropy pool is full it will
+ * block until more entropy is needed.
+ *
+ * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or
+ * add_device_randomness(), depending on whether or not the configuration
+ * option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
+ *
+ * add_interrupt_randomness() uses the interrupt timing as random
+ * inputs to the entropy pool. Using the cycle counters and the irq source
+ * as inputs, it feeds the input pool roughly once a second or after 64
+ * interrupts, crediting 1 bit of entropy for whichever comes first.
+ *
+ **********************************************************************/
+
+static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
+static int __init parse_trust_cpu(char *arg)
+{
+ return kstrtobool(arg, &trust_cpu);
+}
+early_param("random.trust_cpu", parse_trust_cpu);
/*
- * This is a fast mixing routine used by the interrupt randomness
- * collector. It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
+ * The first collection of entropy occurs at system boot while interrupts
+ * are still turned off. Here we push in RDSEED, a timestamp, and utsname().
+ * Depending on the above configuration knob, RDSEED may be considered
+ * sufficient for initialization. Note that much earlier setup may already
+ * have pushed entropy into the input pool by the time we get here.
*/
-static void fast_mix(u32 pool[4])
+int __init rand_initialize(void)
{
- u32 a = pool[0], b = pool[1];
- u32 c = pool[2], d = pool[3];
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
+ size_t i;
+ ktime_t now = ktime_get_real();
+ bool arch_init = true;
+ unsigned long rv;
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
+ for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
+ if (!arch_get_random_seed_long_early(&rv) &&
+ !arch_get_random_long_early(&rv)) {
+ rv = random_get_entropy();
+ arch_init = false;
+ }
+ mix_pool_bytes(&rv, sizeof(rv));
+ }
+ mix_pool_bytes(&now, sizeof(now));
+ mix_pool_bytes(utsname(), sizeof(*(utsname())));
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
+ ++base_crng.generation;
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
+ if (arch_init && trust_cpu && crng_init < 2) {
+ crng_init = 2;
+ pr_notice("crng init done (trusting CPU's manufacturer)\n");
+ }
- pool[0] = a; pool[1] = b;
- pool[2] = c; pool[3] = d;
+ if (ratelimit_disable) {
+ urandom_warning.interval = 0;
+ unseeded_warning.interval = 0;
+ }
+ return 0;
}
-/*********************************************************************
- *
- * Entropy input management
- *
- *********************************************************************/
-
/* There is one of these per entropy source */
struct timer_rand_state {
cycles_t last_time;
long last_delta, last_delta2;
};
-#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
-
/*
* Add device- or boot-specific data to the input pool to help
* initialize it.
@@ -1116,8 +1168,6 @@ void add_device_randomness(const void *b
}
EXPORT_SYMBOL(add_device_randomness);
-static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
-
/*
* This function adds entropy to the entropy "pool" by using timing
* delays. It uses the timer_rand_state structure to make an estimate
@@ -1179,8 +1229,9 @@ void add_input_randomness(unsigned int t
unsigned int value)
{
static unsigned char last_value;
+ static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
- /* ignore autorepeat and the like */
+ /* Ignore autorepeat and the like. */
if (value == last_value)
return;
@@ -1190,6 +1241,119 @@ void add_input_randomness(unsigned int t
}
EXPORT_SYMBOL_GPL(add_input_randomness);
+#ifdef CONFIG_BLOCK
+void add_disk_randomness(struct gendisk *disk)
+{
+ if (!disk || !disk->random)
+ return;
+ /* First major is 1, so we get >= 0x200 here. */
+ add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
+}
+EXPORT_SYMBOL_GPL(add_disk_randomness);
+
+void rand_initialize_disk(struct gendisk *disk)
+{
+ struct timer_rand_state *state;
+
+ /*
+ * If kzalloc returns null, we just won't use that entropy
+ * source.
+ */
+ state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+ if (state) {
+ state->last_time = INITIAL_JIFFIES;
+ disk->random = state;
+ }
+}
+#endif
+
+/*
+ * Interface for in-kernel drivers of true hardware RNGs.
+ * Those devices may produce endless random bits and will be throttled
+ * when our pool is full.
+ */
+void add_hwgenerator_randomness(const void *buffer, size_t count,
+ size_t entropy)
+{
+ if (unlikely(crng_init == 0)) {
+ size_t ret = crng_fast_load(buffer, count);
+ mix_pool_bytes(buffer, ret);
+ count -= ret;
+ buffer += ret;
+ if (!count || crng_init == 0)
+ return;
+ }
+
+ /*
+ * Throttle writing if we're above the trickle threshold.
+ * We'll be woken up again once below POOL_MIN_BITS, when
+ * the calling thread is about to terminate, or once
+ * CRNG_RESEED_INTERVAL has elapsed.
+ */
+ wait_event_interruptible_timeout(random_write_wait,
+ !system_wq || kthread_should_stop() ||
+ input_pool.entropy_count < POOL_MIN_BITS,
+ CRNG_RESEED_INTERVAL);
+ mix_pool_bytes(buffer, count);
+ credit_entropy_bits(entropy);
+}
+EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
+
+/*
+ * Handle random seed passed by bootloader.
+ * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
+ * it would be regarded as device data.
+ * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
+ */
+void add_bootloader_randomness(const void *buf, size_t size)
+{
+ if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
+ add_hwgenerator_randomness(buf, size, size * 8);
+ else
+ add_device_randomness(buf, size);
+}
+EXPORT_SYMBOL_GPL(add_bootloader_randomness);
+
+struct fast_pool {
+ union {
+ u32 pool32[4];
+ u64 pool64[2];
+ };
+ unsigned long last;
+ u16 reg_idx;
+ u8 count;
+};
+
+/*
+ * This is a fast mixing routine used by the interrupt randomness
+ * collector. It's hardcoded for an 128 bit pool and assumes that any
+ * locks that might be needed are taken by the caller.
+ */
+static void fast_mix(u32 pool[4])
+{
+ u32 a = pool[0], b = pool[1];
+ u32 c = pool[2], d = pool[3];
+
+ a += b; c += d;
+ b = rol32(b, 6); d = rol32(d, 27);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 16); d = rol32(d, 14);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 6); d = rol32(d, 27);
+ d ^= a; b ^= c;
+
+ a += b; c += d;
+ b = rol32(b, 16); d = rol32(d, 14);
+ d ^= a; b ^= c;
+
+ pool[0] = a; pool[1] = b;
+ pool[2] = c; pool[3] = d;
+}
+
static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
@@ -1259,22 +1423,11 @@ void add_interrupt_randomness(int irq)
fast_pool->count = 0;
- /* award one bit for the contents of the fast pool */
+ /* Award one bit for the contents of the fast pool. */
credit_entropy_bits(1);
}
EXPORT_SYMBOL_GPL(add_interrupt_randomness);
-#ifdef CONFIG_BLOCK
-void add_disk_randomness(struct gendisk *disk)
-{
- if (!disk || !disk->random)
- return;
- /* first major is 1, so we get >= 0x200 here */
- add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
-}
-EXPORT_SYMBOL_GPL(add_disk_randomness);
-#endif
-
/*
* Each time the timer fires, we expect that we got an unpredictable
* jump in the cycle counter. Even if the timer is running on another
@@ -1324,73 +1477,6 @@ static void try_to_generate_entropy(void
mix_pool_bytes(&stack.now, sizeof(stack.now));
}
-static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
-static int __init parse_trust_cpu(char *arg)
-{
- return kstrtobool(arg, &trust_cpu);
-}
-early_param("random.trust_cpu", parse_trust_cpu);
-
-/*
- * Note that setup_arch() may call add_device_randomness()
- * long before we get here. This allows seeding of the pools
- * with some platform dependent data very early in the boot
- * process. But it limits our options here. We must use
- * statically allocated structures that already have all
- * initializations complete at compile time. We should also
- * take care not to overwrite the precious per platform data
- * we were given.
- */
-int __init rand_initialize(void)
-{
- size_t i;
- ktime_t now = ktime_get_real();
- bool arch_init = true;
- unsigned long rv;
-
- for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
- if (!arch_get_random_seed_long_early(&rv) &&
- !arch_get_random_long_early(&rv)) {
- rv = random_get_entropy();
- arch_init = false;
- }
- mix_pool_bytes(&rv, sizeof(rv));
- }
- mix_pool_bytes(&now, sizeof(now));
- mix_pool_bytes(utsname(), sizeof(*(utsname())));
-
- extract_entropy(base_crng.key, sizeof(base_crng.key));
- ++base_crng.generation;
-
- if (arch_init && trust_cpu && crng_init < 2) {
- crng_init = 2;
- pr_notice("crng init done (trusting CPU's manufacturer)\n");
- }
-
- if (ratelimit_disable) {
- urandom_warning.interval = 0;
- unseeded_warning.interval = 0;
- }
- return 0;
-}
-
-#ifdef CONFIG_BLOCK
-void rand_initialize_disk(struct gendisk *disk)
-{
- struct timer_rand_state *state;
-
- /*
- * If kzalloc returns null, we just won't use that entropy
- * source.
- */
- state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
- if (state) {
- state->last_time = INITIAL_JIFFIES;
- disk->random = state;
- }
-}
-#endif
-
static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
loff_t *ppos)
{
@@ -1685,47 +1771,3 @@ static int __init random_sysctls_init(vo
}
device_initcall(random_sysctls_init);
#endif /* CONFIG_SYSCTL */
-
-/* Interface for in-kernel drivers of true hardware RNGs.
- * Those devices may produce endless random bits and will be throttled
- * when our pool is full.
- */
-void add_hwgenerator_randomness(const void *buffer, size_t count,
- size_t entropy)
-{
- if (unlikely(crng_init == 0)) {
- size_t ret = crng_fast_load(buffer, count);
- mix_pool_bytes(buffer, ret);
- count -= ret;
- buffer += ret;
- if (!count || crng_init == 0)
- return;
- }
-
- /* Throttle writing if we're above the trickle threshold.
- * We'll be woken up again once below POOL_MIN_BITS, when
- * the calling thread is about to terminate, or once
- * CRNG_RESEED_INTERVAL has elapsed.
- */
- wait_event_interruptible_timeout(random_write_wait,
- !system_wq || kthread_should_stop() ||
- input_pool.entropy_count < POOL_MIN_BITS,
- CRNG_RESEED_INTERVAL);
- mix_pool_bytes(buffer, count);
- credit_entropy_bits(entropy);
-}
-EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
-
-/* Handle random seed passed by bootloader.
- * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
- * it would be regarded as device data.
- * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
- */
-void add_bootloader_randomness(const void *buf, size_t size)
-{
- if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
- add_hwgenerator_randomness(buf, size, size * 8);
- else
- add_device_randomness(buf, size);
-}
-EXPORT_SYMBOL_GPL(add_bootloader_randomness);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 035/111] random: group userspace read/write functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (33 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 034/111] random: group entropy collection functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 036/111] random: group sysctl functions Greg Kroah-Hartman
` (81 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a6adf8e7a605250b911e94793fd077933709ff9e upstream.
This pulls all of the userspace read/write-focused functions into the
fifth labeled section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 125 ++++++++++++++++++++++++++++++--------------------
1 file changed, 77 insertions(+), 48 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1477,30 +1477,61 @@ static void try_to_generate_entropy(void
mix_pool_bytes(&stack.now, sizeof(stack.now));
}
-static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
+
+/**********************************************************************
+ *
+ * Userspace reader/writer interfaces.
+ *
+ * getrandom(2) is the primary modern interface into the RNG and should
+ * be used in preference to anything else.
+ *
+ * Reading from /dev/random has the same functionality as calling
+ * getrandom(2) with flags=0. In earlier versions, however, it had
+ * vastly different semantics and should therefore be avoided, to
+ * prevent backwards compatibility issues.
+ *
+ * Reading from /dev/urandom has the same functionality as calling
+ * getrandom(2) with flags=GRND_INSECURE. Because it does not block
+ * waiting for the RNG to be ready, it should not be used.
+ *
+ * Writing to either /dev/random or /dev/urandom adds entropy to
+ * the input pool but does not credit it.
+ *
+ * Polling on /dev/random indicates when the RNG is initialized, on
+ * the read side, and when it wants new entropy, on the write side.
+ *
+ * Both /dev/random and /dev/urandom have the same set of ioctls for
+ * adding entropy, getting the entropy count, zeroing the count, and
+ * reseeding the crng.
+ *
+ **********************************************************************/
+
+SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
+ flags)
{
- static int maxwarn = 10;
+ if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
+ return -EINVAL;
- if (!crng_ready() && maxwarn > 0) {
- maxwarn--;
- if (__ratelimit(&urandom_warning))
- pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
- current->comm, nbytes);
- }
+ /*
+ * Requesting insecure and blocking randomness at the same time makes
+ * no sense.
+ */
+ if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
+ return -EINVAL;
- return get_random_bytes_user(buf, nbytes);
-}
+ if (count > INT_MAX)
+ count = INT_MAX;
-static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
-{
- int ret;
+ if (!(flags & GRND_INSECURE) && !crng_ready()) {
+ int ret;
- ret = wait_for_random_bytes();
- if (ret != 0)
- return ret;
- return get_random_bytes_user(buf, nbytes);
+ if (flags & GRND_NONBLOCK)
+ return -EAGAIN;
+ ret = wait_for_random_bytes();
+ if (unlikely(ret))
+ return ret;
+ }
+ return get_random_bytes_user(buf, count);
}
static __poll_t random_poll(struct file *file, poll_table *wait)
@@ -1552,6 +1583,32 @@ static ssize_t random_write(struct file
return (ssize_t)count;
}
+static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
+ loff_t *ppos)
+{
+ static int maxwarn = 10;
+
+ if (!crng_ready() && maxwarn > 0) {
+ maxwarn--;
+ if (__ratelimit(&urandom_warning))
+ pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
+ current->comm, nbytes);
+ }
+
+ return get_random_bytes_user(buf, nbytes);
+}
+
+static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,
+ loff_t *ppos)
+{
+ int ret;
+
+ ret = wait_for_random_bytes();
+ if (ret != 0)
+ return ret;
+ return get_random_bytes_user(buf, nbytes);
+}
+
static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int size, ent_count;
@@ -1560,7 +1617,7 @@ static long random_ioctl(struct file *f,
switch (cmd) {
case RNDGETENTCNT:
- /* inherently racy, no point locking */
+ /* Inherently racy, no point locking. */
if (put_user(input_pool.entropy_count, p))
return -EFAULT;
return 0;
@@ -1636,34 +1693,6 @@ const struct file_operations urandom_fop
.llseek = noop_llseek,
};
-SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
- flags)
-{
- if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
- return -EINVAL;
-
- /*
- * Requesting insecure and blocking randomness at the same time makes
- * no sense.
- */
- if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
- return -EINVAL;
-
- if (count > INT_MAX)
- count = INT_MAX;
-
- if (!(flags & GRND_INSECURE) && !crng_ready()) {
- int ret;
-
- if (flags & GRND_NONBLOCK)
- return -EAGAIN;
- ret = wait_for_random_bytes();
- if (unlikely(ret))
- return ret;
- }
- return get_random_bytes_user(buf, count);
-}
-
/********************************************************************
*
* Sysctl interface
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 036/111] random: group sysctl functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (34 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 035/111] random: group userspace read/write functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 037/111] random: rewrite header introductory comment Greg Kroah-Hartman
` (80 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 0deff3c43206c24e746b1410f11125707ad3040e upstream.
This pulls all of the sysctl-focused functions into the sixth labeled
section.
No functional changes.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 37 +++++++++++++++++++++++++++++++------
1 file changed, 31 insertions(+), 6 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1693,9 +1693,34 @@ const struct file_operations urandom_fop
.llseek = noop_llseek,
};
+
/********************************************************************
*
- * Sysctl interface
+ * Sysctl interface.
+ *
+ * These are partly unused legacy knobs with dummy values to not break
+ * userspace and partly still useful things. They are usually accessible
+ * in /proc/sys/kernel/random/ and are as follows:
+ *
+ * - boot_id - a UUID representing the current boot.
+ *
+ * - uuid - a random UUID, different each time the file is read.
+ *
+ * - poolsize - the number of bits of entropy that the input pool can
+ * hold, tied to the POOL_BITS constant.
+ *
+ * - entropy_avail - the number of bits of entropy currently in the
+ * input pool. Always <= poolsize.
+ *
+ * - write_wakeup_threshold - the amount of entropy in the input pool
+ * below which write polls to /dev/random will unblock, requesting
+ * more entropy, tied to the POOL_MIN_BITS constant. It is writable
+ * to avoid breaking old userspaces, but writing to it does not
+ * change any behavior of the RNG.
+ *
+ * - urandom_min_reseed_secs - fixed to the meaningless value "60".
+ * It is writable to avoid breaking old userspaces, but writing
+ * to it does not change any behavior of the RNG.
*
********************************************************************/
@@ -1703,8 +1728,8 @@ const struct file_operations urandom_fop
#include <linux/sysctl.h>
-static int random_min_urandom_seed = 60;
-static int random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_random_min_urandom_seed = 60;
+static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
static int sysctl_poolsize = POOL_BITS;
static char sysctl_bootid[16];
@@ -1761,14 +1786,14 @@ static struct ctl_table random_table[] =
},
{
.procname = "write_wakeup_threshold",
- .data = &random_write_wakeup_bits,
+ .data = &sysctl_random_write_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "urandom_min_reseed_secs",
- .data = &random_min_urandom_seed,
+ .data = &sysctl_random_min_urandom_seed,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
@@ -1799,4 +1824,4 @@ static int __init random_sysctls_init(vo
return 0;
}
device_initcall(random_sysctls_init);
-#endif /* CONFIG_SYSCTL */
+#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 037/111] random: rewrite header introductory comment
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (35 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 036/111] random: group sysctl functions Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 038/111] random: defer fast pool mixing to worker Greg Kroah-Hartman
` (79 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5f75d9f3babea8ae0a2d06724656874f41d317f5 upstream.
Now that we've re-documented the various sections, we can remove the
outdated text here and replace it with a high-level overview.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 179 +++++---------------------------------------------
1 file changed, 19 insertions(+), 160 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2,168 +2,27 @@
/*
* Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
- * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
- * rights reserved.
- */
-
-/*
- * Exported interfaces ---- output
- * ===============================
- *
- * There are four exported interfaces; two for use within the kernel,
- * and two for use from userspace.
- *
- * Exported interfaces ---- userspace output
- * -----------------------------------------
- *
- * The userspace interfaces are two character devices /dev/random and
- * /dev/urandom. /dev/random is suitable for use when very high
- * quality randomness is desired (for example, for key generation or
- * one-time pads), as it will only return a maximum of the number of
- * bits of randomness (as estimated by the random number generator)
- * contained in the entropy pool.
- *
- * The /dev/urandom device does not have this limit, and will return
- * as many bytes as are requested. As more and more random bytes are
- * requested without giving time for the entropy pool to recharge,
- * this will result in random numbers that are merely cryptographically
- * strong. For many applications, however, this is acceptable.
- *
- * Exported interfaces ---- kernel output
- * --------------------------------------
- *
- * The primary kernel interfaces are:
- *
- * void get_random_bytes(void *buf, size_t nbytes);
- * u32 get_random_u32()
- * u64 get_random_u64()
- * unsigned int get_random_int()
- * unsigned long get_random_long()
- *
- * These interfaces will return the requested number of random bytes
- * into the given buffer or as a return value. This is equivalent to a
- * read from /dev/urandom. The get_random_{u32,u64,int,long}() family
- * of functions may be higher performance for one-off random integers,
- * because they do a bit of buffering.
- *
- * prandom_u32()
- * -------------
- *
- * For even weaker applications, see the pseudorandom generator
- * prandom_u32(), prandom_max(), and prandom_bytes(). If the random
- * numbers aren't security-critical at all, these are *far* cheaper.
- * Useful for self-tests, random error simulation, randomized backoffs,
- * and any other application where you trust that nobody is trying to
- * maliciously mess with you by guessing the "random" numbers.
- *
- * Exported interfaces ---- input
- * ==============================
- *
- * The current exported interfaces for gathering environmental noise
- * from the devices are:
- *
- * void add_device_randomness(const void *buf, size_t size);
- * void add_input_randomness(unsigned int type, unsigned int code,
- * unsigned int value);
- * void add_interrupt_randomness(int irq);
- * void add_disk_randomness(struct gendisk *disk);
- * void add_hwgenerator_randomness(const void *buffer, size_t count,
- * size_t entropy);
- * void add_bootloader_randomness(const void *buf, size_t size);
- *
- * add_device_randomness() is for adding data to the random pool that
- * is likely to differ between two devices (or possibly even per boot).
- * This would be things like MAC addresses or serial numbers, or the
- * read-out of the RTC. This does *not* add any actual entropy to the
- * pool, but it initializes the pool to different values for devices
- * that might otherwise be identical and have very little entropy
- * available to them (particularly common in the embedded world).
- *
- * add_input_randomness() uses the input layer interrupt timing, as well as
- * the event type information from the hardware.
- *
- * add_interrupt_randomness() uses the interrupt timing as random
- * inputs to the entropy pool. Using the cycle counters and the irq source
- * as inputs, it feeds the randomness roughly once a second.
- *
- * add_disk_randomness() uses what amounts to the seek time of block
- * layer request events, on a per-disk_devt basis, as input to the
- * entropy pool. Note that high-speed solid state drives with very low
- * seek times do not make for good sources of entropy, as their seek
- * times are usually fairly consistent.
- *
- * All of these routines try to estimate how many bits of randomness a
- * particular randomness source. They do this by keeping track of the
- * first and second order deltas of the event timings.
- *
- * add_hwgenerator_randomness() is for true hardware RNGs, and will credit
- * entropy as specified by the caller. If the entropy pool is full it will
- * block until more entropy is needed.
- *
- * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or
- * add_device_randomness(), depending on whether or not the configuration
- * option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
- *
- * Ensuring unpredictability at system startup
- * ============================================
- *
- * When any operating system starts up, it will go through a sequence
- * of actions that are fairly predictable by an adversary, especially
- * if the start-up does not involve interaction with a human operator.
- * This reduces the actual number of bits of unpredictability in the
- * entropy pool below the value in entropy_count. In order to
- * counteract this effect, it helps to carry information in the
- * entropy pool across shut-downs and start-ups. To do this, put the
- * following lines an appropriate script which is run during the boot
- * sequence:
- *
- * echo "Initializing random number generator..."
- * random_seed=/var/run/random-seed
- * # Carry a random seed from start-up to start-up
- * # Load and then save the whole entropy pool
- * if [ -f $random_seed ]; then
- * cat $random_seed >/dev/urandom
- * else
- * touch $random_seed
- * fi
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * and the following lines in an appropriate script which is run as
- * the system is shutdown:
- *
- * # Carry a random seed from shut-down to start-up
- * # Save the whole entropy pool
- * echo "Saving random seed..."
- * random_seed=/var/run/random-seed
- * touch $random_seed
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * For example, on most modern systems using the System V init
- * scripts, such code fragments would be found in
- * /etc/rc.d/init.d/random. On older Linux systems, the correct script
- * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
- *
- * Effectively, these commands cause the contents of the entropy pool
- * to be saved at shut-down time and reloaded into the entropy pool at
- * start-up. (The 'dd' in the addition to the bootup script is to
- * make sure that /etc/random-seed is different for every start-up,
- * even if the system crashes without executing rc.0.) Even with
- * complete knowledge of the start-up activities, predicting the state
- * of the entropy pool requires knowledge of the previous history of
- * the system.
- *
- * Configuring the /dev/random driver under Linux
- * ==============================================
+ * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All rights reserved.
*
- * The /dev/random driver under Linux uses minor numbers 8 and 9 of
- * the /dev/mem major number (#1). So if your system does not have
- * /dev/random and /dev/urandom created already, they can be created
- * by using the commands:
+ * This driver produces cryptographically secure pseudorandom data. It is divided
+ * into roughly six sections, each with a section header:
*
- * mknod /dev/random c 1 8
- * mknod /dev/urandom c 1 9
+ * - Initialization and readiness waiting.
+ * - Fast key erasure RNG, the "crng".
+ * - Entropy accumulation and extraction routines.
+ * - Entropy collection routines.
+ * - Userspace reader/writer interfaces.
+ * - Sysctl interface.
+ *
+ * The high level overview is that there is one input pool, into which
+ * various pieces of data are hashed. Some of that data is then "credited" as
+ * having a certain number of bits of entropy. When enough bits of entropy are
+ * available, the hash is finalized and handed as a key to a stream cipher that
+ * expands it indefinitely for various consumers. This key is periodically
+ * refreshed as the various entropy collectors, described below, add data to the
+ * input pool and credit it. There is currently no Fortuna-like scheduler
+ * involved, which can lead to malicious entropy sources causing a premature
+ * reseed, and the entropy estimates are, at best, conservative guesses.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 038/111] random: defer fast pool mixing to worker
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (36 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 037/111] random: rewrite header introductory comment Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 039/111] random: do not take pool spinlock at boot Greg Kroah-Hartman
` (78 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Peter Zijlstra,
Theodore Tso, Jonathan Neuschäfer,
Sebastian Andrzej Siewior, Sultan Alsawaf, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 58340f8e952b613e0ead0bed58b97b05bf4743c5 upstream.
On PREEMPT_RT, it's problematic to take spinlocks from hard irq
handlers. We can fix this by deferring to a workqueue the dumping of
the fast pool into the input pool.
We accomplish this with some careful rules on fast_pool->count:
- When it's incremented to >= 64, we schedule the work.
- If the top bit is set, we never schedule the work, even if >= 64.
- The worker is responsible for setting it back to 0 when it's done.
There are two small issues around using workqueues for this purpose that
we work around.
The first issue is that mix_interrupt_randomness() might be migrated to
another CPU during CPU hotplug. This issue is rectified by checking that
it hasn't been migrated (after disabling irqs). If it has been migrated,
then we set the count to zero, so that when the CPU comes online again,
it can requeue the work. As part of this, we switch to using an
atomic_t, so that the increment in the irq handler doesn't wipe out the
zeroing if the CPU comes back online while this worker is running.
The second issue is that, though relatively minor in effect, we probably
want to make sure we get a consistent view of the pool onto the stack,
in case it's interrupted by an irq while reading. To do this, we don't
reenable irqs until after the copy. There are only 18 instructions
between the cli and sti, so this is a pretty tiny window.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sultan Alsawaf <sultan@kerneltoast.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 63 ++++++++++++++++++++++++++++++++++++++------------
1 file changed, 49 insertions(+), 14 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1178,9 +1178,10 @@ struct fast_pool {
u32 pool32[4];
u64 pool64[2];
};
+ struct work_struct mix;
unsigned long last;
+ atomic_t count;
u16 reg_idx;
- u8 count;
};
/*
@@ -1230,12 +1231,49 @@ static u32 get_reg(struct fast_pool *f,
return *ptr;
}
+static void mix_interrupt_randomness(struct work_struct *work)
+{
+ struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
+ u32 pool[4];
+
+ /* Check to see if we're running on the wrong CPU due to hotplug. */
+ local_irq_disable();
+ if (fast_pool != this_cpu_ptr(&irq_randomness)) {
+ local_irq_enable();
+ /*
+ * If we are unlucky enough to have been moved to another CPU,
+ * during CPU hotplug while the CPU was shutdown then we set
+ * our count to zero atomically so that when the CPU comes
+ * back online, it can enqueue work again. The _release here
+ * pairs with the atomic_inc_return_acquire in
+ * add_interrupt_randomness().
+ */
+ atomic_set_release(&fast_pool->count, 0);
+ return;
+ }
+
+ /*
+ * Copy the pool to the stack so that the mixer always has a
+ * consistent view, before we reenable irqs again.
+ */
+ memcpy(pool, fast_pool->pool32, sizeof(pool));
+ atomic_set(&fast_pool->count, 0);
+ fast_pool->last = jiffies;
+ local_irq_enable();
+
+ mix_pool_bytes(pool, sizeof(pool));
+ credit_entropy_bits(1);
+ memzero_explicit(pool, sizeof(pool));
+}
+
void add_interrupt_randomness(int irq)
{
+ enum { MIX_INFLIGHT = 1U << 31 };
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
struct pt_regs *regs = get_irq_regs();
unsigned long now = jiffies;
cycles_t cycles = random_get_entropy();
+ unsigned int new_count;
if (cycles == 0)
cycles = get_reg(fast_pool, regs);
@@ -1255,12 +1293,13 @@ void add_interrupt_randomness(int irq)
}
fast_mix(fast_pool->pool32);
- ++fast_pool->count;
+ /* The _acquire here pairs with the atomic_set_release in mix_interrupt_randomness(). */
+ new_count = (unsigned int)atomic_inc_return_acquire(&fast_pool->count);
if (unlikely(crng_init == 0)) {
- if (fast_pool->count >= 64 &&
+ if (new_count >= 64 &&
crng_fast_load(fast_pool->pool32, sizeof(fast_pool->pool32)) > 0) {
- fast_pool->count = 0;
+ atomic_set(&fast_pool->count, 0);
fast_pool->last = now;
if (spin_trylock(&input_pool.lock)) {
_mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
@@ -1270,20 +1309,16 @@ void add_interrupt_randomness(int irq)
return;
}
- if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ))
+ if (new_count & MIX_INFLIGHT)
return;
- if (!spin_trylock(&input_pool.lock))
+ if (new_count < 64 && !time_after(now, fast_pool->last + HZ))
return;
- fast_pool->last = now;
- _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
- spin_unlock(&input_pool.lock);
-
- fast_pool->count = 0;
-
- /* Award one bit for the contents of the fast pool. */
- credit_entropy_bits(1);
+ if (unlikely(!fast_pool->mix.func))
+ INIT_WORK(&fast_pool->mix, mix_interrupt_randomness);
+ atomic_or(MIX_INFLIGHT, &fast_pool->count);
+ queue_work_on(raw_smp_processor_id(), system_highpri_wq, &fast_pool->mix);
}
EXPORT_SYMBOL_GPL(add_interrupt_randomness);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 039/111] random: do not take pool spinlock at boot
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (37 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 038/111] random: defer fast pool mixing to worker Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 040/111] random: unify early init crng load accounting Greg Kroah-Hartman
` (77 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Eric Biggers, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit afba0b80b977b2a8f16234f2acd982f82710ba33 upstream.
Since rand_initialize() is run while interrupts are still off and
nothing else is running, we don't need to repeatedly take and release
the pool spinlock, especially in the RDSEED loop.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -978,10 +978,10 @@ int __init rand_initialize(void)
rv = random_get_entropy();
arch_init = false;
}
- mix_pool_bytes(&rv, sizeof(rv));
+ _mix_pool_bytes(&rv, sizeof(rv));
}
- mix_pool_bytes(&now, sizeof(now));
- mix_pool_bytes(utsname(), sizeof(*(utsname())));
+ _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(utsname(), sizeof(*(utsname())));
extract_entropy(base_crng.key, sizeof(base_crng.key));
++base_crng.generation;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 040/111] random: unify early init crng load accounting
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (38 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 039/111] random: do not take pool spinlock at boot Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 041/111] random: check for crng_init == 0 in add_device_randomness() Greg Kroah-Hartman
` (76 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit da792c6d5f59a76c10a310c5d4c93428fd18f996 upstream.
crng_fast_load() and crng_slow_load() have different semantics:
- crng_fast_load() xors and accounts with crng_init_cnt.
- crng_slow_load() hashes and doesn't account.
However add_hwgenerator_randomness() can afford to hash (it's called
from a kthread), and it should account. Additionally, ones that can
afford to hash don't need to take a trylock but can take a normal lock.
So, we combine these into one function, crng_pre_init_inject(), which
allows us to control these in a uniform way. This will make it simpler
later to simplify this all down when the time comes for that.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 114 +++++++++++++++++++++++++-------------------------
1 file changed, 59 insertions(+), 55 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -386,7 +386,7 @@ static void crng_make_state(u32 chacha_s
* For the fast path, we check whether we're ready, unlocked first, and
* then re-check once locked later. In the case where we're really not
* ready, we do fast key erasure with the base_crng directly, because
- * this is what crng_{fast,slow}_load mutate during early init.
+ * this is what crng_pre_init_inject() mutates during early init.
*/
if (unlikely(!crng_ready())) {
bool ready;
@@ -437,72 +437,75 @@ static void crng_make_state(u32 chacha_s
}
/*
- * This function is for crng_init == 0 only.
+ * This function is for crng_init == 0 only. It loads entropy directly
+ * into the crng's key, without going through the input pool. It is,
+ * generally speaking, not very safe, but we use this only at early
+ * boot time when it's better to have something there rather than
+ * nothing.
+ *
+ * There are two paths, a slow one and a fast one. The slow one
+ * hashes the input along with the current key. The fast one simply
+ * xors it in, and should only be used from interrupt context.
+ *
+ * If account is set, then the crng_init_cnt counter is incremented.
+ * This shouldn't be set by functions like add_device_randomness(),
+ * where we can't trust the buffer passed to it is guaranteed to be
+ * unpredictable (so it might not have any entropy at all).
*
- * crng_fast_load() can be called by code in the interrupt service
- * path. So we can't afford to dilly-dally. Returns the number of
- * bytes processed from cp.
+ * Returns the number of bytes processed from input, which is bounded
+ * by CRNG_INIT_CNT_THRESH if account is true.
*/
-static size_t crng_fast_load(const void *cp, size_t len)
+static size_t crng_pre_init_inject(const void *input, size_t len,
+ bool fast, bool account)
{
static int crng_init_cnt = 0;
unsigned long flags;
- const u8 *src = (const u8 *)cp;
- size_t ret = 0;
- if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return 0;
+ if (fast) {
+ if (!spin_trylock_irqsave(&base_crng.lock, flags))
+ return 0;
+ } else {
+ spin_lock_irqsave(&base_crng.lock, flags);
+ }
+
if (crng_init != 0) {
spin_unlock_irqrestore(&base_crng.lock, flags);
return 0;
}
- while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src;
- src++; crng_init_cnt++; len--; ret++;
- }
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- ++base_crng.generation;
- crng_init = 1;
- }
- spin_unlock_irqrestore(&base_crng.lock, flags);
- if (crng_init == 1)
- pr_notice("fast init done\n");
- return ret;
-}
-/*
- * This function is for crng_init == 0 only.
- *
- * crng_slow_load() is called by add_device_randomness, which has two
- * attributes. (1) We can't trust the buffer passed to it is
- * guaranteed to be unpredictable (so it might not have any entropy at
- * all), and (2) it doesn't have the performance constraints of
- * crng_fast_load().
- *
- * So, we simply hash the contents in with the current key. Finally,
- * we do *not* advance crng_init_cnt since buffer we may get may be
- * something like a fixed DMI table (for example), which might very
- * well be unique to the machine, but is otherwise unvarying.
- */
-static void crng_slow_load(const void *cp, size_t len)
-{
- unsigned long flags;
- struct blake2s_state hash;
+ if (account)
+ len = min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
- blake2s_init(&hash, sizeof(base_crng.key));
-
- if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&base_crng.lock, flags);
- return;
+ if (fast) {
+ const u8 *src = input;
+ size_t i;
+
+ for (i = 0; i < len; ++i)
+ base_crng.key[(crng_init_cnt + i) %
+ sizeof(base_crng.key)] ^= src[i];
+ } else {
+ struct blake2s_state hash;
+
+ blake2s_init(&hash, sizeof(base_crng.key));
+ blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
+ blake2s_update(&hash, input, len);
+ blake2s_final(&hash, base_crng.key);
+ }
+
+ if (account) {
+ crng_init_cnt += len;
+ if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
+ ++base_crng.generation;
+ crng_init = 1;
+ }
}
- blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
- blake2s_update(&hash, cp, len);
- blake2s_final(&hash, base_crng.key);
-
spin_unlock_irqrestore(&base_crng.lock, flags);
+
+ if (crng_init == 1)
+ pr_notice("fast init done\n");
+
+ return len;
}
static void _get_random_bytes(void *buf, size_t nbytes)
@@ -1018,7 +1021,7 @@ void add_device_randomness(const void *b
unsigned long flags;
if (!crng_ready() && size)
- crng_slow_load(buf, size);
+ crng_pre_init_inject(buf, size, false, false);
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(buf, size);
@@ -1135,7 +1138,7 @@ void add_hwgenerator_randomness(const vo
size_t entropy)
{
if (unlikely(crng_init == 0)) {
- size_t ret = crng_fast_load(buffer, count);
+ size_t ret = crng_pre_init_inject(buffer, count, false, true);
mix_pool_bytes(buffer, ret);
count -= ret;
buffer += ret;
@@ -1298,7 +1301,8 @@ void add_interrupt_randomness(int irq)
if (unlikely(crng_init == 0)) {
if (new_count >= 64 &&
- crng_fast_load(fast_pool->pool32, sizeof(fast_pool->pool32)) > 0) {
+ crng_pre_init_inject(fast_pool->pool32, sizeof(fast_pool->pool32),
+ true, true) > 0) {
atomic_set(&fast_pool->count, 0);
fast_pool->last = now;
if (spin_trylock(&input_pool.lock)) {
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 041/111] random: check for crng_init == 0 in add_device_randomness()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (39 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 040/111] random: unify early init crng load accounting Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 042/111] random: pull add_hwgenerator_randomness() declaration into random.h Greg Kroah-Hartman
` (75 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1daf2f387652bf3a7044aea042f5023b3f6b189b upstream.
This has no real functional change, as crng_pre_init_inject() (and
before that, crng_slow_init()) always checks for == 0, not >= 2. So
correct the outer unlocked change to reflect that. Before this used
crng_ready(), which was not correct.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1020,7 +1020,7 @@ void add_device_randomness(const void *b
unsigned long time = random_get_entropy() ^ jiffies;
unsigned long flags;
- if (!crng_ready() && size)
+ if (crng_init == 0 && size)
crng_pre_init_inject(buf, size, false, false);
spin_lock_irqsave(&input_pool.lock, flags);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 042/111] random: pull add_hwgenerator_randomness() declaration into random.h
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (40 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 041/111] random: check for crng_init == 0 in add_device_randomness() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 043/111] random: clear fast pool, crng, and batches in cpuhp bring up Greg Kroah-Hartman
` (74 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Matt Mackall, Theodore Tso,
Herbert Xu, Eric Biggers, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit b777c38239fec5a528e59f55b379e31b1a187524 upstream.
add_hwgenerator_randomness() is a function implemented and documented
inside of random.c. It is the way that hardware RNGs push data into it.
Therefore, it should be declared in random.h. Otherwise sparse complains
with:
random.c:1137:6: warning: symbol 'add_hwgenerator_randomness' was not declared. Should it be static?
The alternative would be to include hw_random.h into random.c, but that
wouldn't really be good for anything except slowing down compile time.
Cc: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/hw_random/core.c | 1 +
include/linux/hw_random.h | 2 --
include/linux/random.h | 2 ++
3 files changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -15,6 +15,7 @@
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/hw_random.h>
+#include <linux/random.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/sched/signal.h>
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -60,7 +60,5 @@ extern int devm_hwrng_register(struct de
/** Unregister a Hardware Random Number Generator driver. */
extern void hwrng_unregister(struct hwrng *rng);
extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng);
-/** Feed random bits into the pool. */
-extern void add_hwgenerator_randomness(const void *buffer, size_t count, size_t entropy);
#endif /* LINUX_HWRANDOM_H_ */
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -32,6 +32,8 @@ static inline void add_latent_entropy(vo
extern void add_input_randomness(unsigned int type, unsigned int code,
unsigned int value) __latent_entropy;
extern void add_interrupt_randomness(int irq) __latent_entropy;
+extern void add_hwgenerator_randomness(const void *buffer, size_t count,
+ size_t entropy);
extern void get_random_bytes(void *buf, size_t nbytes);
extern int wait_for_random_bytes(void);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 043/111] random: clear fast pool, crng, and batches in cpuhp bring up
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (41 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 042/111] random: pull add_hwgenerator_randomness() declaration into random.h Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 044/111] random: round-robin registers as ulong, not u32 Greg Kroah-Hartman
` (73 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Peter Zijlstra,
Theodore Tso, Sultan Alsawaf, Dominik Brodowski,
Sebastian Andrzej Siewior, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 3191dd5a1179ef0fad5a050a1702ae98b6251e8f upstream.
For the irq randomness fast pool, rather than having to use expensive
atomics, which were visibly the most expensive thing in the entire irq
handler, simply take care of the extreme edge case of resetting count to
zero in the cpuhp online handler, just after workqueues have been
reenabled. This simplifies the code a bit and lets us use vanilla
variables rather than atomics, and performance should be improved.
As well, very early on when the CPU comes up, while interrupts are still
disabled, we clear out the per-cpu crng and its batches, so that it
always starts with fresh randomness.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 62 ++++++++++++++++++++++++++++++++++-----------
include/linux/cpuhotplug.h | 2 +
include/linux/random.h | 5 +++
kernel/cpu.c | 11 +++++++
4 files changed, 65 insertions(+), 15 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -698,6 +698,25 @@ u32 get_random_u32(void)
}
EXPORT_SYMBOL(get_random_u32);
+#ifdef CONFIG_SMP
+/*
+ * This function is called when the CPU is coming up, with entry
+ * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP.
+ */
+int random_prepare_cpu(unsigned int cpu)
+{
+ /*
+ * When the cpu comes back online, immediately invalidate both
+ * the per-cpu crng and all batches, so that we serve fresh
+ * randomness.
+ */
+ per_cpu_ptr(&crngs, cpu)->generation = ULONG_MAX;
+ per_cpu_ptr(&batched_entropy_u32, cpu)->position = UINT_MAX;
+ per_cpu_ptr(&batched_entropy_u64, cpu)->position = UINT_MAX;
+ return 0;
+}
+#endif
+
/**
* randomize_page - Generate a random, page aligned address
* @start: The smallest acceptable address the caller will take.
@@ -1183,7 +1202,7 @@ struct fast_pool {
};
struct work_struct mix;
unsigned long last;
- atomic_t count;
+ unsigned int count;
u16 reg_idx;
};
@@ -1219,6 +1238,29 @@ static void fast_mix(u32 pool[4])
static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
+#ifdef CONFIG_SMP
+/*
+ * This function is called when the CPU has just come online, with
+ * entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE.
+ */
+int random_online_cpu(unsigned int cpu)
+{
+ /*
+ * During CPU shutdown and before CPU onlining, add_interrupt_
+ * randomness() may schedule mix_interrupt_randomness(), and
+ * set the MIX_INFLIGHT flag. However, because the worker can
+ * be scheduled on a different CPU during this period, that
+ * flag will never be cleared. For that reason, we zero out
+ * the flag here, which runs just after workqueues are onlined
+ * for the CPU again. This also has the effect of setting the
+ * irq randomness count to zero so that new accumulated irqs
+ * are fresh.
+ */
+ per_cpu_ptr(&irq_randomness, cpu)->count = 0;
+ return 0;
+}
+#endif
+
static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
{
u32 *ptr = (u32 *)regs;
@@ -1243,15 +1285,6 @@ static void mix_interrupt_randomness(str
local_irq_disable();
if (fast_pool != this_cpu_ptr(&irq_randomness)) {
local_irq_enable();
- /*
- * If we are unlucky enough to have been moved to another CPU,
- * during CPU hotplug while the CPU was shutdown then we set
- * our count to zero atomically so that when the CPU comes
- * back online, it can enqueue work again. The _release here
- * pairs with the atomic_inc_return_acquire in
- * add_interrupt_randomness().
- */
- atomic_set_release(&fast_pool->count, 0);
return;
}
@@ -1260,7 +1293,7 @@ static void mix_interrupt_randomness(str
* consistent view, before we reenable irqs again.
*/
memcpy(pool, fast_pool->pool32, sizeof(pool));
- atomic_set(&fast_pool->count, 0);
+ fast_pool->count = 0;
fast_pool->last = jiffies;
local_irq_enable();
@@ -1296,14 +1329,13 @@ void add_interrupt_randomness(int irq)
}
fast_mix(fast_pool->pool32);
- /* The _acquire here pairs with the atomic_set_release in mix_interrupt_randomness(). */
- new_count = (unsigned int)atomic_inc_return_acquire(&fast_pool->count);
+ new_count = ++fast_pool->count;
if (unlikely(crng_init == 0)) {
if (new_count >= 64 &&
crng_pre_init_inject(fast_pool->pool32, sizeof(fast_pool->pool32),
true, true) > 0) {
- atomic_set(&fast_pool->count, 0);
+ fast_pool->count = 0;
fast_pool->last = now;
if (spin_trylock(&input_pool.lock)) {
_mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
@@ -1321,7 +1353,7 @@ void add_interrupt_randomness(int irq)
if (unlikely(!fast_pool->mix.func))
INIT_WORK(&fast_pool->mix, mix_interrupt_randomness);
- atomic_or(MIX_INFLIGHT, &fast_pool->count);
+ fast_pool->count |= MIX_INFLIGHT;
queue_work_on(raw_smp_processor_id(), system_highpri_wq, &fast_pool->mix);
}
EXPORT_SYMBOL_GPL(add_interrupt_randomness);
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -100,6 +100,7 @@ enum cpuhp_state {
CPUHP_AP_ARM_CACHE_B15_RAC_DEAD,
CPUHP_PADATA_DEAD,
CPUHP_AP_DTPM_CPU_DEAD,
+ CPUHP_RANDOM_PREPARE,
CPUHP_WORKQUEUE_PREP,
CPUHP_POWER_NUMA_PREPARE,
CPUHP_HRTIMERS_PREPARE,
@@ -240,6 +241,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_CSKY_ONLINE,
CPUHP_AP_WATCHDOG_ONLINE,
CPUHP_AP_WORKQUEUE_ONLINE,
+ CPUHP_AP_RANDOM_ONLINE,
CPUHP_AP_RCUTREE_ONLINE,
CPUHP_AP_BASE_CACHEINFO_ONLINE,
CPUHP_AP_ONLINE_DYN,
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -156,4 +156,9 @@ static inline bool __init arch_get_rando
}
#endif
+#ifdef CONFIG_SMP
+extern int random_prepare_cpu(unsigned int cpu);
+extern int random_online_cpu(unsigned int cpu);
+#endif
+
#endif /* _LINUX_RANDOM_H */
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -34,6 +34,7 @@
#include <linux/scs.h>
#include <linux/percpu-rwsem.h>
#include <linux/cpuset.h>
+#include <linux/random.h>
#include <trace/events/power.h>
#define CREATE_TRACE_POINTS
@@ -1659,6 +1660,11 @@ static struct cpuhp_step cpuhp_hp_states
.startup.single = perf_event_init_cpu,
.teardown.single = perf_event_exit_cpu,
},
+ [CPUHP_RANDOM_PREPARE] = {
+ .name = "random:prepare",
+ .startup.single = random_prepare_cpu,
+ .teardown.single = NULL,
+ },
[CPUHP_WORKQUEUE_PREP] = {
.name = "workqueue:prepare",
.startup.single = workqueue_prepare_cpu,
@@ -1782,6 +1788,11 @@ static struct cpuhp_step cpuhp_hp_states
.startup.single = workqueue_online_cpu,
.teardown.single = workqueue_offline_cpu,
},
+ [CPUHP_AP_RANDOM_ONLINE] = {
+ .name = "random:online",
+ .startup.single = random_online_cpu,
+ .teardown.single = NULL,
+ },
[CPUHP_AP_RCUTREE_ONLINE] = {
.name = "RCU/tree:online",
.startup.single = rcutree_online_cpu,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 044/111] random: round-robin registers as ulong, not u32
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (42 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 043/111] random: clear fast pool, crng, and batches in cpuhp bring up Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 045/111] random: only wake up writers after zap if threshold was passed Greg Kroah-Hartman
` (72 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit da3951ebdcd1cb1d5c750e08cd05aee7b0c04d9a upstream.
When the interrupt handler does not have a valid cycle counter, it calls
get_reg() to read a register from the irq stack, in round-robin.
Currently it does this assuming that registers are 32-bit. This is
_probably_ the case, and probably all platforms without cycle counters
are in fact 32-bit platforms. But maybe not, and either way, it's not
quite correct. This commit fixes that to deal with `unsigned long`
rather than `u32`.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1261,15 +1261,15 @@ int random_online_cpu(unsigned int cpu)
}
#endif
-static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
+static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs)
{
- u32 *ptr = (u32 *)regs;
+ unsigned long *ptr = (unsigned long *)regs;
unsigned int idx;
if (regs == NULL)
return 0;
idx = READ_ONCE(f->reg_idx);
- if (idx >= sizeof(struct pt_regs) / sizeof(u32))
+ if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long))
idx = 0;
ptr += idx++;
WRITE_ONCE(f->reg_idx, idx);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 045/111] random: only wake up writers after zap if threshold was passed
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (43 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 044/111] random: round-robin registers as ulong, not u32 Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 046/111] random: cleanup UUID handling Greg Kroah-Hartman
` (71 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a3f9e8910e1584d7725ef7d5ac870920d42d0bb4 upstream.
The only time that we need to wake up /dev/random writers on
RNDCLEARPOOL/RNDZAPPOOL is when we're changing from a value that is
greater than or equal to POOL_MIN_BITS to zero, because if we're
changing from below POOL_MIN_BITS to zero, the writers are already
unblocked.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1582,7 +1582,7 @@ static long random_ioctl(struct file *f,
*/
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (xchg(&input_pool.entropy_count, 0)) {
+ if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) {
wake_up_interruptible(&random_write_wait);
kill_fasync(&fasync, SIGIO, POLL_OUT);
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 046/111] random: cleanup UUID handling
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (44 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 045/111] random: only wake up writers after zap if threshold was passed Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 047/111] random: unify cycles_t and jiffies usage and types Greg Kroah-Hartman
` (70 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 64276a9939ff414f2f0db38036cf4e1a0a703394 upstream.
Rather than hard coding various lengths, we can use the right constants.
Strings should be `char *` while buffers should be `u8 *`. Rather than
have a nonsensical and unused maxlength, just remove it. Finally, use
snprintf instead of sprintf, just out of good hygiene.
As well, remove the old comment about returning a binary UUID via the
binary sysctl syscall. That syscall was removed from the kernel in 5.5,
and actually, the "uuid_strategy" function and related infrastructure
for even serving it via the binary sysctl syscall was removed with
894d2491153a ("sysctl drivers: Remove dead binary sysctl support") back
in 2.6.33.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1661,22 +1661,25 @@ const struct file_operations urandom_fop
static int sysctl_random_min_urandom_seed = 60;
static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
static int sysctl_poolsize = POOL_BITS;
-static char sysctl_bootid[16];
+static u8 sysctl_bootid[UUID_SIZE];
/*
* This function is used to return both the bootid UUID, and random
- * UUID. The difference is in whether table->data is NULL; if it is,
+ * UUID. The difference is in whether table->data is NULL; if it is,
* then a new UUID is generated and returned to the user.
- *
- * If the user accesses this via the proc interface, the UUID will be
- * returned as an ASCII string in the standard UUID format; if via the
- * sysctl system call, as 16 bytes of binary data.
*/
static int proc_do_uuid(struct ctl_table *table, int write, void *buffer,
size_t *lenp, loff_t *ppos)
{
- struct ctl_table fake_table;
- unsigned char buf[64], tmp_uuid[16], *uuid;
+ u8 tmp_uuid[UUID_SIZE], *uuid;
+ char uuid_string[UUID_STRING_LEN + 1];
+ struct ctl_table fake_table = {
+ .data = uuid_string,
+ .maxlen = UUID_STRING_LEN
+ };
+
+ if (write)
+ return -EPERM;
uuid = table->data;
if (!uuid) {
@@ -1691,12 +1694,8 @@ static int proc_do_uuid(struct ctl_table
spin_unlock(&bootid_spinlock);
}
- sprintf(buf, "%pU", uuid);
-
- fake_table.data = buf;
- fake_table.maxlen = sizeof(buf);
-
- return proc_dostring(&fake_table, write, buffer, lenp, ppos);
+ snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid);
+ return proc_dostring(&fake_table, 0, buffer, lenp, ppos);
}
static struct ctl_table random_table[] = {
@@ -1731,13 +1730,11 @@ static struct ctl_table random_table[] =
{
.procname = "boot_id",
.data = &sysctl_bootid,
- .maxlen = 16,
.mode = 0444,
.proc_handler = proc_do_uuid,
},
{
.procname = "uuid",
- .maxlen = 16,
.mode = 0444,
.proc_handler = proc_do_uuid,
},
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 047/111] random: unify cycles_t and jiffies usage and types
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (45 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 046/111] random: cleanup UUID handling Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 048/111] random: do crng pre-init loading in worker rather than irq Greg Kroah-Hartman
` (69 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit abded93ec1e9692920fe309f07f40bd1035f2940 upstream.
random_get_entropy() returns a cycles_t, not an unsigned long, which is
sometimes 64 bits on various 32-bit platforms, including x86.
Conversely, jiffies is always unsigned long. This commit fixes things to
use cycles_t for fields that use random_get_entropy(), named "cycles",
and unsigned long for fields that use jiffies, named "now". It's also
good to mix in a cycles_t and a jiffies in the same way for both
add_device_randomness and add_timer_randomness, rather than using xor in
one case. Finally, we unify the order of these volatile reads, always
reading the more precise cycles counter, and then jiffies, so that the
cycle counter is as close to the event as possible.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 56 ++++++++++++++++++++++++--------------------------
1 file changed, 27 insertions(+), 29 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1020,12 +1020,6 @@ int __init rand_initialize(void)
return 0;
}
-/* There is one of these per entropy source */
-struct timer_rand_state {
- cycles_t last_time;
- long last_delta, last_delta2;
-};
-
/*
* Add device- or boot-specific data to the input pool to help
* initialize it.
@@ -1036,19 +1030,26 @@ struct timer_rand_state {
*/
void add_device_randomness(const void *buf, size_t size)
{
- unsigned long time = random_get_entropy() ^ jiffies;
- unsigned long flags;
+ cycles_t cycles = random_get_entropy();
+ unsigned long flags, now = jiffies;
if (crng_init == 0 && size)
crng_pre_init_inject(buf, size, false, false);
spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(&cycles, sizeof(cycles));
+ _mix_pool_bytes(&now, sizeof(now));
_mix_pool_bytes(buf, size);
- _mix_pool_bytes(&time, sizeof(time));
spin_unlock_irqrestore(&input_pool.lock, flags);
}
EXPORT_SYMBOL(add_device_randomness);
+/* There is one of these per entropy source */
+struct timer_rand_state {
+ unsigned long last_time;
+ long last_delta, last_delta2;
+};
+
/*
* This function adds entropy to the entropy "pool" by using timing
* delays. It uses the timer_rand_state structure to make an estimate
@@ -1057,29 +1058,26 @@ EXPORT_SYMBOL(add_device_randomness);
* The number "num" is also added to the pool - it should somehow describe
* the type of event which just happened. This is currently 0-255 for
* keyboard scan codes, and 256 upwards for interrupts.
- *
*/
static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
- struct {
- long jiffies;
- unsigned int cycles;
- unsigned int num;
- } sample;
+ cycles_t cycles = random_get_entropy();
+ unsigned long flags, now = jiffies;
long delta, delta2, delta3;
- sample.jiffies = jiffies;
- sample.cycles = random_get_entropy();
- sample.num = num;
- mix_pool_bytes(&sample, sizeof(sample));
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(&cycles, sizeof(cycles));
+ _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(&num, sizeof(num));
+ spin_unlock_irqrestore(&input_pool.lock, flags);
/*
* Calculate number of bits of randomness we probably added.
* We take into account the first, second and third-order deltas
* in order to make our estimate.
*/
- delta = sample.jiffies - READ_ONCE(state->last_time);
- WRITE_ONCE(state->last_time, sample.jiffies);
+ delta = now - READ_ONCE(state->last_time);
+ WRITE_ONCE(state->last_time, now);
delta2 = delta - READ_ONCE(state->last_delta);
WRITE_ONCE(state->last_delta, delta);
@@ -1305,10 +1303,10 @@ static void mix_interrupt_randomness(str
void add_interrupt_randomness(int irq)
{
enum { MIX_INFLIGHT = 1U << 31 };
+ cycles_t cycles = random_get_entropy();
+ unsigned long now = jiffies;
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
struct pt_regs *regs = get_irq_regs();
- unsigned long now = jiffies;
- cycles_t cycles = random_get_entropy();
unsigned int new_count;
if (cycles == 0)
@@ -1383,28 +1381,28 @@ static void entropy_timer(struct timer_l
static void try_to_generate_entropy(void)
{
struct {
- unsigned long now;
+ cycles_t cycles;
struct timer_list timer;
} stack;
- stack.now = random_get_entropy();
+ stack.cycles = random_get_entropy();
/* Slow counter - or none. Don't even bother */
- if (stack.now == random_get_entropy())
+ if (stack.cycles == random_get_entropy())
return;
timer_setup_on_stack(&stack.timer, entropy_timer, 0);
while (!crng_ready()) {
if (!timer_pending(&stack.timer))
mod_timer(&stack.timer, jiffies + 1);
- mix_pool_bytes(&stack.now, sizeof(stack.now));
+ mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
schedule();
- stack.now = random_get_entropy();
+ stack.cycles = random_get_entropy();
}
del_timer_sync(&stack.timer);
destroy_timer_on_stack(&stack.timer);
- mix_pool_bytes(&stack.now, sizeof(stack.now));
+ mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 048/111] random: do crng pre-init loading in worker rather than irq
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (46 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 047/111] random: unify cycles_t and jiffies usage and types Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 049/111] random: give sysctl_random_min_urandom_seed a more sensible value Greg Kroah-Hartman
` (68 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Sultan Alsawaf, Thomas Gleixner,
Peter Zijlstra, Eric Biggers, Theodore Tso,
Sebastian Andrzej Siewior, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit c2a7de4feb6e09f23af7accc0f882a8fa92e7ae5 upstream.
Taking spinlocks from IRQ context is generally problematic for
PREEMPT_RT. That is, in part, why we take trylocks instead. However, a
spin_try_lock() is also problematic since another spin_lock() invocation
can potentially PI-boost the wrong task, as the spin_try_lock() is
invoked from an IRQ-context, so the task on CPU (random task or idle) is
not the actual owner.
Additionally, by deferring the crng pre-init loading to the worker, we
can use the cryptographic hash function rather than xor, which is
perhaps a meaningful difference when considering this data has only been
through the relatively weak fast_mix() function.
The biggest downside of this approach is that the pre-init loading is
now deferred until later, which means things that need random numbers
after interrupts are enabled, but before workqueues are running -- or
before this particular worker manages to run -- are going to get into
trouble. Hopefully in the real world, this window is rather small,
especially since this code won't run until 64 interrupts had occurred.
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 65 ++++++++++++++------------------------------------
1 file changed, 19 insertions(+), 46 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -443,10 +443,6 @@ static void crng_make_state(u32 chacha_s
* boot time when it's better to have something there rather than
* nothing.
*
- * There are two paths, a slow one and a fast one. The slow one
- * hashes the input along with the current key. The fast one simply
- * xors it in, and should only be used from interrupt context.
- *
* If account is set, then the crng_init_cnt counter is incremented.
* This shouldn't be set by functions like add_device_randomness(),
* where we can't trust the buffer passed to it is guaranteed to be
@@ -455,19 +451,15 @@ static void crng_make_state(u32 chacha_s
* Returns the number of bytes processed from input, which is bounded
* by CRNG_INIT_CNT_THRESH if account is true.
*/
-static size_t crng_pre_init_inject(const void *input, size_t len,
- bool fast, bool account)
+static size_t crng_pre_init_inject(const void *input, size_t len, bool account)
{
static int crng_init_cnt = 0;
+ struct blake2s_state hash;
unsigned long flags;
- if (fast) {
- if (!spin_trylock_irqsave(&base_crng.lock, flags))
- return 0;
- } else {
- spin_lock_irqsave(&base_crng.lock, flags);
- }
+ blake2s_init(&hash, sizeof(base_crng.key));
+ spin_lock_irqsave(&base_crng.lock, flags);
if (crng_init != 0) {
spin_unlock_irqrestore(&base_crng.lock, flags);
return 0;
@@ -476,21 +468,9 @@ static size_t crng_pre_init_inject(const
if (account)
len = min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
- if (fast) {
- const u8 *src = input;
- size_t i;
-
- for (i = 0; i < len; ++i)
- base_crng.key[(crng_init_cnt + i) %
- sizeof(base_crng.key)] ^= src[i];
- } else {
- struct blake2s_state hash;
-
- blake2s_init(&hash, sizeof(base_crng.key));
- blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
- blake2s_update(&hash, input, len);
- blake2s_final(&hash, base_crng.key);
- }
+ blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
+ blake2s_update(&hash, input, len);
+ blake2s_final(&hash, base_crng.key);
if (account) {
crng_init_cnt += len;
@@ -1034,7 +1014,7 @@ void add_device_randomness(const void *b
unsigned long flags, now = jiffies;
if (crng_init == 0 && size)
- crng_pre_init_inject(buf, size, false, false);
+ crng_pre_init_inject(buf, size, false);
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(&cycles, sizeof(cycles));
@@ -1155,7 +1135,7 @@ void add_hwgenerator_randomness(const vo
size_t entropy)
{
if (unlikely(crng_init == 0)) {
- size_t ret = crng_pre_init_inject(buffer, count, false, true);
+ size_t ret = crng_pre_init_inject(buffer, count, true);
mix_pool_bytes(buffer, ret);
count -= ret;
buffer += ret;
@@ -1295,8 +1275,14 @@ static void mix_interrupt_randomness(str
fast_pool->last = jiffies;
local_irq_enable();
- mix_pool_bytes(pool, sizeof(pool));
- credit_entropy_bits(1);
+ if (unlikely(crng_init == 0)) {
+ crng_pre_init_inject(pool, sizeof(pool), true);
+ mix_pool_bytes(pool, sizeof(pool));
+ } else {
+ mix_pool_bytes(pool, sizeof(pool));
+ credit_entropy_bits(1);
+ }
+
memzero_explicit(pool, sizeof(pool));
}
@@ -1329,24 +1315,11 @@ void add_interrupt_randomness(int irq)
fast_mix(fast_pool->pool32);
new_count = ++fast_pool->count;
- if (unlikely(crng_init == 0)) {
- if (new_count >= 64 &&
- crng_pre_init_inject(fast_pool->pool32, sizeof(fast_pool->pool32),
- true, true) > 0) {
- fast_pool->count = 0;
- fast_pool->last = now;
- if (spin_trylock(&input_pool.lock)) {
- _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32));
- spin_unlock(&input_pool.lock);
- }
- }
- return;
- }
-
if (new_count & MIX_INFLIGHT)
return;
- if (new_count < 64 && !time_after(now, fast_pool->last + HZ))
+ if (new_count < 64 && (!time_after(now, fast_pool->last + HZ) ||
+ unlikely(crng_init == 0)))
return;
if (unlikely(!fast_pool->mix.func))
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 049/111] random: give sysctl_random_min_urandom_seed a more sensible value
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (47 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 048/111] random: do crng pre-init loading in worker rather than irq Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 050/111] random: dont let 644 read-only sysctls be written to Greg Kroah-Hartman
` (67 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit d0efdf35a6a71d307a250199af6fce122a7c7e11 upstream.
This isn't used by anything or anywhere, but we can't delete it due to
compatibility. So at least give it the correct value of what it's
supposed to be instead of a garbage one.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1619,7 +1619,7 @@ const struct file_operations urandom_fop
* to avoid breaking old userspaces, but writing to it does not
* change any behavior of the RNG.
*
- * - urandom_min_reseed_secs - fixed to the meaningless value "60".
+ * - urandom_min_reseed_secs - fixed to the value CRNG_RESEED_INTERVAL.
* It is writable to avoid breaking old userspaces, but writing
* to it does not change any behavior of the RNG.
*
@@ -1629,7 +1629,7 @@ const struct file_operations urandom_fop
#include <linux/sysctl.h>
-static int sysctl_random_min_urandom_seed = 60;
+static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ;
static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
static int sysctl_poolsize = POOL_BITS;
static u8 sysctl_bootid[UUID_SIZE];
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 050/111] random: dont let 644 read-only sysctls be written to
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (48 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 049/111] random: give sysctl_random_min_urandom_seed a more sensible value Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 051/111] random: replace custom notifier chain with standard one Greg Kroah-Hartman
` (66 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 77553cf8f44863b31da242cf24671d76ddb61597 upstream.
We leave around these old sysctls for compatibility, and we keep them
"writable" for compatibility, but even after writing, we should keep
reporting the same value. This is consistent with how userspaces tend to
use sysctl_random_write_wakeup_bits, writing to it, and then later
reading from it and using the value.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1669,6 +1669,13 @@ static int proc_do_uuid(struct ctl_table
return proc_dostring(&fake_table, 0, buffer, lenp, ppos);
}
+/* The same as proc_dointvec, but writes don't change anything. */
+static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos);
+}
+
static struct ctl_table random_table[] = {
{
.procname = "poolsize",
@@ -1689,14 +1696,14 @@ static struct ctl_table random_table[] =
.data = &sysctl_random_write_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_do_rointvec,
},
{
.procname = "urandom_min_reseed_secs",
.data = &sysctl_random_min_urandom_seed,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_do_rointvec,
},
{
.procname = "boot_id",
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 051/111] random: replace custom notifier chain with standard one
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (49 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 050/111] random: dont let 644 read-only sysctls be written to Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 052/111] random: use SipHash as interrupt entropy accumulator Greg Kroah-Hartman
` (65 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5acd35487dc911541672b3ffc322851769c32a56 upstream.
We previously rolled our own randomness readiness notifier, which only
has two users in the whole kernel. Replace this with a more standard
atomic notifier block that serves the same purpose with less code. Also
unexport the symbols, because no modules use it, only unconditional
builtins. The only drawback is that it's possible for a notification
handler returning the "stop" code to prevent further processing, but
given that there are only two users, and that we're unexporting this
anyway, that doesn't seem like a significant drawback for the
simplification we receive here.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 67 +++++++++++++------------------------------------
include/linux/random.h | 10 ++-----
lib/random32.c | 12 +++++---
lib/vsprintf.c | 10 ++++---
4 files changed, 35 insertions(+), 64 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -83,8 +83,8 @@ static int crng_init = 0;
/* Various types of waiters for crng_init->2 transition. */
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
static struct fasync_struct *fasync;
-static DEFINE_SPINLOCK(random_ready_list_lock);
-static LIST_HEAD(random_ready_list);
+static DEFINE_SPINLOCK(random_ready_chain_lock);
+static RAW_NOTIFIER_HEAD(random_ready_chain);
/* Control how we warn userspace. */
static struct ratelimit_state unseeded_warning =
@@ -147,72 +147,43 @@ EXPORT_SYMBOL(wait_for_random_bytes);
*
* returns: 0 if callback is successfully added
* -EALREADY if pool is already initialised (callback not called)
- * -ENOENT if module for callback is not alive
*/
-int add_random_ready_callback(struct random_ready_callback *rdy)
+int register_random_ready_notifier(struct notifier_block *nb)
{
- struct module *owner;
unsigned long flags;
- int err = -EALREADY;
+ int ret = -EALREADY;
if (crng_ready())
- return err;
+ return ret;
- owner = rdy->owner;
- if (!try_module_get(owner))
- return -ENOENT;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (crng_ready())
- goto out;
-
- owner = NULL;
-
- list_add(&rdy->list, &random_ready_list);
- err = 0;
-
-out:
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
-
- module_put(owner);
-
- return err;
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ if (!crng_ready())
+ ret = raw_notifier_chain_register(&random_ready_chain, nb);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
+ return ret;
}
-EXPORT_SYMBOL(add_random_ready_callback);
/*
* Delete a previously registered readiness callback function.
*/
-void del_random_ready_callback(struct random_ready_callback *rdy)
+int unregister_random_ready_notifier(struct notifier_block *nb)
{
unsigned long flags;
- struct module *owner = NULL;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (!list_empty(&rdy->list)) {
- list_del_init(&rdy->list);
- owner = rdy->owner;
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
+ int ret;
- module_put(owner);
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ ret = raw_notifier_chain_unregister(&random_ready_chain, nb);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
+ return ret;
}
-EXPORT_SYMBOL(del_random_ready_callback);
static void process_random_ready_list(void)
{
unsigned long flags;
- struct random_ready_callback *rdy, *tmp;
- spin_lock_irqsave(&random_ready_list_lock, flags);
- list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
- struct module *owner = rdy->owner;
-
- list_del_init(&rdy->list);
- rdy->func(rdy);
- module_put(owner);
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ raw_notifier_call_chain(&random_ready_chain, 0, NULL);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
}
#define warn_unseeded_randomness(previous) \
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -10,11 +10,7 @@
#include <uapi/linux/random.h>
-struct random_ready_callback {
- struct list_head list;
- void (*func)(struct random_ready_callback *rdy);
- struct module *owner;
-};
+struct notifier_block;
extern void add_device_randomness(const void *, size_t);
extern void add_bootloader_randomness(const void *, size_t);
@@ -39,8 +35,8 @@ extern void get_random_bytes(void *buf,
extern int wait_for_random_bytes(void);
extern int __init rand_initialize(void);
extern bool rng_is_initialized(void);
-extern int add_random_ready_callback(struct random_ready_callback *rdy);
-extern void del_random_ready_callback(struct random_ready_callback *rdy);
+extern int register_random_ready_notifier(struct notifier_block *nb);
+extern int unregister_random_ready_notifier(struct notifier_block *nb);
extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
#ifndef MODULE
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -551,9 +551,11 @@ static void prandom_reseed(struct timer_
* To avoid worrying about whether it's safe to delay that interrupt
* long enough to seed all CPUs, just schedule an immediate timer event.
*/
-static void prandom_timer_start(struct random_ready_callback *unused)
+static int prandom_timer_start(struct notifier_block *nb,
+ unsigned long action, void *data)
{
mod_timer(&seed_timer, jiffies);
+ return 0;
}
#ifdef CONFIG_RANDOM32_SELFTEST
@@ -617,13 +619,13 @@ core_initcall(prandom32_state_selftest);
*/
static int __init prandom_init_late(void)
{
- static struct random_ready_callback random_ready = {
- .func = prandom_timer_start
+ static struct notifier_block random_ready = {
+ .notifier_call = prandom_timer_start
};
- int ret = add_random_ready_callback(&random_ready);
+ int ret = register_random_ready_notifier(&random_ready);
if (ret == -EALREADY) {
- prandom_timer_start(&random_ready);
+ prandom_timer_start(&random_ready, 0, NULL);
ret = 0;
}
return ret;
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -762,14 +762,16 @@ static void enable_ptr_key_workfn(struct
static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
-static void fill_random_ptr_key(struct random_ready_callback *unused)
+static int fill_random_ptr_key(struct notifier_block *nb,
+ unsigned long action, void *data)
{
/* This may be in an interrupt handler. */
queue_work(system_unbound_wq, &enable_ptr_key_work);
+ return 0;
}
-static struct random_ready_callback random_ready = {
- .func = fill_random_ptr_key
+static struct notifier_block random_ready = {
+ .notifier_call = fill_random_ptr_key
};
static int __init initialize_ptr_random(void)
@@ -783,7 +785,7 @@ static int __init initialize_ptr_random(
return 0;
}
- ret = add_random_ready_callback(&random_ready);
+ ret = register_random_ready_notifier(&random_ready);
if (!ret) {
return 0;
} else if (ret == -EALREADY) {
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 052/111] random: use SipHash as interrupt entropy accumulator
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (50 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 051/111] random: replace custom notifier chain with standard one Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 053/111] random: make consistent usage of crng_ready() Greg Kroah-Hartman
` (64 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Jean-Philippe Aumasson,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit f5eab0e2db4f881fb2b62b3fdad5b9be673dd7ae upstream.
The current fast_mix() function is a piece of classic mailing list
crypto, where it just sort of sprung up by an anonymous author without a
lot of real analysis of what precisely it was accomplishing. As an ARX
permutation alone, there are some easily searchable differential trails
in it, and as a means of preventing malicious interrupts, it completely
fails, since it xors new data into the entire state every time. It can't
really be analyzed as a random permutation, because it clearly isn't,
and it can't be analyzed as an interesting linear algebraic structure
either, because it's also not that. There really is very little one can
say about it in terms of entropy accumulation. It might diffuse bits,
some of the time, maybe, we hope, I guess. But for the most part, it
fails to accomplish anything concrete.
As a reminder, the simple goal of add_interrupt_randomness() is to
simply accumulate entropy until ~64 interrupts have elapsed, and then
dump it into the main input pool, which uses a cryptographic hash.
It would be nice to have something cryptographically strong in the
interrupt handler itself, in case a malicious interrupt compromises a
per-cpu fast pool within the 64 interrupts / 1 second window, and then
inside of that same window somehow can control its return address and
cycle counter, even if that's a bit far fetched. However, with a very
CPU-limited budget, actually doing that remains an active research
project (and perhaps there'll be something useful for Linux to come out
of it). And while the abundance of caution would be nice, this isn't
*currently* the security model, and we don't yet have a fast enough
solution to make it our security model. Plus there's not exactly a
pressing need to do that. (And for the avoidance of doubt, the actual
cluster of 64 accumulated interrupts still gets dumped into our
cryptographically secure input pool.)
So, for now we are going to stick with the existing interrupt security
model, which assumes that each cluster of 64 interrupt data samples is
mostly non-malicious and not colluding with an infoleaker. With this as
our goal, we have a few more choices, simply aiming to accumulate
entropy, while discarding the least amount of it.
We know from <https://eprint.iacr.org/2019/198> that random oracles,
instantiated as computational hash functions, make good entropy
accumulators and extractors, which is the justification for using
BLAKE2s in the main input pool. As mentioned, we don't have that luxury
here, but we also don't have the same security model requirements,
because we're assuming that there aren't malicious inputs. A
pseudorandom function instance can approximately behave like a random
oracle, provided that the key is uniformly random. But since we're not
concerned with malicious inputs, we can pick a fixed key, which is not
secret, knowing that "nature" won't interact with a sufficiently chosen
fixed key by accident. So we pick a PRF with a fixed initial key, and
accumulate into it continuously, dumping the result every 64 interrupts
into our cryptographically secure input pool.
For this, we make use of SipHash-1-x on 64-bit and HalfSipHash-1-x on
32-bit, which are already in use in the kernel's hsiphash family of
functions and achieve the same performance as the function they replace.
It would be nice to do two rounds, but we don't exactly have the CPU
budget handy for that, and one round alone is already sufficient.
As mentioned, we start with a fixed initial key (zeros is fine), and
allow SipHash's symmetry breaking constants to turn that into a useful
starting point. Also, since we're dumping the result (or half of it on
64-bit so as to tax our hash function the same amount on all platforms)
into the cryptographically secure input pool, there's no point in
finalizing SipHash's output, since it'll wind up being finalized by
something much stronger. This means that all we need to do is use the
ordinary round function word-by-word, as normal SipHash does.
Simplified, the flow is as follows:
Initialize:
siphash_state_t state;
siphash_init(&state, key={0, 0, 0, 0});
Update (accumulate) on interrupt:
siphash_update(&state, interrupt_data_and_timing);
Dump into input pool after 64 interrupts:
blake2s_update(&input_pool, &state, sizeof(state) / 2);
The result of all of this is that the security model is unchanged from
before -- we assume non-malicious inputs -- yet we now implement that
model with a stronger argument. I would like to emphasize, again, that
the purpose of this commit is to improve the existing design, by making
it analyzable, without changing any fundamental assumptions. There may
well be value down the road in changing up the existing design, using
something cryptographically strong, or simply using a ring buffer of
samples rather than having a fast_mix() at all, or changing which and
how much data we collect each interrupt so that we can use something
linear, or a variety of other ideas. This commit does not invalidate the
potential for those in the future.
For example, in the future, if we're able to characterize the data we're
collecting on each interrupt, we may be able to inch toward information
theoretic accumulators. <https://eprint.iacr.org/2021/523> shows that `s
= ror32(s, 7) ^ x` and `s = ror64(s, 19) ^ x` make very good
accumulators for 2-monotone distributions, which would apply to
timestamp counters, like random_get_entropy() or jiffies, but would not
apply to our current combination of the two values, or to the various
function addresses and register values we mix in. Alternatively,
<https://eprint.iacr.org/2021/1002> shows that max-period linear
functions with no non-trivial invariant subspace make good extractors,
used in the form `s = f(s) ^ x`. However, this only works if the input
data is both identical and independent, and obviously a collection of
address values and counters fails; so it goes with theoretical papers.
Future directions here may involve trying to characterize more precisely
what we actually need to collect in the interrupt handler, and building
something specific around that.
However, as mentioned, the morass of data we're gathering at the
interrupt handler presently defies characterization, and so we use
SipHash for now, which works well and performs well.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 94 +++++++++++++++++++++++++++++---------------------
1 file changed, 55 insertions(+), 39 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1145,48 +1145,51 @@ void add_bootloader_randomness(const voi
EXPORT_SYMBOL_GPL(add_bootloader_randomness);
struct fast_pool {
- union {
- u32 pool32[4];
- u64 pool64[2];
- };
struct work_struct mix;
+ unsigned long pool[4];
unsigned long last;
unsigned int count;
u16 reg_idx;
};
+static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
+#ifdef CONFIG_64BIT
+ /* SipHash constants */
+ .pool = { 0x736f6d6570736575UL, 0x646f72616e646f6dUL,
+ 0x6c7967656e657261UL, 0x7465646279746573UL }
+#else
+ /* HalfSipHash constants */
+ .pool = { 0, 0, 0x6c796765U, 0x74656462U }
+#endif
+};
+
/*
- * This is a fast mixing routine used by the interrupt randomness
- * collector. It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
+ * This is [Half]SipHash-1-x, starting from an empty key. Because
+ * the key is fixed, it assumes that its inputs are non-malicious,
+ * and therefore this has no security on its own. s represents the
+ * 128 or 256-bit SipHash state, while v represents a 128-bit input.
*/
-static void fast_mix(u32 pool[4])
+static void fast_mix(unsigned long s[4], const unsigned long *v)
{
- u32 a = pool[0], b = pool[1];
- u32 c = pool[2], d = pool[3];
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
+ size_t i;
- pool[0] = a; pool[1] = b;
- pool[2] = c; pool[3] = d;
+ for (i = 0; i < 16 / sizeof(long); ++i) {
+ s[3] ^= v[i];
+#ifdef CONFIG_64BIT
+ s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32);
+ s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2];
+ s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0];
+ s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32);
+#else
+ s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16);
+ s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2];
+ s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0];
+ s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16);
+#endif
+ s[0] ^= v[i];
+ }
}
-static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
-
#ifdef CONFIG_SMP
/*
* This function is called when the CPU has just come online, with
@@ -1228,7 +1231,15 @@ static unsigned long get_reg(struct fast
static void mix_interrupt_randomness(struct work_struct *work)
{
struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
- u32 pool[4];
+ /*
+ * The size of the copied stack pool is explicitly 16 bytes so that we
+ * tax mix_pool_byte()'s compression function the same amount on all
+ * platforms. This means on 64-bit we copy half the pool into this,
+ * while on 32-bit we copy all of it. The entropy is supposed to be
+ * sufficiently dispersed between bits that in the sponge-like
+ * half case, on average we don't wind up "losing" some.
+ */
+ u8 pool[16];
/* Check to see if we're running on the wrong CPU due to hotplug. */
local_irq_disable();
@@ -1241,7 +1252,7 @@ static void mix_interrupt_randomness(str
* Copy the pool to the stack so that the mixer always has a
* consistent view, before we reenable irqs again.
*/
- memcpy(pool, fast_pool->pool32, sizeof(pool));
+ memcpy(pool, fast_pool->pool, sizeof(pool));
fast_pool->count = 0;
fast_pool->last = jiffies;
local_irq_enable();
@@ -1265,25 +1276,30 @@ void add_interrupt_randomness(int irq)
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
struct pt_regs *regs = get_irq_regs();
unsigned int new_count;
+ union {
+ u32 u32[4];
+ u64 u64[2];
+ unsigned long longs[16 / sizeof(long)];
+ } irq_data;
if (cycles == 0)
cycles = get_reg(fast_pool, regs);
if (sizeof(cycles) == 8)
- fast_pool->pool64[0] ^= cycles ^ rol64(now, 32) ^ irq;
+ irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq;
else {
- fast_pool->pool32[0] ^= cycles ^ irq;
- fast_pool->pool32[1] ^= now;
+ irq_data.u32[0] = cycles ^ irq;
+ irq_data.u32[1] = now;
}
if (sizeof(unsigned long) == 8)
- fast_pool->pool64[1] ^= regs ? instruction_pointer(regs) : _RET_IP_;
+ irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;
else {
- fast_pool->pool32[2] ^= regs ? instruction_pointer(regs) : _RET_IP_;
- fast_pool->pool32[3] ^= get_reg(fast_pool, regs);
+ irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_;
+ irq_data.u32[3] = get_reg(fast_pool, regs);
}
- fast_mix(fast_pool->pool32);
+ fast_mix(fast_pool->pool, irq_data.longs);
new_count = ++fast_pool->count;
if (new_count & MIX_INFLIGHT)
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 053/111] random: make consistent usage of crng_ready()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (51 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 052/111] random: use SipHash as interrupt entropy accumulator Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 054/111] random: reseed more often immediately after booting Greg Kroah-Hartman
` (63 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a96cfe2d427064325ecbf56df8816c6b871ec285 upstream.
Rather than sometimes checking `crng_init < 2`, we should always use the
crng_ready() macro, so that should we change anything later, it's
consistent. Additionally, that macro already has a likely() around it,
which means we don't need to open code our own likely() and unlikely()
annotations.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -125,18 +125,13 @@ static void try_to_generate_entropy(void
*/
int wait_for_random_bytes(void)
{
- if (likely(crng_ready()))
- return 0;
-
- do {
+ while (!crng_ready()) {
int ret;
ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
if (ret)
return ret > 0 ? 0 : ret;
-
try_to_generate_entropy();
- } while (!crng_ready());
-
+ }
return 0;
}
EXPORT_SYMBOL(wait_for_random_bytes);
@@ -291,7 +286,7 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (crng_init < 2) {
+ if (!crng_ready()) {
crng_init = 2;
finalize_init = true;
}
@@ -359,7 +354,7 @@ static void crng_make_state(u32 chacha_s
* ready, we do fast key erasure with the base_crng directly, because
* this is what crng_pre_init_inject() mutates during early init.
*/
- if (unlikely(!crng_ready())) {
+ if (!crng_ready()) {
bool ready;
spin_lock_irqsave(&base_crng.lock, flags);
@@ -802,7 +797,7 @@ static void credit_entropy_bits(size_t n
entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
- if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
+ if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
crng_reseed();
}
@@ -959,7 +954,7 @@ int __init rand_initialize(void)
extract_entropy(base_crng.key, sizeof(base_crng.key));
++base_crng.generation;
- if (arch_init && trust_cpu && crng_init < 2) {
+ if (arch_init && trust_cpu && !crng_ready()) {
crng_init = 2;
pr_notice("crng init done (trusting CPU's manufacturer)\n");
}
@@ -1548,7 +1543,7 @@ static long random_ioctl(struct file *f,
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (crng_init < 2)
+ if (!crng_ready())
return -ENODATA;
crng_reseed();
return 0;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 054/111] random: reseed more often immediately after booting
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (52 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 053/111] random: make consistent usage of crng_ready() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 055/111] random: check for signal and try earlier when generating entropy Greg Kroah-Hartman
` (62 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Eric Biggers,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 7a7ff644aeaf071d433caffb3b8ea57354b55bd3 upstream.
In order to chip away at the "premature first" problem, we augment our
existing entropy accounting with more frequent reseedings at boot.
The idea is that at boot, we're getting entropy from various places, and
we're not very sure which of early boot entropy is good and which isn't.
Even when we're crediting the entropy, we're still not totally certain
that it's any good. Since boot is the one time (aside from a compromise)
that we have zero entropy, it's important that we shepherd entropy into
the crng fairly often.
At the same time, we don't want a "premature next" problem, whereby an
attacker can brute force individual bits of added entropy. In lieu of
going full-on Fortuna (for now), we can pick a simpler strategy of just
reseeding more often during the first 5 minutes after boot. This is
still bounded by the 256-bit entropy credit requirement, so we'll skip a
reseeding if we haven't reached that, but in case entropy /is/ coming
in, this ensures that it makes its way into the crng rather rapidly
during these early stages.
Ordinarily we reseed if the previous reseeding is 300 seconds old. This
commit changes things so that for the first 600 seconds of boot time, we
reseed if the previous reseeding is uptime / 2 seconds old. That means
that we'll reseed at the very least double the uptime of the previous
reseeding.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -336,6 +336,28 @@ static void crng_fast_key_erasure(u8 key
}
/*
+ * Return whether the crng seed is considered to be sufficiently
+ * old that a reseeding might be attempted. This happens if the last
+ * reseeding was CRNG_RESEED_INTERVAL ago, or during early boot, at
+ * an interval proportional to the uptime.
+ */
+static bool crng_has_old_seed(void)
+{
+ static bool early_boot = true;
+ unsigned long interval = CRNG_RESEED_INTERVAL;
+
+ if (unlikely(READ_ONCE(early_boot))) {
+ time64_t uptime = ktime_get_seconds();
+ if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
+ WRITE_ONCE(early_boot, false);
+ else
+ interval = max_t(unsigned int, 5 * HZ,
+ (unsigned int)uptime / 2 * HZ);
+ }
+ return time_after(jiffies, READ_ONCE(base_crng.birth) + interval);
+}
+
+/*
* This function returns a ChaCha state that you may use for generating
* random data. It also returns up to 32 bytes on its own of random data
* that may be used; random_data_len may not be greater than 32.
@@ -368,10 +390,10 @@ static void crng_make_state(u32 chacha_s
}
/*
- * If the base_crng is more than 5 minutes old, we reseed, which
- * in turn bumps the generation counter that we check below.
+ * If the base_crng is old enough, we try to reseed, which in turn
+ * bumps the generation counter that we check below.
*/
- if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL)))
+ if (unlikely(crng_has_old_seed()))
crng_reseed();
local_lock_irqsave(&crngs.lock, flags);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 055/111] random: check for signal and try earlier when generating entropy
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (53 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 054/111] random: reseed more often immediately after booting Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 056/111] random: skip fast_init if hwrng provides large chunk of entropy Greg Kroah-Hartman
` (61 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 3e504d2026eb6c8762cd6040ae57db166516824a upstream.
Rather than waiting a full second in an interruptable waiter before
trying to generate entropy, try to generate entropy first and wait
second. While waiting one second might give an extra second for getting
entropy from elsewhere, we're already pretty late in the init process
here, and whatever else is generating entropy will still continue to
contribute. This has implications on signal handling: we call
try_to_generate_entropy() from wait_for_random_bytes(), and
wait_for_random_bytes() always uses wait_event_interruptible_timeout()
when waiting, since it's called by userspace code in restartable
contexts, where signals can pend. Since try_to_generate_entropy() now
runs first, if a signal is pending, it's necessary for
try_to_generate_entropy() to check for signals, since it won't hit the
wait until after try_to_generate_entropy() has returned. And even before
this change, when entering a busy loop in try_to_generate_entropy(), we
should have been checking to see if any signals are pending, so that a
process doesn't get stuck in that loop longer than expected.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -127,10 +127,11 @@ int wait_for_random_bytes(void)
{
while (!crng_ready()) {
int ret;
+
+ try_to_generate_entropy();
ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
if (ret)
return ret > 0 ? 0 : ret;
- try_to_generate_entropy();
}
return 0;
}
@@ -1369,7 +1370,7 @@ static void try_to_generate_entropy(void
return;
timer_setup_on_stack(&stack.timer, entropy_timer, 0);
- while (!crng_ready()) {
+ while (!crng_ready() && !signal_pending(current)) {
if (!timer_pending(&stack.timer))
mod_timer(&stack.timer, jiffies + 1);
mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 056/111] random: skip fast_init if hwrng provides large chunk of entropy
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (54 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 055/111] random: check for signal and try earlier when generating entropy Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 057/111] random: treat bootloader trust toggle the same way as cpu trust toggle Greg Kroah-Hartman
` (60 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit af704c856e888fb044b058d731d61b46eeec499d upstream.
At boot time, EFI calls add_bootloader_randomness(), which in turn calls
add_hwgenerator_randomness(). Currently add_hwgenerator_randomness()
feeds the first 64 bytes of randomness to the "fast init"
non-crypto-grade phase. But if add_hwgenerator_randomness() gets called
with more than POOL_MIN_BITS of entropy, there's no point in passing it
off to the "fast init" stage, since that's enough entropy to bootstrap
the real RNG. The "fast init" stage is just there to provide _something_
in the case where we don't have enough entropy to properly bootstrap the
RNG. But if we do have enough entropy to bootstrap the RNG, the current
logic doesn't serve a purpose. So, in the case where we're passed
greater than or equal to POOL_MIN_BITS of entropy, this commit makes us
skip the "fast init" phase.
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1123,7 +1123,7 @@ void rand_initialize_disk(struct gendisk
void add_hwgenerator_randomness(const void *buffer, size_t count,
size_t entropy)
{
- if (unlikely(crng_init == 0)) {
+ if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) {
size_t ret = crng_pre_init_inject(buffer, count, true);
mix_pool_bytes(buffer, ret);
count -= ret;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 057/111] random: treat bootloader trust toggle the same way as cpu trust toggle
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (55 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 056/111] random: skip fast_init if hwrng provides large chunk of entropy Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 058/111] random: re-add removed comment about get_random_{u32,u64} reseeding Greg Kroah-Hartman
` (59 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Graham Christensen,
Ard Biesheuvel, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit d97c68d178fbf8aaaf21b69b446f2dfb13909316 upstream.
If CONFIG_RANDOM_TRUST_CPU is set, the RNG initializes using RDRAND.
But, the user can disable (or enable) this behavior by setting
`random.trust_cpu=0/1` on the kernel command line. This allows system
builders to do reasonable things while avoiding howls from tinfoil
hatters. (Or vice versa.)
CONFIG_RANDOM_TRUST_BOOTLOADER is basically the same thing, but regards
the seed passed via EFI or device tree, which might come from RDRAND or
a TPM or somewhere else. In order to allow distros to more easily enable
this while avoiding those same howls (or vice versa), this commit adds
the corresponding `random.trust_bootloader=0/1` toggle.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Graham Christensen <graham@grahamc.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://github.com/NixOS/nixpkgs/pull/165355
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
drivers/char/Kconfig | 3 ++-
drivers/char/random.c | 8 +++++++-
3 files changed, 15 insertions(+), 2 deletions(-)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4355,6 +4355,12 @@
fully seed the kernel's CRNG. Default is controlled
by CONFIG_RANDOM_TRUST_CPU.
+ random.trust_bootloader={on,off}
+ [KNL] Enable or disable trusting the use of a
+ seed passed by the bootloader (if available) to
+ fully seed the kernel's CRNG. Default is controlled
+ by CONFIG_RANDOM_TRUST_BOOTLOADER.
+
randomize_kstack_offset=
[KNL] Enable or disable kernel stack offset
randomization, which provides roughly 5 bits of
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -449,6 +449,7 @@ config RANDOM_TRUST_BOOTLOADER
device randomness. Say Y here to assume the entropy provided by the
booloader is trustworthy so it will be added to the kernel's entropy
pool. Otherwise, say N here so it will be regarded as device input that
- only mixes the entropy pool.
+ only mixes the entropy pool. This can also be configured at boot with
+ "random.trust_bootloader=on/off".
endmenu
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -943,11 +943,17 @@ static bool drain_entropy(void *buf, siz
**********************************************************************/
static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
+static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
static int __init parse_trust_cpu(char *arg)
{
return kstrtobool(arg, &trust_cpu);
}
+static int __init parse_trust_bootloader(char *arg)
+{
+ return kstrtobool(arg, &trust_bootloader);
+}
early_param("random.trust_cpu", parse_trust_cpu);
+early_param("random.trust_bootloader", parse_trust_bootloader);
/*
* The first collection of entropy occurs at system boot while interrupts
@@ -1155,7 +1161,7 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_random
*/
void add_bootloader_randomness(const void *buf, size_t size)
{
- if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
+ if (trust_bootloader)
add_hwgenerator_randomness(buf, size, size * 8);
else
add_device_randomness(buf, size);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 058/111] random: re-add removed comment about get_random_{u32,u64} reseeding
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (56 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 057/111] random: treat bootloader trust toggle the same way as cpu trust toggle Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 059/111] random: mix build-time latent entropy into pool at init Greg Kroah-Hartman
` (58 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit dd7aa36e535797926d8eb311da7151919130139d upstream.
The comment about get_random_{u32,u64}() not invoking reseeding got
added in an unrelated commit, that then was recently reverted by
0313bc278dac ("Revert "random: block in /dev/urandom""). So this adds
that little comment snippet back, and improves the wording a bit too.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -224,9 +224,10 @@ static void _warn_unseeded_randomness(co
*
* These interfaces will return the requested number of random bytes
* into the given buffer or as a return value. This is equivalent to
- * a read from /dev/urandom. The integer family of functions may be
- * higher performance for one-off random integers, because they do a
- * bit of buffering.
+ * a read from /dev/urandom. The u32, u64, int, and long family of
+ * functions may be higher performance for one-off random integers,
+ * because they do a bit of buffering and do not invoke reseeding
+ * until the buffer is emptied.
*
*********************************************************************/
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 059/111] random: mix build-time latent entropy into pool at init
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (57 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 058/111] random: re-add removed comment about get_random_{u32,u64} reseeding Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 060/111] random: do not split fast init input in add_hwgenerator_randomness() Greg Kroah-Hartman
` (57 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Theodore Tso,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1754abb3e7583c570666fa1e1ee5b317e88c89a0 upstream.
Prior, the "input_pool_data" array needed no real initialization, and so
it was easy to mark it with __latent_entropy to populate it during
compile-time. In switching to using a hash function, this required us to
specifically initialize it to some specific state, which means we
dropped the __latent_entropy attribute. An unfortunate side effect was
this meant the pool was no longer seeded using compile-time random data.
In order to bring this back, we declare an array in rand_initialize()
with __latent_entropy and call mix_pool_bytes() on that at init, which
accomplishes the same thing as before. We make this __initconst, so that
it doesn't take up space at runtime after init.
Fixes: 6e8ec2552c7d ("random: use computational hash for entropy extraction")
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -970,6 +970,11 @@ int __init rand_initialize(void)
bool arch_init = true;
unsigned long rv;
+#if defined(LATENT_ENTROPY_PLUGIN)
+ static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
+ _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
+#endif
+
for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
if (!arch_get_random_seed_long_early(&rv) &&
!arch_get_random_long_early(&rv)) {
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 060/111] random: do not split fast init input in add_hwgenerator_randomness()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (58 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 059/111] random: mix build-time latent entropy into pool at init Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 061/111] random: do not allow user to keep crng key around on stack Greg Kroah-Hartman
` (56 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jan Varho, Jason A. Donenfeld
From: Jan Varho <jan.varho@gmail.com>
commit 527a9867af29ff89f278d037db704e0ed50fb666 upstream.
add_hwgenerator_randomness() tries to only use the required amount of input
for fast init, but credits all the entropy, rather than a fraction of
it. Since it's hard to determine how much entropy is left over out of a
non-unformly random sample, either give it all to fast init or credit
it, but don't attempt to do both. In the process, we can clean up the
injection code to no longer need to return a value.
Signed-off-by: Jan Varho <jan.varho@gmail.com>
[Jason: expanded commit message]
Fixes: 73c7733f122e ("random: do not throw away excess input to crng_fast_load")
Cc: stable@vger.kernel.org # 5.17+, requires af704c856e88
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -437,11 +437,8 @@ static void crng_make_state(u32 chacha_s
* This shouldn't be set by functions like add_device_randomness(),
* where we can't trust the buffer passed to it is guaranteed to be
* unpredictable (so it might not have any entropy at all).
- *
- * Returns the number of bytes processed from input, which is bounded
- * by CRNG_INIT_CNT_THRESH if account is true.
*/
-static size_t crng_pre_init_inject(const void *input, size_t len, bool account)
+static void crng_pre_init_inject(const void *input, size_t len, bool account)
{
static int crng_init_cnt = 0;
struct blake2s_state hash;
@@ -452,18 +449,15 @@ static size_t crng_pre_init_inject(const
spin_lock_irqsave(&base_crng.lock, flags);
if (crng_init != 0) {
spin_unlock_irqrestore(&base_crng.lock, flags);
- return 0;
+ return;
}
- if (account)
- len = min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
-
blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
blake2s_update(&hash, input, len);
blake2s_final(&hash, base_crng.key);
if (account) {
- crng_init_cnt += len;
+ crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
++base_crng.generation;
crng_init = 1;
@@ -474,8 +468,6 @@ static size_t crng_pre_init_inject(const
if (crng_init == 1)
pr_notice("fast init done\n");
-
- return len;
}
static void _get_random_bytes(void *buf, size_t nbytes)
@@ -1136,12 +1128,9 @@ void add_hwgenerator_randomness(const vo
size_t entropy)
{
if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) {
- size_t ret = crng_pre_init_inject(buffer, count, true);
- mix_pool_bytes(buffer, ret);
- count -= ret;
- buffer += ret;
- if (!count || crng_init == 0)
- return;
+ crng_pre_init_inject(buffer, count, true);
+ mix_pool_bytes(buffer, count);
+ return;
}
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 061/111] random: do not allow user to keep crng key around on stack
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (59 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 060/111] random: do not split fast init input in add_hwgenerator_randomness() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 062/111] random: check for signal_pending() outside of need_resched() check Greg Kroah-Hartman
` (55 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Jann Horn, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit aba120cc101788544aa3e2c30c8da88513892350 upstream.
The fast key erasure RNG design relies on the key that's used to be used
and then discarded. We do this, making judicious use of
memzero_explicit(). However, reads to /dev/urandom and calls to
getrandom() involve a copy_to_user(), and userspace can use FUSE or
userfaultfd, or make a massive call, dynamically remap memory addresses
as it goes, and set the process priority to idle, in order to keep a
kernel stack alive indefinitely. By probing
/proc/sys/kernel/random/entropy_avail to learn when the crng key is
refreshed, a malicious userspace could mount this attack every 5 minutes
thereafter, breaking the crng's forward secrecy.
In order to fix this, we just overwrite the stack's key with the first
32 bytes of the "free" fast key erasure output. If we're returning <= 32
bytes to the user, then we can still return those bytes directly, so
that short reads don't become slower. And for long reads, the difference
is hopefully lost in the amortization, so it doesn't change much, with
that amortization helping variously for medium reads.
We don't need to do this for get_random_bytes() and the various
kernel-space callers, and later, if we ever switch to always batching,
this won't be necessary either, so there's no need to change the API of
these functions.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jann Horn <jannh@google.com>
Fixes: c92e040d575a ("random: add backtracking protection to the CRNG")
Fixes: 186873c549df ("random: use simpler fast key erasure flow on per-cpu keys")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 35 +++++++++++++++++++++++------------
1 file changed, 23 insertions(+), 12 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -532,19 +532,29 @@ static ssize_t get_random_bytes_user(voi
if (!nbytes)
return 0;
- len = min_t(size_t, 32, nbytes);
- crng_make_state(chacha_state, output, len);
-
- if (copy_to_user(buf, output, len))
- return -EFAULT;
- nbytes -= len;
- buf += len;
- ret += len;
+ /*
+ * Immediately overwrite the ChaCha key at index 4 with random
+ * bytes, in case userspace causes copy_to_user() below to sleep
+ * forever, so that we still retain forward secrecy in that case.
+ */
+ crng_make_state(chacha_state, (u8 *)&chacha_state[4], CHACHA_KEY_SIZE);
+ /*
+ * However, if we're doing a read of len <= 32, we don't need to
+ * use chacha_state after, so we can simply return those bytes to
+ * the user directly.
+ */
+ if (nbytes <= CHACHA_KEY_SIZE) {
+ ret = copy_to_user(buf, &chacha_state[4], nbytes) ? -EFAULT : nbytes;
+ goto out_zero_chacha;
+ }
- while (nbytes) {
+ do {
if (large_request && need_resched()) {
- if (signal_pending(current))
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
break;
+ }
schedule();
}
@@ -561,10 +571,11 @@ static ssize_t get_random_bytes_user(voi
nbytes -= len;
buf += len;
ret += len;
- }
+ } while (nbytes);
- memzero_explicit(chacha_state, sizeof(chacha_state));
memzero_explicit(output, sizeof(output));
+out_zero_chacha:
+ memzero_explicit(chacha_state, sizeof(chacha_state));
return ret;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 062/111] random: check for signal_pending() outside of need_resched() check
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (60 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 061/111] random: do not allow user to keep crng key around on stack Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 063/111] random: check for signals every PAGE_SIZE chunk of /dev/[u]random Greg Kroah-Hartman
` (54 subsequent siblings)
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jann Horn, Jason A. Donenfeld
From: Jann Horn <jannh@google.com>
commit 1448769c9cdb69ad65287f4f7ab58bc5f2f5d7ba upstream.
signal_pending() checks TIF_NOTIFY_SIGNAL and TIF_SIGPENDING, which
signal that the task should bail out of the syscall when possible. This
is a separate concept from need_resched(), which checks
TIF_NEED_RESCHED, signaling that the task should preempt.
In particular, with the current code, the signal_pending() bailout
probably won't work reliably.
Change this to look like other functions that read lots of data, such as
read_zero().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -549,13 +549,13 @@ static ssize_t get_random_bytes_user(voi
}
do {
- if (large_request && need_resched()) {
+ if (large_request) {
if (signal_pending(current)) {
if (!ret)
ret = -ERESTARTSYS;
break;
}
- schedule();
+ cond_resched();
}
chacha20_block(chacha_state, output);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 063/111] random: check for signals every PAGE_SIZE chunk of /dev/[u]random
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2022-05-27 8:49 ` [PATCH 5.17 062/111] random: check for signal_pending() outside of need_resched() check Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 064/111] random: allow partial reads if later user copies fail Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Jann Horn, Theodore Tso, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e3c1c4fd9e6d14059ed93ebfe15e1c57793b1a05 upstream.
In 1448769c9cdb ("random: check for signal_pending() outside of
need_resched() check"), Jann pointed out that we previously were only
checking the TIF_NOTIFY_SIGNAL and TIF_SIGPENDING flags if the process
had TIF_NEED_RESCHED set, which meant in practice, super long reads to
/dev/[u]random would delay signal handling by a long time. I tried this
using the below program, and indeed I wasn't able to interrupt a
/dev/urandom read until after several megabytes had been read. The bug
he fixed has always been there, and so code that reads from /dev/urandom
without checking the return value of read() has mostly worked for a long
time, for most sizes, not just for <= 256.
Maybe it makes sense to keep that code working. The reason it was so
small prior, ignoring the fact that it didn't work anyway, was likely
because /dev/random used to block, and that could happen for pretty
large lengths of time while entropy was gathered. But now, it's just a
chacha20 call, which is extremely fast and is just operating on pure
data, without having to wait for some external event. In that sense,
/dev/[u]random is a lot more like /dev/zero.
Taking a page out of /dev/zero's read_zero() function, it always returns
at least one chunk, and then checks for signals after each chunk. Chunk
sizes there are of length PAGE_SIZE. Let's just copy the same thing for
/dev/[u]random, and check for signals and cond_resched() for every
PAGE_SIZE amount of data. This makes the behavior more consistent with
expectations, and should mitigate the impact of Jann's fix for the
age-old signal check bug.
---- test program ----
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <sys/random.h>
static unsigned char x[~0U];
static void handle(int) { }
int main(int argc, char *argv[])
{
pid_t pid = getpid(), child;
signal(SIGUSR1, handle);
if (!(child = fork())) {
for (;;)
kill(pid, SIGUSR1);
}
pause();
printf("interrupted after reading %zd bytes\n", getrandom(x, sizeof(x), 0));
kill(child, SIGTERM);
return 0;
}
Cc: Jann Horn <jannh@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -523,7 +523,6 @@ EXPORT_SYMBOL(get_random_bytes);
static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
{
- bool large_request = nbytes > 256;
ssize_t ret = 0;
size_t len;
u32 chacha_state[CHACHA_STATE_WORDS];
@@ -549,15 +548,6 @@ static ssize_t get_random_bytes_user(voi
}
do {
- if (large_request) {
- if (signal_pending(current)) {
- if (!ret)
- ret = -ERESTARTSYS;
- break;
- }
- cond_resched();
- }
-
chacha20_block(chacha_state, output);
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
@@ -571,6 +561,13 @@ static ssize_t get_random_bytes_user(voi
nbytes -= len;
buf += len;
ret += len;
+
+ BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0);
+ if (!(ret % PAGE_SIZE) && nbytes) {
+ if (signal_pending(current))
+ break;
+ cond_resched();
+ }
} while (nbytes);
memzero_explicit(output, sizeof(output));
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 064/111] random: allow partial reads if later user copies fail
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (62 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 063/111] random: check for signals every PAGE_SIZE chunk of /dev/[u]random Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 065/111] random: make random_get_entropy() return an unsigned long Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Linus Torvalds, Jann Horn,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5209aed5137880fa229746cb521f715e55596460 upstream.
Rather than failing entirely if a copy_to_user() fails at some point,
instead we should return a partial read for the amount that succeeded
prior, unless none succeeded at all, in which case we return -EFAULT as
before.
This makes it consistent with other reader interfaces. For example, the
following snippet for /dev/zero outputs "4" followed by "1":
int fd;
void *x = mmap(NULL, 4096, PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
assert(x != MAP_FAILED);
fd = open("/dev/zero", O_RDONLY);
assert(fd >= 0);
printf("%zd\n", read(fd, x, 4));
printf("%zd\n", read(fd, x + 4095, 4));
close(fd);
This brings that same standard behavior to the various RNG reader
interfaces.
While we're at it, we can streamline the loop logic a little bit.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -523,8 +523,7 @@ EXPORT_SYMBOL(get_random_bytes);
static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
{
- ssize_t ret = 0;
- size_t len;
+ size_t len, left, ret = 0;
u32 chacha_state[CHACHA_STATE_WORDS];
u8 output[CHACHA_BLOCK_SIZE];
@@ -543,37 +542,40 @@ static ssize_t get_random_bytes_user(voi
* the user directly.
*/
if (nbytes <= CHACHA_KEY_SIZE) {
- ret = copy_to_user(buf, &chacha_state[4], nbytes) ? -EFAULT : nbytes;
+ ret = nbytes - copy_to_user(buf, &chacha_state[4], nbytes);
goto out_zero_chacha;
}
- do {
+ for (;;) {
chacha20_block(chacha_state, output);
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE);
- if (copy_to_user(buf, output, len)) {
- ret = -EFAULT;
+ left = copy_to_user(buf, output, len);
+ if (left) {
+ ret += len - left;
break;
}
- nbytes -= len;
buf += len;
ret += len;
+ nbytes -= len;
+ if (!nbytes)
+ break;
BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0);
- if (!(ret % PAGE_SIZE) && nbytes) {
+ if (ret % PAGE_SIZE == 0) {
if (signal_pending(current))
break;
cond_resched();
}
- } while (nbytes);
+ }
memzero_explicit(output, sizeof(output));
out_zero_chacha:
memzero_explicit(chacha_state, sizeof(chacha_state));
- return ret;
+ return ret ? ret : -EFAULT;
}
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 065/111] random: make random_get_entropy() return an unsigned long
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (63 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 064/111] random: allow partial reads if later user copies fail Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 066/111] random: document crng_fast_key_erasure() destination possibility Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Theodore Tso,
Thomas Gleixner, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit b0c3e796f24b588b862b61ce235d3c9417dc8983 upstream.
Some implementations were returning type `unsigned long`, while others
that fell back to get_cycles() were implicitly returning a `cycles_t` or
an untyped constant int literal. That makes for weird and confusing
code, and basically all code in the kernel already handled it like it
was an `unsigned long`. I recently tried to handle it as the largest
type it could be, a `cycles_t`, but doing so doesn't really help with
much.
Instead let's just make random_get_entropy() return an unsigned long all
the time. This also matches the commonly used `arch_get_random_long()`
function, so now RDRAND and RDTSC return the same sized integer, which
means one can fallback to the other more gracefully.
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 20 +++++++-------------
include/linux/timex.h | 2 +-
2 files changed, 8 insertions(+), 14 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1013,7 +1013,7 @@ int __init rand_initialize(void)
*/
void add_device_randomness(const void *buf, size_t size)
{
- cycles_t cycles = random_get_entropy();
+ unsigned long cycles = random_get_entropy();
unsigned long flags, now = jiffies;
if (crng_init == 0 && size)
@@ -1044,8 +1044,7 @@ struct timer_rand_state {
*/
static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
- cycles_t cycles = random_get_entropy();
- unsigned long flags, now = jiffies;
+ unsigned long cycles = random_get_entropy(), now = jiffies, flags;
long delta, delta2, delta3;
spin_lock_irqsave(&input_pool.lock, flags);
@@ -1300,8 +1299,7 @@ static void mix_interrupt_randomness(str
void add_interrupt_randomness(int irq)
{
enum { MIX_INFLIGHT = 1U << 31 };
- cycles_t cycles = random_get_entropy();
- unsigned long now = jiffies;
+ unsigned long cycles = random_get_entropy(), now = jiffies;
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
struct pt_regs *regs = get_irq_regs();
unsigned int new_count;
@@ -1314,16 +1312,12 @@ void add_interrupt_randomness(int irq)
if (cycles == 0)
cycles = get_reg(fast_pool, regs);
- if (sizeof(cycles) == 8)
+ if (sizeof(unsigned long) == 8) {
irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq;
- else {
+ irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;
+ } else {
irq_data.u32[0] = cycles ^ irq;
irq_data.u32[1] = now;
- }
-
- if (sizeof(unsigned long) == 8)
- irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;
- else {
irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_;
irq_data.u32[3] = get_reg(fast_pool, regs);
}
@@ -1370,7 +1364,7 @@ static void entropy_timer(struct timer_l
static void try_to_generate_entropy(void)
{
struct {
- cycles_t cycles;
+ unsigned long cycles;
struct timer_list timer;
} stack;
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -75,7 +75,7 @@
* By default we use get_cycles() for this purpose, but individual
* architectures may override this in their asm/timex.h header file.
*/
-#define random_get_entropy() get_cycles()
+#define random_get_entropy() ((unsigned long)get_cycles())
#endif
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 066/111] random: document crng_fast_key_erasure() destination possibility
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (64 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 065/111] random: make random_get_entropy() return an unsigned long Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 067/111] random: fix sysctl documentation nits Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Eric Biggers, Eric Biggers,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 8717627d6ac53251ee012c3c7aca392f29f38a42 upstream.
This reverts 35a33ff3807d ("random: use memmove instead of memcpy for
remaining 32 bytes"), which was made on a totally bogus basis. The thing
it was worried about overlapping came from the stack, not from one of
its arguments, as Eric pointed out.
But the fact that this confusion even happened draws attention to the
fact that it's a bit non-obvious that the random_data parameter can
alias chacha_state, and in fact should do so when the caller can't rely
on the stack being cleared in a timely manner. So this commit documents
that.
Reported-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -318,6 +318,13 @@ static void crng_reseed(void)
* the resultant ChaCha state to the user, along with the second
* half of the block containing 32 bytes of random data that may
* be used; random_data_len may not be greater than 32.
+ *
+ * The returned ChaCha state contains within it a copy of the old
+ * key value, at index 4, so the state should always be zeroed out
+ * immediately after using in order to maintain forward secrecy.
+ * If the state cannot be erased in a timely manner, then it is
+ * safer to set the random_data parameter to &chacha_state[4] so
+ * that this function overwrites it before returning.
*/
static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
u32 chacha_state[CHACHA_STATE_WORDS],
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 067/111] random: fix sysctl documentation nits
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (65 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 066/111] random: document crng_fast_key_erasure() destination possibility Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 068/111] init: call time_init() before rand_initialize() Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 069c4ea6871c18bd368f27756e0f91ffb524a788 upstream.
A semicolon was missing, and the almost-alphabetical-but-not ordering
was confusing, so regroup these by category instead.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/admin-guide/sysctl/kernel.rst | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1025,6 +1025,9 @@ This is a directory, with the following
* ``boot_id``: a UUID generated the first time this is retrieved, and
unvarying after that;
+* ``uuid``: a UUID generated every time this is retrieved (this can
+ thus be used to generate UUIDs at will);
+
* ``entropy_avail``: the pool's entropy count, in bits;
* ``poolsize``: the entropy pool size, in bits;
@@ -1032,10 +1035,7 @@ This is a directory, with the following
* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum
number of seconds between urandom pool reseeding). This file is
writable for compatibility purposes, but writing to it has no effect
- on any RNG behavior.
-
-* ``uuid``: a UUID generated every time this is retrieved (this can
- thus be used to generate UUIDs at will);
+ on any RNG behavior;
* ``write_wakeup_threshold``: when the entropy count drops below this
(as a number of bits), processes waiting to write to ``/dev/random``
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 068/111] init: call time_init() before rand_initialize()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (66 preceding siblings ...)
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@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 069/111] ia64: define get_cycles macro for arch-override Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Andrew Morton, Stafford Horne,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit fe222a6ca2d53c38433cba5d3be62a39099e708e upstream.
Currently time_init() is called after rand_initialize(), but
rand_initialize() makes use of the timer on various platforms, and
sometimes this timer needs to be initialized by time_init() first. In
order for random_get_entropy() to not return zero during early boot when
it's potentially used as an entropy source, reverse the order of these
two calls. The block doing random initialization was right before
time_init() before, so changing the order shouldn't have any complicated
effects.
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Stafford Horne <shorne@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
init/main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/init/main.c
+++ b/init/main.c
@@ -1035,11 +1035,13 @@ asmlinkage __visible void __init __no_sa
softirq_init();
timekeeping_init();
kfence_init();
+ time_init();
/*
* For best initial stack canary entropy, prepare it after:
* - setup_arch() for any UEFI RNG entropy and boot cmdline access
* - timekeeping_init() for ktime entropy used in rand_initialize()
+ * - time_init() for making random_get_entropy() work on some platforms
* - rand_initialize() to get any arch-specific entropy like RDRAND
* - add_latent_entropy() to get any latent entropy
* - adding command line entropy
@@ -1049,7 +1051,6 @@ asmlinkage __visible void __init __no_sa
add_device_randomness(command_line, strlen(command_line));
boot_init_stack_canary();
- time_init();
perf_event_init();
profile_init();
call_function_init();
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 069/111] ia64: define get_cycles macro for arch-override
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (67 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 068/111] init: call time_init() before rand_initialize() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 070/111] s390: " Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 57c0900b91d8891ab43f0e6b464d059fda51d102 upstream.
Itanium defines a get_cycles() function, but it does not do the usual
`#define get_cycles get_cycles` dance, making it impossible for generic
code to see if an arch-specific function was defined. While the
get_cycles() ifdef is not currently used, the following timekeeping
patch in this series will depend on the macro existing (or not existing)
when defining random_get_entropy().
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/ia64/include/asm/timex.h | 1 +
1 file changed, 1 insertion(+)
--- a/arch/ia64/include/asm/timex.h
+++ b/arch/ia64/include/asm/timex.h
@@ -39,6 +39,7 @@ get_cycles (void)
ret = ia64_getreg(_IA64_REG_AR_ITC);
return ret;
}
+#define get_cycles get_cycles
extern void ia64_cpu_local_tick (void);
extern unsigned long long ia64_native_sched_clock (void);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 070/111] s390: define get_cycles macro for arch-override
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (68 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 069/111] ia64: define get_cycles macro for arch-override Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 071/111] parisc: " Greg Kroah-Hartman
` (46 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Vasily Gorbik, Alexander Gordeev, Christian Borntraeger,
Sven Schnelle, Heiko Carstens, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 2e3df523256cb9836de8441e9c791a796759bb3c upstream.
S390x defines a get_cycles() function, but it does not do the usual
`#define get_cycles get_cycles` dance, making it impossible for generic
code to see if an arch-specific function was defined. While the
get_cycles() ifdef is not currently used, the following timekeeping
patch in this series will depend on the macro existing (or not existing)
when defining random_get_entropy().
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/s390/include/asm/timex.h | 1 +
1 file changed, 1 insertion(+)
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -201,6 +201,7 @@ static inline cycles_t get_cycles(void)
{
return (cycles_t) get_tod_clock() >> 2;
}
+#define get_cycles get_cycles
int get_phys_clock(unsigned long *clock);
void init_cpu_timer(void);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 071/111] parisc: define get_cycles macro for arch-override
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (69 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 070/111] s390: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 072/111] alpha: " Greg Kroah-Hartman
` (45 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Helge Deller, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 8865bbe6ba1120e67f72201b7003a16202cd42be upstream.
PA-RISC defines a get_cycles() function, but it does not do the usual
`#define get_cycles get_cycles` dance, making it impossible for generic
code to see if an arch-specific function was defined. While the
get_cycles() ifdef is not currently used, the following timekeeping
patch in this series will depend on the macro existing (or not existing)
when defining random_get_entropy().
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/parisc/include/asm/timex.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/parisc/include/asm/timex.h
+++ b/arch/parisc/include/asm/timex.h
@@ -13,9 +13,10 @@
typedef unsigned long cycles_t;
-static inline cycles_t get_cycles (void)
+static inline cycles_t get_cycles(void)
{
return mfctl(16);
}
+#define get_cycles get_cycles
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 072/111] alpha: define get_cycles macro for arch-override
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (70 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 071/111] parisc: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 073/111] powerpc: " Greg Kroah-Hartman
` (44 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Richard Henderson, Ivan Kokshaysky, Matt Turner,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1097710bc9660e1e588cf2186a35db3d95c4d258 upstream.
Alpha defines a get_cycles() function, but it does not do the usual
`#define get_cycles get_cycles` dance, making it impossible for generic
code to see if an arch-specific function was defined. While the
get_cycles() ifdef is not currently used, the following timekeeping
patch in this series will depend on the macro existing (or not existing)
when defining random_get_entropy().
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/alpha/include/asm/timex.h | 1 +
1 file changed, 1 insertion(+)
--- a/arch/alpha/include/asm/timex.h
+++ b/arch/alpha/include/asm/timex.h
@@ -28,5 +28,6 @@ static inline cycles_t get_cycles (void)
__asm__ __volatile__ ("rpcc %0" : "=r"(ret));
return ret;
}
+#define get_cycles get_cycles
#endif
fo {
POOL_BYTES = POOL_WORDS * sizeof(u32),
POOL_BITS = POOL_BYTES * 8,
POOL_BITSHIFT = ilog2(POOL_WORDS) + 5,
- POOL_FRACBITS = POOL_WORDS << (ENTROPY_SHIFT + 5),
+ POOL_FRACBITS = POOL_WORDS << (POOL_ENTROPY_SHIFT + 5),
/* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
POOL_TAP1 = 104,
@@ -650,7 +650,7 @@ static void process_random_ready_list(vo
static void credit_entropy_bits(int nbits)
{
int entropy_count, entropy_bits, orig;
- int nfrac = nbits << ENTROPY_SHIFT;
+ int nfrac = nbits << POOL_ENTROPY_SHIFT;
if (!nbits)
return;
@@ -683,7 +683,7 @@ retry:
* turns no matter how large nbits is.
*/
int pnfrac = nfrac;
- const int s = POOL_BITSHIFT + ENTROPY_SHIFT + 2;
+ const int s = POOL_BITSHIFT + POOL_ENTROPY_SHIFT + 2;
/* The +2 corresponds to the /4 in the denominator */
do {
@@ -704,9 +704,9 @@ retry:
if (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig)
goto retry;
- trace_credit_entropy_bits(nbits, entropy_count >> ENTROPY_SHIFT, _RET_IP_);
+ trace_credit_entropy_bits(nbits, entropy_count >> POOL_ENTROPY_SHIFT, _RET_IP_);
- entropy_bits = entropy_count >> ENTROPY_SHIFT;
+ entropy_bits = entropy_count >> POOL_ENTROPY_SHIFT;
if (crng_init < 2 && entropy_bits >= 128)
crng_reseed(&primary_crng, true);
}
@@ -1187,7 +1187,7 @@ void add_input_randomness(unsigned int t
last_value = value;
add_timer_randomness(&input_timer_state,
(type << 4) ^ code ^ (code >> 4) ^ value);
- trace_add_input_randomness(ENTROPY_BITS());
+ trace_add_input_randomness(POOL_ENTROPY_BITS());
}
EXPORT_SYMBOL_GPL(add_input_randomness);
@@ -1286,7 +1286,7 @@ void add_disk_randomness(struct gendisk
return;
/* first major is 1, so we get >= 0x200 here */
add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
- trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS());
+ trace_add_disk_randomness(disk_devt(disk), POOL_ENTROPY_BITS());
}
EXPORT_SYMBOL_GPL(add_disk_randomness);
#endif
@@ -1313,7 +1313,7 @@ retry:
entropy_count = orig = READ_ONCE(input_pool.entropy_count);
ibytes = nbytes;
/* never pull more than available */
- have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
+ have_bytes = entropy_count >> (POOL_ENTROPY_SHIFT + 3);
if (have_bytes < 0)
have_bytes = 0;
@@ -1325,7 +1325,7 @@ retry:
pr_warn("negative entropy count: count %d\n", entropy_count);
entropy_count = 0;
}
- nfrac = ibytes << (ENTROPY_SHIFT + 3);
+ nfrac = ibytes << (POOL_ENTROPY_SHIFT + 3);
if ((size_t) entropy_count > nfrac)
entropy_count -= nfrac;
else
@@ -1335,7 +1335,7 @@ retry:
goto retry;
trace_debit_entropy(8 * ibytes);
- if (ibytes && ENTROPY_BITS() < random_write_wakeup_bits) {
+ if (ibytes && POOL_ENTROPY_BITS() < random_write_wakeup_bits) {
wake_up_interruptible(&random_write_wait);
kill_fasync(&fasync, SIGIO, POLL_OUT);
}
@@ -1423,7 +1423,7 @@ static ssize_t _extract_entropy(void *bu
*/
static ssize_t extract_entropy(void *buf, size_t nbytes, int min)
{
- trace_extract_entropy(nbytes, ENTROPY_BITS(), _RET_IP_);
+ trace_extract_entropy(nbytes, POOL_ENTROPY_BITS(), _RET_IP_);
nbytes = account(nbytes, min);
return _extract_entropy(buf, nbytes);
}
@@ -1749,9 +1749,9 @@ urandom_read_nowarn(struct file *file, c
{
int ret;
- nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
+ nbytes = min_t(size_t, nbytes, INT_MAX >> (POOL_ENTROPY_SHIFT + 3));
ret = extract_crng_user(buf, nbytes);
- trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS());
+ trace_urandom_read(8 * nbytes, 0, POOL_ENTROPY_BITS());
return ret;
}
@@ -1791,7 +1791,7 @@ random_poll(struct file *file, poll_tabl
mask = 0;
if (crng_ready())
mask |= EPOLLIN | EPOLLRDNORM;
- if (ENTROPY_BITS() < random_write_wakeup_bits)
+ if (POOL_ENTROPY_BITS() < random_write_wakeup_bits)
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;
}
@@ -1847,7 +1847,7 @@ static long random_ioctl(struct file *f,
switch (cmd) {
case RNDGETENTCNT:
/* inherently racy, no point locking */
- ent_count = ENTROPY_BITS();
+ ent_count = POOL_ENTROPY_BITS();
if (put_user(ent_count, p))
return -EFAULT;
return 0;
@@ -2008,7 +2008,7 @@ static int proc_do_entropy(struct ctl_ta
struct ctl_table fake_table;
int entropy_count;
- entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
+ entropy_count = *(int *)table->data >> POOL_ENTROPY_SHIFT;
fake_table.data = &entropy_count;
fake_table.maxlen = sizeof(entropy_count);
@@ -2227,7 +2227,7 @@ void add_hwgenerator_randomness(const ch
*/
wait_event_interruptible(random_write_wait,
!system_wq || kthread_should_stop() ||
- ENTROPY_BITS() <= random_write_wakeup_bits);
+ POOL_ENTROPY_BITS() <= random_write_wakeup_bits);
mix_pool_bytes(buffer, count);
credit_entropy_bits(entropy);
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 073/111] powerpc: define get_cycles macro for arch-override
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (71 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 072/111] alpha: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 074/111] timekeeping: Add raw clock fallback for random_get_entropy() Greg Kroah-Hartman
` (43 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 408835832158df0357e18e96da7f2d1ed6b80e7f upstream.
PowerPC defines a get_cycles() function, but it does not do the usual
`#define get_cycles get_cycles` dance, making it impossible for generic
code to see if an arch-specific function was defined. While the
get_cycles() ifdef is not currently used, the following timekeeping
patch in this series will depend on the macro existing (or not existing)
when defining random_get_entropy().
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/include/asm/timex.h | 1 +
1 file changed, 1 insertion(+)
--- a/arch/powerpc/include/asm/timex.h
+++ b/arch/powerpc/include/asm/timex.h
@@ -19,6 +19,7 @@ static inline cycles_t get_cycles(void)
{
return mftb();
}
+#define get_cycles get_cycles
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_TIMEX_H */
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 074/111] timekeeping: Add raw clock fallback for random_get_entropy()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (72 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 073/111] powerpc: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 075/111] m68k: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
` (42 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Jason A. Donenfeld,
Arnd Bergmann, Theodore Tso
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1366992e16bddd5e2d9a561687f367f9f802e2e4 upstream.
The addition of random_get_entropy_fallback() provides access to
whichever time source has the highest frequency, which is useful for
gathering entropy on platforms without available cycle counters. It's
not necessarily as good as being able to quickly access a cycle counter
that the CPU has, but it's still something, even when it falls back to
being jiffies-based.
In the event that a given arch does not define get_cycles(), falling
back to the get_cycles() default implementation that returns 0 is really
not the best we can do. Instead, at least calling
random_get_entropy_fallback() would be preferable, because that always
needs to return _something_, even falling back to jiffies eventually.
It's not as though random_get_entropy_fallback() is super high precision
or guaranteed to be entropic, but basically anything that's not zero all
the time is better than returning zero all the time.
Finally, since random_get_entropy_fallback() is used during extremely
early boot when randomizing freelists in mm_init(), it can be called
before timekeeping has been initialized. In that case there really is
nothing we can do; jiffies hasn't even started ticking yet. So just give
up and return 0.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/timex.h | 8 ++++++++
kernel/time/timekeeping.c | 15 +++++++++++++++
2 files changed, 23 insertions(+)
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -62,6 +62,8 @@
#include <linux/types.h>
#include <linux/param.h>
+unsigned long random_get_entropy_fallback(void);
+
#include <asm/timex.h>
#ifndef random_get_entropy
@@ -74,8 +76,14 @@
*
* By default we use get_cycles() for this purpose, but individual
* architectures may override this in their asm/timex.h header file.
+ * If a given arch does not have get_cycles(), then we fallback to
+ * using random_get_entropy_fallback().
*/
+#ifdef get_cycles
#define random_get_entropy() ((unsigned long)get_cycles())
+#else
+#define random_get_entropy() random_get_entropy_fallback()
+#endif
#endif
/*
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -17,6 +17,7 @@
#include <linux/clocksource.h>
#include <linux/jiffies.h>
#include <linux/time.h>
+#include <linux/timex.h>
#include <linux/tick.h>
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
@@ -2380,6 +2381,20 @@ static int timekeeping_validate_timex(co
return 0;
}
+/**
+ * random_get_entropy_fallback - Returns the raw clock source value,
+ * used by random.c for platforms with no valid random_get_entropy().
+ */
+unsigned long random_get_entropy_fallback(void)
+{
+ struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
+ struct clocksource *clock = READ_ONCE(tkr->clock);
+
+ if (unlikely(timekeeping_suspended || !clock))
+ return 0;
+ return clock->read(clock);
+}
+EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
/**
* do_adjtimex() - Accessor function to NTP __do_adjtimex function
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 075/111] m68k: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (73 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 074/111] timekeeping: Add raw clock fallback for random_get_entropy() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 076/111] riscv: " Greg Kroah-Hartman
` (41 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Geert Uytterhoeven, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 0f392c95391f2d708b12971a07edaa7973f9eece upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/m68k/include/asm/timex.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -35,7 +35,7 @@ static inline unsigned long random_get_e
{
if (mach_random_get_entropy)
return mach_random_get_entropy();
- return 0;
+ return random_get_entropy_fallback();
}
#define random_get_entropy random_get_entropy
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 076/111] riscv: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (74 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 075/111] m68k: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 077/111] mips: use fallback for random_get_entropy() instead of just c0 random Greg Kroah-Hartman
` (40 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Paul Walmsley, Palmer Dabbelt, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 6d01238623faa9425f820353d2066baf6c9dc872 upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/riscv/include/asm/timex.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/riscv/include/asm/timex.h
+++ b/arch/riscv/include/asm/timex.h
@@ -41,7 +41,7 @@ static inline u32 get_cycles_hi(void)
static inline unsigned long random_get_entropy(void)
{
if (unlikely(clint_time_val == NULL))
- return 0;
+ return random_get_entropy_fallback();
return get_cycles();
}
#define random_get_entropy() random_get_entropy()
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 077/111] mips: use fallback for random_get_entropy() instead of just c0 random
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (75 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 076/111] riscv: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 078/111] arm: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
` (39 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Maciej W. Rozycki, Thomas Bogendoerfer, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1c99c6a7c3c599a68321b01b9ec243215ede5a68 upstream.
For situations in which we don't have a c0 counter register available,
we've been falling back to reading the c0 "random" register, which is
usually bounded by the amount of TLB entries and changes every other
cycle or so. This means it wraps extremely often. We can do better by
combining this fast-changing counter with a potentially slower-changing
counter from random_get_entropy_fallback() in the more significant bits.
This commit combines the two, taking into account that the changing bits
are in a different bit position depending on the CPU model. In addition,
we previously were falling back to 0 for ancient CPUs that Linux does
not support anyway; remove that dead path entirely.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Tested-by: Maciej W. Rozycki <macro@orcam.me.uk>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/mips/include/asm/timex.h | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
--- a/arch/mips/include/asm/timex.h
+++ b/arch/mips/include/asm/timex.h
@@ -76,25 +76,24 @@ static inline cycles_t get_cycles(void)
else
return 0; /* no usable counter */
}
+#define get_cycles get_cycles
/*
* Like get_cycles - but where c0_count is not available we desperately
* use c0_random in an attempt to get at least a little bit of entropy.
- *
- * R6000 and R6000A neither have a count register nor a random register.
- * That leaves no entropy source in the CPU itself.
*/
static inline unsigned long random_get_entropy(void)
{
- unsigned int prid = read_c0_prid();
- unsigned int imp = prid & PRID_IMP_MASK;
+ unsigned int c0_random;
- if (can_use_mips_counter(prid))
+ if (can_use_mips_counter(read_c0_prid()))
return read_c0_count();
- else if (likely(imp != PRID_IMP_R6000 && imp != PRID_IMP_R6000A))
- return read_c0_random();
+
+ if (cpu_has_3kex)
+ c0_random = (read_c0_random() >> 8) & 0x3f;
else
- return 0; /* no usable register */
+ c0_random = read_c0_random() & 0x3f;
+ return (random_get_entropy_fallback() << 6) | (0x3f - c0_random);
}
#define random_get_entropy random_get_entropy
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 078/111] arm: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (76 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 077/111] mips: use fallback for random_get_entropy() instead of just c0 random Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 079/111] nios2: " Greg Kroah-Hartman
` (38 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Russell King (Oracle),
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit ff8a8f59c99f6a7c656387addc4d9f2247d75077 upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/include/asm/timex.h | 1 +
1 file changed, 1 insertion(+)
--- a/arch/arm/include/asm/timex.h
+++ b/arch/arm/include/asm/timex.h
@@ -11,5 +11,6 @@
typedef unsigned long cycles_t;
#define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; })
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 079/111] nios2: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (77 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 078/111] arm: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 080/111] x86/tsc: Use " Greg Kroah-Hartman
` (37 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Dinh Nguyen, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit c04e72700f2293013dab40208e809369378f224c upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/nios2/include/asm/timex.h | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -8,5 +8,8 @@
typedef unsigned long cycles_t;
extern cycles_t get_cycles(void);
+#define get_cycles get_cycles
+
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 080/111] x86/tsc: Use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (78 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 079/111] nios2: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 081/111] um: use " Greg Kroah-Hartman
` (36 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld, Thomas Gleixner,
Arnd Bergmann, Borislav Petkov, x86
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 3bd4abc07a267e6a8b33d7f8717136e18f921c53 upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is suboptimal. Instead, fallback
to calling random_get_entropy_fallback(), which isn't extremely high
precision or guaranteed to be entropic, but is certainly better than
returning zero all the time.
If CONFIG_X86_TSC=n, then it's possible for the kernel to run on systems
without RDTSC, such as 486 and certain 586, so the fallback code is only
required for that case.
As well, fix up both the new function and the get_cycles() function from
which it was derived to use cpu_feature_enabled() rather than
boot_cpu_has(), and use !IS_ENABLED() instead of #ifndef.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/timex.h | 9 +++++++++
arch/x86/include/asm/tsc.h | 7 +++----
2 files changed, 12 insertions(+), 4 deletions(-)
--- a/arch/x86/include/asm/timex.h
+++ b/arch/x86/include/asm/timex.h
@@ -5,6 +5,15 @@
#include <asm/processor.h>
#include <asm/tsc.h>
+static inline unsigned long random_get_entropy(void)
+{
+ if (!IS_ENABLED(CONFIG_X86_TSC) &&
+ !cpu_feature_enabled(X86_FEATURE_TSC))
+ return random_get_entropy_fallback();
+ return rdtsc();
+}
+#define random_get_entropy random_get_entropy
+
/* Assume we use the PIT time source for the clock tick */
#define CLOCK_TICK_RATE PIT_TICK_RATE
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -20,13 +20,12 @@ extern void disable_TSC(void);
static inline cycles_t get_cycles(void)
{
-#ifndef CONFIG_X86_TSC
- if (!boot_cpu_has(X86_FEATURE_TSC))
+ if (!IS_ENABLED(CONFIG_X86_TSC) &&
+ !cpu_feature_enabled(X86_FEATURE_TSC))
return 0;
-#endif
-
return rdtsc();
}
+#define get_cycles get_cycles
extern struct system_counterval_t convert_art_to_tsc(u64 art);
extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 081/111] um: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (79 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 080/111] x86/tsc: Use " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 082/111] sparc: " Greg Kroah-Hartman
` (35 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Richard Weinberger, Anton Ivanov, Johannes Berg,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 9f13fb0cd11ed2327abff69f6501a2c124c88b5a upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
This is accomplished by just including the asm-generic code like on
other architectures, which means we can get rid of the empty stub
function here.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/um/include/asm/timex.h | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
--- a/arch/um/include/asm/timex.h
+++ b/arch/um/include/asm/timex.h
@@ -2,13 +2,8 @@
#ifndef __UM_TIMEX_H
#define __UM_TIMEX_H
-typedef unsigned long cycles_t;
-
-static inline cycles_t get_cycles (void)
-{
- return 0;
-}
-
#define CLOCK_TICK_RATE (HZ)
+#include <asm-generic/timex.h>
+
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 082/111] sparc: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (80 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 081/111] um: use " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 083/111] xtensa: " Greg Kroah-Hartman
` (34 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
David S. Miller, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit ac9756c79797bb98972736b13cfb239fd2cffb79 upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
This is accomplished by just including the asm-generic code like on
other architectures, which means we can get rid of the empty stub
function here.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/sparc/include/asm/timex_32.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
--- a/arch/sparc/include/asm/timex_32.h
+++ b/arch/sparc/include/asm/timex_32.h
@@ -9,8 +9,6 @@
#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-/* XXX Maybe do something better at some point... -DaveM */
-typedef unsigned long cycles_t;
-#define get_cycles() (0)
+#include <asm-generic/timex.h>
#endif
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 083/111] xtensa: use fallback for random_get_entropy() instead of zero
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (81 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 082/111] sparc: " Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 084/111] random: insist on random_get_entropy() existing in order to simplify Greg Kroah-Hartman
` (33 subsequent siblings)
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Arnd Bergmann,
Max Filippov, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e10e2f58030c5c211d49042a8c2a1b93d40b2ffb upstream.
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.
This is accomplished by just including the asm-generic code like on
other architectures, which means we can get rid of the empty stub
function here.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/xtensa/include/asm/timex.h | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/arch/xtensa/include/asm/timex.h
+++ b/arch/xtensa/include/asm/timex.h
@@ -29,10 +29,6 @@
extern unsigned long ccount_freq;
-typedef unsigned long long cycles_t;
-
-#define get_cycles() (0)
-
void local_timer_setup(unsigned cpu);
/*
@@ -59,4 +55,6 @@ static inline void set_linux_timer (unsi
xtensa_set_sr(ccompare, SREG_CCOMPARE + LINUX_TIMER);
}
+#include <asm-generic/timex.h>
+
#endif /* _XTENSA_TIMEX_H */
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 084/111] random: insist on random_get_entropy() existing in order to simplify
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@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 085/111] random: do not use batches when !crng_ready() Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Theodore Tso, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 4b758eda851eb9336ca86a0041a4d3da55f66511 upstream.
All platforms are now guaranteed to provide some value for
random_get_entropy(). In case some bug leads to this not being so, we
print a warning, because that indicates that something is really very
wrong (and likely other things are impacted too). This should never be
hit, but it's a good and cheap way of finding out if something ever is
problematic.
Since we now have viable fallback code for random_get_entropy() on all
platforms, which is, in the worst case, not worse than jiffies, we can
count on getting the best possible value out of it. That means there's
no longer a use for using jiffies as entropy input. It also means we no
longer have a reason for doing the round-robin register flow in the IRQ
handler, which was always of fairly dubious value.
Instead we can greatly simplify the IRQ handler inputs and also unify
the construction between 64-bits and 32-bits. We now collect the cycle
counter and the return address, since those are the two things that
matter. Because the return address and the irq number are likely
related, to the extent we mix in the irq number, we can just xor it into
the top unchanging bytes of the return address, rather than the bottom
changing bytes of the cycle counter as before. Then, we can do a fixed 2
rounds of SipHash/HSipHash. Finally, we use the same construction of
hashing only half of the [H]SipHash state on 32-bit and 64-bit. We're
not actually discarding any entropy, since that entropy is carried
through until the next time. And more importantly, it lets us do the
same sponge-like construction everywhere.
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 86 +++++++++++++++-----------------------------------
1 file changed, 26 insertions(+), 60 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1020,15 +1020,14 @@ int __init rand_initialize(void)
*/
void add_device_randomness(const void *buf, size_t size)
{
- unsigned long cycles = random_get_entropy();
- unsigned long flags, now = jiffies;
+ unsigned long entropy = random_get_entropy();
+ unsigned long flags;
if (crng_init == 0 && size)
crng_pre_init_inject(buf, size, false);
spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&cycles, sizeof(cycles));
- _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(&entropy, sizeof(entropy));
_mix_pool_bytes(buf, size);
spin_unlock_irqrestore(&input_pool.lock, flags);
}
@@ -1051,12 +1050,11 @@ struct timer_rand_state {
*/
static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
- unsigned long cycles = random_get_entropy(), now = jiffies, flags;
+ unsigned long entropy = random_get_entropy(), now = jiffies, flags;
long delta, delta2, delta3;
spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&cycles, sizeof(cycles));
- _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(&entropy, sizeof(entropy));
_mix_pool_bytes(&num, sizeof(num));
spin_unlock_irqrestore(&input_pool.lock, flags);
@@ -1184,7 +1182,6 @@ struct fast_pool {
unsigned long pool[4];
unsigned long last;
unsigned int count;
- u16 reg_idx;
};
static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
@@ -1202,13 +1199,13 @@ static DEFINE_PER_CPU(struct fast_pool,
* This is [Half]SipHash-1-x, starting from an empty key. Because
* the key is fixed, it assumes that its inputs are non-malicious,
* and therefore this has no security on its own. s represents the
- * 128 or 256-bit SipHash state, while v represents a 128-bit input.
+ * four-word SipHash state, while v represents a two-word input.
*/
-static void fast_mix(unsigned long s[4], const unsigned long *v)
+static void fast_mix(unsigned long s[4], const unsigned long v[2])
{
size_t i;
- for (i = 0; i < 16 / sizeof(long); ++i) {
+ for (i = 0; i < 2; ++i) {
s[3] ^= v[i];
#ifdef CONFIG_64BIT
s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32);
@@ -1248,33 +1245,17 @@ int random_online_cpu(unsigned int cpu)
}
#endif
-static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs)
-{
- unsigned long *ptr = (unsigned long *)regs;
- unsigned int idx;
-
- if (regs == NULL)
- return 0;
- idx = READ_ONCE(f->reg_idx);
- if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long))
- idx = 0;
- ptr += idx++;
- WRITE_ONCE(f->reg_idx, idx);
- return *ptr;
-}
-
static void mix_interrupt_randomness(struct work_struct *work)
{
struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
/*
- * The size of the copied stack pool is explicitly 16 bytes so that we
- * tax mix_pool_byte()'s compression function the same amount on all
- * platforms. This means on 64-bit we copy half the pool into this,
- * while on 32-bit we copy all of it. The entropy is supposed to be
- * sufficiently dispersed between bits that in the sponge-like
- * half case, on average we don't wind up "losing" some.
+ * The size of the copied stack pool is explicitly 2 longs so that we
+ * only ever ingest half of the siphash output each time, retaining
+ * the other half as the next "key" that carries over. The entropy is
+ * supposed to be sufficiently dispersed between bits so on average
+ * we don't wind up "losing" some.
*/
- u8 pool[16];
+ unsigned long pool[2];
/* Check to see if we're running on the wrong CPU due to hotplug. */
local_irq_disable();
@@ -1306,36 +1287,21 @@ static void mix_interrupt_randomness(str
void add_interrupt_randomness(int irq)
{
enum { MIX_INFLIGHT = 1U << 31 };
- unsigned long cycles = random_get_entropy(), now = jiffies;
+ unsigned long entropy = random_get_entropy();
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
struct pt_regs *regs = get_irq_regs();
unsigned int new_count;
- union {
- u32 u32[4];
- u64 u64[2];
- unsigned long longs[16 / sizeof(long)];
- } irq_data;
-
- if (cycles == 0)
- cycles = get_reg(fast_pool, regs);
-
- if (sizeof(unsigned long) == 8) {
- irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq;
- irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;
- } else {
- irq_data.u32[0] = cycles ^ irq;
- irq_data.u32[1] = now;
- irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_;
- irq_data.u32[3] = get_reg(fast_pool, regs);
- }
- fast_mix(fast_pool->pool, irq_data.longs);
+ fast_mix(fast_pool->pool, (unsigned long[2]){
+ entropy,
+ (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq)
+ });
new_count = ++fast_pool->count;
if (new_count & MIX_INFLIGHT)
return;
- if (new_count < 64 && (!time_after(now, fast_pool->last + HZ) ||
+ if (new_count < 64 && (!time_is_before_jiffies(fast_pool->last + HZ) ||
unlikely(crng_init == 0)))
return;
@@ -1371,28 +1337,28 @@ static void entropy_timer(struct timer_l
static void try_to_generate_entropy(void)
{
struct {
- unsigned long cycles;
+ unsigned long entropy;
struct timer_list timer;
} stack;
- stack.cycles = random_get_entropy();
+ stack.entropy = random_get_entropy();
/* Slow counter - or none. Don't even bother */
- if (stack.cycles == random_get_entropy())
+ if (stack.entropy == random_get_entropy())
return;
timer_setup_on_stack(&stack.timer, entropy_timer, 0);
while (!crng_ready() && !signal_pending(current)) {
if (!timer_pending(&stack.timer))
mod_timer(&stack.timer, jiffies + 1);
- mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
+ mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
schedule();
- stack.cycles = random_get_entropy();
+ stack.entropy = random_get_entropy();
}
del_timer_sync(&stack.timer);
destroy_timer_on_stack(&stack.timer);
- mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
+ mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 085/111] random: do not use batches when !crng_ready()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (83 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 084/111] random: insist on random_get_entropy() existing in order to simplify Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 086/111] random: use first 128 bits of input as fast init Greg Kroah-Hartman
` (31 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit cbe89e5a375a51bbb952929b93fa973416fea74e upstream.
It's too hard to keep the batches synchronized, and pointless anyway,
since in !crng_ready(), we're updating the base_crng key really often,
where batching only hurts. So instead, if the crng isn't ready, just
call into get_random_bytes(). At this stage nothing is performance
critical anyhow.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -465,10 +465,8 @@ static void crng_pre_init_inject(const v
if (account) {
crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- ++base_crng.generation;
+ if (crng_init_cnt >= CRNG_INIT_CNT_THRESH)
crng_init = 1;
- }
}
spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -624,6 +622,11 @@ u64 get_random_u64(void)
warn_unseeded_randomness(&previous);
+ if (!crng_ready()) {
+ _get_random_bytes(&ret, sizeof(ret));
+ return ret;
+ }
+
local_lock_irqsave(&batched_entropy_u64.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u64);
@@ -658,6 +661,11 @@ u32 get_random_u32(void)
warn_unseeded_randomness(&previous);
+ if (!crng_ready()) {
+ _get_random_bytes(&ret, sizeof(ret));
+ return ret;
+ }
+
local_lock_irqsave(&batched_entropy_u32.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u32);
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 086/111] random: use first 128 bits of input as fast init
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (84 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 085/111] random: do not use batches when !crng_ready() Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.17 087/111] random: do not pretend to handle premature next security model Greg Kroah-Hartman
` (30 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5c3b747ef54fa2a7318776777f6044540d99f721 upstream.
Before, the first 64 bytes of input, regardless of how entropic it was,
would be used to mutate the crng base key directly, and none of those
bytes would be credited as having entropy. Then 256 bits of credited
input would be accumulated, and only then would the rng transition from
the earlier "fast init" phase into being actually initialized.
The thinking was that by mixing and matching fast init and real init, an
attacker who compromised the fast init state, considered easy to do
given how little entropy might be in those first 64 bytes, would then be
able to bruteforce bits from the actual initialization. By keeping these
separate, bruteforcing became impossible.
However, by not crediting potentially creditable bits from those first 64
bytes of input, we delay initialization, and actually make the problem
worse, because it means the user is drawing worse random numbers for a
longer period of time.
Instead, we can take the first 128 bits as fast init, and allow them to
be credited, and then hold off on the next 128 bits until they've
accumulated. This is still a wide enough margin to prevent bruteforcing
the rng state, while still initializing much faster.
Then, rather than trying to piecemeal inject into the base crng key at
various points, instead just extract from the pool when we need it, for
the crng_init==0 phase. Performance may even be better for the various
inputs here, since there are likely more calls to mix_pool_bytes() then
there are to get_random_bytes() during this phase of system execution.
Since the preinit injection code is gone, bootloader randomness can then
do something significantly more straight forward, removing the weird
system_wq hack in hwgenerator randomness.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 146 ++++++++++++++++----------------------------------
1 file changed, 49 insertions(+), 97 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -231,10 +231,7 @@ static void _warn_unseeded_randomness(co
*
*********************************************************************/
-enum {
- CRNG_RESEED_INTERVAL = 300 * HZ,
- CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE
-};
+enum { CRNG_RESEED_INTERVAL = 300 * HZ };
static struct {
u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long));
@@ -258,6 +255,8 @@ static DEFINE_PER_CPU(struct crng, crngs
/* Used by crng_reseed() to extract a new seed from the input pool. */
static bool drain_entropy(void *buf, size_t nbytes);
+/* Used by crng_make_state() to extract a new seed when crng_init==0. */
+static void extract_entropy(void *buf, size_t nbytes);
/*
* This extracts a new crng key from the input pool, but only if there is a
@@ -382,17 +381,20 @@ static void crng_make_state(u32 chacha_s
/*
* For the fast path, we check whether we're ready, unlocked first, and
* then re-check once locked later. In the case where we're really not
- * ready, we do fast key erasure with the base_crng directly, because
- * this is what crng_pre_init_inject() mutates during early init.
+ * ready, we do fast key erasure with the base_crng directly, extracting
+ * when crng_init==0.
*/
if (!crng_ready()) {
bool ready;
spin_lock_irqsave(&base_crng.lock, flags);
ready = crng_ready();
- if (!ready)
+ if (!ready) {
+ if (crng_init == 0)
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_fast_key_erasure(base_crng.key, chacha_state,
random_data, random_data_len);
+ }
spin_unlock_irqrestore(&base_crng.lock, flags);
if (!ready)
return;
@@ -433,48 +435,6 @@ static void crng_make_state(u32 chacha_s
local_unlock_irqrestore(&crngs.lock, flags);
}
-/*
- * This function is for crng_init == 0 only. It loads entropy directly
- * into the crng's key, without going through the input pool. It is,
- * generally speaking, not very safe, but we use this only at early
- * boot time when it's better to have something there rather than
- * nothing.
- *
- * If account is set, then the crng_init_cnt counter is incremented.
- * This shouldn't be set by functions like add_device_randomness(),
- * where we can't trust the buffer passed to it is guaranteed to be
- * unpredictable (so it might not have any entropy at all).
- */
-static void crng_pre_init_inject(const void *input, size_t len, bool account)
-{
- static int crng_init_cnt = 0;
- struct blake2s_state hash;
- unsigned long flags;
-
- blake2s_init(&hash, sizeof(base_crng.key));
-
- spin_lock_irqsave(&base_crng.lock, flags);
- if (crng_init != 0) {
- spin_unlock_irqrestore(&base_crng.lock, flags);
- return;
- }
-
- blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
- blake2s_update(&hash, input, len);
- blake2s_final(&hash, base_crng.key);
-
- if (account) {
- crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH)
- crng_init = 1;
- }
-
- spin_unlock_irqrestore(&base_crng.lock, flags);
-
- if (crng_init == 1)
- pr_notice("fast init done\n");
-}
-
static void _get_random_bytes(void *buf, size_t nbytes)
{
u32 chacha_state[CHACHA_STATE_WORDS];
@@ -787,7 +747,8 @@ EXPORT_SYMBOL(get_random_bytes_arch);
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
+ POOL_MIN_BITS = POOL_BITS, /* No point in settling for less. */
+ POOL_FAST_INIT_BITS = POOL_MIN_BITS / 2
};
/* For notifying userspace should write into /dev/random. */
@@ -824,24 +785,6 @@ static void mix_pool_bytes(const void *i
spin_unlock_irqrestore(&input_pool.lock, flags);
}
-static void credit_entropy_bits(size_t nbits)
-{
- unsigned int entropy_count, orig, add;
-
- if (!nbits)
- return;
-
- add = min_t(size_t, nbits, POOL_BITS);
-
- do {
- orig = READ_ONCE(input_pool.entropy_count);
- entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
- } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
-
- if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
- crng_reseed();
-}
-
/*
* This is an HKDF-like construction for using the hashed collected entropy
* as a PRF key, that's then expanded block-by-block.
@@ -907,6 +850,33 @@ static bool drain_entropy(void *buf, siz
return true;
}
+static void credit_entropy_bits(size_t nbits)
+{
+ unsigned int entropy_count, orig, add;
+ unsigned long flags;
+
+ if (!nbits)
+ return;
+
+ add = min_t(size_t, nbits, POOL_BITS);
+
+ do {
+ orig = READ_ONCE(input_pool.entropy_count);
+ entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
+
+ if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
+ crng_reseed();
+ else if (unlikely(crng_init == 0 && entropy_count >= POOL_FAST_INIT_BITS)) {
+ spin_lock_irqsave(&base_crng.lock, flags);
+ if (crng_init == 0) {
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
+ crng_init = 1;
+ }
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ }
+}
+
/**********************************************************************
*
@@ -949,9 +919,9 @@ static bool drain_entropy(void *buf, siz
* entropy as specified by the caller. If the entropy pool is full it will
* block until more entropy is needed.
*
- * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or
- * add_device_randomness(), depending on whether or not the configuration
- * option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
+ * add_bootloader_randomness() is called by bootloader drivers, such as EFI
+ * and device tree, and credits its input depending on whether or not the
+ * configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
*
* add_interrupt_randomness() uses the interrupt timing as random
* inputs to the entropy pool. Using the cycle counters and the irq source
@@ -1031,9 +1001,6 @@ void add_device_randomness(const void *b
unsigned long entropy = random_get_entropy();
unsigned long flags;
- if (crng_init == 0 && size)
- crng_pre_init_inject(buf, size, false);
-
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(&entropy, sizeof(entropy));
_mix_pool_bytes(buf, size);
@@ -1149,12 +1116,6 @@ void rand_initialize_disk(struct gendisk
void add_hwgenerator_randomness(const void *buffer, size_t count,
size_t entropy)
{
- if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) {
- crng_pre_init_inject(buffer, count, true);
- mix_pool_bytes(buffer, count);
- return;
- }
-
/*
* Throttle writing if we're above the trickle threshold.
* We'll be woken up again once below POOL_MIN_BITS, when
@@ -1162,7 +1123,7 @@ void add_hwgenerator_randomness(const vo
* CRNG_RESEED_INTERVAL has elapsed.
*/
wait_event_interruptible_timeout(random_write_wait,
- !system_wq || kthread_should_stop() ||
+ kthread_should_stop() ||
input_pool.entropy_count < POOL_MIN_BITS,
CRNG_RESEED_INTERVAL);
mix_pool_bytes(buffer, count);
@@ -1171,17 +1132,14 @@ void add_hwgenerator_randomness(const vo
EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
/*
- * Handle random seed passed by bootloader.
- * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
- * it would be regarded as device data.
- * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
+ * Handle random seed passed by bootloader, and credit it if
+ * CONFIG_RANDOM_TRUST_BOOTLOADER is set.
*/
void add_bootloader_randomness(const void *buf, size_t size)
{
+ mix_pool_bytes(buf, size);
if (trust_bootloader)
- add_hwgenerator_randomness(buf, size, size * 8);
- else
- add_device_randomness(buf, size);
+ credit_entropy_bits(size * 8);
}
EXPORT_SYMBOL_GPL(add_bootloader_randomness);
@@ -1281,13 +1239,8 @@ static void mix_interrupt_randomness(str
fast_pool->last = jiffies;
local_irq_enable();
- if (unlikely(crng_init == 0)) {
- crng_pre_init_inject(pool, sizeof(pool), true);
- mix_pool_bytes(pool, sizeof(pool));
- } else {
- mix_pool_bytes(pool, sizeof(pool));
- credit_entropy_bits(1);
- }
+ mix_pool_bytes(pool, sizeof(pool));
+ credit_entropy_bits(1);
memzero_explicit(pool, sizeof(pool));
}
@@ -1309,8 +1262,7 @@ void add_interrupt_randomness(int irq)
if (new_count & MIX_INFLIGHT)
return;
- if (new_count < 64 && (!time_is_before_jiffies(fast_pool->last + HZ) ||
- unlikely(crng_init == 0)))
+ if (new_count < 64 && !time_is_before_jiffies(fast_pool->last + HZ))
return;
if (unlikely(!fast_pool->mix.func))
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 087/111] random: do not pretend to handle premature next security model
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (85 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 086/111] random: use first 128 bits of input as fast init Greg Kroah-Hartman
@ 2022-05-27 8:49 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 088/111] random: order timer entropy functions below interrupt functions Greg Kroah-Hartman
` (29 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:49 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Nadia Heninger,
Tom Ristenpart, Eric Biggers, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e85c0fc1d94c52483a603651748d4c76d6aa1c6b upstream.
Per the thread linked below, "premature next" is not considered to be a
realistic threat model, and leads to more serious security problems.
"Premature next" is the scenario in which:
- Attacker compromises the current state of a fully initialized RNG via
some kind of infoleak.
- New bits of entropy are added directly to the key used to generate the
/dev/urandom stream, without any buffering or pooling.
- Attacker then, somehow having read access to /dev/urandom, samples RNG
output and brute forces the individual new bits that were added.
- Result: the RNG never "recovers" from the initial compromise, a
so-called violation of what academics term "post-compromise security".
The usual solutions to this involve some form of delaying when entropy
gets mixed into the crng. With Fortuna, this involves multiple input
buckets. With what the Linux RNG was trying to do prior, this involves
entropy estimation.
However, by delaying when entropy gets mixed in, it also means that RNG
compromises are extremely dangerous during the window of time before
the RNG has gathered enough entropy, during which time nonces may become
predictable (or repeated), ephemeral keys may not be secret, and so
forth. Moreover, it's unclear how realistic "premature next" is from an
attack perspective, if these attacks even make sense in practice.
Put together -- and discussed in more detail in the thread below --
these constitute grounds for just doing away with the current code that
pretends to handle premature next. I say "pretends" because it wasn't
doing an especially great job at it either; should we change our mind
about this direction, we would probably implement Fortuna to "fix" the
"problem", in which case, removing the pretend solution still makes
sense.
This also reduces the crng reseed period from 5 minutes down to 1
minute. The rationale from the thread might lead us toward reducing that
even further in the future (or even eliminating it), but that remains a
topic of a future commit.
At a high level, this patch changes semantics from:
Before: Seed for the first time after 256 "bits" of estimated
entropy have been accumulated since the system booted. Thereafter,
reseed once every five minutes, but only if 256 new "bits" have been
accumulated since the last reseeding.
After: Seed for the first time after 256 "bits" of estimated entropy
have been accumulated since the system booted. Thereafter, reseed
once every minute.
Most of this patch is renaming and removing: POOL_MIN_BITS becomes
POOL_INIT_BITS, credit_entropy_bits() becomes credit_init_bits(),
crng_reseed() loses its "force" parameter since it's now always true,
the drain_entropy() function no longer has any use so it's removed,
entropy estimation is skipped if we've already init'd, the various
notifiers for "low on entropy" are now only active prior to init, and
finally, some documentation comments are cleaned up here and there.
Link: https://lore.kernel.org/lkml/YmlMGx6+uigkGiZ0@zx2c4.com/
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Nadia Heninger <nadiah@cs.ucsd.edu>
Cc: Tom Ristenpart <ristenpart@cornell.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 174 +++++++++++++++++---------------------------------
1 file changed, 62 insertions(+), 112 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -15,14 +15,12 @@
* - Sysctl interface.
*
* The high level overview is that there is one input pool, into which
- * various pieces of data are hashed. Some of that data is then "credited" as
- * having a certain number of bits of entropy. When enough bits of entropy are
- * available, the hash is finalized and handed as a key to a stream cipher that
- * expands it indefinitely for various consumers. This key is periodically
- * refreshed as the various entropy collectors, described below, add data to the
- * input pool and credit it. There is currently no Fortuna-like scheduler
- * involved, which can lead to malicious entropy sources causing a premature
- * reseed, and the entropy estimates are, at best, conservative guesses.
+ * various pieces of data are hashed. Prior to initialization, some of that
+ * data is then "credited" as having a certain number of bits of entropy.
+ * When enough bits of entropy are available, the hash is finalized and
+ * handed as a key to a stream cipher that expands it indefinitely for
+ * various consumers. This key is periodically refreshed as the various
+ * entropy collectors, described below, add data to the input pool.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -231,7 +229,10 @@ static void _warn_unseeded_randomness(co
*
*********************************************************************/
-enum { CRNG_RESEED_INTERVAL = 300 * HZ };
+enum {
+ CRNG_RESEED_START_INTERVAL = HZ,
+ CRNG_RESEED_INTERVAL = 60 * HZ
+};
static struct {
u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long));
@@ -253,16 +254,10 @@ static DEFINE_PER_CPU(struct crng, crngs
.lock = INIT_LOCAL_LOCK(crngs.lock),
};
-/* Used by crng_reseed() to extract a new seed from the input pool. */
-static bool drain_entropy(void *buf, size_t nbytes);
-/* Used by crng_make_state() to extract a new seed when crng_init==0. */
+/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
static void extract_entropy(void *buf, size_t nbytes);
-/*
- * This extracts a new crng key from the input pool, but only if there is a
- * sufficient amount of entropy available, in order to mitigate bruteforcing
- * of newly added bits.
- */
+/* This extracts a new crng key from the input pool. */
static void crng_reseed(void)
{
unsigned long flags;
@@ -270,9 +265,7 @@ static void crng_reseed(void)
u8 key[CHACHA_KEY_SIZE];
bool finalize_init = false;
- /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */
- if (!drain_entropy(key, sizeof(key)))
- return;
+ extract_entropy(key, sizeof(key));
/*
* We copy the new key into the base_crng, overwriting the old one,
@@ -344,10 +337,10 @@ static void crng_fast_key_erasure(u8 key
}
/*
- * Return whether the crng seed is considered to be sufficiently
- * old that a reseeding might be attempted. This happens if the last
- * reseeding was CRNG_RESEED_INTERVAL ago, or during early boot, at
- * an interval proportional to the uptime.
+ * Return whether the crng seed is considered to be sufficiently old
+ * that a reseeding is needed. This happens if the last reseeding
+ * was CRNG_RESEED_INTERVAL ago, or during early boot, at an interval
+ * proportional to the uptime.
*/
static bool crng_has_old_seed(void)
{
@@ -359,7 +352,7 @@ static bool crng_has_old_seed(void)
if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
WRITE_ONCE(early_boot, false);
else
- interval = max_t(unsigned int, 5 * HZ,
+ interval = max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
(unsigned int)uptime / 2 * HZ);
}
return time_after(jiffies, READ_ONCE(base_crng.birth) + interval);
@@ -401,8 +394,8 @@ static void crng_make_state(u32 chacha_s
}
/*
- * If the base_crng is old enough, we try to reseed, which in turn
- * bumps the generation counter that we check below.
+ * If the base_crng is old enough, we reseed, which in turn bumps the
+ * generation counter that we check below.
*/
if (unlikely(crng_has_old_seed()))
crng_reseed();
@@ -734,30 +727,24 @@ EXPORT_SYMBOL(get_random_bytes_arch);
*
* After which, if added entropy should be credited:
*
- * static void credit_entropy_bits(size_t nbits)
+ * static void credit_init_bits(size_t nbits)
*
- * Finally, extract entropy via these two, with the latter one
- * setting the entropy count to zero and extracting only if there
- * is POOL_MIN_BITS entropy credited prior:
+ * Finally, extract entropy via:
*
* static void extract_entropy(void *buf, size_t nbytes)
- * static bool drain_entropy(void *buf, size_t nbytes)
*
**********************************************************************/
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_MIN_BITS = POOL_BITS, /* No point in settling for less. */
- POOL_FAST_INIT_BITS = POOL_MIN_BITS / 2
+ POOL_INIT_BITS = POOL_BITS, /* No point in settling for less. */
+ POOL_FAST_INIT_BITS = POOL_INIT_BITS / 2
};
-/* For notifying userspace should write into /dev/random. */
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-
static struct {
struct blake2s_state hash;
spinlock_t lock;
- unsigned int entropy_count;
+ unsigned int init_bits;
} input_pool = {
.hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
@@ -772,9 +759,9 @@ static void _mix_pool_bytes(const void *
}
/*
- * This function adds bytes into the entropy "pool". It does not
- * update the entropy estimate. The caller should call
- * credit_entropy_bits if this is appropriate.
+ * This function adds bytes into the input pool. It does not
+ * update the initialization bit counter; the caller should call
+ * credit_init_bits if this is appropriate.
*/
static void mix_pool_bytes(const void *in, size_t nbytes)
{
@@ -831,43 +818,24 @@ static void extract_entropy(void *buf, s
memzero_explicit(&block, sizeof(block));
}
-/*
- * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we
- * set the entropy count to zero (but don't actually touch any data). Only then
- * can we extract a new key with extract_entropy().
- */
-static bool drain_entropy(void *buf, size_t nbytes)
-{
- unsigned int entropy_count;
- do {
- entropy_count = READ_ONCE(input_pool.entropy_count);
- if (entropy_count < POOL_MIN_BITS)
- return false;
- } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
- extract_entropy(buf, nbytes);
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- return true;
-}
-
-static void credit_entropy_bits(size_t nbits)
+static void credit_init_bits(size_t nbits)
{
- unsigned int entropy_count, orig, add;
+ unsigned int init_bits, orig, add;
unsigned long flags;
- if (!nbits)
+ if (crng_ready() || !nbits)
return;
add = min_t(size_t, nbits, POOL_BITS);
do {
- orig = READ_ONCE(input_pool.entropy_count);
- entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
- } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
+ orig = READ_ONCE(input_pool.init_bits);
+ init_bits = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.init_bits, orig, init_bits) != orig);
- if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
+ if (!crng_ready() && init_bits >= POOL_INIT_BITS)
crng_reseed();
- else if (unlikely(crng_init == 0 && entropy_count >= POOL_FAST_INIT_BITS)) {
+ else if (unlikely(crng_init == 0 && init_bits >= POOL_FAST_INIT_BITS)) {
spin_lock_irqsave(&base_crng.lock, flags);
if (crng_init == 0) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
@@ -973,13 +941,10 @@ int __init rand_initialize(void)
_mix_pool_bytes(&now, sizeof(now));
_mix_pool_bytes(utsname(), sizeof(*(utsname())));
- extract_entropy(base_crng.key, sizeof(base_crng.key));
- ++base_crng.generation;
-
- if (arch_init && trust_cpu && !crng_ready()) {
- crng_init = 2;
- pr_notice("crng init done (trusting CPU's manufacturer)\n");
- }
+ if (crng_ready())
+ crng_reseed();
+ else if (arch_init && trust_cpu)
+ credit_init_bits(BLAKE2S_BLOCK_SIZE * 8);
if (ratelimit_disable) {
urandom_warning.interval = 0;
@@ -1033,6 +998,9 @@ static void add_timer_randomness(struct
_mix_pool_bytes(&num, sizeof(num));
spin_unlock_irqrestore(&input_pool.lock, flags);
+ if (crng_ready())
+ return;
+
/*
* Calculate number of bits of randomness we probably added.
* We take into account the first, second and third-order deltas
@@ -1063,7 +1031,7 @@ static void add_timer_randomness(struct
* Round down by 1 bit on general principles,
* and limit entropy estimate to 12 bits.
*/
- credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11));
+ credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11));
}
void add_input_randomness(unsigned int type, unsigned int code,
@@ -1116,18 +1084,15 @@ void rand_initialize_disk(struct gendisk
void add_hwgenerator_randomness(const void *buffer, size_t count,
size_t entropy)
{
+ mix_pool_bytes(buffer, count);
+ credit_init_bits(entropy);
+
/*
- * Throttle writing if we're above the trickle threshold.
- * We'll be woken up again once below POOL_MIN_BITS, when
- * the calling thread is about to terminate, or once
- * CRNG_RESEED_INTERVAL has elapsed.
+ * Throttle writing to once every CRNG_RESEED_INTERVAL, unless
+ * we're not yet initialized.
*/
- wait_event_interruptible_timeout(random_write_wait,
- kthread_should_stop() ||
- input_pool.entropy_count < POOL_MIN_BITS,
- CRNG_RESEED_INTERVAL);
- mix_pool_bytes(buffer, count);
- credit_entropy_bits(entropy);
+ if (!kthread_should_stop() && crng_ready())
+ schedule_timeout_interruptible(CRNG_RESEED_INTERVAL);
}
EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
@@ -1139,7 +1104,7 @@ void add_bootloader_randomness(const voi
{
mix_pool_bytes(buf, size);
if (trust_bootloader)
- credit_entropy_bits(size * 8);
+ credit_init_bits(size * 8);
}
EXPORT_SYMBOL_GPL(add_bootloader_randomness);
@@ -1240,7 +1205,7 @@ static void mix_interrupt_randomness(str
local_irq_enable();
mix_pool_bytes(pool, sizeof(pool));
- credit_entropy_bits(1);
+ credit_init_bits(1);
memzero_explicit(pool, sizeof(pool));
}
@@ -1287,7 +1252,7 @@ EXPORT_SYMBOL_GPL(add_interrupt_randomne
*/
static void entropy_timer(struct timer_list *t)
{
- credit_entropy_bits(1);
+ credit_init_bits(1);
}
/*
@@ -1380,16 +1345,8 @@ SYSCALL_DEFINE3(getrandom, char __user *
static __poll_t random_poll(struct file *file, poll_table *wait)
{
- __poll_t mask;
-
poll_wait(file, &crng_init_wait, wait);
- poll_wait(file, &random_write_wait, wait);
- mask = 0;
- if (crng_ready())
- mask |= EPOLLIN | EPOLLRDNORM;
- if (input_pool.entropy_count < POOL_MIN_BITS)
- mask |= EPOLLOUT | EPOLLWRNORM;
- return mask;
+ return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
}
static int write_pool(const char __user *ubuf, size_t count)
@@ -1462,7 +1419,7 @@ static long random_ioctl(struct file *f,
switch (cmd) {
case RNDGETENTCNT:
/* Inherently racy, no point locking. */
- if (put_user(input_pool.entropy_count, p))
+ if (put_user(input_pool.init_bits, p))
return -EFAULT;
return 0;
case RNDADDTOENTCNT:
@@ -1472,7 +1429,7 @@ static long random_ioctl(struct file *f,
return -EFAULT;
if (ent_count < 0)
return -EINVAL;
- credit_entropy_bits(ent_count);
+ credit_init_bits(ent_count);
return 0;
case RNDADDENTROPY:
if (!capable(CAP_SYS_ADMIN))
@@ -1486,20 +1443,13 @@ static long random_ioctl(struct file *f,
retval = write_pool((const char __user *)p, size);
if (retval < 0)
return retval;
- credit_entropy_bits(ent_count);
+ credit_init_bits(ent_count);
return 0;
case RNDZAPENTCNT:
case RNDCLEARPOOL:
- /*
- * Clear the entropy pool counters. We no longer clear
- * the entropy pool, as that's silly.
- */
+ /* No longer has any effect. */
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
return 0;
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
@@ -1558,7 +1508,7 @@ const struct file_operations urandom_fop
*
* - write_wakeup_threshold - the amount of entropy in the input pool
* below which write polls to /dev/random will unblock, requesting
- * more entropy, tied to the POOL_MIN_BITS constant. It is writable
+ * more entropy, tied to the POOL_INIT_BITS constant. It is writable
* to avoid breaking old userspaces, but writing to it does not
* change any behavior of the RNG.
*
@@ -1573,7 +1523,7 @@ const struct file_operations urandom_fop
#include <linux/sysctl.h>
static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ;
-static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_random_write_wakeup_bits = POOL_INIT_BITS;
static int sysctl_poolsize = POOL_BITS;
static u8 sysctl_bootid[UUID_SIZE];
@@ -1629,7 +1579,7 @@ static struct ctl_table random_table[] =
},
{
.procname = "entropy_avail",
- .data = &input_pool.entropy_count,
+ .data = &input_pool.init_bits,
.maxlen = sizeof(int),
.mode = 0444,
.proc_handler = proc_dointvec,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 088/111] random: order timer entropy functions below interrupt functions
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (86 preceding siblings ...)
2022-05-27 8:49 ` [PATCH 5.17 087/111] random: do not pretend to handle premature next security model Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 089/111] random: do not use input pool from hard IRQs Greg Kroah-Hartman
` (28 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a4b5c26b79ffdfcfb816c198f2fc2b1e7b5b580f upstream.
There are no code changes here; this is just a reordering of functions,
so that in subsequent commits, the timer entropy functions can call into
the interrupt ones.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 238 +++++++++++++++++++++++++-------------------------
1 file changed, 119 insertions(+), 119 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -854,13 +854,13 @@ static void credit_init_bits(size_t nbit
* the above entropy accumulation routines:
*
* void add_device_randomness(const void *buf, size_t size);
- * void add_input_randomness(unsigned int type, unsigned int code,
- * unsigned int value);
- * void add_disk_randomness(struct gendisk *disk);
* void add_hwgenerator_randomness(const void *buffer, size_t count,
* size_t entropy);
* void add_bootloader_randomness(const void *buf, size_t size);
* void add_interrupt_randomness(int irq);
+ * void add_input_randomness(unsigned int type, unsigned int code,
+ * unsigned int value);
+ * void add_disk_randomness(struct gendisk *disk);
*
* add_device_randomness() adds data to the input pool that
* is likely to differ between two devices (or possibly even per boot).
@@ -870,19 +870,6 @@ static void credit_init_bits(size_t nbit
* that might otherwise be identical and have very little entropy
* available to them (particularly common in the embedded world).
*
- * add_input_randomness() uses the input layer interrupt timing, as well
- * as the event type information from the hardware.
- *
- * add_disk_randomness() uses what amounts to the seek time of block
- * layer request events, on a per-disk_devt basis, as input to the
- * entropy pool. Note that high-speed solid state drives with very low
- * seek times do not make for good sources of entropy, as their seek
- * times are usually fairly consistent.
- *
- * The above two routines try to estimate how many bits of entropy
- * to credit. They do this by keeping track of the first and second
- * order deltas of the event timings.
- *
* add_hwgenerator_randomness() is for true hardware RNGs, and will credit
* entropy as specified by the caller. If the entropy pool is full it will
* block until more entropy is needed.
@@ -896,6 +883,19 @@ static void credit_init_bits(size_t nbit
* as inputs, it feeds the input pool roughly once a second or after 64
* interrupts, crediting 1 bit of entropy for whichever comes first.
*
+ * add_input_randomness() uses the input layer interrupt timing, as well
+ * as the event type information from the hardware.
+ *
+ * add_disk_randomness() uses what amounts to the seek time of block
+ * layer request events, on a per-disk_devt basis, as input to the
+ * entropy pool. Note that high-speed solid state drives with very low
+ * seek times do not make for good sources of entropy, as their seek
+ * times are usually fairly consistent.
+ *
+ * The last two routines try to estimate how many bits of entropy
+ * to credit. They do this by keeping track of the first and second
+ * order deltas of the event timings.
+ *
**********************************************************************/
static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
@@ -973,109 +973,6 @@ void add_device_randomness(const void *b
}
EXPORT_SYMBOL(add_device_randomness);
-/* There is one of these per entropy source */
-struct timer_rand_state {
- unsigned long last_time;
- long last_delta, last_delta2;
-};
-
-/*
- * This function adds entropy to the entropy "pool" by using timing
- * delays. It uses the timer_rand_state structure to make an estimate
- * of how many bits of entropy this call has added to the pool.
- *
- * The number "num" is also added to the pool - it should somehow describe
- * the type of event which just happened. This is currently 0-255 for
- * keyboard scan codes, and 256 upwards for interrupts.
- */
-static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
-{
- unsigned long entropy = random_get_entropy(), now = jiffies, flags;
- long delta, delta2, delta3;
-
- spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&entropy, sizeof(entropy));
- _mix_pool_bytes(&num, sizeof(num));
- spin_unlock_irqrestore(&input_pool.lock, flags);
-
- if (crng_ready())
- return;
-
- /*
- * Calculate number of bits of randomness we probably added.
- * We take into account the first, second and third-order deltas
- * in order to make our estimate.
- */
- delta = now - READ_ONCE(state->last_time);
- WRITE_ONCE(state->last_time, now);
-
- delta2 = delta - READ_ONCE(state->last_delta);
- WRITE_ONCE(state->last_delta, delta);
-
- delta3 = delta2 - READ_ONCE(state->last_delta2);
- WRITE_ONCE(state->last_delta2, delta2);
-
- if (delta < 0)
- delta = -delta;
- if (delta2 < 0)
- delta2 = -delta2;
- if (delta3 < 0)
- delta3 = -delta3;
- if (delta > delta2)
- delta = delta2;
- if (delta > delta3)
- delta = delta3;
-
- /*
- * delta is now minimum absolute delta.
- * Round down by 1 bit on general principles,
- * and limit entropy estimate to 12 bits.
- */
- credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11));
-}
-
-void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value)
-{
- static unsigned char last_value;
- static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
-
- /* Ignore autorepeat and the like. */
- if (value == last_value)
- return;
-
- last_value = value;
- add_timer_randomness(&input_timer_state,
- (type << 4) ^ code ^ (code >> 4) ^ value);
-}
-EXPORT_SYMBOL_GPL(add_input_randomness);
-
-#ifdef CONFIG_BLOCK
-void add_disk_randomness(struct gendisk *disk)
-{
- if (!disk || !disk->random)
- return;
- /* First major is 1, so we get >= 0x200 here. */
- add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
-}
-EXPORT_SYMBOL_GPL(add_disk_randomness);
-
-void rand_initialize_disk(struct gendisk *disk)
-{
- struct timer_rand_state *state;
-
- /*
- * If kzalloc returns null, we just won't use that entropy
- * source.
- */
- state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
- if (state) {
- state->last_time = INITIAL_JIFFIES;
- disk->random = state;
- }
-}
-#endif
-
/*
* Interface for in-kernel drivers of true hardware RNGs.
* Those devices may produce endless random bits and will be throttled
@@ -1237,6 +1134,109 @@ void add_interrupt_randomness(int irq)
}
EXPORT_SYMBOL_GPL(add_interrupt_randomness);
+/* There is one of these per entropy source */
+struct timer_rand_state {
+ unsigned long last_time;
+ long last_delta, last_delta2;
+};
+
+/*
+ * This function adds entropy to the entropy "pool" by using timing
+ * delays. It uses the timer_rand_state structure to make an estimate
+ * of how many bits of entropy this call has added to the pool.
+ *
+ * The number "num" is also added to the pool - it should somehow describe
+ * the type of event which just happened. This is currently 0-255 for
+ * keyboard scan codes, and 256 upwards for interrupts.
+ */
+static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
+{
+ unsigned long entropy = random_get_entropy(), now = jiffies, flags;
+ long delta, delta2, delta3;
+
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(&entropy, sizeof(entropy));
+ _mix_pool_bytes(&num, sizeof(num));
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+
+ if (crng_ready())
+ return;
+
+ /*
+ * Calculate number of bits of randomness we probably added.
+ * We take into account the first, second and third-order deltas
+ * in order to make our estimate.
+ */
+ delta = now - READ_ONCE(state->last_time);
+ WRITE_ONCE(state->last_time, now);
+
+ delta2 = delta - READ_ONCE(state->last_delta);
+ WRITE_ONCE(state->last_delta, delta);
+
+ delta3 = delta2 - READ_ONCE(state->last_delta2);
+ WRITE_ONCE(state->last_delta2, delta2);
+
+ if (delta < 0)
+ delta = -delta;
+ if (delta2 < 0)
+ delta2 = -delta2;
+ if (delta3 < 0)
+ delta3 = -delta3;
+ if (delta > delta2)
+ delta = delta2;
+ if (delta > delta3)
+ delta = delta3;
+
+ /*
+ * delta is now minimum absolute delta.
+ * Round down by 1 bit on general principles,
+ * and limit entropy estimate to 12 bits.
+ */
+ credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11));
+}
+
+void add_input_randomness(unsigned int type, unsigned int code,
+ unsigned int value)
+{
+ static unsigned char last_value;
+ static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
+
+ /* Ignore autorepeat and the like. */
+ if (value == last_value)
+ return;
+
+ last_value = value;
+ add_timer_randomness(&input_timer_state,
+ (type << 4) ^ code ^ (code >> 4) ^ value);
+}
+EXPORT_SYMBOL_GPL(add_input_randomness);
+
+#ifdef CONFIG_BLOCK
+void add_disk_randomness(struct gendisk *disk)
+{
+ if (!disk || !disk->random)
+ return;
+ /* First major is 1, so we get >= 0x200 here. */
+ add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
+}
+EXPORT_SYMBOL_GPL(add_disk_randomness);
+
+void rand_initialize_disk(struct gendisk *disk)
+{
+ struct timer_rand_state *state;
+
+ /*
+ * If kzalloc returns null, we just won't use that entropy
+ * source.
+ */
+ state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+ if (state) {
+ state->last_time = INITIAL_JIFFIES;
+ disk->random = state;
+ }
+}
+#endif
+
/*
* Each time the timer fires, we expect that we got an unpredictable
* jump in the cycle counter. Even if the timer is running on another
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 089/111] random: do not use input pool from hard IRQs
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (87 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 088/111] random: order timer entropy functions below interrupt functions Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 090/111] random: help compiler out with fast_mix() by using simpler arguments Greg Kroah-Hartman
` (27 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Thomas Gleixner, Filipe Manana,
Peter Zijlstra, Borislav Petkov, Theodore Tso,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e3e33fc2ea7fcefd0d761db9d6219f83b4248f5c upstream.
Years ago, a separate fast pool was added for interrupts, so that the
cost associated with taking the input pool spinlocks and mixing into it
would be avoided in places where latency is critical. However, one
oversight was that add_input_randomness() and add_disk_randomness()
still sometimes are called directly from the interrupt handler, rather
than being deferred to a thread. This means that some unlucky interrupts
will be caught doing a blake2s_compress() call and potentially spinning
on input_pool.lock, which can also be taken by unprivileged users by
writing into /dev/urandom.
In order to fix this, add_timer_randomness() now checks whether it is
being called from a hard IRQ and if so, just mixes into the per-cpu IRQ
fast pool using fast_mix(), which is much faster and can be done
lock-free. A nice consequence of this, as well, is that it means hard
IRQ context FPU support is likely no longer useful.
The entropy estimation algorithm used by add_timer_randomness() is also
somewhat different than the one used for add_interrupt_randomness(). The
former looks at deltas of deltas of deltas, while the latter just waits
for 64 interrupts for one bit or for one second since the last bit. In
order to bridge these, and since add_interrupt_randomness() runs after
an add_timer_randomness() that's called from hard IRQ, we add to the
fast pool credit the related amount, and then subtract one to account
for add_interrupt_randomness()'s contribution.
A downside of this, however, is that the num argument is potentially
attacker controlled, which puts a bit more pressure on the fast_mix()
sponge to do more than it's really intended to do. As a mitigating
factor, the first 96 bits of input aren't attacker controlled (a cycle
counter followed by zeros), which means it's essentially two rounds of
siphash rather than one, which is somewhat better. It's also not that
much different from add_interrupt_randomness()'s use of the irq stack
instruction pointer register.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Filipe Manana <fdmanana@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 51 +++++++++++++++++++++++++++++++++++---------------
1 file changed, 36 insertions(+), 15 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1084,6 +1084,7 @@ static void mix_interrupt_randomness(str
* we don't wind up "losing" some.
*/
unsigned long pool[2];
+ unsigned int count;
/* Check to see if we're running on the wrong CPU due to hotplug. */
local_irq_disable();
@@ -1097,12 +1098,13 @@ static void mix_interrupt_randomness(str
* consistent view, before we reenable irqs again.
*/
memcpy(pool, fast_pool->pool, sizeof(pool));
+ count = fast_pool->count;
fast_pool->count = 0;
fast_pool->last = jiffies;
local_irq_enable();
mix_pool_bytes(pool, sizeof(pool));
- credit_init_bits(1);
+ credit_init_bits(max(1u, (count & U16_MAX) / 64));
memzero_explicit(pool, sizeof(pool));
}
@@ -1142,22 +1144,30 @@ struct timer_rand_state {
/*
* This function adds entropy to the entropy "pool" by using timing
- * delays. It uses the timer_rand_state structure to make an estimate
- * of how many bits of entropy this call has added to the pool.
- *
- * The number "num" is also added to the pool - it should somehow describe
- * the type of event which just happened. This is currently 0-255 for
- * keyboard scan codes, and 256 upwards for interrupts.
+ * delays. It uses the timer_rand_state structure to make an estimate
+ * of how many bits of entropy this call has added to the pool. The
+ * value "num" is also added to the pool; it should somehow describe
+ * the type of event that just happened.
*/
static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
unsigned long entropy = random_get_entropy(), now = jiffies, flags;
long delta, delta2, delta3;
+ unsigned int bits;
- spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&entropy, sizeof(entropy));
- _mix_pool_bytes(&num, sizeof(num));
- spin_unlock_irqrestore(&input_pool.lock, flags);
+ /*
+ * If we're in a hard IRQ, add_interrupt_randomness() will be called
+ * sometime after, so mix into the fast pool.
+ */
+ if (in_hardirq()) {
+ fast_mix(this_cpu_ptr(&irq_randomness)->pool,
+ (unsigned long[2]){ entropy, num });
+ } else {
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(&entropy, sizeof(entropy));
+ _mix_pool_bytes(&num, sizeof(num));
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+ }
if (crng_ready())
return;
@@ -1188,11 +1198,22 @@ static void add_timer_randomness(struct
delta = delta3;
/*
- * delta is now minimum absolute delta.
- * Round down by 1 bit on general principles,
- * and limit entropy estimate to 12 bits.
+ * delta is now minimum absolute delta. Round down by 1 bit
+ * on general principles, and limit entropy estimate to 11 bits.
+ */
+ bits = min(fls(delta >> 1), 11);
+
+ /*
+ * As mentioned above, if we're in a hard IRQ, add_interrupt_randomness()
+ * will run after this, which uses a different crediting scheme of 1 bit
+ * per every 64 interrupts. In order to let that function do accounting
+ * close to the one in this function, we credit a full 64/64 bit per bit,
+ * and then subtract one to account for the extra one added.
*/
- credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11));
+ if (in_hardirq())
+ this_cpu_ptr(&irq_randomness)->count += max(1u, bits * 64) - 1;
+ else
+ credit_init_bits(bits);
}
void add_input_randomness(unsigned int type, unsigned int code,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 090/111] random: help compiler out with fast_mix() by using simpler arguments
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (88 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 089/111] random: do not use input pool from hard IRQs Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 091/111] siphash: use one source of truth for siphash permutations Greg Kroah-Hartman
` (26 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 791332b3cbb080510954a4c152ce02af8832eac9 upstream.
Now that fast_mix() has more than one caller, gcc no longer inlines it.
That's fine. But it also doesn't handle the compound literal argument we
pass it very efficiently, nor does it handle the loop as well as it
could. So just expand the code to spell out this function so that it
generates the same code as it did before. Performance-wise, this now
behaves as it did before the last commit. The difference in actual code
size on x86 is 45 bytes, which is less than a cache line.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 44 +++++++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 21 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1029,25 +1029,30 @@ static DEFINE_PER_CPU(struct fast_pool,
* and therefore this has no security on its own. s represents the
* four-word SipHash state, while v represents a two-word input.
*/
-static void fast_mix(unsigned long s[4], const unsigned long v[2])
+static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2)
{
- size_t i;
-
- for (i = 0; i < 2; ++i) {
- s[3] ^= v[i];
#ifdef CONFIG_64BIT
- s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32);
- s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2];
- s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0];
- s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32);
+#define PERM() do { \
+ s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32); \
+ s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2]; \
+ s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0]; \
+ s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32); \
+} while (0)
#else
- s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16);
- s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2];
- s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0];
- s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16);
+#define PERM() do { \
+ s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16); \
+ s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2]; \
+ s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0]; \
+ s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16); \
+} while (0)
#endif
- s[0] ^= v[i];
- }
+
+ s[3] ^= v1;
+ PERM();
+ s[0] ^= v1;
+ s[3] ^= v2;
+ PERM();
+ s[0] ^= v2;
}
#ifdef CONFIG_SMP
@@ -1117,10 +1122,8 @@ void add_interrupt_randomness(int irq)
struct pt_regs *regs = get_irq_regs();
unsigned int new_count;
- fast_mix(fast_pool->pool, (unsigned long[2]){
- entropy,
- (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq)
- });
+ fast_mix(fast_pool->pool, entropy,
+ (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq));
new_count = ++fast_pool->count;
if (new_count & MIX_INFLIGHT)
@@ -1160,8 +1163,7 @@ static void add_timer_randomness(struct
* sometime after, so mix into the fast pool.
*/
if (in_hardirq()) {
- fast_mix(this_cpu_ptr(&irq_randomness)->pool,
- (unsigned long[2]){ entropy, num });
+ fast_mix(this_cpu_ptr(&irq_randomness)->pool, entropy, num);
} else {
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(&entropy, sizeof(entropy));
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 091/111] siphash: use one source of truth for siphash permutations
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (89 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 090/111] random: help compiler out with fast_mix() by using simpler arguments Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 092/111] random: use symbolic constants for crng_init states Greg Kroah-Hartman
` (25 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e73aaae2fa9024832e1f42e30c787c7baf61d014 upstream.
The SipHash family of permutations is currently used in three places:
- siphash.c itself, used in the ordinary way it was intended.
- random32.c, in a construction from an anonymous contributor.
- random.c, as part of its fast_mix function.
Each one of these places reinvents the wheel with the same C code, same
rotation constants, and same symmetry-breaking constants.
This commit tidies things up a bit by placing macros for the
permutations and constants into siphash.h, where each of the three .c
users can access them. It also leaves a note dissuading more users of
them from emerging.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 30 +++++++-----------------------
include/linux/prandom.h | 23 +++++++----------------
include/linux/siphash.h | 28 ++++++++++++++++++++++++++++
lib/siphash.c | 32 ++++++++++----------------------
4 files changed, 52 insertions(+), 61 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -51,6 +51,7 @@
#include <linux/completion.h>
#include <linux/uuid.h>
#include <linux/uaccess.h>
+#include <linux/siphash.h>
#include <crypto/chacha.h>
#include <crypto/blake2s.h>
#include <asm/processor.h>
@@ -1014,12 +1015,11 @@ struct fast_pool {
static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
#ifdef CONFIG_64BIT
- /* SipHash constants */
- .pool = { 0x736f6d6570736575UL, 0x646f72616e646f6dUL,
- 0x6c7967656e657261UL, 0x7465646279746573UL }
+#define FASTMIX_PERM SIPHASH_PERMUTATION
+ .pool = { SIPHASH_CONST_0, SIPHASH_CONST_1, SIPHASH_CONST_2, SIPHASH_CONST_3 }
#else
- /* HalfSipHash constants */
- .pool = { 0, 0, 0x6c796765U, 0x74656462U }
+#define FASTMIX_PERM HSIPHASH_PERMUTATION
+ .pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 }
#endif
};
@@ -1031,27 +1031,11 @@ static DEFINE_PER_CPU(struct fast_pool,
*/
static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2)
{
-#ifdef CONFIG_64BIT
-#define PERM() do { \
- s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32); \
- s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2]; \
- s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0]; \
- s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32); \
-} while (0)
-#else
-#define PERM() do { \
- s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16); \
- s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2]; \
- s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0]; \
- s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16); \
-} while (0)
-#endif
-
s[3] ^= v1;
- PERM();
+ FASTMIX_PERM(s[0], s[1], s[2], s[3]);
s[0] ^= v1;
s[3] ^= v2;
- PERM();
+ FASTMIX_PERM(s[0], s[1], s[2], s[3]);
s[0] ^= v2;
}
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -10,6 +10,7 @@
#include <linux/types.h>
#include <linux/percpu.h>
+#include <linux/siphash.h>
u32 prandom_u32(void);
void prandom_bytes(void *buf, size_t nbytes);
@@ -27,15 +28,10 @@ DECLARE_PER_CPU(unsigned long, net_rand_
* The core SipHash round function. Each line can be executed in
* parallel given enough CPU resources.
*/
-#define PRND_SIPROUND(v0, v1, v2, v3) ( \
- v0 += v1, v1 = rol64(v1, 13), v2 += v3, v3 = rol64(v3, 16), \
- v1 ^= v0, v0 = rol64(v0, 32), v3 ^= v2, \
- v0 += v3, v3 = rol64(v3, 21), v2 += v1, v1 = rol64(v1, 17), \
- v3 ^= v0, v1 ^= v2, v2 = rol64(v2, 32) \
-)
+#define PRND_SIPROUND(v0, v1, v2, v3) SIPHASH_PERMUTATION(v0, v1, v2, v3)
-#define PRND_K0 (0x736f6d6570736575 ^ 0x6c7967656e657261)
-#define PRND_K1 (0x646f72616e646f6d ^ 0x7465646279746573)
+#define PRND_K0 (SIPHASH_CONST_0 ^ SIPHASH_CONST_2)
+#define PRND_K1 (SIPHASH_CONST_1 ^ SIPHASH_CONST_3)
#elif BITS_PER_LONG == 32
/*
@@ -43,14 +39,9 @@ DECLARE_PER_CPU(unsigned long, net_rand_
* This is weaker, but 32-bit machines are not used for high-traffic
* applications, so there is less output for an attacker to analyze.
*/
-#define PRND_SIPROUND(v0, v1, v2, v3) ( \
- v0 += v1, v1 = rol32(v1, 5), v2 += v3, v3 = rol32(v3, 8), \
- v1 ^= v0, v0 = rol32(v0, 16), v3 ^= v2, \
- v0 += v3, v3 = rol32(v3, 7), v2 += v1, v1 = rol32(v1, 13), \
- v3 ^= v0, v1 ^= v2, v2 = rol32(v2, 16) \
-)
-#define PRND_K0 0x6c796765
-#define PRND_K1 0x74656462
+#define PRND_SIPROUND(v0, v1, v2, v3) HSIPHASH_PERMUTATION(v0, v1, v2, v3)
+#define PRND_K0 (HSIPHASH_CONST_0 ^ HSIPHASH_CONST_2)
+#define PRND_K1 (HSIPHASH_CONST_1 ^ HSIPHASH_CONST_3)
#else
#error Unsupported BITS_PER_LONG
--- a/include/linux/siphash.h
+++ b/include/linux/siphash.h
@@ -138,4 +138,32 @@ static inline u32 hsiphash(const void *d
return ___hsiphash_aligned(data, len, key);
}
+/*
+ * These macros expose the raw SipHash and HalfSipHash permutations.
+ * Do not use them directly! If you think you have a use for them,
+ * be sure to CC the maintainer of this file explaining why.
+ */
+
+#define SIPHASH_PERMUTATION(a, b, c, d) ( \
+ (a) += (b), (b) = rol64((b), 13), (b) ^= (a), (a) = rol64((a), 32), \
+ (c) += (d), (d) = rol64((d), 16), (d) ^= (c), \
+ (a) += (d), (d) = rol64((d), 21), (d) ^= (a), \
+ (c) += (b), (b) = rol64((b), 17), (b) ^= (c), (c) = rol64((c), 32))
+
+#define SIPHASH_CONST_0 0x736f6d6570736575ULL
+#define SIPHASH_CONST_1 0x646f72616e646f6dULL
+#define SIPHASH_CONST_2 0x6c7967656e657261ULL
+#define SIPHASH_CONST_3 0x7465646279746573ULL
+
+#define HSIPHASH_PERMUTATION(a, b, c, d) ( \
+ (a) += (b), (b) = rol32((b), 5), (b) ^= (a), (a) = rol32((a), 16), \
+ (c) += (d), (d) = rol32((d), 8), (d) ^= (c), \
+ (a) += (d), (d) = rol32((d), 7), (d) ^= (a), \
+ (c) += (b), (b) = rol32((b), 13), (b) ^= (c), (c) = rol32((c), 16))
+
+#define HSIPHASH_CONST_0 0U
+#define HSIPHASH_CONST_1 0U
+#define HSIPHASH_CONST_2 0x6c796765U
+#define HSIPHASH_CONST_3 0x74656462U
+
#endif /* _LINUX_SIPHASH_H */
--- a/lib/siphash.c
+++ b/lib/siphash.c
@@ -18,19 +18,13 @@
#include <asm/word-at-a-time.h>
#endif
-#define SIPROUND \
- do { \
- v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \
- v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \
- v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \
- v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \
- } while (0)
+#define SIPROUND SIPHASH_PERMUTATION(v0, v1, v2, v3)
#define PREAMBLE(len) \
- u64 v0 = 0x736f6d6570736575ULL; \
- u64 v1 = 0x646f72616e646f6dULL; \
- u64 v2 = 0x6c7967656e657261ULL; \
- u64 v3 = 0x7465646279746573ULL; \
+ u64 v0 = SIPHASH_CONST_0; \
+ u64 v1 = SIPHASH_CONST_1; \
+ u64 v2 = SIPHASH_CONST_2; \
+ u64 v3 = SIPHASH_CONST_3; \
u64 b = ((u64)(len)) << 56; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \
@@ -389,19 +383,13 @@ u32 hsiphash_4u32(const u32 first, const
}
EXPORT_SYMBOL(hsiphash_4u32);
#else
-#define HSIPROUND \
- do { \
- v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \
- v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \
- v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \
- v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \
- } while (0)
+#define HSIPROUND HSIPHASH_PERMUTATION(v0, v1, v2, v3)
#define HPREAMBLE(len) \
- u32 v0 = 0; \
- u32 v1 = 0; \
- u32 v2 = 0x6c796765U; \
- u32 v3 = 0x74656462U; \
+ u32 v0 = HSIPHASH_CONST_0; \
+ u32 v1 = HSIPHASH_CONST_1; \
+ u32 v2 = HSIPHASH_CONST_2; \
+ u32 v3 = HSIPHASH_CONST_3; \
u32 b = ((u32)(len)) << 24; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 092/111] random: use symbolic constants for crng_init states
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (90 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 091/111] siphash: use one source of truth for siphash permutations Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 093/111] random: avoid initializing twice in credit race Greg Kroah-Hartman
` (24 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Joe Perches,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit e3d2c5e79a999aa4e7d6f0127e16d3da5a4ff70d upstream.
crng_init represents a state machine, with three states, and various
rules for transitions. For the longest time, we've been managing these
with "0", "1", and "2", and expecting people to figure it out. To make
the code more obvious, replace these with proper enum values
representing the transition, and then redocument what each of these
states mean.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 38 +++++++++++++++++++-------------------
1 file changed, 19 insertions(+), 19 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -70,16 +70,16 @@
*********************************************************************/
/*
- * crng_init = 0 --> Uninitialized
- * 1 --> Initialized
- * 2 --> Initialized from input_pool
- *
* crng_init is protected by base_crng->lock, and only increases
- * its value (from 0->1->2).
+ * its value (from empty->early->ready).
*/
-static int crng_init = 0;
-#define crng_ready() (likely(crng_init > 1))
-/* Various types of waiters for crng_init->2 transition. */
+static enum {
+ CRNG_EMPTY = 0, /* Little to no entropy collected */
+ CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */
+ CRNG_READY = 2 /* Fully initialized with POOL_READY_BITS collected */
+} crng_init = CRNG_EMPTY;
+#define crng_ready() (likely(crng_init >= CRNG_READY))
+/* Various types of waiters for crng_init->CRNG_READY transition. */
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
static struct fasync_struct *fasync;
static DEFINE_SPINLOCK(random_ready_chain_lock);
@@ -282,7 +282,7 @@ static void crng_reseed(void)
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
if (!crng_ready()) {
- crng_init = 2;
+ crng_init = CRNG_READY;
finalize_init = true;
}
spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -376,7 +376,7 @@ static void crng_make_state(u32 chacha_s
* For the fast path, we check whether we're ready, unlocked first, and
* then re-check once locked later. In the case where we're really not
* ready, we do fast key erasure with the base_crng directly, extracting
- * when crng_init==0.
+ * when crng_init is CRNG_EMPTY.
*/
if (!crng_ready()) {
bool ready;
@@ -384,7 +384,7 @@ static void crng_make_state(u32 chacha_s
spin_lock_irqsave(&base_crng.lock, flags);
ready = crng_ready();
if (!ready) {
- if (crng_init == 0)
+ if (crng_init == CRNG_EMPTY)
extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_fast_key_erasure(base_crng.key, chacha_state,
random_data, random_data_len);
@@ -738,8 +738,8 @@ EXPORT_SYMBOL(get_random_bytes_arch);
enum {
POOL_BITS = BLAKE2S_HASH_SIZE * 8,
- POOL_INIT_BITS = POOL_BITS, /* No point in settling for less. */
- POOL_FAST_INIT_BITS = POOL_INIT_BITS / 2
+ POOL_READY_BITS = POOL_BITS, /* When crng_init->CRNG_READY */
+ POOL_EARLY_BITS = POOL_READY_BITS / 2 /* When crng_init->CRNG_EARLY */
};
static struct {
@@ -834,13 +834,13 @@ static void credit_init_bits(size_t nbit
init_bits = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, init_bits) != orig);
- if (!crng_ready() && init_bits >= POOL_INIT_BITS)
+ if (!crng_ready() && init_bits >= POOL_READY_BITS)
crng_reseed();
- else if (unlikely(crng_init == 0 && init_bits >= POOL_FAST_INIT_BITS)) {
+ else if (unlikely(crng_init == CRNG_EMPTY && init_bits >= POOL_EARLY_BITS)) {
spin_lock_irqsave(&base_crng.lock, flags);
- if (crng_init == 0) {
+ if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
- crng_init = 1;
+ crng_init = CRNG_EARLY;
}
spin_unlock_irqrestore(&base_crng.lock, flags);
}
@@ -1515,7 +1515,7 @@ const struct file_operations urandom_fop
*
* - write_wakeup_threshold - the amount of entropy in the input pool
* below which write polls to /dev/random will unblock, requesting
- * more entropy, tied to the POOL_INIT_BITS constant. It is writable
+ * more entropy, tied to the POOL_READY_BITS constant. It is writable
* to avoid breaking old userspaces, but writing to it does not
* change any behavior of the RNG.
*
@@ -1530,7 +1530,7 @@ const struct file_operations urandom_fop
#include <linux/sysctl.h>
static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ;
-static int sysctl_random_write_wakeup_bits = POOL_INIT_BITS;
+static int sysctl_random_write_wakeup_bits = POOL_READY_BITS;
static int sysctl_poolsize = POOL_BITS;
static u8 sysctl_bootid[UUID_SIZE];
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 093/111] random: avoid initializing twice in credit race
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (91 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 092/111] random: use symbolic constants for crng_init states Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 094/111] random: move initialization out of reseeding hot path Greg Kroah-Hartman
` (23 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit fed7ef061686cc813b1f3d8d0edc6c35b4d3537b upstream.
Since all changes of crng_init now go through credit_init_bits(), we can
fix a long standing race in which two concurrent callers of
credit_init_bits() have the new bit count >= some threshold, but are
doing so with crng_init as a lower threshold, checked outside of a lock,
resulting in crng_reseed() or similar being called twice.
In order to fix this, we can use the original cmpxchg value of the bit
count, and only change crng_init when the bit count transitions from
below a threshold to meeting the threshold.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -821,7 +821,7 @@ static void extract_entropy(void *buf, s
static void credit_init_bits(size_t nbits)
{
- unsigned int init_bits, orig, add;
+ unsigned int new, orig, add;
unsigned long flags;
if (crng_ready() || !nbits)
@@ -831,12 +831,12 @@ static void credit_init_bits(size_t nbit
do {
orig = READ_ONCE(input_pool.init_bits);
- init_bits = min_t(unsigned int, POOL_BITS, orig + add);
- } while (cmpxchg(&input_pool.init_bits, orig, init_bits) != orig);
+ new = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
- if (!crng_ready() && init_bits >= POOL_READY_BITS)
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS)
crng_reseed();
- else if (unlikely(crng_init == CRNG_EMPTY && init_bits >= POOL_EARLY_BITS)) {
+ else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 094/111] random: move initialization out of reseeding hot path
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (92 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 093/111] random: avoid initializing twice in credit race Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 095/111] random: remove ratelimiting for in-kernel unseeded randomness Greg Kroah-Hartman
` (22 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 68c9c8b192c6dae9be6278e98ee44029d5da2d31 upstream.
Initialization happens once -- by way of credit_init_bits() -- and then
it never happens again. Therefore, it doesn't need to be in
crng_reseed(), which is a hot path that is called multiple times. It
also doesn't make sense to have there, as initialization activity is
better associated with initialization routines.
After the prior commit, crng_reseed() now won't be called by multiple
concurrent callers, which means that we can safely move the
"finialize_init" logic into crng_init_bits() unconditionally.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 42 +++++++++++++++++++-----------------------
1 file changed, 19 insertions(+), 23 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -264,7 +264,6 @@ static void crng_reseed(void)
unsigned long flags;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
- bool finalize_init = false;
extract_entropy(key, sizeof(key));
@@ -281,28 +280,10 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (!crng_ready()) {
+ if (!crng_ready())
crng_init = CRNG_READY;
- finalize_init = true;
- }
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
- if (finalize_init) {
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
- }
}
/*
@@ -834,10 +815,25 @@ static void credit_init_bits(size_t nbit
new = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
- if (orig < POOL_READY_BITS && new >= POOL_READY_BITS)
- crng_reseed();
- else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+ crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ process_random_ready_list();
+ wake_up_interruptible(&crng_init_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ pr_notice("crng init done\n");
+ if (unseeded_warning.missed) {
+ pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
+ unseeded_warning.missed);
+ unseeded_warning.missed = 0;
+ }
+ if (urandom_warning.missed) {
+ pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+ urandom_warning.missed);
+ urandom_warning.missed = 0;
+ }
+ } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
+ /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_init = CRNG_EARLY;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 095/111] random: remove ratelimiting for in-kernel unseeded randomness
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (93 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 094/111] random: move initialization out of reseeding hot path Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 096/111] random: use proper jiffies comparison macro Greg Kroah-Hartman
` (21 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Dominik Brodowski,
Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit cc1e127bfa95b5fb2f9307e7168bf8b2b45b4c5e upstream.
The CONFIG_WARN_ALL_UNSEEDED_RANDOM debug option controls whether the
kernel warns about all unseeded randomness or just the first instance.
There's some complicated rate limiting and comparison to the previous
caller, such that even with CONFIG_WARN_ALL_UNSEEDED_RANDOM enabled,
developers still don't see all the messages or even an accurate count of
how many were missed. This is the result of basically parallel
mechanisms aimed at accomplishing more or less the same thing, added at
different points in random.c history, which sort of compete with the
first-instance-only limiting we have now.
It turns out, however, that nobody cares about the first unseeded
randomness instance of in-kernel users. The same first user has been
there for ages now, and nobody is doing anything about it. It isn't even
clear that anybody _can_ do anything about it. Most places that can do
something about it have switched over to using get_random_bytes_wait()
or wait_for_random_bytes(), which is the right thing to do, but there is
still much code that needs randomness sometimes during init, and as a
geeneral rule, if you're not using one of the _wait functions or the
readiness notifier callback, you're bound to be doing it wrong just
based on that fact alone.
So warning about this same first user that can't easily change is simply
not an effective mechanism for anything at all. Users can't do anything
about it, as the Kconfig text points out -- the problem isn't in
userspace code -- and kernel developers don't or more often can't react
to it.
Instead, show the warning for all instances when CONFIG_WARN_ALL_UNSEEDED_RANDOM
is set, so that developers can debug things need be, or if it isn't set,
don't show a warning at all.
At the same time, CONFIG_WARN_ALL_UNSEEDED_RANDOM now implies setting
random.ratelimit_disable=1 on by default, since if you care about one
you probably care about the other too. And we can clean up usage around
the related urandom_warning ratelimiter as well (whose behavior isn't
changing), so that it properly counts missed messages after the 10
message threshold is reached.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 61 ++++++++++++++------------------------------------
lib/Kconfig.debug | 3 --
2 files changed, 19 insertions(+), 45 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -86,11 +86,10 @@ static DEFINE_SPINLOCK(random_ready_chai
static RAW_NOTIFIER_HEAD(random_ready_chain);
/* Control how we warn userspace. */
-static struct ratelimit_state unseeded_warning =
- RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
static struct ratelimit_state urandom_warning =
RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
-static int ratelimit_disable __read_mostly;
+static int ratelimit_disable __read_mostly =
+ IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM);
module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
@@ -181,27 +180,15 @@ static void process_random_ready_list(vo
spin_unlock_irqrestore(&random_ready_chain_lock, flags);
}
-#define warn_unseeded_randomness(previous) \
- _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
+#define warn_unseeded_randomness() \
+ _warn_unseeded_randomness(__func__, (void *)_RET_IP_)
-static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
+static void _warn_unseeded_randomness(const char *func_name, void *caller)
{
-#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- const bool print_once = false;
-#else
- static bool print_once __read_mostly;
-#endif
-
- if (print_once || crng_ready() ||
- (previous && (caller == READ_ONCE(*previous))))
+ if (!IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) || crng_ready())
return;
- WRITE_ONCE(*previous, caller);
-#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- print_once = true;
-#endif
- if (__ratelimit(&unseeded_warning))
- printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
- func_name, caller, crng_init);
+ printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
+ func_name, caller, crng_init);
}
@@ -454,9 +441,7 @@ static void _get_random_bytes(void *buf,
*/
void get_random_bytes(void *buf, size_t nbytes)
{
- static void *previous;
-
- warn_unseeded_randomness(&previous);
+ warn_unseeded_randomness();
_get_random_bytes(buf, nbytes);
}
EXPORT_SYMBOL(get_random_bytes);
@@ -552,10 +537,9 @@ u64 get_random_u64(void)
u64 ret;
unsigned long flags;
struct batched_entropy *batch;
- static void *previous;
unsigned long next_gen;
- warn_unseeded_randomness(&previous);
+ warn_unseeded_randomness();
if (!crng_ready()) {
_get_random_bytes(&ret, sizeof(ret));
@@ -591,10 +575,9 @@ u32 get_random_u32(void)
u32 ret;
unsigned long flags;
struct batched_entropy *batch;
- static void *previous;
unsigned long next_gen;
- warn_unseeded_randomness(&previous);
+ warn_unseeded_randomness();
if (!crng_ready()) {
_get_random_bytes(&ret, sizeof(ret));
@@ -821,16 +804,9 @@ static void credit_init_bits(size_t nbit
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
+ if (urandom_warning.missed)
pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
urandom_warning.missed);
- urandom_warning.missed = 0;
- }
} else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
/* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
@@ -943,10 +919,6 @@ int __init rand_initialize(void)
else if (arch_init && trust_cpu)
credit_init_bits(BLAKE2S_BLOCK_SIZE * 8);
- if (ratelimit_disable) {
- urandom_warning.interval = 0;
- unseeded_warning.interval = 0;
- }
return 0;
}
@@ -1392,11 +1364,14 @@ static ssize_t urandom_read(struct file
{
static int maxwarn = 10;
- if (!crng_ready() && maxwarn > 0) {
- maxwarn--;
- if (__ratelimit(&urandom_warning))
+ if (!crng_ready()) {
+ if (!ratelimit_disable && maxwarn <= 0)
+ ++urandom_warning.missed;
+ else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
+ --maxwarn;
pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
current->comm, nbytes);
+ }
}
return get_random_bytes_user(buf, nbytes);
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1566,8 +1566,7 @@ config WARN_ALL_UNSEEDED_RANDOM
so architecture maintainers really need to do what they can
to get the CRNG seeded sooner after the system is booted.
However, since users cannot do anything actionable to
- address this, by default the kernel will issue only a single
- warning for the first use of unseeded randomness.
+ address this, by default this option is disabled.
Say Y here if you want to receive warnings for all uses of
unseeded randomness. This will be of use primarily for
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 096/111] random: use proper jiffies comparison macro
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (94 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 095/111] random: remove ratelimiting for in-kernel unseeded randomness Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 097/111] random: handle latent entropy and command line from random_init() Greg Kroah-Hartman
` (20 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 8a5b8a4a4ceb353b4dd5bafd09e2b15751bcdb51 upstream.
This expands to exactly the same code that it replaces, but makes things
consistent by using the same macro for jiffy comparisons throughout.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -324,7 +324,7 @@ static bool crng_has_old_seed(void)
interval = max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
(unsigned int)uptime / 2 * HZ);
}
- return time_after(jiffies, READ_ONCE(base_crng.birth) + interval);
+ return time_is_before_jiffies(READ_ONCE(base_crng.birth) + interval);
}
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 097/111] random: handle latent entropy and command line from random_init()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (95 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 096/111] random: use proper jiffies comparison macro Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 098/111] random: credit architectural init the exact amount Greg Kroah-Hartman
` (19 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 2f14062bb14b0fcfcc21e6dc7d5b5c0d25966164 upstream.
Currently, start_kernel() adds latent entropy and the command line to
the entropy bool *after* the RNG has been initialized, deferring when
it's actually used by things like stack canaries until the next time
the pool is seeded. This surely is not intended.
Rather than splitting up which entropy gets added where and when between
start_kernel() and random_init(), just do everything in random_init(),
which should eliminate these kinds of bugs in the future.
While we're at it, rename the awkwardly titled "rand_initialize()" to
the more standard "random_init()" nomenclature.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 17 ++++++++++-------
include/linux/random.h | 16 +++++++---------
init/main.c | 10 +++-------
3 files changed, 20 insertions(+), 23 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -886,12 +886,13 @@ early_param("random.trust_bootloader", p
/*
* The first collection of entropy occurs at system boot while interrupts
- * are still turned off. Here we push in RDSEED, a timestamp, and utsname().
- * Depending on the above configuration knob, RDSEED may be considered
- * sufficient for initialization. Note that much earlier setup may already
- * have pushed entropy into the input pool by the time we get here.
+ * are still turned off. Here we push in latent entropy, RDSEED, a timestamp,
+ * utsname(), and the command line. Depending on the above configuration knob,
+ * RDSEED may be considered sufficient for initialization. Note that much
+ * earlier setup may already have pushed entropy into the input pool by the
+ * time we get here.
*/
-int __init rand_initialize(void)
+int __init random_init(const char *command_line)
{
size_t i;
ktime_t now = ktime_get_real();
@@ -913,6 +914,8 @@ int __init rand_initialize(void)
}
_mix_pool_bytes(&now, sizeof(now));
_mix_pool_bytes(utsname(), sizeof(*(utsname())));
+ _mix_pool_bytes(command_line, strlen(command_line));
+ add_latent_entropy();
if (crng_ready())
crng_reseed();
@@ -1591,8 +1594,8 @@ static struct ctl_table random_table[] =
};
/*
- * rand_initialize() is called before sysctl_init(),
- * so we cannot call register_sysctl_init() in rand_initialize()
+ * random_init() is called before sysctl_init(),
+ * so we cannot call register_sysctl_init() in random_init()
*/
static int __init random_sysctls_init(void)
{
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -14,26 +14,24 @@ struct notifier_block;
extern void add_device_randomness(const void *, size_t);
extern void add_bootloader_randomness(const void *, size_t);
+extern void add_input_randomness(unsigned int type, unsigned int code,
+ unsigned int value) __latent_entropy;
+extern void add_interrupt_randomness(int irq) __latent_entropy;
+extern void add_hwgenerator_randomness(const void *buffer, size_t count,
+ size_t entropy);
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
static inline void add_latent_entropy(void)
{
- add_device_randomness((const void *)&latent_entropy,
- sizeof(latent_entropy));
+ add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy));
}
#else
static inline void add_latent_entropy(void) {}
#endif
-extern void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value) __latent_entropy;
-extern void add_interrupt_randomness(int irq) __latent_entropy;
-extern void add_hwgenerator_randomness(const void *buffer, size_t count,
- size_t entropy);
-
extern void get_random_bytes(void *buf, size_t nbytes);
extern int wait_for_random_bytes(void);
-extern int __init rand_initialize(void);
+extern int __init random_init(const char *command_line);
extern bool rng_is_initialized(void);
extern int register_random_ready_notifier(struct notifier_block *nb);
extern int unregister_random_ready_notifier(struct notifier_block *nb);
--- a/init/main.c
+++ b/init/main.c
@@ -1040,15 +1040,11 @@ asmlinkage __visible void __init __no_sa
/*
* For best initial stack canary entropy, prepare it after:
* - setup_arch() for any UEFI RNG entropy and boot cmdline access
- * - timekeeping_init() for ktime entropy used in rand_initialize()
+ * - timekeeping_init() for ktime entropy used in random_init()
* - time_init() for making random_get_entropy() work on some platforms
- * - rand_initialize() to get any arch-specific entropy like RDRAND
- * - add_latent_entropy() to get any latent entropy
- * - adding command line entropy
+ * - random_init() to initialize the RNG from from early entropy sources
*/
- rand_initialize();
- add_latent_entropy();
- add_device_randomness(command_line, strlen(command_line));
+ random_init(command_line);
boot_init_stack_canary();
perf_event_init();
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 098/111] random: credit architectural init the exact amount
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (96 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 097/111] random: handle latent entropy and command line from random_init() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 099/111] random: use static branch for crng_ready() Greg Kroah-Hartman
` (18 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 12e45a2a6308105469968951e6d563e8f4fea187 upstream.
RDRAND and RDSEED can fail sometimes, which is fine. We currently
initialize the RNG with 512 bits of RDRAND/RDSEED. We only need 256 bits
of those to succeed in order to initialize the RNG. Instead of the
current "all or nothing" approach, actually credit these contributions
the amount that is actually contributed.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -894,9 +894,8 @@ early_param("random.trust_bootloader", p
*/
int __init random_init(const char *command_line)
{
- size_t i;
ktime_t now = ktime_get_real();
- bool arch_init = true;
+ unsigned int i, arch_bytes;
unsigned long rv;
#if defined(LATENT_ENTROPY_PLUGIN)
@@ -904,11 +903,12 @@ int __init random_init(const char *comma
_mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
#endif
- for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
+ for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
+ i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
if (!arch_get_random_seed_long_early(&rv) &&
!arch_get_random_long_early(&rv)) {
rv = random_get_entropy();
- arch_init = false;
+ arch_bytes -= sizeof(rv);
}
_mix_pool_bytes(&rv, sizeof(rv));
}
@@ -919,8 +919,8 @@ int __init random_init(const char *comma
if (crng_ready())
crng_reseed();
- else if (arch_init && trust_cpu)
- credit_init_bits(BLAKE2S_BLOCK_SIZE * 8);
+ else if (trust_cpu)
+ credit_init_bits(arch_bytes * 8);
return 0;
}
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 099/111] random: use static branch for crng_ready()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (97 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 098/111] random: credit architectural init the exact amount Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 100/111] random: remove extern from functions in header Greg Kroah-Hartman
` (17 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Theodore Tso, Sultan Alsawaf,
Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit f5bda35fba615ace70a656d4700423fa6c9bebee upstream.
Since crng_ready() is only false briefly during initialization and then
forever after becomes true, we don't need to evaluate it after, making
it a prime candidate for a static branch.
One complication, however, is that it changes state in a particular call
to credit_init_bits(), which might be made from atomic context, which
means we must kick off a workqueue to change the static key. Further
complicating things, credit_init_bits() may be called sufficiently early
on in system initialization such that system_wq is NULL.
Fortunately, there exists the nice function execute_in_process_context(),
which will immediately execute the function if !in_interrupt(), and
otherwise defer it to a workqueue. During early init, before workqueues
are available, in_interrupt() is always false, because interrupts
haven't even been enabled yet, which means the function in that case
executes immediately. Later on, after workqueues are available,
in_interrupt() might be true, but in that case, the work is queued in
system_wq and all goes well.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -77,8 +77,9 @@ static enum {
CRNG_EMPTY = 0, /* Little to no entropy collected */
CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */
CRNG_READY = 2 /* Fully initialized with POOL_READY_BITS collected */
-} crng_init = CRNG_EMPTY;
-#define crng_ready() (likely(crng_init >= CRNG_READY))
+} crng_init __read_mostly = CRNG_EMPTY;
+static DEFINE_STATIC_KEY_FALSE(crng_is_ready);
+#define crng_ready() (static_branch_likely(&crng_is_ready) || crng_init >= CRNG_READY)
/* Various types of waiters for crng_init->CRNG_READY transition. */
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
static struct fasync_struct *fasync;
@@ -108,6 +109,11 @@ bool rng_is_initialized(void)
}
EXPORT_SYMBOL(rng_is_initialized);
+static void crng_set_ready(struct work_struct *work)
+{
+ static_branch_enable(&crng_is_ready);
+}
+
/* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
static void try_to_generate_entropy(void);
@@ -267,7 +273,7 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (!crng_ready())
+ if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
@@ -785,6 +791,7 @@ static void extract_entropy(void *buf, s
static void credit_init_bits(size_t nbits)
{
+ static struct execute_work set_ready;
unsigned int new, orig, add;
unsigned long flags;
@@ -800,6 +807,7 @@ static void credit_init_bits(size_t nbit
if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ execute_in_process_context(crng_set_ready, &set_ready);
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
@@ -1309,7 +1317,7 @@ SYSCALL_DEFINE3(getrandom, char __user *
if (count > INT_MAX)
count = INT_MAX;
- if (!(flags & GRND_INSECURE) && !crng_ready()) {
+ if (!crng_ready() && !(flags & GRND_INSECURE)) {
int ret;
if (flags & GRND_NONBLOCK)
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 100/111] random: remove extern from functions in header
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (98 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 099/111] random: use static branch for crng_ready() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 101/111] random: use proper return types on get_random_{int,long}_wait() Greg Kroah-Hartman
` (16 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 7782cfeca7d420e8bb707613d4cfb0f7ff29bb3a upstream.
Accoriding to the kernel style guide, having `extern` on functions in
headers is old school and deprecated, and doesn't add anything. So remove
them from random.h, and tidy up the file a little bit too.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/random.h | 71 +++++++++++++++++++------------------------------
1 file changed, 28 insertions(+), 43 deletions(-)
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -12,13 +12,12 @@
struct notifier_block;
-extern void add_device_randomness(const void *, size_t);
-extern void add_bootloader_randomness(const void *, size_t);
-extern void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value) __latent_entropy;
-extern void add_interrupt_randomness(int irq) __latent_entropy;
-extern void add_hwgenerator_randomness(const void *buffer, size_t count,
- size_t entropy);
+void add_device_randomness(const void *, size_t);
+void add_bootloader_randomness(const void *, size_t);
+void add_input_randomness(unsigned int type, unsigned int code,
+ unsigned int value) __latent_entropy;
+void add_interrupt_randomness(int irq) __latent_entropy;
+void add_hwgenerator_randomness(const void *buffer, size_t count, size_t entropy);
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
static inline void add_latent_entropy(void)
@@ -26,21 +25,11 @@ static inline void add_latent_entropy(vo
add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy));
}
#else
-static inline void add_latent_entropy(void) {}
-#endif
-
-extern void get_random_bytes(void *buf, size_t nbytes);
-extern int wait_for_random_bytes(void);
-extern int __init random_init(const char *command_line);
-extern bool rng_is_initialized(void);
-extern int register_random_ready_notifier(struct notifier_block *nb);
-extern int unregister_random_ready_notifier(struct notifier_block *nb);
-extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
-
-#ifndef MODULE
-extern const struct file_operations random_fops, urandom_fops;
+static inline void add_latent_entropy(void) { }
#endif
+void get_random_bytes(void *buf, size_t nbytes);
+size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
u32 get_random_u32(void);
u64 get_random_u64(void);
static inline unsigned int get_random_int(void)
@@ -72,11 +61,17 @@ static inline unsigned long get_random_l
static inline unsigned long get_random_canary(void)
{
- unsigned long val = get_random_long();
-
- return val & CANARY_MASK;
+ return get_random_long() & CANARY_MASK;
}
+unsigned long randomize_page(unsigned long start, unsigned long range);
+
+int __init random_init(const char *command_line);
+bool rng_is_initialized(void);
+int wait_for_random_bytes(void);
+int register_random_ready_notifier(struct notifier_block *nb);
+int unregister_random_ready_notifier(struct notifier_block *nb);
+
/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
* Returns the result of the call to wait_for_random_bytes. */
static inline int get_random_bytes_wait(void *buf, size_t nbytes)
@@ -100,8 +95,6 @@ declare_get_random_var_wait(int)
declare_get_random_var_wait(long)
#undef declare_get_random_var
-unsigned long randomize_page(unsigned long start, unsigned long range);
-
/*
* This is designed to be standalone for just prandom
* users, but for now we include it from <linux/random.h>
@@ -112,22 +105,10 @@ unsigned long randomize_page(unsigned lo
#ifdef CONFIG_ARCH_RANDOM
# include <asm/archrandom.h>
#else
-static inline bool __must_check arch_get_random_long(unsigned long *v)
-{
- return false;
-}
-static inline bool __must_check arch_get_random_int(unsigned int *v)
-{
- return false;
-}
-static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
-{
- return false;
-}
-static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
-{
- return false;
-}
+static inline bool __must_check arch_get_random_long(unsigned long *v) { return false; }
+static inline bool __must_check arch_get_random_int(unsigned int *v) { return false; }
+static inline bool __must_check arch_get_random_seed_long(unsigned long *v) { return false; }
+static inline bool __must_check arch_get_random_seed_int(unsigned int *v) { return false; }
#endif
/*
@@ -151,8 +132,12 @@ static inline bool __init arch_get_rando
#endif
#ifdef CONFIG_SMP
-extern int random_prepare_cpu(unsigned int cpu);
-extern int random_online_cpu(unsigned int cpu);
+int random_prepare_cpu(unsigned int cpu);
+int random_online_cpu(unsigned int cpu);
+#endif
+
+#ifndef MODULE
+extern const struct file_operations random_fops, urandom_fops;
#endif
#endif /* _LINUX_RANDOM_H */
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 101/111] random: use proper return types on get_random_{int,long}_wait()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (99 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 100/111] random: remove extern from functions in header Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 102/111] random: make consistent use of buf and len Greg Kroah-Hartman
` (15 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 7c3a8a1db5e03d02cc0abb3357a84b8b326dfac3 upstream.
Before these were returning signed values, but the API is intended to be
used with unsigned values.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/random.h | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -81,18 +81,18 @@ static inline int get_random_bytes_wait(
return ret;
}
-#define declare_get_random_var_wait(var) \
- static inline int get_random_ ## var ## _wait(var *out) { \
+#define declare_get_random_var_wait(name, ret_type) \
+ static inline int get_random_ ## name ## _wait(ret_type *out) { \
int ret = wait_for_random_bytes(); \
if (unlikely(ret)) \
return ret; \
- *out = get_random_ ## var(); \
+ *out = get_random_ ## name(); \
return 0; \
}
-declare_get_random_var_wait(u32)
-declare_get_random_var_wait(u64)
-declare_get_random_var_wait(int)
-declare_get_random_var_wait(long)
+declare_get_random_var_wait(u32, u32)
+declare_get_random_var_wait(u64, u32)
+declare_get_random_var_wait(int, unsigned int)
+declare_get_random_var_wait(long, unsigned long)
#undef declare_get_random_var
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 102/111] random: make consistent use of buf and len
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (100 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 101/111] random: use proper return types on get_random_{int,long}_wait() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 103/111] random: move initialization functions out of hot pages Greg Kroah-Hartman
` (14 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit a19402634c435a4eae226df53c141cdbb9922e7b upstream.
The current code was a mix of "nbytes", "count", "size", "buffer", "in",
and so forth. Instead, let's clean this up by naming input parameters
"buf" (or "ubuf") and "len", so that you always understand that you're
reading this variety of function argument.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 193 +++++++++++++++++++++++--------------------------
include/linux/random.h | 10 +-
2 files changed, 99 insertions(+), 104 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -208,7 +208,7 @@ static void _warn_unseeded_randomness(co
*
* There are a few exported interfaces for use by other drivers:
*
- * void get_random_bytes(void *buf, size_t nbytes)
+ * void get_random_bytes(void *buf, size_t len)
* u32 get_random_u32()
* u64 get_random_u64()
* unsigned int get_random_int()
@@ -249,7 +249,7 @@ static DEFINE_PER_CPU(struct crng, crngs
};
/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
-static void extract_entropy(void *buf, size_t nbytes);
+static void extract_entropy(void *buf, size_t len);
/* This extracts a new crng key from the input pool. */
static void crng_reseed(void)
@@ -403,24 +403,24 @@ static void crng_make_state(u32 chacha_s
local_unlock_irqrestore(&crngs.lock, flags);
}
-static void _get_random_bytes(void *buf, size_t nbytes)
+static void _get_random_bytes(void *buf, size_t len)
{
u32 chacha_state[CHACHA_STATE_WORDS];
u8 tmp[CHACHA_BLOCK_SIZE];
- size_t len;
+ size_t first_block_len;
- if (!nbytes)
+ if (!len)
return;
- len = min_t(size_t, 32, nbytes);
- crng_make_state(chacha_state, buf, len);
- nbytes -= len;
- buf += len;
+ first_block_len = min_t(size_t, 32, len);
+ crng_make_state(chacha_state, buf, first_block_len);
+ len -= first_block_len;
+ buf += first_block_len;
- while (nbytes) {
- if (nbytes < CHACHA_BLOCK_SIZE) {
+ while (len) {
+ if (len < CHACHA_BLOCK_SIZE) {
chacha20_block(chacha_state, tmp);
- memcpy(buf, tmp, nbytes);
+ memcpy(buf, tmp, len);
memzero_explicit(tmp, sizeof(tmp));
break;
}
@@ -428,7 +428,7 @@ static void _get_random_bytes(void *buf,
chacha20_block(chacha_state, buf);
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
- nbytes -= CHACHA_BLOCK_SIZE;
+ len -= CHACHA_BLOCK_SIZE;
buf += CHACHA_BLOCK_SIZE;
}
@@ -445,20 +445,20 @@ static void _get_random_bytes(void *buf,
* wait_for_random_bytes() should be called and return 0 at least once
* at any point prior.
*/
-void get_random_bytes(void *buf, size_t nbytes)
+void get_random_bytes(void *buf, size_t len)
{
warn_unseeded_randomness();
- _get_random_bytes(buf, nbytes);
+ _get_random_bytes(buf, len);
}
EXPORT_SYMBOL(get_random_bytes);
-static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
+static ssize_t get_random_bytes_user(void __user *ubuf, size_t len)
{
- size_t len, left, ret = 0;
+ size_t block_len, left, ret = 0;
u32 chacha_state[CHACHA_STATE_WORDS];
u8 output[CHACHA_BLOCK_SIZE];
- if (!nbytes)
+ if (!len)
return 0;
/*
@@ -472,8 +472,8 @@ static ssize_t get_random_bytes_user(voi
* use chacha_state after, so we can simply return those bytes to
* the user directly.
*/
- if (nbytes <= CHACHA_KEY_SIZE) {
- ret = nbytes - copy_to_user(buf, &chacha_state[4], nbytes);
+ if (len <= CHACHA_KEY_SIZE) {
+ ret = len - copy_to_user(ubuf, &chacha_state[4], len);
goto out_zero_chacha;
}
@@ -482,17 +482,17 @@ static ssize_t get_random_bytes_user(voi
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
- len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE);
- left = copy_to_user(buf, output, len);
+ block_len = min_t(size_t, len, CHACHA_BLOCK_SIZE);
+ left = copy_to_user(ubuf, output, block_len);
if (left) {
- ret += len - left;
+ ret += block_len - left;
break;
}
- buf += len;
- ret += len;
- nbytes -= len;
- if (!nbytes)
+ ubuf += block_len;
+ ret += block_len;
+ len -= block_len;
+ if (!len)
break;
BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0);
@@ -666,24 +666,24 @@ unsigned long randomize_page(unsigned lo
* use. Use get_random_bytes() instead. It returns the number of
* bytes filled in.
*/
-size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes)
+size_t __must_check get_random_bytes_arch(void *buf, size_t len)
{
- size_t left = nbytes;
+ size_t left = len;
u8 *p = buf;
while (left) {
unsigned long v;
- size_t chunk = min_t(size_t, left, sizeof(unsigned long));
+ size_t block_len = min_t(size_t, left, sizeof(unsigned long));
if (!arch_get_random_long(&v))
break;
- memcpy(p, &v, chunk);
- p += chunk;
- left -= chunk;
+ memcpy(p, &v, block_len);
+ p += block_len;
+ left -= block_len;
}
- return nbytes - left;
+ return len - left;
}
EXPORT_SYMBOL(get_random_bytes_arch);
@@ -694,15 +694,15 @@ EXPORT_SYMBOL(get_random_bytes_arch);
*
* Callers may add entropy via:
*
- * static void mix_pool_bytes(const void *in, size_t nbytes)
+ * static void mix_pool_bytes(const void *buf, size_t len)
*
* After which, if added entropy should be credited:
*
- * static void credit_init_bits(size_t nbits)
+ * static void credit_init_bits(size_t bits)
*
* Finally, extract entropy via:
*
- * static void extract_entropy(void *buf, size_t nbytes)
+ * static void extract_entropy(void *buf, size_t len)
*
**********************************************************************/
@@ -724,9 +724,9 @@ static struct {
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
};
-static void _mix_pool_bytes(const void *in, size_t nbytes)
+static void _mix_pool_bytes(const void *buf, size_t len)
{
- blake2s_update(&input_pool.hash, in, nbytes);
+ blake2s_update(&input_pool.hash, buf, len);
}
/*
@@ -734,12 +734,12 @@ static void _mix_pool_bytes(const void *
* update the initialization bit counter; the caller should call
* credit_init_bits if this is appropriate.
*/
-static void mix_pool_bytes(const void *in, size_t nbytes)
+static void mix_pool_bytes(const void *buf, size_t len)
{
unsigned long flags;
spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(in, nbytes);
+ _mix_pool_bytes(buf, len);
spin_unlock_irqrestore(&input_pool.lock, flags);
}
@@ -747,7 +747,7 @@ static void mix_pool_bytes(const void *i
* This is an HKDF-like construction for using the hashed collected entropy
* as a PRF key, that's then expanded block-by-block.
*/
-static void extract_entropy(void *buf, size_t nbytes)
+static void extract_entropy(void *buf, size_t len)
{
unsigned long flags;
u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
@@ -776,12 +776,12 @@ static void extract_entropy(void *buf, s
spin_unlock_irqrestore(&input_pool.lock, flags);
memzero_explicit(next_key, sizeof(next_key));
- while (nbytes) {
- i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
+ while (len) {
+ i = min_t(size_t, len, BLAKE2S_HASH_SIZE);
/* output = HASHPRF(seed, RDSEED || ++counter) */
++block.counter;
blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
- nbytes -= i;
+ len -= i;
buf += i;
}
@@ -789,16 +789,16 @@ static void extract_entropy(void *buf, s
memzero_explicit(&block, sizeof(block));
}
-static void credit_init_bits(size_t nbits)
+static void credit_init_bits(size_t bits)
{
static struct execute_work set_ready;
unsigned int new, orig, add;
unsigned long flags;
- if (crng_ready() || !nbits)
+ if (crng_ready() || !bits)
return;
- add = min_t(size_t, nbits, POOL_BITS);
+ add = min_t(size_t, bits, POOL_BITS);
do {
orig = READ_ONCE(input_pool.init_bits);
@@ -834,13 +834,11 @@ static void credit_init_bits(size_t nbit
* The following exported functions are used for pushing entropy into
* the above entropy accumulation routines:
*
- * void add_device_randomness(const void *buf, size_t size);
- * void add_hwgenerator_randomness(const void *buffer, size_t count,
- * size_t entropy);
- * void add_bootloader_randomness(const void *buf, size_t size);
+ * void add_device_randomness(const void *buf, size_t len);
+ * void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy);
+ * void add_bootloader_randomness(const void *buf, size_t len);
* void add_interrupt_randomness(int irq);
- * void add_input_randomness(unsigned int type, unsigned int code,
- * unsigned int value);
+ * void add_input_randomness(unsigned int type, unsigned int code, unsigned int value);
* void add_disk_randomness(struct gendisk *disk);
*
* add_device_randomness() adds data to the input pool that
@@ -904,7 +902,7 @@ int __init random_init(const char *comma
{
ktime_t now = ktime_get_real();
unsigned int i, arch_bytes;
- unsigned long rv;
+ unsigned long entropy;
#if defined(LATENT_ENTROPY_PLUGIN)
static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
@@ -912,13 +910,13 @@ int __init random_init(const char *comma
#endif
for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
- i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
- if (!arch_get_random_seed_long_early(&rv) &&
- !arch_get_random_long_early(&rv)) {
- rv = random_get_entropy();
- arch_bytes -= sizeof(rv);
+ i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
+ if (!arch_get_random_seed_long_early(&entropy) &&
+ !arch_get_random_long_early(&entropy)) {
+ entropy = random_get_entropy();
+ arch_bytes -= sizeof(entropy);
}
- _mix_pool_bytes(&rv, sizeof(rv));
+ _mix_pool_bytes(&entropy, sizeof(entropy));
}
_mix_pool_bytes(&now, sizeof(now));
_mix_pool_bytes(utsname(), sizeof(*(utsname())));
@@ -941,14 +939,14 @@ int __init random_init(const char *comma
* the entropy pool having similar initial state across largely
* identical devices.
*/
-void add_device_randomness(const void *buf, size_t size)
+void add_device_randomness(const void *buf, size_t len)
{
unsigned long entropy = random_get_entropy();
unsigned long flags;
spin_lock_irqsave(&input_pool.lock, flags);
_mix_pool_bytes(&entropy, sizeof(entropy));
- _mix_pool_bytes(buf, size);
+ _mix_pool_bytes(buf, len);
spin_unlock_irqrestore(&input_pool.lock, flags);
}
EXPORT_SYMBOL(add_device_randomness);
@@ -958,10 +956,9 @@ EXPORT_SYMBOL(add_device_randomness);
* Those devices may produce endless random bits and will be throttled
* when our pool is full.
*/
-void add_hwgenerator_randomness(const void *buffer, size_t count,
- size_t entropy)
+void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy)
{
- mix_pool_bytes(buffer, count);
+ mix_pool_bytes(buf, len);
credit_init_bits(entropy);
/*
@@ -977,11 +974,11 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_random
* Handle random seed passed by bootloader, and credit it if
* CONFIG_RANDOM_TRUST_BOOTLOADER is set.
*/
-void add_bootloader_randomness(const void *buf, size_t size)
+void add_bootloader_randomness(const void *buf, size_t len)
{
- mix_pool_bytes(buf, size);
+ mix_pool_bytes(buf, len);
if (trust_bootloader)
- credit_init_bits(size * 8);
+ credit_init_bits(len * 8);
}
EXPORT_SYMBOL_GPL(add_bootloader_randomness);
@@ -1181,8 +1178,7 @@ static void add_timer_randomness(struct
credit_init_bits(bits);
}
-void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value)
+void add_input_randomness(unsigned int type, unsigned int code, unsigned int value)
{
static unsigned char last_value;
static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
@@ -1301,8 +1297,7 @@ static void try_to_generate_entropy(void
*
**********************************************************************/
-SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
- flags)
+SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags)
{
if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
return -EINVAL;
@@ -1314,8 +1309,8 @@ SYSCALL_DEFINE3(getrandom, char __user *
if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
return -EINVAL;
- if (count > INT_MAX)
- count = INT_MAX;
+ if (len > INT_MAX)
+ len = INT_MAX;
if (!crng_ready() && !(flags & GRND_INSECURE)) {
int ret;
@@ -1326,7 +1321,7 @@ SYSCALL_DEFINE3(getrandom, char __user *
if (unlikely(ret))
return ret;
}
- return get_random_bytes_user(buf, count);
+ return get_random_bytes_user(ubuf, len);
}
static __poll_t random_poll(struct file *file, poll_table *wait)
@@ -1335,21 +1330,21 @@ static __poll_t random_poll(struct file
return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
}
-static int write_pool(const char __user *ubuf, size_t count)
+static int write_pool(const char __user *ubuf, size_t len)
{
- size_t len;
+ size_t block_len;
int ret = 0;
u8 block[BLAKE2S_BLOCK_SIZE];
- while (count) {
- len = min(count, sizeof(block));
- if (copy_from_user(block, ubuf, len)) {
+ while (len) {
+ block_len = min(len, sizeof(block));
+ if (copy_from_user(block, ubuf, block_len)) {
ret = -EFAULT;
goto out;
}
- count -= len;
- ubuf += len;
- mix_pool_bytes(block, len);
+ len -= block_len;
+ ubuf += block_len;
+ mix_pool_bytes(block, block_len);
cond_resched();
}
@@ -1358,20 +1353,20 @@ out:
return ret;
}
-static ssize_t random_write(struct file *file, const char __user *buffer,
- size_t count, loff_t *ppos)
+static ssize_t random_write(struct file *file, const char __user *ubuf,
+ size_t len, loff_t *ppos)
{
int ret;
- ret = write_pool(buffer, count);
+ ret = write_pool(ubuf, len);
if (ret)
return ret;
- return (ssize_t)count;
+ return (ssize_t)len;
}
-static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
+static ssize_t urandom_read(struct file *file, char __user *ubuf,
+ size_t len, loff_t *ppos)
{
static int maxwarn = 10;
@@ -1381,22 +1376,22 @@ static ssize_t urandom_read(struct file
else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
--maxwarn;
pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
- current->comm, nbytes);
+ current->comm, len);
}
}
- return get_random_bytes_user(buf, nbytes);
+ return get_random_bytes_user(ubuf, len);
}
-static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
+static ssize_t random_read(struct file *file, char __user *ubuf,
+ size_t len, loff_t *ppos)
{
int ret;
ret = wait_for_random_bytes();
if (ret != 0)
return ret;
- return get_random_bytes_user(buf, nbytes);
+ return get_random_bytes_user(ubuf, len);
}
static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
@@ -1521,7 +1516,7 @@ static u8 sysctl_bootid[UUID_SIZE];
* UUID. The difference is in whether table->data is NULL; if it is,
* then a new UUID is generated and returned to the user.
*/
-static int proc_do_uuid(struct ctl_table *table, int write, void *buffer,
+static int proc_do_uuid(struct ctl_table *table, int write, void *buf,
size_t *lenp, loff_t *ppos)
{
u8 tmp_uuid[UUID_SIZE], *uuid;
@@ -1548,14 +1543,14 @@ static int proc_do_uuid(struct ctl_table
}
snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid);
- return proc_dostring(&fake_table, 0, buffer, lenp, ppos);
+ return proc_dostring(&fake_table, 0, buf, lenp, ppos);
}
/* The same as proc_dointvec, but writes don't change anything. */
-static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer,
+static int proc_do_rointvec(struct ctl_table *table, int write, void *buf,
size_t *lenp, loff_t *ppos)
{
- return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos);
+ return write ? 0 : proc_dointvec(table, 0, buf, lenp, ppos);
}
static struct ctl_table random_table[] = {
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -12,12 +12,12 @@
struct notifier_block;
-void add_device_randomness(const void *, size_t);
-void add_bootloader_randomness(const void *, size_t);
+void add_device_randomness(const void *buf, size_t len);
+void add_bootloader_randomness(const void *buf, size_t len);
void add_input_randomness(unsigned int type, unsigned int code,
unsigned int value) __latent_entropy;
void add_interrupt_randomness(int irq) __latent_entropy;
-void add_hwgenerator_randomness(const void *buffer, size_t count, size_t entropy);
+void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy);
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
static inline void add_latent_entropy(void)
@@ -28,8 +28,8 @@ static inline void add_latent_entropy(vo
static inline void add_latent_entropy(void) { }
#endif
-void get_random_bytes(void *buf, size_t nbytes);
-size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
+void get_random_bytes(void *buf, size_t len);
+size_t __must_check get_random_bytes_arch(void *buf, size_t len);
u32 get_random_u32(void);
u64 get_random_u64(void);
static inline unsigned int get_random_int(void)
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 103/111] random: move initialization functions out of hot pages
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (101 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 102/111] random: make consistent use of buf and len Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 104/111] random: move randomize_page() into mm where it belongs Greg Kroah-Hartman
` (13 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 560181c27b582557d633ecb608110075433383af upstream.
Much of random.c is devoted to initializing the rng and accounting for
when a sufficient amount of entropy has been added. In a perfect world,
this would all happen during init, and so we could mark these functions
as __init. But in reality, this isn't the case: sometimes the rng only
finishes initializing some seconds after system init is finished.
For this reason, at the moment, a whole host of functions that are only
used relatively close to system init and then never again are intermixed
with functions that are used in hot code all the time. This creates more
cache misses than necessary.
In order to pack the hot code closer together, this commit moves the
initialization functions that can't be marked as __init into
.text.unlikely by way of the __cold attribute.
Of particular note is moving credit_init_bits() into a macro wrapper
that inlines the crng_ready() static branch check. This avoids a
function call to a nop+ret, and most notably prevents extra entropy
arithmetic from being computed in mix_interrupt_randomness().
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -109,7 +109,7 @@ bool rng_is_initialized(void)
}
EXPORT_SYMBOL(rng_is_initialized);
-static void crng_set_ready(struct work_struct *work)
+static void __cold crng_set_ready(struct work_struct *work)
{
static_branch_enable(&crng_is_ready);
}
@@ -148,7 +148,7 @@ EXPORT_SYMBOL(wait_for_random_bytes);
* returns: 0 if callback is successfully added
* -EALREADY if pool is already initialised (callback not called)
*/
-int register_random_ready_notifier(struct notifier_block *nb)
+int __cold register_random_ready_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret = -EALREADY;
@@ -166,7 +166,7 @@ int register_random_ready_notifier(struc
/*
* Delete a previously registered readiness callback function.
*/
-int unregister_random_ready_notifier(struct notifier_block *nb)
+int __cold unregister_random_ready_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
@@ -177,7 +177,7 @@ int unregister_random_ready_notifier(str
return ret;
}
-static void process_random_ready_list(void)
+static void __cold process_random_ready_list(void)
{
unsigned long flags;
@@ -187,15 +187,9 @@ static void process_random_ready_list(vo
}
#define warn_unseeded_randomness() \
- _warn_unseeded_randomness(__func__, (void *)_RET_IP_)
-
-static void _warn_unseeded_randomness(const char *func_name, void *caller)
-{
- if (!IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) || crng_ready())
- return;
- printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
- func_name, caller, crng_init);
-}
+ if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \
+ printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \
+ __func__, (void *)_RET_IP_, crng_init)
/*********************************************************************
@@ -614,7 +608,7 @@ EXPORT_SYMBOL(get_random_u32);
* This function is called when the CPU is coming up, with entry
* CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP.
*/
-int random_prepare_cpu(unsigned int cpu)
+int __cold random_prepare_cpu(unsigned int cpu)
{
/*
* When the cpu comes back online, immediately invalidate both
@@ -789,13 +783,15 @@ static void extract_entropy(void *buf, s
memzero_explicit(&block, sizeof(block));
}
-static void credit_init_bits(size_t bits)
+#define credit_init_bits(bits) if (!crng_ready()) _credit_init_bits(bits)
+
+static void __cold _credit_init_bits(size_t bits)
{
static struct execute_work set_ready;
unsigned int new, orig, add;
unsigned long flags;
- if (crng_ready() || !bits)
+ if (!bits)
return;
add = min_t(size_t, bits, POOL_BITS);
@@ -974,7 +970,7 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_random
* Handle random seed passed by bootloader, and credit it if
* CONFIG_RANDOM_TRUST_BOOTLOADER is set.
*/
-void add_bootloader_randomness(const void *buf, size_t len)
+void __cold add_bootloader_randomness(const void *buf, size_t len)
{
mix_pool_bytes(buf, len);
if (trust_bootloader)
@@ -1020,7 +1016,7 @@ static void fast_mix(unsigned long s[4],
* This function is called when the CPU has just come online, with
* entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE.
*/
-int random_online_cpu(unsigned int cpu)
+int __cold random_online_cpu(unsigned int cpu)
{
/*
* During CPU shutdown and before CPU onlining, add_interrupt_
@@ -1175,7 +1171,7 @@ static void add_timer_randomness(struct
if (in_hardirq())
this_cpu_ptr(&irq_randomness)->count += max(1u, bits * 64) - 1;
else
- credit_init_bits(bits);
+ _credit_init_bits(bits);
}
void add_input_randomness(unsigned int type, unsigned int code, unsigned int value)
@@ -1203,7 +1199,7 @@ void add_disk_randomness(struct gendisk
}
EXPORT_SYMBOL_GPL(add_disk_randomness);
-void rand_initialize_disk(struct gendisk *disk)
+void __cold rand_initialize_disk(struct gendisk *disk)
{
struct timer_rand_state *state;
@@ -1232,7 +1228,7 @@ void rand_initialize_disk(struct gendisk
*
* So the re-arming always happens in the entropy loop itself.
*/
-static void entropy_timer(struct timer_list *t)
+static void __cold entropy_timer(struct timer_list *t)
{
credit_init_bits(1);
}
@@ -1241,7 +1237,7 @@ static void entropy_timer(struct timer_l
* If we have an actual cycle counter, see if we can
* generate enough entropy with timing noise
*/
-static void try_to_generate_entropy(void)
+static void __cold try_to_generate_entropy(void)
{
struct {
unsigned long entropy;
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 104/111] random: move randomize_page() into mm where it belongs
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (102 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 103/111] random: move initialization functions out of hot pages Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 105/111] random: unify batched entropy implementations Greg Kroah-Hartman
` (12 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Andrew Morton, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 5ad7dd882e45d7fe432c32e896e2aaa0b21746ea upstream.
randomize_page is an mm function. It is documented like one. It contains
the history of one. It has the naming convention of one. It looks
just like another very similar function in mm, randomize_stack_top().
And it has always been maintained and updated by mm people. There is no
need for it to be in random.c. In the "which shape does not look like
the other ones" test, pointing to randomize_page() is correct.
So move randomize_page() into mm/util.c, right next to the similar
randomize_stack_top() function.
This commit contains no actual code changes.
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 32 --------------------------------
include/linux/mm.h | 1 +
include/linux/random.h | 2 --
mm/util.c | 32 ++++++++++++++++++++++++++++++++
4 files changed, 33 insertions(+), 34 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -622,38 +622,6 @@ int __cold random_prepare_cpu(unsigned i
}
#endif
-/**
- * randomize_page - Generate a random, page aligned address
- * @start: The smallest acceptable address the caller will take.
- * @range: The size of the area, starting at @start, within which the
- * random address must fall.
- *
- * If @start + @range would overflow, @range is capped.
- *
- * NOTE: Historical use of randomize_range, which this replaces, presumed that
- * @start was already page aligned. We now align it regardless.
- *
- * Return: A page aligned address within [start, start + range). On error,
- * @start is returned.
- */
-unsigned long randomize_page(unsigned long start, unsigned long range)
-{
- if (!PAGE_ALIGNED(start)) {
- range -= PAGE_ALIGN(start) - start;
- start = PAGE_ALIGN(start);
- }
-
- if (start > ULONG_MAX - range)
- range = ULONG_MAX - start;
-
- range >>= PAGE_SHIFT;
-
- if (range == 0)
- return start;
-
- return start + (get_random_long() % range << PAGE_SHIFT);
-}
-
/*
* This function will use the architecture-specific hardware random
* number generator if it is available. It is not recommended for
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2678,6 +2678,7 @@ extern int install_special_mapping(struc
unsigned long flags, struct page **pages);
unsigned long randomize_stack_top(unsigned long stack_top);
+unsigned long randomize_page(unsigned long start, unsigned long range);
extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -64,8 +64,6 @@ static inline unsigned long get_random_c
return get_random_long() & CANARY_MASK;
}
-unsigned long randomize_page(unsigned long start, unsigned long range);
-
int __init random_init(const char *command_line);
bool rng_is_initialized(void);
int wait_for_random_bytes(void);
--- a/mm/util.c
+++ b/mm/util.c
@@ -343,6 +343,38 @@ unsigned long randomize_stack_top(unsign
#endif
}
+/**
+ * randomize_page - Generate a random, page aligned address
+ * @start: The smallest acceptable address the caller will take.
+ * @range: The size of the area, starting at @start, within which the
+ * random address must fall.
+ *
+ * If @start + @range would overflow, @range is capped.
+ *
+ * NOTE: Historical use of randomize_range, which this replaces, presumed that
+ * @start was already page aligned. We now align it regardless.
+ *
+ * Return: A page aligned address within [start, start + range). On error,
+ * @start is returned.
+ */
+unsigned long randomize_page(unsigned long start, unsigned long range)
+{
+ if (!PAGE_ALIGNED(start)) {
+ range -= PAGE_ALIGN(start) - start;
+ start = PAGE_ALIGN(start);
+ }
+
+ if (start > ULONG_MAX - range)
+ range = ULONG_MAX - start;
+
+ range >>= PAGE_SHIFT;
+
+ if (range == 0)
+ return start;
+
+ return start + (get_random_long() % range << PAGE_SHIFT);
+}
+
#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
unsigned long arch_randomize_brk(struct mm_struct *mm)
{
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 105/111] random: unify batched entropy implementations
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (103 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 104/111] random: move randomize_page() into mm where it belongs Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 106/111] random: convert to using fops->read_iter() Greg Kroah-Hartman
` (11 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 3092adcef3ffd2ef59634998297ca8358461ebce upstream.
There are currently two separate batched entropy implementations, for
u32 and u64, with nearly identical code, with the goal of avoiding
unaligned memory accesses and letting the buffers be used more
efficiently. Having to maintain these two functions independently is a
bit of a hassle though, considering that they always need to be kept in
sync.
This commit factors them out into a type-generic macro, so that the
expansion produces the same code as before, such that diffing the
assembly shows no differences. This will also make it easier in the
future to add u16 and u8 batches.
This was initially tested using an always_inline function and letting
gcc constant fold the type size in, but the code gen was less efficient,
and in general it was more verbose and harder to follow. So this patch
goes with the boring macro solution, similar to what's already done for
the _wait functions in random.h.
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 145 ++++++++++++++++++--------------------------------
1 file changed, 54 insertions(+), 91 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -509,99 +509,62 @@ out_zero_chacha:
* provided by this function is okay, the function wait_for_random_bytes()
* should be called and return 0 at least once at any point prior.
*/
-struct batched_entropy {
- union {
- /*
- * We make this 1.5x a ChaCha block, so that we get the
- * remaining 32 bytes from fast key erasure, plus one full
- * block from the detached ChaCha state. We can increase
- * the size of this later if needed so long as we keep the
- * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.
- */
- u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))];
- u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
- };
- local_lock_t lock;
- unsigned long generation;
- unsigned int position;
-};
+#define DEFINE_BATCHED_ENTROPY(type) \
+struct batch_ ##type { \
+ /* \
+ * We make this 1.5x a ChaCha block, so that we get the \
+ * remaining 32 bytes from fast key erasure, plus one full \
+ * block from the detached ChaCha state. We can increase \
+ * the size of this later if needed so long as we keep the \
+ * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. \
+ */ \
+ type entropy[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(type))]; \
+ local_lock_t lock; \
+ unsigned long generation; \
+ unsigned int position; \
+}; \
+ \
+static DEFINE_PER_CPU(struct batch_ ##type, batched_entropy_ ##type) = { \
+ .lock = INIT_LOCAL_LOCK(batched_entropy_ ##type.lock), \
+ .position = UINT_MAX \
+}; \
+ \
+type get_random_ ##type(void) \
+{ \
+ type ret; \
+ unsigned long flags; \
+ struct batch_ ##type *batch; \
+ unsigned long next_gen; \
+ \
+ warn_unseeded_randomness(); \
+ \
+ if (!crng_ready()) { \
+ _get_random_bytes(&ret, sizeof(ret)); \
+ return ret; \
+ } \
+ \
+ local_lock_irqsave(&batched_entropy_ ##type.lock, flags); \
+ batch = raw_cpu_ptr(&batched_entropy_##type); \
+ \
+ next_gen = READ_ONCE(base_crng.generation); \
+ if (batch->position >= ARRAY_SIZE(batch->entropy) || \
+ next_gen != batch->generation) { \
+ _get_random_bytes(batch->entropy, sizeof(batch->entropy)); \
+ batch->position = 0; \
+ batch->generation = next_gen; \
+ } \
+ \
+ ret = batch->entropy[batch->position]; \
+ batch->entropy[batch->position] = 0; \
+ ++batch->position; \
+ local_unlock_irqrestore(&batched_entropy_ ##type.lock, flags); \
+ return ret; \
+} \
+EXPORT_SYMBOL(get_random_ ##type);
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock),
- .position = UINT_MAX
-};
-
-u64 get_random_u64(void)
-{
- u64 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- unsigned long next_gen;
-
- warn_unseeded_randomness();
-
- if (!crng_ready()) {
- _get_random_bytes(&ret, sizeof(ret));
- return ret;
- }
-
- local_lock_irqsave(&batched_entropy_u64.lock, flags);
- batch = raw_cpu_ptr(&batched_entropy_u64);
-
- next_gen = READ_ONCE(base_crng.generation);
- if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
- next_gen != batch->generation) {
- _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
- batch->position = 0;
- batch->generation = next_gen;
- }
-
- ret = batch->entropy_u64[batch->position];
- batch->entropy_u64[batch->position] = 0;
- ++batch->position;
- local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u64);
-
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock),
- .position = UINT_MAX
-};
-
-u32 get_random_u32(void)
-{
- u32 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- unsigned long next_gen;
-
- warn_unseeded_randomness();
-
- if (!crng_ready()) {
- _get_random_bytes(&ret, sizeof(ret));
- return ret;
- }
-
- local_lock_irqsave(&batched_entropy_u32.lock, flags);
- batch = raw_cpu_ptr(&batched_entropy_u32);
-
- next_gen = READ_ONCE(base_crng.generation);
- if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
- next_gen != batch->generation) {
- _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
- batch->position = 0;
- batch->generation = next_gen;
- }
-
- ret = batch->entropy_u32[batch->position];
- batch->entropy_u32[batch->position] = 0;
- ++batch->position;
- local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u32);
+DEFINE_BATCHED_ENTROPY(u64)
+DEFINE_BATCHED_ENTROPY(u32)
#ifdef CONFIG_SMP
/*
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 106/111] random: convert to using fops->read_iter()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (104 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 105/111] random: unify batched entropy implementations Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 107/111] random: convert to using fops->write_iter() Greg Kroah-Hartman
` (10 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Jens Axboe, Al Viro, Jason A. Donenfeld
From: Jens Axboe <axboe@kernel.dk>
commit 1b388e7765f2eaa137cf5d92b47ef5925ad83ced upstream.
This is a pre-requisite to wiring up splice() again for the random
and urandom drivers. It also allows us to remove the INT_MAX check in
getrandom(), because import_single_range() applies capping internally.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[Jason: rewrote get_random_bytes_user() to simplify and also incorporate
additional suggestions from Al.]
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 66 ++++++++++++++++++++++----------------------------
1 file changed, 30 insertions(+), 36 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -52,6 +52,7 @@
#include <linux/uuid.h>
#include <linux/uaccess.h>
#include <linux/siphash.h>
+#include <linux/uio.h>
#include <crypto/chacha.h>
#include <crypto/blake2s.h>
#include <asm/processor.h>
@@ -446,13 +447,13 @@ void get_random_bytes(void *buf, size_t
}
EXPORT_SYMBOL(get_random_bytes);
-static ssize_t get_random_bytes_user(void __user *ubuf, size_t len)
+static ssize_t get_random_bytes_user(struct iov_iter *iter)
{
- size_t block_len, left, ret = 0;
u32 chacha_state[CHACHA_STATE_WORDS];
- u8 output[CHACHA_BLOCK_SIZE];
+ u8 block[CHACHA_BLOCK_SIZE];
+ size_t ret = 0, copied;
- if (!len)
+ if (unlikely(!iov_iter_count(iter)))
return 0;
/*
@@ -466,30 +467,22 @@ static ssize_t get_random_bytes_user(voi
* use chacha_state after, so we can simply return those bytes to
* the user directly.
*/
- if (len <= CHACHA_KEY_SIZE) {
- ret = len - copy_to_user(ubuf, &chacha_state[4], len);
+ if (iov_iter_count(iter) <= CHACHA_KEY_SIZE) {
+ ret = copy_to_iter(&chacha_state[4], CHACHA_KEY_SIZE, iter);
goto out_zero_chacha;
}
for (;;) {
- chacha20_block(chacha_state, output);
+ chacha20_block(chacha_state, block);
if (unlikely(chacha_state[12] == 0))
++chacha_state[13];
- block_len = min_t(size_t, len, CHACHA_BLOCK_SIZE);
- left = copy_to_user(ubuf, output, block_len);
- if (left) {
- ret += block_len - left;
- break;
- }
-
- ubuf += block_len;
- ret += block_len;
- len -= block_len;
- if (!len)
+ copied = copy_to_iter(block, sizeof(block), iter);
+ ret += copied;
+ if (!iov_iter_count(iter) || copied != sizeof(block))
break;
- BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0);
+ BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
if (ret % PAGE_SIZE == 0) {
if (signal_pending(current))
break;
@@ -497,7 +490,7 @@ static ssize_t get_random_bytes_user(voi
}
}
- memzero_explicit(output, sizeof(output));
+ memzero_explicit(block, sizeof(block));
out_zero_chacha:
memzero_explicit(chacha_state, sizeof(chacha_state));
return ret ? ret : -EFAULT;
@@ -1226,6 +1219,10 @@ static void __cold try_to_generate_entro
SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags)
{
+ struct iov_iter iter;
+ struct iovec iov;
+ int ret;
+
if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
return -EINVAL;
@@ -1236,19 +1233,18 @@ SYSCALL_DEFINE3(getrandom, char __user *
if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
return -EINVAL;
- if (len > INT_MAX)
- len = INT_MAX;
-
if (!crng_ready() && !(flags & GRND_INSECURE)) {
- int ret;
-
if (flags & GRND_NONBLOCK)
return -EAGAIN;
ret = wait_for_random_bytes();
if (unlikely(ret))
return ret;
}
- return get_random_bytes_user(ubuf, len);
+
+ ret = import_single_range(READ, ubuf, len, &iov, &iter);
+ if (unlikely(ret))
+ return ret;
+ return get_random_bytes_user(&iter);
}
static __poll_t random_poll(struct file *file, poll_table *wait)
@@ -1292,8 +1288,7 @@ static ssize_t random_write(struct file
return (ssize_t)len;
}
-static ssize_t urandom_read(struct file *file, char __user *ubuf,
- size_t len, loff_t *ppos)
+static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
{
static int maxwarn = 10;
@@ -1302,23 +1297,22 @@ static ssize_t urandom_read(struct file
++urandom_warning.missed;
else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
--maxwarn;
- pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
- current->comm, len);
+ pr_notice("%s: uninitialized urandom read (%zu bytes read)\n",
+ current->comm, iov_iter_count(iter));
}
}
- return get_random_bytes_user(ubuf, len);
+ return get_random_bytes_user(iter);
}
-static ssize_t random_read(struct file *file, char __user *ubuf,
- size_t len, loff_t *ppos)
+static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
{
int ret;
ret = wait_for_random_bytes();
if (ret != 0)
return ret;
- return get_random_bytes_user(ubuf, len);
+ return get_random_bytes_user(iter);
}
static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
@@ -1380,7 +1374,7 @@ static int random_fasync(int fd, struct
}
const struct file_operations random_fops = {
- .read = random_read,
+ .read_iter = random_read_iter,
.write = random_write,
.poll = random_poll,
.unlocked_ioctl = random_ioctl,
@@ -1390,7 +1384,7 @@ const struct file_operations random_fops
};
const struct file_operations urandom_fops = {
- .read = urandom_read,
+ .read_iter = urandom_read_iter,
.write = random_write,
.unlocked_ioctl = random_ioctl,
.compat_ioctl = compat_ptr_ioctl,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 107/111] random: convert to using fops->write_iter()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (105 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 106/111] random: convert to using fops->read_iter() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 108/111] random: wire up fops->splice_{read,write}_iter() Greg Kroah-Hartman
` (9 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Jens Axboe, Al Viro, Jason A. Donenfeld
From: Jens Axboe <axboe@kernel.dk>
commit 22b0a222af4df8ee9bb8e07013ab44da9511b047 upstream.
Now that the read side has been converted to fix a regression with
splice, convert the write side as well to have some symmetry in the
interface used (and help deprecate ->write()).
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[Jason: cleaned up random_ioctl a bit, require full writes in
RNDADDENTROPY since it's crediting entropy, simplify control flow of
write_pool(), and incorporate suggestions from Al.]
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 67 ++++++++++++++++++++++++++------------------------
1 file changed, 35 insertions(+), 32 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1253,39 +1253,31 @@ static __poll_t random_poll(struct file
return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
}
-static int write_pool(const char __user *ubuf, size_t len)
+static ssize_t write_pool(struct iov_iter *iter)
{
- size_t block_len;
- int ret = 0;
u8 block[BLAKE2S_BLOCK_SIZE];
+ ssize_t ret = 0;
+ size_t copied;
- while (len) {
- block_len = min(len, sizeof(block));
- if (copy_from_user(block, ubuf, block_len)) {
- ret = -EFAULT;
- goto out;
- }
- len -= block_len;
- ubuf += block_len;
- mix_pool_bytes(block, block_len);
+ if (unlikely(!iov_iter_count(iter)))
+ return 0;
+
+ for (;;) {
+ copied = copy_from_iter(block, sizeof(block), iter);
+ ret += copied;
+ mix_pool_bytes(block, copied);
+ if (!iov_iter_count(iter) || copied != sizeof(block))
+ break;
cond_resched();
}
-out:
memzero_explicit(block, sizeof(block));
- return ret;
+ return ret ? ret : -EFAULT;
}
-static ssize_t random_write(struct file *file, const char __user *ubuf,
- size_t len, loff_t *ppos)
+static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *iter)
{
- int ret;
-
- ret = write_pool(ubuf, len);
- if (ret)
- return ret;
-
- return (ssize_t)len;
+ return write_pool(iter);
}
static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
@@ -1317,9 +1309,8 @@ static ssize_t random_read_iter(struct k
static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
- int size, ent_count;
int __user *p = (int __user *)arg;
- int retval;
+ int ent_count;
switch (cmd) {
case RNDGETENTCNT:
@@ -1336,20 +1327,32 @@ static long random_ioctl(struct file *f,
return -EINVAL;
credit_init_bits(ent_count);
return 0;
- case RNDADDENTROPY:
+ case RNDADDENTROPY: {
+ struct iov_iter iter;
+ struct iovec iov;
+ ssize_t ret;
+ int len;
+
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(ent_count, p++))
return -EFAULT;
if (ent_count < 0)
return -EINVAL;
- if (get_user(size, p++))
+ if (get_user(len, p++))
+ return -EFAULT;
+ ret = import_single_range(WRITE, p, len, &iov, &iter);
+ if (unlikely(ret))
+ return ret;
+ ret = write_pool(&iter);
+ if (unlikely(ret < 0))
+ return ret;
+ /* Since we're crediting, enforce that it was all written into the pool. */
+ if (unlikely(ret != len))
return -EFAULT;
- retval = write_pool((const char __user *)p, size);
- if (retval < 0)
- return retval;
credit_init_bits(ent_count);
return 0;
+ }
case RNDZAPENTCNT:
case RNDCLEARPOOL:
/* No longer has any effect. */
@@ -1375,7 +1378,7 @@ static int random_fasync(int fd, struct
const struct file_operations random_fops = {
.read_iter = random_read_iter,
- .write = random_write,
+ .write_iter = random_write_iter,
.poll = random_poll,
.unlocked_ioctl = random_ioctl,
.compat_ioctl = compat_ptr_ioctl,
@@ -1385,7 +1388,7 @@ const struct file_operations random_fops
const struct file_operations urandom_fops = {
.read_iter = urandom_read_iter,
- .write = random_write,
+ .write_iter = random_write_iter,
.unlocked_ioctl = random_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.fasync = random_fasync,
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 108/111] random: wire up fops->splice_{read,write}_iter()
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (106 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 107/111] random: convert to using fops->write_iter() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 109/111] random: check for signals after page of pool writes Greg Kroah-Hartman
` (8 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Jens Axboe, Al Viro, Jason A. Donenfeld
From: Jens Axboe <axboe@kernel.dk>
commit 79025e727a846be6fd215ae9cdb654368ac3f9a6 upstream.
Now that random/urandom is using {read,write}_iter, we can wire it up to
using the generic splice handlers.
Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[Jason: added the splice_write path. Note that sendfile() and such still
does not work for read, though it does for write, because of a file
type restriction in splice_direct_to_actor(), which I'll address
separately.]
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1384,6 +1384,8 @@ const struct file_operations random_fops
.compat_ioctl = compat_ptr_ioctl,
.fasync = random_fasync,
.llseek = noop_llseek,
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_file_splice_write,
};
const struct file_operations urandom_fops = {
@@ -1393,6 +1395,8 @@ const struct file_operations urandom_fop
.compat_ioctl = compat_ptr_ioctl,
.fasync = random_fasync,
.llseek = noop_llseek,
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_file_splice_write,
};
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 109/111] random: check for signals after page of pool writes
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (107 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 108/111] random: wire up fops->splice_{read,write}_iter() Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 110/111] ACPI: sysfs: Fix BERT error region memory mapping Greg Kroah-Hartman
` (7 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Dominik Brodowski, Jason A. Donenfeld
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 1ce6c8d68f8ac587f54d0a271ac594d3d51f3efb upstream.
get_random_bytes_user() checks for signals after producing a PAGE_SIZE
worth of output, just like /dev/zero does. write_pool() is doing
basically the same work (actually, slightly more expensive), and so
should stop to check for signals in the same way. Let's also name it
write_pool_user() to match get_random_bytes_user(), so this won't be
misused in the future.
Before this patch, massive writes to /dev/urandom would tie up the
process for an extremely long time and make it unterminatable. After, it
can be successfully interrupted. The following test program can be used
to see this works as intended:
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
static unsigned char x[~0U];
static void handle(int) { }
int main(int argc, char *argv[])
{
pid_t pid = getpid(), child;
int fd;
signal(SIGUSR1, handle);
if (!(child = fork())) {
for (;;)
kill(pid, SIGUSR1);
}
fd = open("/dev/urandom", O_WRONLY);
pause();
printf("interrupted after writing %zd bytes\n", write(fd, x, sizeof(x)));
close(fd);
kill(child, SIGTERM);
return 0;
}
Result before: "interrupted after writing 2147479552 bytes"
Result after: "interrupted after writing 4096 bytes"
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1253,7 +1253,7 @@ static __poll_t random_poll(struct file
return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
}
-static ssize_t write_pool(struct iov_iter *iter)
+static ssize_t write_pool_user(struct iov_iter *iter)
{
u8 block[BLAKE2S_BLOCK_SIZE];
ssize_t ret = 0;
@@ -1268,7 +1268,13 @@ static ssize_t write_pool(struct iov_ite
mix_pool_bytes(block, copied);
if (!iov_iter_count(iter) || copied != sizeof(block))
break;
- cond_resched();
+
+ BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+ if (ret % PAGE_SIZE == 0) {
+ if (signal_pending(current))
+ break;
+ cond_resched();
+ }
}
memzero_explicit(block, sizeof(block));
@@ -1277,7 +1283,7 @@ static ssize_t write_pool(struct iov_ite
static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *iter)
{
- return write_pool(iter);
+ return write_pool_user(iter);
}
static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
@@ -1344,7 +1350,7 @@ static long random_ioctl(struct file *f,
ret = import_single_range(WRITE, p, len, &iov, &iter);
if (unlikely(ret))
return ret;
- ret = write_pool(&iter);
+ ret = write_pool_user(&iter);
if (unlikely(ret < 0))
return ret;
/* Since we're crediting, enforce that it was all written into the pool. */
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 110/111] ACPI: sysfs: Fix BERT error region memory mapping
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (108 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 109/111] random: check for signals after page of pool writes Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.17 111/111] ALSA: ctxfi: Add SB046x PCI ID Greg Kroah-Hartman
` (6 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Lorenzo Pieralisi, Veronika Kabatova,
Aristeu Rozanski, Ard Biesheuvel, Rafael J. Wysocki,
dann frazier
From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
commit 1bbc21785b7336619fb6a67f1fff5afdaf229acc upstream.
Currently the sysfs interface maps the BERT error region as "memory"
(through acpi_os_map_memory()) in order to copy the error records into
memory buffers through memory operations (eg memory_read_from_buffer()).
The OS system cannot detect whether the BERT error region is part of
system RAM or it is "device memory" (eg BMC memory) and therefore it
cannot detect which memory attributes the bus to memory support (and
corresponding kernel mapping, unless firmware provides the required
information).
The acpi_os_map_memory() arch backend implementation determines the
mapping attributes. On arm64, if the BERT error region is not present in
the EFI memory map, the error region is mapped as device-nGnRnE; this
triggers alignment faults since memcpy unaligned accesses are not
allowed in device-nGnRnE regions.
The ACPI sysfs code cannot therefore map by default the BERT error
region with memory semantics but should use a safer default.
Change the sysfs code to map the BERT error region as MMIO (through
acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
error region into the kernel buffer.
Link: https://lore.kernel.org/linux-arm-kernel/31ffe8fc-f5ee-2858-26c5-0fd8bdd68702@arm.com
Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Veronika Kabatova <vkabatov@redhat.com>
Tested-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct fil
loff_t offset, size_t count)
{
struct acpi_data_attr *data_attr;
- void *base;
- ssize_t rc;
+ void __iomem *base;
+ ssize_t size;
data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
+ size = data_attr->attr.size;
- base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
+ if (offset < 0)
+ return -EINVAL;
+
+ if (offset >= size)
+ return 0;
+
+ if (count > size - offset)
+ count = size - offset;
+
+ base = acpi_os_map_iomem(data_attr->addr, size);
if (!base)
return -ENOMEM;
- rc = memory_read_from_buffer(buf, count, &offset, base,
- data_attr->attr.size);
- acpi_os_unmap_memory(base, data_attr->attr.size);
- return rc;
+ memcpy_fromio(buf, base + offset, count);
+
+ acpi_os_unmap_iomem(base, size);
+
+ return count;
}
static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
^ permalink raw reply [flat|nested] 118+ messages in thread* [PATCH 5.17 111/111] ALSA: ctxfi: Add SB046x PCI ID
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (109 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 110/111] ACPI: sysfs: Fix BERT error region memory mapping Greg Kroah-Hartman
@ 2022-05-27 8:50 ` Greg Kroah-Hartman
2022-05-27 22:39 ` [PATCH 5.17 000/111] 5.17.12-rc1 review Guenter Roeck
` (5 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Greg Kroah-Hartman @ 2022-05-27 8:50 UTC (permalink / raw)
To: linux-kernel; +Cc: Greg Kroah-Hartman, stable, Edward Matijevic, Takashi Iwai
From: Edward Matijevic <motolav@gmail.com>
commit 1b073ebb174d0c7109b438e0a5eb4495137803ec upstream.
Adds the PCI ID for X-Fi cards sold under the Platnum and XtremeMusic names
Before: snd_ctxfi 0000:05:05.0: chip 20K1 model Unknown (1102:0021) is found
After: snd_ctxfi 0000:05:05.0: chip 20K1 model SB046x (1102:0021) is found
[ This is only about defining the model name string, and the rest is
handled just like before, as a default unknown device.
Edward confirmed that the stuff has been working fine -- tiwai ]
Signed-off-by: Edward Matijevic <motolav@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/cae7d1a4-8bd9-7dfe-7427-db7e766f7272@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/pci/ctxfi/ctatc.c | 2 ++
sound/pci/ctxfi/cthardware.h | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)
--- a/sound/pci/ctxfi/ctatc.c
+++ b/sound/pci/ctxfi/ctatc.c
@@ -36,6 +36,7 @@
| ((IEC958_AES3_CON_FS_48000) << 24))
static const struct snd_pci_quirk subsys_20k1_list[] = {
+ SND_PCI_QUIRK(PCI_VENDOR_ID_CREATIVE, 0x0021, "SB046x", CTSB046X),
SND_PCI_QUIRK(PCI_VENDOR_ID_CREATIVE, 0x0022, "SB055x", CTSB055X),
SND_PCI_QUIRK(PCI_VENDOR_ID_CREATIVE, 0x002f, "SB055x", CTSB055X),
SND_PCI_QUIRK(PCI_VENDOR_ID_CREATIVE, 0x0029, "SB073x", CTSB073X),
@@ -64,6 +65,7 @@ static const struct snd_pci_quirk subsys
static const char *ct_subsys_name[NUM_CTCARDS] = {
/* 20k1 models */
+ [CTSB046X] = "SB046x",
[CTSB055X] = "SB055x",
[CTSB073X] = "SB073x",
[CTUAA] = "UAA",
--- a/sound/pci/ctxfi/cthardware.h
+++ b/sound/pci/ctxfi/cthardware.h
@@ -26,8 +26,9 @@ enum CHIPTYP {
enum CTCARDS {
/* 20k1 models */
+ CTSB046X,
+ CT20K1_MODEL_FIRST = CTSB046X,
CTSB055X,
- CT20K1_MODEL_FIRST = CTSB055X,
CTSB073X,
CTUAA,
CT20K1_UNKNOWN,
^ permalink raw reply [flat|nested] 118+ messages in thread* Re: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (110 preceding siblings ...)
2022-05-27 8:50 ` [PATCH 5.17 111/111] ALSA: ctxfi: Add SB046x PCI ID Greg Kroah-Hartman
@ 2022-05-27 22:39 ` Guenter Roeck
2022-05-28 2:00 ` Justin Forbes
` (4 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Guenter Roeck @ 2022-05-27 22:39 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, stable, torvalds, akpm, shuah, patches,
lkft-triage, pavel, jonathanh, f.fainelli, sudipm.mukherjee,
slade
On Fri, May 27, 2022 at 10:48:32AM +0200, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
>
Build results:
total: 155 pass: 155 fail: 0
Qemu test results:
total: 489 pass: 489 fail: 0
Tested-by: Guenter Roeck <linux@roeck-us.net>
Guenter
^ permalink raw reply [flat|nested] 118+ messages in thread* Re: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (111 preceding siblings ...)
2022-05-27 22:39 ` [PATCH 5.17 000/111] 5.17.12-rc1 review Guenter Roeck
@ 2022-05-28 2:00 ` Justin Forbes
2022-05-28 10:43 ` Naresh Kamboju
` (3 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Justin Forbes @ 2022-05-28 2:00 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, stable, torvalds, akpm, linux, shuah, patches,
lkft-triage, pavel, jonathanh, f.fainelli, sudipm.mukherjee,
slade
On Fri, May 27, 2022 at 10:48:32AM +0200, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
> https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.17.12-rc1.gz
> or in the git tree and branch at:
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.17.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h
Tested rc1 against the Fedora build system (aarch64, armv7, ppc64le,
s390x, x86_64), and boot tested x86_64. No regressions noted.
Tested-by: Justin M. Forbes <jforbes@fedoraproject.org>
^ permalink raw reply [flat|nested] 118+ messages in thread* Re: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (112 preceding siblings ...)
2022-05-28 2:00 ` Justin Forbes
@ 2022-05-28 10:43 ` Naresh Kamboju
2022-05-28 11:06 ` Ron Economos
` (2 subsequent siblings)
116 siblings, 0 replies; 118+ messages in thread
From: Naresh Kamboju @ 2022-05-28 10:43 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, stable, torvalds, akpm, linux, shuah, patches,
lkft-triage, pavel, jonathanh, f.fainelli, sudipm.mukherjee,
slade
On Fri, 27 May 2022 at 14:21, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
> https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.17.12-rc1.gz
> or in the git tree and branch at:
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.17.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h
Results from Linaro’s test farm.
No regressions on arm64, arm, x86_64, and i386.
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
## Build
* kernel: 5.17.12-rc1
* git: https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc
* git branch: linux-5.17.y
* git commit: 118948632858649db5531086bb74e586db579fbf
* git describe: v5.17.11-112-g118948632858
* test details:
https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-5.17.y/build/v5.17.11-112-g118948632858/
## Test Regressions (compared to v5.17.11)
No test regressions found.
## Metric Regressions (compared to v5.17.11)
No metric regressions found.
## Test Fixes (compared to v5.17.11)
No test fixes found.
## Metric Fixes (compared to v5.17.11)
No metric fixes found.
## Test result summary
total: 97605, pass: 84424, fail: 334, skip: 12047, xfail: 800
## Build Summary
* arc: 10 total, 10 passed, 0 failed
* arm: 296 total, 293 passed, 3 failed
* arm64: 47 total, 47 passed, 0 failed
* i386: 44 total, 40 passed, 4 failed
* mips: 41 total, 38 passed, 3 failed
* parisc: 14 total, 14 passed, 0 failed
* powerpc: 59 total, 56 passed, 3 failed
* riscv: 27 total, 27 passed, 0 failed
* s390: 26 total, 23 passed, 3 failed
* sh: 26 total, 24 passed, 2 failed
* sparc: 14 total, 14 passed, 0 failed
* x86_64: 47 total, 46 passed, 1 failed
## Test suites summary
* fwts
* igt-gpu-tools
* kselftest-android
* kselftest-arm64
* kselftest-breakpoints
* kselftest-capabilities
* kselftest-cgroup
* kselftest-clone3
* kselftest-core
* kselftest-cpu-hotplug
* kselftest-cpufreq
* kselftest-drivers
* kselftest-efivarfs
* kselftest-filesystems
* kselftest-firmware
* kselftest-fpu
* kselftest-futex
* kselftest-gpio
* kselftest-intel_pstate
* kselftest-ipc
* kselftest-ir
* kselftest-kcmp
* kselftest-kexec
* kselftest-kvm
* kselftest-lib
* kselftest-livepatch
* kselftest-membarrier
* kselftest-memfd
* kselftest-memory-hotplug
* kselftest-mincore
* kselftest-mount
* kselftest-mqueue
* kselftest-net
* kselftest-openat2
* kselftest-pid_namespace
* kselftest-pidfd
* kselftest-proc
* kselftest-pstore
* kselftest-ptrace
* kselftest-rseq
* kselftest-rtc
* kselftest-seccomp
* kselftest-sigaltstack
* kselftest-size
* kselftest-splice
* kselftest-static_keys
* kselftest-sync
* kselftest-sysctl
* kselftest-timens
* kselftest-timers
* kselftest-tmpfs
* kselftest-tpm2
* kselftest-user
* kselftest-vm
* kselftest-x86
* kselftest-zram
* kunit
* kvm-unit-tests
* libgpiod
* libhugetlbfs
* linux-log-parser
* ltp-cap_bounds-tests
* ltp-commands-tests
* ltp-containers-tests
* ltp-controllers-tests
* ltp-cpuhotplug-tests
* ltp-crypto-tests
* ltp-cve-tests
* ltp-cve-tests
* ltp-dio-tests
* ltp-fcntl-locktests-tests
* ltp-filecaps-tests
* ltp-fs-tests
* ltp-fs_bind-tests
* ltp-fs_perms_simple-tests
* ltp-fsx-tests
* ltp-hugetlb-tests
* ltp-io-tests
* ltp-ipc-tests
* ltp-math-tests
* ltp-mm-tests
* ltp-nptl-tests
* ltp-open-posix-tests
* ltp-pty-tests
* ltp-sched-tests
* ltp-securebits-tests
* ltp-syscalls-tests
* ltp-tracing-tests
* network-basic-tests
* packetdrill
* perf
* perf/Zstd-perf.data-compression
* prep-inline
* rcutorture
* ssuite
* v4l2-compliance
* vdso
--
Linaro LKFT
https://lkft.linaro.org
^ permalink raw reply [flat|nested] 118+ messages in thread* Re: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (113 preceding siblings ...)
2022-05-28 10:43 ` Naresh Kamboju
@ 2022-05-28 11:06 ` Ron Economos
2022-05-28 15:01 ` Fox Chen
2022-05-28 15:25 ` Sudip Mukherjee
116 siblings, 0 replies; 118+ messages in thread
From: Ron Economos @ 2022-05-28 11:06 UTC (permalink / raw)
To: Greg Kroah-Hartman, linux-kernel
Cc: stable, torvalds, akpm, linux, shuah, patches, lkft-triage,
pavel, jonathanh, f.fainelli, sudipm.mukherjee, slade
On 5/27/22 1:48 AM, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
> https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.17.12-rc1.gz
> or in the git tree and branch at:
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.17.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h
Built and booted successfully on RISC-V RV64 (HiFive Unmatched).
Tested-by: Ron Economos <re@w6rz.net>
^ permalink raw reply [flat|nested] 118+ messages in thread* RE: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (114 preceding siblings ...)
2022-05-28 11:06 ` Ron Economos
@ 2022-05-28 15:01 ` Fox Chen
2022-05-28 15:25 ` Sudip Mukherjee
116 siblings, 0 replies; 118+ messages in thread
From: Fox Chen @ 2022-05-28 15:01 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, torvalds, akpm, linux, shuah,
patches, lkft-triage, pavel, jonathanh, f.fainelli,
sudipm.mukherjee, slade, Fox Chen
On Fri, 27 May 2022 10:48:32 +0200, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
> https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.17.12-rc1.gz
> or in the git tree and branch at:
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.17.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h
>
5.17.12-rc1 Successfully Compiled and booted on my Raspberry PI 4b (8g) (bcm2711)
Tested-by: Fox Chen <foxhlchen@gmail.com>
^ permalink raw reply [flat|nested] 118+ messages in thread* Re: [PATCH 5.17 000/111] 5.17.12-rc1 review
2022-05-27 8:48 [PATCH 5.17 000/111] 5.17.12-rc1 review Greg Kroah-Hartman
` (115 preceding siblings ...)
2022-05-28 15:01 ` Fox Chen
@ 2022-05-28 15:25 ` Sudip Mukherjee
116 siblings, 0 replies; 118+ messages in thread
From: Sudip Mukherjee @ 2022-05-28 15:25 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, stable, torvalds, akpm, linux, shuah, patches,
lkft-triage, pavel, jonathanh, f.fainelli, slade
Hi Greg,
On Fri, May 27, 2022 at 10:48:32AM +0200, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 5.17.12 release.
> There are 111 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Sun, 29 May 2022 08:46:36 +0000.
> Anything received after that time might be too late.
Build test:
mips (gcc version 11.3.1 20220517): 60 configs -> no failure
arm (gcc version 11.3.1 20220517): 100 configs -> no new failure
arm64 (gcc version 11.3.1 20220517): 3 configs -> no failure
x86_64 (gcc version 11.3.1 20220517): 4 configs -> no failure
Boot test:
x86_64: Booted on my test laptop. No regression.
arm64: Booted on rpi4b (4GB model). No regression. [1]
mips: Booted on ci20 board. No regression. [2]
[1]. https://openqa.qa.codethink.co.uk/tests/1223
[2]. https://openqa.qa.codethink.co.uk/tests/1224
Tested-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
--
Regards
Sudip
^ permalink raw reply [flat|nested] 118+ messages in thread