LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Andy Lutomirski <luto@kernel.org>
To: Theodore Tso <tytso@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 5/7] random: Remove the blocking pool
Date: Thu, 29 Aug 2019 18:11:40 -0700
Message-ID: <20b68f4b045d071d3c653f4381c043a76e332861.1567126741.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1567126741.git.luto@kernel.org>

There is no longer any interface to read data from the blocking
pool, so remove it.

This enables quite a bit of code deletion, much of which will be
done in subsequent patches.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 drivers/char/random.c | 106 ------------------------------------------
 1 file changed, 106 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 29a158d9353c..4521138231ed 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -470,7 +470,6 @@ static const struct poolinfo {
 /*
  * Static global variables
  */
-static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
 static struct fasync_struct *fasync;
 
@@ -530,7 +529,6 @@ struct entropy_store {
 	__u32 *pool;
 	const char *name;
 	struct entropy_store *pull;
-	struct work_struct push_work;
 
 	/* read-write data: */
 	unsigned long last_pulled;
@@ -549,9 +547,7 @@ static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
 				size_t nbytes, int fips);
 
 static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
-static void push_to_pool(struct work_struct *work);
 static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
-static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
 
 static struct entropy_store input_pool = {
 	.poolinfo = &poolinfo_table[0],
@@ -560,16 +556,6 @@ static struct entropy_store input_pool = {
 	.pool = input_pool_data
 };
 
-static struct entropy_store blocking_pool = {
-	.poolinfo = &poolinfo_table[1],
-	.name = "blocking",
-	.pull = &input_pool,
-	.lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
-	.pool = blocking_pool_data,
-	.push_work = __WORK_INITIALIZER(blocking_pool.push_work,
-					push_to_pool),
-};
-
 static __u32 const twist_table[8] = {
 	0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
 	0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
@@ -765,15 +751,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 		entropy_count = 0;
 	} else if (entropy_count > pool_size)
 		entropy_count = pool_size;
-	if ((r == &blocking_pool) && !r->initialized &&
-	    (entropy_count >> ENTROPY_SHIFT) > 128)
-		has_initialized = 1;
 	if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
 		goto retry;
 
 	if (has_initialized) {
 		r->initialized = 1;
-		wake_up_interruptible(&random_read_wait);
 		kill_fasync(&fasync, SIGIO, POLL_IN);
 	}
 
@@ -782,7 +764,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 
 	if (r == &input_pool) {
 		int entropy_bits = entropy_count >> ENTROPY_SHIFT;
-		struct entropy_store *other = &blocking_pool;
 
 		if (crng_init < 2) {
 			if (entropy_bits < 128)
@@ -790,27 +771,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 			crng_reseed(&primary_crng, r);
 			entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
 		}
-
-		/* initialize the blocking pool if necessary */
-		if (entropy_bits >= random_read_wakeup_bits &&
-		    !other->initialized) {
-			schedule_work(&other->push_work);
-			return;
-		}
-
-		/* should we wake readers? */
-		if (entropy_bits >= random_read_wakeup_bits &&
-		    wq_has_sleeper(&random_read_wait)) {
-			wake_up_interruptible(&random_read_wait);
-		}
-		/* If the input pool is getting full, and the blocking
-		 * pool has room, send some entropy to the blocking
-		 * pool.
-		 */
-		if (!work_pending(&other->push_work) &&
-		    (ENTROPY_BITS(r) > 6 * r->poolinfo->poolbytes) &&
-		    (ENTROPY_BITS(other) <= 6 * other->poolinfo->poolbytes))
-			schedule_work(&other->push_work);
 	}
 }
 
@@ -1422,22 +1382,6 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
 	credit_entropy_bits(r, bytes*8);
 }
 
-/*
- * Used as a workqueue function so that when the input pool is getting
- * full, we can "spill over" some entropy to the output pools.  That
- * way the output pools can store some of the excess entropy instead
- * of letting it go to waste.
- */
-static void push_to_pool(struct work_struct *work)
-{
-	struct entropy_store *r = container_of(work, struct entropy_store,
-					      push_work);
-	BUG_ON(!r);
-	_xfer_secondary_pool(r, random_read_wakeup_bits/8);
-	trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
-			   r->pull->entropy_count >> ENTROPY_SHIFT);
-}
-
 /*
  * This function decides how many bytes to actually take from the
  * given pool, and also debits the entropy count accordingly.
@@ -1616,54 +1560,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 	return _extract_entropy(r, buf, nbytes, fips_enabled);
 }
 
-/*
- * This function extracts randomness from the "entropy pool", and
- * returns it in a userspace buffer.
- */
-static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
-				    size_t nbytes)
-{
-	ssize_t ret = 0, i;
-	__u8 tmp[EXTRACT_SIZE];
-	int large_request = (nbytes > 256);
-
-	trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
-	if (!r->initialized && r->pull) {
-		xfer_secondary_pool(r, ENTROPY_BITS(r->pull)/8);
-		if (!r->initialized)
-			return 0;
-	}
-	xfer_secondary_pool(r, nbytes);
-	nbytes = account(r, nbytes, 0, 0);
-
-	while (nbytes) {
-		if (large_request && need_resched()) {
-			if (signal_pending(current)) {
-				if (ret == 0)
-					ret = -ERESTARTSYS;
-				break;
-			}
-			schedule();
-		}
-
-		extract_buf(r, tmp);
-		i = min_t(int, nbytes, EXTRACT_SIZE);
-		if (copy_to_user(buf, tmp, i)) {
-			ret = -EFAULT;
-			break;
-		}
-
-		nbytes -= i;
-		buf += i;
-		ret += i;
-	}
-
-	/* Wipe data just returned from memory */
-	memzero_explicit(tmp, sizeof(tmp));
-
-	return ret;
-}
-
 #define warn_unseeded_randomness(previous) \
 	_warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
 
@@ -1893,7 +1789,6 @@ static void __init init_std_data(struct entropy_store *r)
 int __init rand_initialize(void)
 {
 	init_std_data(&input_pool);
-	init_std_data(&blocking_pool);
 	crng_initialize(&primary_crng);
 	crng_global_init_time = jiffies;
 	if (ratelimit_disable) {
@@ -2053,7 +1948,6 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		input_pool.entropy_count = 0;
-		blocking_pool.entropy_count = 0;
 		return 0;
 	case RNDRESEEDCRNG:
 		if (!capable(CAP_SYS_ADMIN))
-- 
2.21.0


  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30  1:11 [PATCH 0/7] Rework random blocking Andy Lutomirski
2019-08-30  1:11 ` [PATCH 1/7] random: Don't wake crng_init_wait when crng_init == 1 Andy Lutomirski
2019-08-30  1:11 ` [PATCH 2/7] random: Add GRND_INSECURE to return best-effort non-cryptographic bytes Andy Lutomirski
2019-08-30  1:11 ` [PATCH 3/7] random: Ignore GRND_RANDOM in getentropy(2) Andy Lutomirski
2019-08-30  1:11 ` [PATCH 4/7] random: Make /dev/random be almost like /dev/urandom Andy Lutomirski
2019-08-30  1:11 ` Andy Lutomirski [this message]
2019-08-30  1:11 ` [PATCH 6/7] random: Delete code to pull data into pools Andy Lutomirski
2019-08-30  1:11 ` [PATCH 7/7] random: Remove kernel.random.read_wakeup_threshold Andy Lutomirski
2019-08-30  1:49 ` [PATCH 0/7] Rework random blocking Theodore Y. Ts'o
2019-08-30  2:01   ` Andy Lutomirski
2019-09-09  9:42 ` Pavel Machek
2019-09-09 22:57   ` Andy Lutomirski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20b68f4b045d071d3c653f4381c043a76e332861.1567126741.git.luto@kernel.org \
    --to=luto@kernel.org \
    --cc=Jason@zx2c4.com \
    --cc=keescook@chromium.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=tytso@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git