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From: Andy Lutomirski <luto@kernel.org>
To: Ted Ts'o <tytso@mit.edu>
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>,
	"Ahmed S. Darwish" <darwish.07@gmail.com>,
	Lennart Poettering <mzxreary@0pointer.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Alexander E. Patrakov" <patrakov@gmail.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Willy Tarreau <w@1wt.eu>, Matthew Garrett <mjg59@srcf.ucam.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-man <linux-man@vger.kernel.org>,
	Stephan Mueller <smueller@chronox.de>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 5/8] random: Make /dev/random be almost like /dev/urandom
Date: Mon, 23 Dec 2019 00:20:48 -0800
Message-ID: <5e6ac8831c6cf2e56a7a4b39616d1732b2bdd06c.1577088521.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1577088521.git.luto@kernel.org>

This patch changes the read semantics of /dev/random to be the same
as /dev/urandom except that reads will block until the CRNG is
ready.

None of the cleanups that this enables have been done yet.  As a
result, this gives a warning about an unused function.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 drivers/char/random.c | 55 +++++++++++--------------------------------
 1 file changed, 14 insertions(+), 41 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index c0a3032b30ca..cf131f5989a1 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -354,7 +354,6 @@
 #define INPUT_POOL_WORDS	(1 << (INPUT_POOL_SHIFT-5))
 #define OUTPUT_POOL_SHIFT	10
 #define OUTPUT_POOL_WORDS	(1 << (OUTPUT_POOL_SHIFT-5))
-#define SEC_XFER_SIZE		512
 #define EXTRACT_SIZE		10
 
 
@@ -803,7 +802,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 		if (entropy_bits >= random_read_wakeup_bits &&
 		    wq_has_sleeper(&random_read_wait)) {
 			wake_up_interruptible(&random_read_wait);
-			kill_fasync(&fasync, SIGIO, POLL_IN);
 		}
 		/* If the input pool is getting full, and the blocking
 		 * pool has room, send some entropy to the blocking
@@ -1031,6 +1029,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
 		crng_init = 2;
 		process_random_ready_list();
 		wake_up_interruptible(&crng_init_wait);
+		kill_fasync(&fasync, SIGIO, POLL_IN);
 		pr_notice("random: crng init done\n");
 		if (unseeded_warning.missed) {
 			pr_notice("random: %d get_random_xx warning(s) missed "
@@ -1981,43 +1980,6 @@ void rand_initialize_disk(struct gendisk *disk)
 }
 #endif
 
-static ssize_t
-_random_read(int nonblock, char __user *buf, size_t nbytes)
-{
-	ssize_t n;
-
-	if (nbytes == 0)
-		return 0;
-
-	nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
-	while (1) {
-		n = extract_entropy_user(&blocking_pool, buf, nbytes);
-		if (n < 0)
-			return n;
-		trace_random_read(n*8, (nbytes-n)*8,
-				  ENTROPY_BITS(&blocking_pool),
-				  ENTROPY_BITS(&input_pool));
-		if (n > 0)
-			return n;
-
-		/* Pool is (near) empty.  Maybe wait and retry. */
-		if (nonblock)
-			return -EAGAIN;
-
-		wait_event_interruptible(random_read_wait,
-		    blocking_pool.initialized &&
-		    (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits));
-		if (signal_pending(current))
-			return -ERESTARTSYS;
-	}
-}
-
-static ssize_t
-random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
-{
-	return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
-}
-
 static ssize_t
 urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes,
 		    loff_t *ppos)
@@ -2050,15 +2012,26 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 	return urandom_read_nowarn(file, buf, nbytes, ppos);
 }
 
+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 urandom_read_nowarn(file, buf, nbytes, ppos);
+}
+
 static __poll_t
 random_poll(struct file *file, poll_table * wait)
 {
 	__poll_t mask;
 
-	poll_wait(file, &random_read_wait, wait);
+	poll_wait(file, &crng_init_wait, wait);
 	poll_wait(file, &random_write_wait, wait);
 	mask = 0;
-	if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
+	if (crng_ready())
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
 		mask |= EPOLLOUT | EPOLLWRNORM;
-- 
2.23.0


  parent reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-23  8:20 [PATCH v3 0/8] Rework random blocking Andy Lutomirski
2019-12-23  8:20 ` [PATCH v3 1/8] random: Don't wake crng_init_wait when crng_init == 1 Andy Lutomirski
2020-01-07 20:42   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 2/8] random: Add a urandom_read_nowait() for random APIs that don't warn Andy Lutomirski
2020-01-07 20:43   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 3/8] random: Add GRND_INSECURE to return best-effort non-cryptographic bytes Andy Lutomirski
2020-01-07 20:44   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 4/8] random: Ignore GRND_RANDOM in getentropy(2) Andy Lutomirski
2020-01-07 20:44   ` Theodore Y. Ts'o
2019-12-23  8:20 ` Andy Lutomirski [this message]
2020-01-07 21:02   ` [PATCH v3 5/8] random: Make /dev/random be almost like /dev/urandom Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 6/8] random: Remove the blocking pool Andy Lutomirski
2020-01-07 21:03   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 7/8] random: Delete code to pull data into pools Andy Lutomirski
2020-01-07 21:03   ` Theodore Y. Ts'o
2019-12-23  8:20 ` [PATCH v3 8/8] random: Remove kernel.random.read_wakeup_threshold Andy Lutomirski
2020-01-07 21:04   ` Theodore Y. Ts'o
2019-12-26  9:29 ` [PATCH v3 0/8] Rework random blocking Stephan Müller
2019-12-26 10:03   ` Matthew Garrett
2019-12-26 11:40     ` Stephan Mueller
2019-12-26 11:12   ` Andy Lutomirski
2019-12-26 12:03     ` Stephan Mueller
2019-12-26 12:46       ` Andy Lutomirski
2019-12-27  9:55         ` Stephan Mueller
2019-12-26 14:04       ` Theodore Y. Ts'o
2019-12-26 23:29         ` Andy Lutomirski
2019-12-27 10:29           ` Stephan Mueller
2019-12-27 13:04             ` Theodore Y. Ts'o
2019-12-27 21:22               ` Stephan Mueller
2019-12-27 22:08                 ` Theodore Y. Ts'o
2019-12-28  2:06                   ` Andy Lutomirski
2019-12-29 14:49                     ` Theodore Y. Ts'o
2019-12-29 15:08                       ` Andy Lutomirski
2019-12-28  7:01                   ` Willy Tarreau
2020-01-09 22:02                   ` Kurt Roeckx
2020-01-09 22:40                     ` Theodore Y. Ts'o
2020-01-09 23:02                       ` Kurt Roeckx
2020-01-10  7:53                         ` Stephan Mueller
2020-01-10  0:30                     ` Andy Lutomirski

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