From: "Theodore Ts'o" <tytso@mit.edu>
To: Linux Kernel Developers List <linux-kernel@vger.kernel.org>
Cc: linux-crypto@vger.kernel.org, smueller@chronox.de,
herbert@gondor.apana.org.au, andi@firstfloor.org,
sandyinchina@gmail.com, jsd@av8n.com, hpa@zytor.com,
"Theodore Ts'o" <tytso@mit.edu>,
stable@kernel.org
Subject: [PATCH 2/7] random: print a warning for the first ten uninitialized random users
Date: Mon, 13 Jun 2016 11:48:34 -0400 [thread overview]
Message-ID: <1465832919-11316-3-git-send-email-tytso@mit.edu> (raw)
In-Reply-To: <1465832919-11316-1-git-send-email-tytso@mit.edu>
Since systemd is consistently using /dev/urandom before it is
initialized, we can't see the other potentially dangerous users of
/dev/urandom immediately after boot. So print the first ten such
complaints instead.
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
drivers/char/random.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 4e2627a..74596d3 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1458,12 +1458,16 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
static ssize_t
urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
+ static int maxwarn = 10;
int ret;
- if (unlikely(nonblocking_pool.initialized == 0))
- printk_once(KERN_NOTICE "random: %s urandom read "
- "with %d bits of entropy available\n",
- current->comm, nonblocking_pool.entropy_total);
+ if (unlikely(nonblocking_pool.initialized == 0) &&
+ maxwarn > 0) {
+ maxwarn--;
+ printk(KERN_NOTICE "random: %s: uninitialized urandom read "
+ "(%d bytes read, %d bits of entropy available)\n",
+ current->comm, nbytes, nonblocking_pool.entropy_total);
+ }
nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
--
2.5.0
next prev parent reply other threads:[~2016-06-13 15:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-13 15:48 [PATCH-v4 0/7] random: replace urandom pool with a CRNG Theodore Ts'o
2016-06-13 15:48 ` [PATCH 1/7] random: initialize the non-blocking pool via add_hwgenerator_randomness() Theodore Ts'o
2016-06-13 15:48 ` Theodore Ts'o [this message]
2016-06-13 15:48 ` [PATCH 3/7] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o
2016-06-13 15:48 ` [PATCH 4/7] random: properly align get_random_int_hash Theodore Ts'o
2016-06-13 15:48 ` [PATCH 5/7] random: replace non-blocking pool with a Chacha20-based CRNG Theodore Ts'o
2016-06-13 18:00 ` Stephan Mueller
2016-06-13 19:03 ` Theodore Ts'o
2016-06-15 14:59 ` Herbert Xu
2016-06-19 23:18 ` Theodore Ts'o
2016-06-20 1:25 ` Herbert Xu
2016-06-20 5:02 ` Theodore Ts'o
2016-06-20 5:19 ` Herbert Xu
2016-06-20 15:01 ` Theodore Ts'o
2016-06-20 15:49 ` Stephan Mueller
2016-06-20 18:52 ` H. Peter Anvin
2016-06-20 23:48 ` Theodore Ts'o
2016-06-26 18:47 ` Pavel Machek
2016-06-26 19:10 ` Stephan Mueller
2016-06-26 22:51 ` Theodore Ts'o
2016-06-13 15:48 ` [PATCH 6/7] random: make /dev/urandom scalable for silly userspace programs Theodore Ts'o
2016-08-21 9:53 ` Jan Varho
2016-08-21 11:36 ` Theodore Ts'o
2016-06-13 15:48 ` [PATCH 7/7] random: add backtracking protection to the CRNG Theodore Ts'o
2016-06-26 18:47 ` Pavel Machek
2016-06-26 23:05 ` Theodore Ts'o
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