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| author | Theodore Ts'o <tytso@mit.edu> | 2018-04-25 08:12:32 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-02 01:13:04 +0300 |
| commit | 17e20c8b5a2c0165516f9595e6ef65471326d532 (patch) | |
| tree | 2a37333ea063a416d71369e830ef4ef638491e6d /drivers/char/random.c | |
| parent | c3ff2da5cef05676d490fa9057b2dceb5e48cdb9 (diff) | |
| download | linux-17e20c8b5a2c0165516f9595e6ef65471326d532.tar.xz | |
random: rate limit unseeded randomness warnings
commit 4e00b339e264802851aff8e73cde7d24b57b18ce upstream.
On systems without sufficient boot randomness, no point spamming dmesg.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index dbfb3e69600b..ddeac4eefd0a 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -259,6 +259,7 @@ #include <linux/kmemcheck.h> #include <linux/workqueue.h> #include <linux/irq.h> +#include <linux/ratelimit.h> #include <linux/syscalls.h> #include <linux/completion.h> #include <linux/uuid.h> @@ -444,6 +445,16 @@ static void _crng_backtrack_protect(struct crng_state *crng, __u8 tmp[CHACHA20_BLOCK_SIZE], int used); static void process_random_ready_list(void); +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"); + /********************************************************************** * * OS independent entropy store. Here are the functions which handle @@ -886,6 +897,18 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) process_random_ready_list(); wake_up_interruptible(&crng_init_wait); pr_notice("random: crng init done\n"); + if (unseeded_warning.missed) { + pr_notice("random: %d get_random_xx warning(s) missed " + "due to ratelimiting\n", + unseeded_warning.missed); + unseeded_warning.missed = 0; + } + if (urandom_warning.missed) { + pr_notice("random: %d urandom warning(s) missed " + "due to ratelimiting\n", + urandom_warning.missed); + urandom_warning.missed = 0; + } } spin_unlock_irqrestore(&crng->lock, flags); } @@ -1699,6 +1722,10 @@ static int rand_initialize(void) init_std_data(&blocking_pool); crng_initialize(&primary_crng); crng_global_init_time = jiffies; + if (ratelimit_disable) { + urandom_warning.interval = 0; + unseeded_warning.interval = 0; + } return 0; } early_initcall(rand_initialize); @@ -1766,9 +1793,10 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) if (!crng_ready() && maxwarn > 0) { maxwarn--; - printk(KERN_NOTICE "random: %s: uninitialized urandom read " - "(%zd bytes read)\n", - current->comm, nbytes); + if (__ratelimit(&urandom_warning)) + printk(KERN_NOTICE "random: %s: uninitialized " + "urandom read (%zd bytes read)\n", + current->comm, nbytes); spin_lock_irqsave(&primary_crng.lock, flags); crng_init_cnt = 0; spin_unlock_irqrestore(&primary_crng.lock, flags); |