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random: rate limit unseeded randomness warnings

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On systems without sufficient boot randomness, no point spamming dmesg.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2018-04-25 01:12:32 -04:00
parent 6c1e851c4e
commit 4e00b339e2
1 changed files with 34 additions and 5 deletions
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39
drivers/char/random.c
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@ -261,6 +261,7 @@
#include <linux/ptrace.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>
@ -438,6 +439,16 @@ static void _crng_backtrack_protect(struct crng_state *crng,
static void process_random_ready_list(void);
static void _get_random_bytes(void *buf, int nbytes);
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
@ -932,6 +943,18 @@ 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;
}
}
}
@ -1572,8 +1595,9 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller,
#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
print_once = true;
#endif
pr_notice("random: %s called from %pS with crng_init=%d\n",
func_name, caller, crng_init);
if (__ratelimit(&unseeded_warning))
pr_notice("random: %s called from %pS with crng_init=%d\n",
func_name, caller, crng_init);
}
/*
@ -1767,6 +1791,10 @@ 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);
@ -1834,9 +1862,10 @@ 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);