Commit 4e00b339 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

random: rate limit unseeded randomness warnings 



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

Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent 6c1e851c

drivers/char/random.c

+34 −5
Original line number Diff line number Diff line
@@ -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;

		}

	}

}
@@ -1572,6 +1595,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, 
#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM

	print_once = true;

#endif

	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);
@@ -1834,8 +1862,9 @@ 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",

		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;