random: cap the rate which the /dev/urandom pool gets reseeded (f5c2742c) · Commits · 戴 / test

drivers/char/random.c

+24 −0

Original line number	Original line	Diff line number	Diff line
	@@ -306,6 +306,13 @@ static int random_read_wakeup_thresh = 64;
	*/		*/
	static int random_write_wakeup_thresh = 128;		static int random_write_wakeup_thresh = 128;

			/*
			* The minimum number of seconds between urandom pool resending. We
			* do this to limit the amount of entropy that can be drained from the
			* input pool even if there are heavy demands on /dev/urandom.
			*/
			static int random_min_urandom_seed = 60;

	/*		/*
	* When the input pool goes over trickle_thresh, start dropping most		* When the input pool goes over trickle_thresh, start dropping most
	* samples to avoid wasting CPU time and reduce lock contention.		* samples to avoid wasting CPU time and reduce lock contention.
	@@ -438,6 +445,7 @@ struct entropy_store {
	struct entropy_store *pull;		struct entropy_store *pull;

	/* read-write data: */		/* read-write data: */
			unsigned long last_pulled;
	spinlock_t lock;		spinlock_t lock;
	unsigned short add_ptr;		unsigned short add_ptr;
	unsigned short input_rotate;		unsigned short input_rotate;
	@@ -887,6 +895,14 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
	{		{
	__u32 tmp[OUTPUT_POOL_WORDS];		__u32 tmp[OUTPUT_POOL_WORDS];

			if (r->limit == 0 && random_min_urandom_seed) {
			unsigned long now = jiffies;

			if (time_before(now,
			r->last_pulled + random_min_urandom_seed * HZ))
			return;
			r->last_pulled = now;
			}
	if (r->pull &&		if (r->pull &&
	r->entropy_count < (nbytes << (ENTROPY_SHIFT + 3)) &&		r->entropy_count < (nbytes << (ENTROPY_SHIFT + 3)) &&
	r->entropy_count < r->poolinfo->poolfracbits) {		r->entropy_count < r->poolinfo->poolfracbits) {
	@@ -1190,6 +1206,7 @@ static void init_std_data(struct entropy_store *r)
	r->entropy_count = 0;		r->entropy_count = 0;
	r->entropy_total = 0;		r->entropy_total = 0;
	r->last_data_init = 0;		r->last_data_init = 0;
			r->last_pulled = jiffies;
	mix_pool_bytes(r, &now, sizeof(now), NULL);		mix_pool_bytes(r, &now, sizeof(now), NULL);
	for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {		for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
	if (!arch_get_random_long(&rv))		if (!arch_get_random_long(&rv))
	@@ -1540,6 +1557,13 @@ struct ctl_table random_table[] = {
	.extra1 = &min_write_thresh,		.extra1 = &min_write_thresh,
	.extra2 = &max_write_thresh,		.extra2 = &max_write_thresh,
	},		},
			{
			.procname = "urandom_min_reseed_secs",
			.data = &random_min_urandom_seed,
			.maxlen = sizeof(int),
			.mode = 0644,
			.proc_handler = proc_dointvec,
			},
	{		{
	.procname = "boot_id",		.procname = "boot_id",
	.data = &sysctl_bootid,		.data = &sysctl_bootid,

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