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Commit 40db23e5 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

random: make add_timer_randomness() fill the nonblocking pool first 



Change add_timer_randomness() so that it directs incoming entropy to
the nonblocking pool first if it hasn't been fully initialized yet.
This matches the strategy we use in add_interrupt_randomness(), which
allows us to push the randomness where we need it the most during when
the system is first booting up, so that get_random_bytes() and
/dev/urandom become safe to use as soon as possible.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent f80bbd8b

drivers/char/random.c

+4 −3
Original line number Diff line number Diff line
@@ -761,6 +761,7 @@ static struct timer_rand_state input_timer_state; 
 */

static void add_timer_randomness(struct timer_rand_state *state, unsigned num)

{

	struct entropy_store	*r;

	struct {

		long jiffies;

		unsigned cycles;
@@ -773,7 +774,8 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) 
	sample.jiffies = jiffies;

	sample.cycles = random_get_entropy();

	sample.num = num;

	mix_pool_bytes(&input_pool, &sample, sizeof(sample), NULL);

	r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;

	mix_pool_bytes(r, &sample, sizeof(sample), NULL);



	/*

	 * Calculate number of bits of randomness we probably added.
@@ -807,8 +809,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) 
		 * Round down by 1 bit on general principles,

		 * and limit entropy entimate to 12 bits.

		 */

		credit_entropy_bits(&input_pool,

				    min_t(int, fls(delta>>1), 11));

		credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));

	}

	preempt_enable();

}