Commit cbe89e5a authored by Jason A. Donenfeld's avatar Jason A. Donenfeld
Browse files

random: do not use batches when !crng_ready() 



It's too hard to keep the batches synchronized, and pointless anyway,
since in !crng_ready(), we're updating the base_crng key really often,
where batching only hurts. So instead, if the crng isn't ready, just
call into get_random_bytes(). At this stage nothing is performance
critical anyhow.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent b7b67d13

drivers/char/random.c

+11 −3
Original line number Diff line number Diff line
@@ -466,11 +466,9 @@ static void crng_pre_init_inject(const void *input, size_t len, bool account) 


	if (account) {

		crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);

		if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {

			++base_crng.generation;

		if (crng_init_cnt >= CRNG_INIT_CNT_THRESH)

			crng_init = 1;

	}

	}



	spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -625,6 +623,11 @@ u64 get_random_u64(void) 


	warn_unseeded_randomness(&previous);



	if  (!crng_ready()) {

		_get_random_bytes(&ret, sizeof(ret));

		return ret;

	}



	local_lock_irqsave(&batched_entropy_u64.lock, flags);

	batch = raw_cpu_ptr(&batched_entropy_u64);
@@ -659,6 +662,11 @@ u32 get_random_u32(void) 


	warn_unseeded_randomness(&previous);



	if  (!crng_ready()) {

		_get_random_bytes(&ret, sizeof(ret));

		return ret;

	}



	local_lock_irqsave(&batched_entropy_u32.lock, flags);

	batch = raw_cpu_ptr(&batched_entropy_u32);