From cbe89e5a375a51bbb952929b93fa973416fea74e Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 3 May 2022 14:14:32 +0200 Subject: [PATCH] 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 Reviewed-by: Dominik Brodowski Signed-off-by: Jason A. Donenfeld --- drivers/char/random.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 2d10942..a9f887b 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -466,10 +466,8 @@ 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); -- 2.7.4