| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.18 21/47] random: do not use batches when !crng_ready() | Date | Fri, 27 May 2022 10:50:01 +0200 |
| |
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit cbe89e5a375a51bbb952929b93fa973416fea74e upstream.
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: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/char/random.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -465,10 +465,8 @@ static void crng_pre_init_inject(const v 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); @@ -624,6 +622,11 @@ 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); @@ -658,6 +661,11 @@ 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);
|