iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

random: do not use batches when !crng_ready()

Browse Source 
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>
This commit is contained in:
Jason A. Donenfeld 2022-05-03 14:14:32 +02:00 committed by Greg Kroah-Hartman
parent f4c98fe1d1
commit 273aebb50b
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/char/random.c
View File

@ -467,10 +467,8 @@ 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);
@ -626,6 +624,11 @@ 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);
@ -660,6 +663,11 @@ 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);