lkml.org 
[lkml]   [2022]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.15 120/145] random: do not use batches when !crng_ready()
Date
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
@@ -467,10 +467,8 @@ 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);
@@ -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);


\
 
 \ /
  Last update: 2022-05-27 14:18    [W:0.773 / U:0.652 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site