This is a note to let you know that I've just added the patch titled
random: move initialization out of reseeding hot path
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
random-move-initialization-out-of-reseeding-hot-path.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu May 26 04:17:01 PM CEST 2022
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Date: Mon, 9 May 2022 13:53:24 +0200
Subject: random: move initialization out of reseeding hot path
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
commit 68c9c8b192c6dae9be6278e98ee44029d5da2d31 upstream.
Initialization happens once -- by way of credit_init_bits() -- and then
it never happens again. Therefore, it doesn't need to be in
crng_reseed(), which is a hot path that is called multiple times. It
also doesn't make sense to have there, as initialization activity is
better associated with initialization routines.
After the prior commit, crng_reseed() now won't be called by multiple
concurrent callers, which means that we can safely move the
"finialize_init" logic into crng_init_bits() unconditionally.
Reviewed-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/random.c | 42 +++++++++++++++++++-----------------------
1 file changed, 19 insertions(+), 23 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -264,7 +264,6 @@ static void crng_reseed(void)
unsigned long flags;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
- bool finalize_init = false;
extract_entropy(key, sizeof(key));
@@ -281,28 +280,10 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (!crng_ready()) {
+ if (!crng_ready())
crng_init = CRNG_READY;
- finalize_init = true;
- }
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
- if (finalize_init) {
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
- }
}
/*
@@ -834,10 +815,25 @@ static void credit_init_bits(size_t nbit
new = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
- if (orig < POOL_READY_BITS && new >= POOL_READY_BITS)
- crng_reseed();
- else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+ crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ process_random_ready_list();
+ wake_up_interruptible(&crng_init_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ pr_notice("crng init done\n");
+ if (unseeded_warning.missed) {
+ pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
+ unseeded_warning.missed);
+ unseeded_warning.missed = 0;
+ }
+ if (urandom_warning.missed) {
+ pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+ urandom_warning.missed);
+ urandom_warning.missed = 0;
+ }
+ } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
+ /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_init = CRNG_EARLY;
Patches currently in stable-queue which might be from Jason@xxxxxxxxx are
queue-5.18/random-remove-ratelimiting-for-in-kernel-unseeded-randomness.patch
queue-5.18/random-fix-sysctl-documentation-nits.patch
queue-5.18/random-help-compiler-out-with-fast_mix-by-using-simpler-arguments.patch
queue-5.18/siphash-use-one-source-of-truth-for-siphash-permutations.patch
queue-5.18/um-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/random-order-timer-entropy-functions-below-interrupt-functions.patch
queue-5.18/random-unify-batched-entropy-implementations.patch
queue-5.18/random-make-consistent-use-of-buf-and-len.patch
queue-5.18/random-move-randomize_page-into-mm-where-it-belongs.patch
queue-5.18/random-use-first-128-bits-of-input-as-fast-init.patch
queue-5.18/random-use-proper-return-types-on-get_random_-int-long-_wait.patch
queue-5.18/s390-define-get_cycles-macro-for-arch-override.patch
queue-5.18/timekeeping-add-raw-clock-fallback-for-random_get_entropy.patch
queue-5.18/random-use-static-branch-for-crng_ready.patch
queue-5.18/arm-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/mips-use-fallback-for-random_get_entropy-instead-of-just-c0-random.patch
queue-5.18/random-avoid-initializing-twice-in-credit-race.patch
queue-5.18/random-move-initialization-functions-out-of-hot-pages.patch
queue-5.18/random-do-not-pretend-to-handle-premature-next-security-model.patch
queue-5.18/random-do-not-use-batches-when-crng_ready.patch
queue-5.18/m68k-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/random-move-initialization-out-of-reseeding-hot-path.patch
queue-5.18/x86-tsc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/random-credit-architectural-init-the-exact-amount.patch
queue-5.18/random-check-for-signals-after-page-of-pool-writes.patch
queue-5.18/random-remove-extern-from-functions-in-header.patch
queue-5.18/random-do-not-use-input-pool-from-hard-irqs.patch
queue-5.18/random-wire-up-fops-splice_-read-write-_iter.patch
queue-5.18/random-insist-on-random_get_entropy-existing-in-order-to-simplify.patch
queue-5.18/powerpc-define-get_cycles-macro-for-arch-override.patch
queue-5.18/parisc-define-get_cycles-macro-for-arch-override.patch
queue-5.18/sparc-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/nios2-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/init-call-time_init-before-rand_initialize.patch
queue-5.18/riscv-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/ia64-define-get_cycles-macro-for-arch-override.patch
queue-5.18/random-handle-latent-entropy-and-command-line-from-random_init.patch
queue-5.18/random-use-proper-jiffies-comparison-macro.patch
queue-5.18/alpha-define-get_cycles-macro-for-arch-override.patch
queue-5.18/random-convert-to-using-fops-read_iter.patch
queue-5.18/xtensa-use-fallback-for-random_get_entropy-instead-of-zero.patch
queue-5.18/random-use-symbolic-constants-for-crng_init-states.patch
queue-5.18/random-convert-to-using-fops-write_iter.patch
