Messages in this thread Patch in this message |  | | From | "Jason A. Donenfeld" <> | Subject | [PATCH] random: mix build-time latent entropy into pool at init | Date | Thu, 31 Mar 2022 11:07:06 -0400 |
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Prior, the "input_pool_data" array needed no real initialization, and so it was easy to mark it with __latent_entropy to populate it during compile-time. In switching to using a hash function, this required us to specifically initialize it to some specific state, which means we dropped the __latent_entropy attribute. An unfortunate side effect was this meant the pool was no longer seeded using compile-time random data. In order to bring this back, we declare an array in rand_initialize() with __latent_entropy and call mix_pool_bytes() on that at init, which accomplishes the same thing as before.
Fixes: 6e8ec2552c7d ("random: use computational hash for entropy extraction") Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- drivers/char/random.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 40107f8b9e9e..3a245686809c 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -975,6 +975,11 @@ int __init rand_initialize(void) bool arch_init = true; unsigned long rv; +#if defined(LATENT_ENTROPY_PLUGIN) + static u8 init_latent_entropy[BLAKE2S_BLOCK_SIZE] __latent_entropy; + _mix_pool_bytes(init_latent_entropy, sizeof(init_latent_entropy)); +#endif + for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { if (!arch_get_random_seed_long_early(&rv) && !arch_get_random_long_early(&rv)) { -- 2.35.1
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