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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-03-31 11:01:01 -0400 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-03-31 16:43:27 -0400 |
| commit | 1754abb3e7583c570666fa1e1ee5b317e88c89a0 (patch) | |
| tree | 3e4afaa65c5a9390d30d0652974e2943b395da45 | |
| parent | 0396e46dc46523cba8401a0df84f67cc0b6067ab (diff) | |
| download | linux-1754abb3e7583c570666fa1e1ee5b317e88c89a0.tar.gz | |
random: mix build-time latent entropy into pool at init
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. We make this __initconst, so that
it doesn't take up space at runtime after init.
Fixes: 6e8ec2552c7d ("random: use computational hash for entropy extraction")
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
| -rw-r--r-- | drivers/char/random.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 40107f8b9e9ead..1d82429697512a 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 const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy; + _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed)); +#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)) { |