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random: early initialization of ChaCha constants 

Previously, the ChaCha constants for the primary pool were only
initialized in crng_initialize_primary(), called by rand_initialize().
However, some randomness is actually extracted from the primary pool
beforehand, e.g. by kmem_cache_create(). Therefore, statically
initialize the ChaCha constants for the primary pool.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: <linux-crypto@vger.kernel.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Dominik Brodowski 2021-12-31 09:26:08 +01:00 committed by Jason A. Donenfeld
parent 7b87324112
commit 96562f2868
2 changed files with 15 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/char/random.c
View File

@ -457,6 +457,10 @@ struct crng_state {
static struct crng_state primary_crng = {
.lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
.state[0] = CHACHA_CONSTANT_EXPA,
.state[1] = CHACHA_CONSTANT_ND_3,
.state[2] = CHACHA_CONSTANT_2_BY,
.state[3] = CHACHA_CONSTANT_TE_K,
};
/*
@ -823,7 +827,6 @@ static void crng_initialize_secondary(struct crng_state *crng)
static void __init crng_initialize_primary(struct crng_state *crng)
{
chacha_init_consts(crng->state);
_extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0);
if (crng_init_try_arch_early(crng) && trust_cpu && crng_init < 2) {
invalidate_batched_entropy();

15
include/crypto/chacha.h
View File

@ -47,12 +47,19 @@ static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
hchacha_block_generic(state, out, nrounds);
}
enum chacha_constants { /* expand 32-byte k */
CHACHA_CONSTANT_EXPA = 0x61707865U,
CHACHA_CONSTANT_ND_3 = 0x3320646eU,
CHACHA_CONSTANT_2_BY = 0x79622d32U,
CHACHA_CONSTANT_TE_K = 0x6b206574U
};
static inline void chacha_init_consts(u32 *state)
{
state[0] = 0x61707865; /* "expa" */
state[1] = 0x3320646e; /* "nd 3" */
state[2] = 0x79622d32; /* "2-by" */
state[3] = 0x6b206574; /* "te k" */
state[0] = CHACHA_CONSTANT_EXPA;
state[1] = CHACHA_CONSTANT_ND_3;
state[2] = CHACHA_CONSTANT_2_BY;
state[3] = CHACHA_CONSTANT_TE_K;
}
void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);