Commit 96562f28 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Jason A. Donenfeld
Browse files

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: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent 7b873241

drivers/char/random.c

+4 −1
Original line number Diff line number Diff line
@@ -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();

include/crypto/chacha.h

+11 −4
Original line number Diff line number Diff line
@@ -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);