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random: initialize ChaCha20 constants with correct endianness 

On big endian CPUs, the ChaCha20-based CRNG is using the wrong
endianness for the ChaCha20 constants.

This doesn't matter cryptographically, but technically it means it's not
ChaCha20 anymore.  Fix it to always use the standard constants.

Cc: linux-crypto@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2021-03-21 22:13:47 -07:00 committed by Herbert Xu
parent 30d0f6a956
commit a181e0fdb2
2 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/char/random.c
View File

@ -819,7 +819,7 @@ static bool __init crng_init_try_arch_early(struct crng_state *crng)
static void __maybe_unused crng_initialize_secondary(struct crng_state *crng)
{
memcpy(&crng->state[0], "expand 32-byte k", 16);
chacha_init_consts(crng->state);
_get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
crng_init_try_arch(crng);
crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
@ -827,7 +827,7 @@ static void __maybe_unused crng_initialize_secondary(struct crng_state *crng)
static void __init crng_initialize_primary(struct crng_state *crng)
{
memcpy(&crng->state[0], "expand 32-byte k", 16);
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) {
invalidate_batched_entropy();

9
include/crypto/chacha.h
View File

@ -47,13 +47,18 @@ static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
hchacha_block_generic(state, out, nrounds);
}
void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
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" */
}
void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
{
chacha_init_consts(state);
state[4] = key[0];
state[5] = key[1];
state[6] = key[2];