From 7ec9cf3a155f1c3002c4aa4928f54447c7bb5ba3 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Sun, 21 Mar 2021 22:13:47 -0700 Subject: [PATCH] random: initialize ChaCha20 constants with correct endianness commit a181e0fdb2164268274453b5b291589edbb9b22d upstream. 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 Cc: Jann Horn Cc: Theodore Ts'o Acked-by: Ard Biesheuvel Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 4 ++-- include/crypto/chacha20.h | 8 ++++++++ 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 7057d521695be..2c059987d28fe 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -817,7 +817,7 @@ static bool __init crng_init_try_arch_early(struct crng_state *crng) static void 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; @@ -825,7 +825,7 @@ static void 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 && crng_init < 2) { invalidate_batched_entropy(); diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h index f76302d99e2be..da08504e347e5 100644 --- a/include/crypto/chacha20.h +++ b/include/crypto/chacha20.h @@ -24,4 +24,12 @@ int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, unsigned int keysize); int crypto_chacha20_crypt(struct skcipher_request *req); +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" */ +} + #endif -- 2.47.3