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 <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>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 4dcbae2..528e093 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -817,7 +817,7 @@
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 __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 254298b..2bfbd77 100644
--- a/include/crypto/chacha20.h
+++ b/include/crypto/chacha20.h
@@ -24,4 +24,12 @@
int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes);
+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