From: Eric Biggers ebiggers@google.com
[ Upstream commit a5e9f557098e54af44ade5d501379be18435bfbf ]
In commit 9f480faec58c ("crypto: chacha20 - Fix keystream alignment for chacha20_block()"), I had missed that chacha20_block() can be called directly on the buffer passed to get_random_bytes(), which can have any alignment. So, while my commit didn't break anything, it didn't fully solve the alignment problems.
Revert my solution and just update chacha20_block() to use put_unaligned_le32(), so the output buffer need not be aligned. This is simpler, and on many CPUs it's the same speed.
But, I kept the 'tmp' buffers in extract_crng_user() and _get_random_bytes() 4-byte aligned, since that alignment is actually needed for _crng_backtrack_protect() too.
Reported-by: Stephan Müller smueller@chronox.de Cc: Theodore Ts'o tytso@mit.edu Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org --- crypto/chacha20_generic.c | 7 ++++--- drivers/char/random.c | 24 ++++++++++++------------ include/crypto/chacha20.h | 3 +-- lib/chacha20.c | 6 +++--- 4 files changed, 20 insertions(+), 20 deletions(-)
diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c index e451c3cb6a56e..3ae96587caf9a 100644 --- a/crypto/chacha20_generic.c +++ b/crypto/chacha20_generic.c @@ -18,20 +18,21 @@ static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src, unsigned int bytes) { - u32 stream[CHACHA20_BLOCK_WORDS]; + /* aligned to potentially speed up crypto_xor() */ + u8 stream[CHACHA20_BLOCK_SIZE] __aligned(sizeof(long));
if (dst != src) memcpy(dst, src, bytes);
while (bytes >= CHACHA20_BLOCK_SIZE) { chacha20_block(state, stream); - crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE); + crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE); bytes -= CHACHA20_BLOCK_SIZE; dst += CHACHA20_BLOCK_SIZE; } if (bytes) { chacha20_block(state, stream); - crypto_xor(dst, (const u8 *)stream, bytes); + crypto_xor(dst, stream, bytes); } }
diff --git a/drivers/char/random.c b/drivers/char/random.c index 0a84b7f468ad0..86fe1df902393 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -433,9 +433,9 @@ static int crng_init_cnt = 0; static unsigned long crng_global_init_time = 0; #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) static void _extract_crng(struct crng_state *crng, - __u32 out[CHACHA20_BLOCK_WORDS]); + __u8 out[CHACHA20_BLOCK_SIZE]); static void _crng_backtrack_protect(struct crng_state *crng, - __u32 tmp[CHACHA20_BLOCK_WORDS], int used); + __u8 tmp[CHACHA20_BLOCK_SIZE], int used); static void process_random_ready_list(void); static void _get_random_bytes(void *buf, int nbytes);
@@ -929,7 +929,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) unsigned long flags; int i, num; union { - __u32 block[CHACHA20_BLOCK_WORDS]; + __u8 block[CHACHA20_BLOCK_SIZE]; __u32 key[8]; } buf;
@@ -976,7 +976,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) }
static void _extract_crng(struct crng_state *crng, - __u32 out[CHACHA20_BLOCK_WORDS]) + __u8 out[CHACHA20_BLOCK_SIZE]) { unsigned long v, flags;
@@ -993,7 +993,7 @@ static void _extract_crng(struct crng_state *crng, spin_unlock_irqrestore(&crng->lock, flags); }
-static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS]) +static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) { struct crng_state *crng = NULL;
@@ -1011,7 +1011,7 @@ static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS]) * enough) to mutate the CRNG key to provide backtracking protection. */ static void _crng_backtrack_protect(struct crng_state *crng, - __u32 tmp[CHACHA20_BLOCK_WORDS], int used) + __u8 tmp[CHACHA20_BLOCK_SIZE], int used) { unsigned long flags; __u32 *s, *d; @@ -1023,14 +1023,14 @@ static void _crng_backtrack_protect(struct crng_state *crng, used = 0; } spin_lock_irqsave(&crng->lock, flags); - s = &tmp[used / sizeof(__u32)]; + s = (__u32 *) &tmp[used]; d = &crng->state[4]; for (i=0; i < 8; i++) *d++ ^= *s++; spin_unlock_irqrestore(&crng->lock, flags); }
-static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used) +static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used) { struct crng_state *crng = NULL;
@@ -1046,7 +1046,7 @@ static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used) static ssize_t extract_crng_user(void __user *buf, size_t nbytes) { ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE; - __u32 tmp[CHACHA20_BLOCK_WORDS]; + __u8 tmp[CHACHA20_BLOCK_SIZE] __aligned(4); int large_request = (nbytes > 256);
while (nbytes) { @@ -1625,7 +1625,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, */ static void _get_random_bytes(void *buf, int nbytes) { - __u32 tmp[CHACHA20_BLOCK_WORDS]; + __u8 tmp[CHACHA20_BLOCK_SIZE] __aligned(4);
trace_get_random_bytes(nbytes, _RET_IP_);
@@ -2251,7 +2251,7 @@ u64 get_random_u64(void) batch = raw_cpu_ptr(&batched_entropy_u64); spin_lock_irqsave(&batch->batch_lock, flags); if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { - extract_crng((__u32 *)batch->entropy_u64); + extract_crng((u8 *)batch->entropy_u64); batch->position = 0; } ret = batch->entropy_u64[batch->position++]; @@ -2278,7 +2278,7 @@ u32 get_random_u32(void) batch = raw_cpu_ptr(&batched_entropy_u32); spin_lock_irqsave(&batch->batch_lock, flags); if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { - extract_crng(batch->entropy_u32); + extract_crng((u8 *)batch->entropy_u32); batch->position = 0; } ret = batch->entropy_u32[batch->position++]; diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h index b83d66073db03..f76302d99e2be 100644 --- a/include/crypto/chacha20.h +++ b/include/crypto/chacha20.h @@ -13,13 +13,12 @@ #define CHACHA20_IV_SIZE 16 #define CHACHA20_KEY_SIZE 32 #define CHACHA20_BLOCK_SIZE 64 -#define CHACHA20_BLOCK_WORDS (CHACHA20_BLOCK_SIZE / sizeof(u32))
struct chacha20_ctx { u32 key[8]; };
-void chacha20_block(u32 *state, u32 *stream); +void chacha20_block(u32 *state, u8 *stream); void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv); int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, unsigned int keysize); diff --git a/lib/chacha20.c b/lib/chacha20.c index c1cc50fb68c9f..d907fec6a9ed1 100644 --- a/lib/chacha20.c +++ b/lib/chacha20.c @@ -16,9 +16,9 @@ #include <asm/unaligned.h> #include <crypto/chacha20.h>
-void chacha20_block(u32 *state, u32 *stream) +void chacha20_block(u32 *state, u8 *stream) { - u32 x[16], *out = stream; + u32 x[16]; int i;
for (i = 0; i < ARRAY_SIZE(x); i++) @@ -67,7 +67,7 @@ void chacha20_block(u32 *state, u32 *stream) }
for (i = 0; i < ARRAY_SIZE(x); i++) - out[i] = cpu_to_le32(x[i] + state[i]); + put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
state[12]++; }