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Donenfeld" , Martin Willi , Ard Biesheuvel , linux-kernel@vger.kernel.org, Eric Biggers Subject: [PATCH 5/5] crypto: chacha20 - Fix keystream alignment for chacha20_block() Date: Wed, 22 Nov 2017 11:51:39 -0800 Message-Id: <20171122195139.121269-6-ebiggers3@gmail.com> X-Mailer: git-send-email 2.15.0.448.gf294e3d99a-goog In-Reply-To: <20171122195139.121269-1-ebiggers3@gmail.com> References: <20171122195139.121269-1-ebiggers3@gmail.com> Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers When chacha20_block() outputs the keystream block, it uses 'u32' stores directly. However, the callers (crypto/chacha20_generic.c and drivers/char/random.c) declare the keystream buffer as a 'u8' array, which is not guaranteed to have the needed alignment. Fix it by having both callers declare the keystream as a 'u32' array. For now this is preferable to switching over to the unaligned access macros because chacha20_block() is only being used in cases where we can easily control the alignment (stack buffers). Signed-off-by: Eric Biggers --- crypto/chacha20_generic.c | 6 +++--- drivers/char/random.c | 24 ++++++++++++------------ include/crypto/chacha20.h | 3 ++- lib/chacha20.c | 2 +- 4 files changed, 18 insertions(+), 17 deletions(-) diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c index bb4affbd591c..e451c3cb6a56 100644 --- a/crypto/chacha20_generic.c +++ b/crypto/chacha20_generic.c @@ -18,20 +18,20 @@ static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src, unsigned int bytes) { - u8 stream[CHACHA20_BLOCK_SIZE]; + u32 stream[CHACHA20_BLOCK_WORDS]; if (dst != src) memcpy(dst, src, bytes); while (bytes >= CHACHA20_BLOCK_SIZE) { chacha20_block(state, stream); - crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE); + crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE); bytes -= CHACHA20_BLOCK_SIZE; dst += CHACHA20_BLOCK_SIZE; } if (bytes) { chacha20_block(state, stream); - crypto_xor(dst, stream, bytes); + crypto_xor(dst, (const u8 *)stream, bytes); } } diff --git a/drivers/char/random.c b/drivers/char/random.c index ec42c8bb9b0d..11304bbc78cc 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -431,9 +431,9 @@ static int crng_init = 0; static int crng_init_cnt = 0; #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) static void _extract_crng(struct crng_state *crng, - __u8 out[CHACHA20_BLOCK_SIZE]); + __u32 out[CHACHA20_BLOCK_WORDS]); static void _crng_backtrack_protect(struct crng_state *crng, - __u8 tmp[CHACHA20_BLOCK_SIZE], int used); + __u32 tmp[CHACHA20_BLOCK_WORDS], int used); static void process_random_ready_list(void); static void _get_random_bytes(void *buf, int nbytes); @@ -817,7 +817,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) unsigned long flags; int i, num; union { - __u8 block[CHACHA20_BLOCK_SIZE]; + __u32 block[CHACHA20_BLOCK_WORDS]; __u32 key[8]; } buf; @@ -851,7 +851,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) } static void _extract_crng(struct crng_state *crng, - __u8 out[CHACHA20_BLOCK_SIZE]) + __u32 out[CHACHA20_BLOCK_WORDS]) { unsigned long v, flags; @@ -867,7 +867,7 @@ static void _extract_crng(struct crng_state *crng, spin_unlock_irqrestore(&crng->lock, flags); } -static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) +static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS]) { struct crng_state *crng = NULL; @@ -885,7 +885,7 @@ static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) * enough) to mutate the CRNG key to provide backtracking protection. */ static void _crng_backtrack_protect(struct crng_state *crng, - __u8 tmp[CHACHA20_BLOCK_SIZE], int used) + __u32 tmp[CHACHA20_BLOCK_WORDS], int used) { unsigned long flags; __u32 *s, *d; @@ -897,14 +897,14 @@ static void _crng_backtrack_protect(struct crng_state *crng, used = 0; } spin_lock_irqsave(&crng->lock, flags); - s = (__u32 *) &tmp[used]; + s = &tmp[used / sizeof(__u32)]; d = &crng->state[4]; for (i=0; i < 8; i++) *d++ ^= *s++; spin_unlock_irqrestore(&crng->lock, flags); } -static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used) +static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used) { struct crng_state *crng = NULL; @@ -920,7 +920,7 @@ static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used) static ssize_t extract_crng_user(void __user *buf, size_t nbytes) { ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE; - __u8 tmp[CHACHA20_BLOCK_SIZE]; + __u32 tmp[CHACHA20_BLOCK_WORDS]; int large_request = (nbytes > 256); while (nbytes) { @@ -1507,7 +1507,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, */ static void _get_random_bytes(void *buf, int nbytes) { - __u8 tmp[CHACHA20_BLOCK_SIZE]; + __u32 tmp[CHACHA20_BLOCK_WORDS]; trace_get_random_bytes(nbytes, _RET_IP_); @@ -2114,7 +2114,7 @@ u64 get_random_u64(void) if (use_lock) read_lock_irqsave(&batched_entropy_reset_lock, flags); if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { - extract_crng((u8 *)batch->entropy_u64); + extract_crng((__u32 *)batch->entropy_u64); batch->position = 0; } ret = batch->entropy_u64[batch->position++]; @@ -2144,7 +2144,7 @@ u32 get_random_u32(void) if (use_lock) read_lock_irqsave(&batched_entropy_reset_lock, flags); if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { - extract_crng((u8 *)batch->entropy_u32); + extract_crng(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 caaa470389e0..b83d66073db0 100644 --- a/include/crypto/chacha20.h +++ b/include/crypto/chacha20.h @@ -13,12 +13,13 @@ #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, void *stream); +void chacha20_block(u32 *state, u32 *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 250ceed9ec9a..29d3801dee24 100644 --- a/lib/chacha20.c +++ b/lib/chacha20.c @@ -21,7 +21,7 @@ static inline u32 rotl32(u32 v, u8 n) return (v << n) | (v >> (sizeof(v) * 8 - n)); } -extern void chacha20_block(u32 *state, void *stream) +void chacha20_block(u32 *state, u32 *stream) { u32 x[16], *out = stream; int i;