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Commit d863ca1a authored by Alexander Alexeev's avatar Alexander Alexeev
Browse files

BACKPORT: crypto: chacha20 - Fix keystream alignment for chacha20_block() 

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).

Based on commit: https://github.com/torvalds/linux/commit/9f480faec58cd6197a007ea1dcac6b7c3daf1139



Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 5fb2def0

crypto/chacha20_generic.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -23,20 +23,20 @@ static inline u32 le32_to_cpuvp(const void *p) 
static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,

static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,

			     unsigned int bytes)

			     unsigned int bytes)

{

{

	u8 stream[CHACHA20_BLOCK_SIZE];

	u32 stream[CHACHA20_BLOCK_WORDS];





	if (dst != src)

	if (dst != src)

		memcpy(dst, src, bytes);

		memcpy(dst, src, bytes);





	while (bytes >= CHACHA20_BLOCK_SIZE) {

	while (bytes >= CHACHA20_BLOCK_SIZE) {

		chacha20_block(state, stream);

		chacha20_block(state, stream);

		crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);

		crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE);

		bytes -= CHACHA20_BLOCK_SIZE;

		bytes -= CHACHA20_BLOCK_SIZE;

		dst += CHACHA20_BLOCK_SIZE;

		dst += CHACHA20_BLOCK_SIZE;

	}

	}

	if (bytes) {

	if (bytes) {

		chacha20_block(state, stream);

		chacha20_block(state, stream);

		crypto_xor(dst, stream, bytes);

		crypto_xor(dst, (const u8 *)stream, bytes);

	}

	}

}

}

drivers/char/random.c

+10 −10
Original line number Original line Diff line number Diff line
@@ -438,9 +438,9 @@ static int crng_init = 0; 
static int crng_init_cnt = 0;

static int crng_init_cnt = 0;

#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)

#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)

static void _extract_crng(struct crng_state *crng,

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,

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 process_random_ready_list(void);





/**********************************************************************

/**********************************************************************
@@ -813,7 +813,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) 
	unsigned long	flags;

	unsigned long	flags;

	int		i, num;

	int		i, num;

	union {

	union {

		__u8	block[CHACHA20_BLOCK_SIZE];

		__u32	block[CHACHA20_BLOCK_WORDS];

		__u32	key[8];

		__u32	key[8];

	} buf;

	} buf;
@@ -858,7 +858,7 @@ static inline void crng_wait_ready(void) 
}

}





static void _extract_crng(struct crng_state *crng,

static void _extract_crng(struct crng_state *crng,

			  __u8 out[CHACHA20_BLOCK_SIZE])

			  __u32 out[CHACHA20_BLOCK_WORDS])

{

{

	unsigned long v, flags;

	unsigned long v, flags;
@@ -874,7 +874,7 @@ static void _extract_crng(struct crng_state *crng, 
	spin_unlock_irqrestore(&crng->lock, flags);

	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;

	struct crng_state *crng = NULL;

	crng = &primary_crng;

	crng = &primary_crng;
@@ -886,7 +886,7 @@ static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) 
 * enough) to mutate the CRNG key to provide backtracking protection.

 * enough) to mutate the CRNG key to provide backtracking protection.

 */

 */

static void _crng_backtrack_protect(struct crng_state *crng,

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;

	unsigned long	flags;

	__u32		*s, *d;

	__u32		*s, *d;
@@ -898,14 +898,14 @@ static void _crng_backtrack_protect(struct crng_state *crng, 
		used = 0;

		used = 0;

	}

	}

	spin_lock_irqsave(&crng->lock, flags);

	spin_lock_irqsave(&crng->lock, flags);

	s = (__u32 *) &tmp[used];

	s = &tmp[used / sizeof(__u32)];

	d = &crng->state[4];

	d = &crng->state[4];

	for (i=0; i < 8; i++)

	for (i=0; i < 8; i++)

		*d++ ^= *s++;

		*d++ ^= *s++;

	spin_unlock_irqrestore(&crng->lock, flags);

	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;

	struct crng_state *crng = NULL;
@@ -916,7 +916,7 @@ static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used) 
static ssize_t extract_crng_user(void __user *buf, size_t nbytes)

static ssize_t extract_crng_user(void __user *buf, size_t nbytes)

{

{

	ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;

	ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;

	__u8 tmp[CHACHA20_BLOCK_SIZE];

	__u32 tmp[CHACHA20_BLOCK_WORDS];

	int large_request = (nbytes > 256);

	int large_request = (nbytes > 256);





	while (nbytes) {

	while (nbytes) {
@@ -1469,7 +1469,7 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, 
 */

 */

void get_random_bytes(void *buf, int nbytes)

void get_random_bytes(void *buf, int nbytes)

{

{

	__u8 tmp[CHACHA20_BLOCK_SIZE];

	__u32 tmp[CHACHA20_BLOCK_WORDS];





#if DEBUG_RANDOM_BOOT > 0

#if DEBUG_RANDOM_BOOT > 0

	if (!crng_ready())

	if (!crng_ready())

include/crypto/chacha20.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -11,12 +11,13 @@ 
#define CHACHA20_IV_SIZE	16

#define CHACHA20_IV_SIZE	16

#define CHACHA20_KEY_SIZE	32

#define CHACHA20_KEY_SIZE	32

#define CHACHA20_BLOCK_SIZE	64

#define CHACHA20_BLOCK_SIZE	64

#define CHACHA20_BLOCK_WORDS	(CHACHA20_BLOCK_SIZE / sizeof(u32))





struct chacha20_ctx {

struct chacha20_ctx {

	u32 key[8];

	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);

void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv);

int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,

int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,

			   unsigned int keysize);

			   unsigned int keysize);

lib/chacha20.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -21,7 +21,7 @@ static inline u32 rotl32(u32 v, u8 n) 
	return (v << n) | (v >> (sizeof(v) * 8 - 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;

	u32 x[16], *out = stream;

	int i;

	int i;