Commit 95477377 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[CRYPTO] Add alignmask for low-level cipher implementations 



The VIA Padlock device requires the input and output buffers to
be aligned on 16-byte boundaries.  This patch adds the alignmask
attribute for low-level cipher implementations to indicate their
alignment requirements.

The mid-level crypt() function will copy the input/output buffers
if they are not aligned correctly before they are passed to the
low-level implementation.

Strictly speaking, some of the software implementations require
the buffers to be aligned on 4-byte boundaries as they do 32-bit
loads.  However, it is not clear whether it is better to copy
the buffers or pay the penalty for unaligned loads/stores.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 40725181

crypto/api.c

+6 −0
Original line number Diff line number Diff line
@@ -169,6 +169,12 @@ int crypto_register_alg(struct crypto_alg *alg) 
	int ret = 0;

	struct crypto_alg *q;



	if (alg->cra_alignmask & (alg->cra_alignmask + 1))

		return -EINVAL;



	if (alg->cra_alignmask > PAGE_SIZE)

		return -EINVAL;

	

	down_write(&crypto_alg_sem);

	

	list_for_each_entry(q, &crypto_alg_list, cra_list) {

crypto/cipher.c

+36 −7
Original line number Diff line number Diff line
@@ -41,8 +41,10 @@ static unsigned int crypt_slow(const struct cipher_desc *desc, 
			       struct scatter_walk *in,

			       struct scatter_walk *out, unsigned int bsize)

{

	u8 src[bsize];

	u8 dst[bsize];

	unsigned int alignmask = desc->tfm->__crt_alg->cra_alignmask;

	u8 buffer[bsize * 2 + alignmask];

	u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);

	u8 *dst = src + bsize;

	unsigned int n;



	n = scatterwalk_copychunks(src, in, bsize, 0);
@@ -59,15 +61,24 @@ static unsigned int crypt_slow(const struct cipher_desc *desc, 
static inline unsigned int crypt_fast(const struct cipher_desc *desc,

				      struct scatter_walk *in,

				      struct scatter_walk *out,

				      unsigned int nbytes)

				      unsigned int nbytes, u8 *tmp)

{

	u8 *src, *dst;



	src = in->data;

	dst = scatterwalk_samebuf(in, out) ? src : out->data;



	if (tmp) {

		memcpy(tmp, in->data, nbytes);

		src = tmp;

		dst = tmp;

	}



	nbytes = desc->prfn(desc, dst, src, nbytes);



	if (tmp)

		memcpy(out->data, tmp, nbytes);



	scatterwalk_advance(in, nbytes);

	scatterwalk_advance(out, nbytes);
@@ -87,6 +98,8 @@ static int crypt(const struct cipher_desc *desc, 
	struct scatter_walk walk_in, walk_out;

	struct crypto_tfm *tfm = desc->tfm;

	const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);

	unsigned int alignmask = tfm->__crt_alg->cra_alignmask;

	unsigned long buffer = 0;



	if (!nbytes)

		return 0;
@@ -100,16 +113,27 @@ static int crypt(const struct cipher_desc *desc, 
	scatterwalk_start(&walk_out, dst);



	for(;;) {

		unsigned int n;

		unsigned int n = nbytes;

		u8 *tmp = NULL;



		if (!scatterwalk_aligned(&walk_in, alignmask) ||

		    !scatterwalk_aligned(&walk_out, alignmask)) {

			if (!buffer) {

				buffer = __get_free_page(GFP_ATOMIC);

				if (!buffer)

					n = 0;

			}

			tmp = (u8 *)buffer;

		}



		scatterwalk_map(&walk_in, 0);

		scatterwalk_map(&walk_out, 1);



		n = scatterwalk_clamp(&walk_in, nbytes);

		n = scatterwalk_clamp(&walk_in, n);

		n = scatterwalk_clamp(&walk_out, n);



		if (likely(n >= bsize))

			n = crypt_fast(desc, &walk_in, &walk_out, n);

			n = crypt_fast(desc, &walk_in, &walk_out, n, tmp);

		else

			n = crypt_slow(desc, &walk_in, &walk_out, bsize);
@@ -119,10 +143,15 @@ static int crypt(const struct cipher_desc *desc, 
		scatterwalk_done(&walk_out, 1, nbytes);



		if (!nbytes)

			return 0;

			break;



		crypto_yield(tfm);

	}



	if (buffer)

		free_page(buffer);



	return 0;

}



static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,

crypto/scatterwalk.h

+6 −0
Original line number Diff line number Diff line
@@ -55,6 +55,12 @@ static inline void scatterwalk_advance(struct scatter_walk *walk, 
	walk->len_this_segment -= nbytes;

}



static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,

					       unsigned int alignmask)

{

	return !(walk->offset & alignmask);

}



void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);

int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);

void scatterwalk_map(struct scatter_walk *walk, int out);

include/linux/crypto.h

+1 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ struct crypto_alg { 
	u32 cra_flags;

	unsigned int cra_blocksize;

	unsigned int cra_ctxsize;

	unsigned int cra_alignmask;

	const char cra_name[CRYPTO_MAX_ALG_NAME];



	union {

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