[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: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2005-07-06 13:52:09 -07:00 committed by David S. Miller
parent 40725181b7
commit 9547737799
4 changed files with 49 additions and 7 deletions

View file

@ -168,6 +168,12 @@ 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);

View file

@ -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,

View file

@ -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);

View file

@ -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 {