[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 <[EMAIL PROTECTED]>
---
crypto/api.c | 6 ++++++
crypto/cipher.c | 43 ++++++++++++++++++++++++++++++++++++-------
crypto/scatterwalk.h | 6 ++++++
include/linux/crypto.h | 1 +
4 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/crypto/api.c b/crypto/api.c
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -168,6 +168,12 @@ int crypto_register_alg(struct crypto_al
{
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);
diff --git a/crypto/cipher.c b/crypto/cipher.c
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -41,8 +41,10 @@ static unsigned int crypt_slow(const str
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 str
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_des
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_des
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_des
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,
diff --git a/crypto/scatterwalk.h b/crypto/scatterwalk.h
--- a/crypto/scatterwalk.h
+++ b/crypto/scatterwalk.h
@@ -55,6 +55,12 @@ static inline void scatterwalk_advance(s
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);
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -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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