[CRYPTO] Add alignmask for low-level cipher implementations
Herbert Xu [Wed, 6 Jul 2005 20:52:09 +0000 (13:52 -0700)]
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>

crypto/api.c
crypto/cipher.c
crypto/scatterwalk.h
include/linux/crypto.h

index 394169a..f55856b 100644 (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);
        
index 54c4a56..85eb12f 100644 (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,
index 5495bb9..e79925c 100644 (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);
index 26ce01c..ac9d49b 100644 (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 {