Hi Herbert,
Changes v2:
* use __be64 for A and R variables
* eliminate tbe variable
* use initial IV value with cpu_to_be64 when accessing variable A
---8<---
The code is simplified by using two __be64 values for the operation
instead of using two arrays of u8. This allows to get rid of the memory
alignment code. In addition, the crypto_xor can be replaced with a
native XOR operation. Finally, the definition of the variables is
re-arranged such that the data structures come before simple variables
to potentially reduce memory space.
Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
---
crypto/keywrap.c | 84 ++++++++++++++++++--------------------------------------
1 file changed, 26 insertions(+), 58 deletions(-)
diff --git a/crypto/keywrap.c b/crypto/keywrap.c
index 72014f963ba7..744e35134c45 100644
--- a/crypto/keywrap.c
+++ b/crypto/keywrap.c
@@ -93,18 +93,10 @@ struct crypto_kw_ctx {
struct crypto_kw_block {
#define SEMIBSIZE 8
- u8 A[SEMIBSIZE];
- u8 R[SEMIBSIZE];
+ __be64 A;
+ __be64 R;
};
-/* convert 64 bit integer into its string representation */
-static inline void crypto_kw_cpu_to_be64(u64 val, u8 *buf)
-{
- __be64 *a = (__be64 *)buf;
-
- *a = cpu_to_be64(val);
-}
-
/*
* Fast forward the SGL to the "end" length minus SEMIBSIZE.
* The start in the SGL defined by the fast-forward is returned with
@@ -139,17 +131,10 @@ static int crypto_kw_decrypt(struct blkcipher_desc *desc,
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_kw_ctx *ctx = crypto_blkcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
-
- unsigned long alignmask = max_t(unsigned long, SEMIBSIZE,
- crypto_cipher_alignmask(child));
- unsigned int i;
-
- u8 blockbuf[sizeof(struct crypto_kw_block) + alignmask];
- struct crypto_kw_block *block = (struct crypto_kw_block *)
- PTR_ALIGN(blockbuf + 0, alignmask + 1);
-
- u64 t = 6 * ((nbytes) >> 3);
+ struct crypto_kw_block block;
struct scatterlist *lsrc, *ldst;
+ u64 t = 6 * ((nbytes) >> 3);
+ unsigned int i;
int ret = 0;
/*
@@ -160,7 +145,7 @@ static int crypto_kw_decrypt(struct blkcipher_desc *desc,
return -EINVAL;
/* Place the IV into block A */
- memcpy(block->A, desc->info, SEMIBSIZE);
+ memcpy(&block.A, desc->info, SEMIBSIZE);
/*
* src scatterlist is read-only. dst scatterlist is r/w. During the
@@ -171,32 +156,27 @@ static int crypto_kw_decrypt(struct blkcipher_desc *desc,
ldst = dst;
for (i = 0; i < 6; i++) {
- u8 tbe_buffer[SEMIBSIZE + alignmask];
- /* alignment for the crypto_xor and the _to_be64 operation */
- u8 *tbe = PTR_ALIGN(tbe_buffer + 0, alignmask + 1);
- unsigned int tmp_nbytes = nbytes;
struct scatter_walk src_walk, dst_walk;
+ unsigned int tmp_nbytes = nbytes;
while (tmp_nbytes) {
/* move pointer by tmp_nbytes in the SGL */
crypto_kw_scatterlist_ff(&src_walk, lsrc, tmp_nbytes);
/* get the source block */
- scatterwalk_copychunks(block->R, &src_walk, SEMIBSIZE,
+ scatterwalk_copychunks(&block.R, &src_walk, SEMIBSIZE,
false);
- /* perform KW operation: get counter as byte string */
- crypto_kw_cpu_to_be64(t, tbe);
/* perform KW operation: modify IV with counter */
- crypto_xor(block->A, tbe, SEMIBSIZE);
+ block.A ^= cpu_to_be64(t);
t--;
/* perform KW operation: decrypt block */
- crypto_cipher_decrypt_one(child, (u8*)block,
- (u8*)block);
+ crypto_cipher_decrypt_one(child, (u8*)&block,
+ (u8*)&block);
/* move pointer by tmp_nbytes in the SGL */
crypto_kw_scatterlist_ff(&dst_walk, ldst, tmp_nbytes);
/* Copy block->R into place */
- scatterwalk_copychunks(block->R, &dst_walk, SEMIBSIZE,
+ scatterwalk_copychunks(&block.R, &dst_walk, SEMIBSIZE,
true);
tmp_nbytes -= SEMIBSIZE;
@@ -208,11 +188,10 @@ static int crypto_kw_decrypt(struct blkcipher_desc *desc,
}
/* Perform authentication check */
- if (crypto_memneq("\xA6\xA6\xA6\xA6\xA6\xA6\xA6\xA6", block->A,
- SEMIBSIZE))
+ if (block.A != cpu_to_be64(0xa6a6a6a6a6a6a6a6))
ret = -EBADMSG;
- memzero_explicit(block, sizeof(struct crypto_kw_block));
+ memzero_explicit(&block, sizeof(struct crypto_kw_block));
return ret;
}
@@ -224,17 +203,10 @@ static int crypto_kw_encrypt(struct blkcipher_desc *desc,
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_kw_ctx *ctx = crypto_blkcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
-
- unsigned long alignmask = max_t(unsigned long, SEMIBSIZE,
- crypto_cipher_alignmask(child));
- unsigned int i;
-
- u8 blockbuf[sizeof(struct crypto_kw_block) + alignmask];
- struct crypto_kw_block *block = (struct crypto_kw_block *)
- PTR_ALIGN(blockbuf + 0, alignmask + 1);
-
- u64 t = 1;
+ struct crypto_kw_block block;
struct scatterlist *lsrc, *ldst;
+ u64 t = 1;
+ unsigned int i;
/*
* Require at least 2 semiblocks (note, the 3rd semiblock that is
@@ -249,7 +221,7 @@ static int crypto_kw_encrypt(struct blkcipher_desc *desc,
* Place the predefined IV into block A -- for encrypt, the caller
* does not need to provide an IV, but he needs to fetch the final IV.
*/
- memcpy(block->A, "\xA6\xA6\xA6\xA6\xA6\xA6\xA6\xA6", SEMIBSIZE);
+ block.A = cpu_to_be64(0xa6a6a6a6a6a6a6a6);
/*
* src scatterlist is read-only. dst scatterlist is r/w. During the
@@ -260,30 +232,26 @@ static int crypto_kw_encrypt(struct blkcipher_desc *desc,
ldst = dst;
for (i = 0; i < 6; i++) {
- u8 tbe_buffer[SEMIBSIZE + alignmask];
- u8 *tbe = PTR_ALIGN(tbe_buffer + 0, alignmask + 1);
- unsigned int tmp_nbytes = nbytes;
struct scatter_walk src_walk, dst_walk;
+ unsigned int tmp_nbytes = nbytes;
scatterwalk_start(&src_walk, lsrc);
scatterwalk_start(&dst_walk, ldst);
while (tmp_nbytes) {
/* get the source block */
- scatterwalk_copychunks(block->R, &src_walk, SEMIBSIZE,
+ scatterwalk_copychunks(&block.R, &src_walk, SEMIBSIZE,
false);
/* perform KW operation: encrypt block */
- crypto_cipher_encrypt_one(child, (u8 *)block,
- (u8 *)block);
- /* perform KW operation: get counter as byte string */
- crypto_kw_cpu_to_be64(t, tbe);
+ crypto_cipher_encrypt_one(child, (u8 *)&block,
+ (u8 *)&block);
/* perform KW operation: modify IV with counter */
- crypto_xor(block->A, tbe, SEMIBSIZE);
+ block.A ^= cpu_to_be64(t);
t++;
/* Copy block->R into place */
- scatterwalk_copychunks(block->R, &dst_walk, SEMIBSIZE,
+ scatterwalk_copychunks(&block.R, &dst_walk, SEMIBSIZE,
true);
tmp_nbytes -= SEMIBSIZE;
@@ -295,9 +263,9 @@ static int crypto_kw_encrypt(struct blkcipher_desc *desc,
}
/* establish the IV for the caller to pick up */
- memcpy(desc->info, block->A, SEMIBSIZE);
+ memcpy(desc->info, &block.A, SEMIBSIZE);
- memzero_explicit(block, sizeof(struct crypto_kw_block));
+ memzero_explicit(&block, sizeof(struct crypto_kw_block));
return 0;
}
--
2.13.5
