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Commit 9e49451d authored by Stephan Mueller's avatar Stephan Mueller Committed by Herbert Xu
Browse files

crypto: keywrap - simplify code 



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: default avatarStephan Mueller <smueller@chronox.de>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 5b3f3a8b

crypto/keywrap.c

+26 −58
Original line number Diff line number Diff line
@@ -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;

}