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[CRYPTO] pcbc: Use crypto_xor
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This patch replaces the custom xor in CBC with the generic crypto_xor.

It changes the operations for in-place encryption slightly to avoid
calling crypto_xor with tmpbuf since it is not necessarily aligned.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Herbert Xu committed Jan 10, 2008
1 parent 50b6544 commit d0b9007
Showing 1 changed file with 24 additions and 81 deletions.
105 changes: 24 additions & 81 deletions crypto/pcbc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,6 @@

struct crypto_pcbc_ctx {
struct crypto_cipher *child;
void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
};

static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
Expand All @@ -45,9 +44,7 @@ static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,

static int crypto_pcbc_encrypt_segment(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
struct crypto_cipher *tfm)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
Expand All @@ -58,10 +55,10 @@ static int crypto_pcbc_encrypt_segment(struct blkcipher_desc *desc,
u8 *iv = walk->iv;

do {
xor(iv, src, bsize);
crypto_xor(iv, src, bsize);
fn(crypto_cipher_tfm(tfm), dst, iv);
memcpy(iv, dst, bsize);
xor(iv, src, bsize);
crypto_xor(iv, src, bsize);

src += bsize;
dst += bsize;
Expand All @@ -72,9 +69,7 @@ static int crypto_pcbc_encrypt_segment(struct blkcipher_desc *desc,

static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
struct crypto_cipher *tfm)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
Expand All @@ -86,10 +81,10 @@ static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,

do {
memcpy(tmpbuf, src, bsize);
xor(iv, tmpbuf, bsize);
crypto_xor(iv, src, bsize);
fn(crypto_cipher_tfm(tfm), src, iv);
memcpy(iv, src, bsize);
xor(iv, tmpbuf, bsize);
memcpy(iv, tmpbuf, bsize);
crypto_xor(iv, src, bsize);

src += bsize;
} while ((nbytes -= bsize) >= bsize);
Expand All @@ -107,19 +102,18 @@ static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
int err;

blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt(desc, &walk);

while ((nbytes = walk.nbytes)) {
if (walk.src.virt.addr == walk.dst.virt.addr)
nbytes = crypto_pcbc_encrypt_inplace(desc, &walk, child,
xor);
nbytes = crypto_pcbc_encrypt_inplace(desc, &walk,
child);
else
nbytes = crypto_pcbc_encrypt_segment(desc, &walk, child,
xor);
nbytes = crypto_pcbc_encrypt_segment(desc, &walk,
child);
err = blkcipher_walk_done(desc, &walk, nbytes);
}

Expand All @@ -128,9 +122,7 @@ static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,

static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
struct crypto_cipher *tfm)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_decrypt;
Expand All @@ -142,9 +134,9 @@ static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,

do {
fn(crypto_cipher_tfm(tfm), dst, src);
xor(dst, iv, bsize);
crypto_xor(dst, iv, bsize);
memcpy(iv, src, bsize);
xor(iv, dst, bsize);
crypto_xor(iv, dst, bsize);

src += bsize;
dst += bsize;
Expand All @@ -157,9 +149,7 @@ static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,

static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
struct crypto_cipher *tfm)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_decrypt;
Expand All @@ -172,9 +162,9 @@ static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
do {
memcpy(tmpbuf, src, bsize);
fn(crypto_cipher_tfm(tfm), src, src);
xor(src, iv, bsize);
crypto_xor(src, iv, bsize);
memcpy(iv, tmpbuf, bsize);
xor(iv, src, bsize);
crypto_xor(iv, src, bsize);

src += bsize;
} while ((nbytes -= bsize) >= bsize);
Expand All @@ -192,79 +182,31 @@ static int crypto_pcbc_decrypt(struct blkcipher_desc *desc,
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
int err;

blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt(desc, &walk);

while ((nbytes = walk.nbytes)) {
if (walk.src.virt.addr == walk.dst.virt.addr)
nbytes = crypto_pcbc_decrypt_inplace(desc, &walk, child,
xor);
nbytes = crypto_pcbc_decrypt_inplace(desc, &walk,
child);
else
nbytes = crypto_pcbc_decrypt_segment(desc, &walk, child,
xor);
nbytes = crypto_pcbc_decrypt_segment(desc, &walk,
child);
err = blkcipher_walk_done(desc, &walk, nbytes);
}

return err;
}

static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
{
do {
*a++ ^= *b++;
} while (--bs);
}

static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
{
u32 *a = (u32 *)dst;
u32 *b = (u32 *)src;

do {
*a++ ^= *b++;
} while ((bs -= 4));
}

static void xor_64(u8 *a, const u8 *b, unsigned int bs)
{
((u32 *)a)[0] ^= ((u32 *)b)[0];
((u32 *)a)[1] ^= ((u32 *)b)[1];
}

static void xor_128(u8 *a, const u8 *b, unsigned int bs)
{
((u32 *)a)[0] ^= ((u32 *)b)[0];
((u32 *)a)[1] ^= ((u32 *)b)[1];
((u32 *)a)[2] ^= ((u32 *)b)[2];
((u32 *)a)[3] ^= ((u32 *)b)[3];
}

static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_spawn *spawn = crypto_instance_ctx(inst);
struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
struct crypto_cipher *cipher;

switch (crypto_tfm_alg_blocksize(tfm)) {
case 8:
ctx->xor = xor_64;
break;

case 16:
ctx->xor = xor_128;
break;

default:
if (crypto_tfm_alg_blocksize(tfm) % 4)
ctx->xor = xor_byte;
else
ctx->xor = xor_quad;
}

cipher = crypto_spawn_cipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
Expand Down Expand Up @@ -304,8 +246,9 @@ static struct crypto_instance *crypto_pcbc_alloc(struct rtattr **tb)
inst->alg.cra_alignmask = alg->cra_alignmask;
inst->alg.cra_type = &crypto_blkcipher_type;

if (!(alg->cra_blocksize % 4))
inst->alg.cra_alignmask |= 3;
/* We access the data as u32s when xoring. */
inst->alg.cra_alignmask |= __alignof__(u32) - 1;

inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
Expand Down

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