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linux/crypto/cbc.c
Herbert Xu ebc610e5bc [CRYPTO] templates: Pass type/mask when creating instances 
This patch passes the type/mask along when constructing instances of
templates.  This is in preparation for templates that may support
multiple types of instances depending on what is requested.  For example,
the planned software async crypto driver will use this construct.

For the moment this allows us to check whether the instance constructed
is of the correct type and avoid returning success if the type does not
match.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-05-02 14:38:31 +10:00

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/*
* CBC: Cipher Block Chaining mode
*
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
struct crypto_cbc_ctx {
struct crypto_cipher *child;
void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
};
static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key,
unsigned int keylen)
{
struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent);
struct crypto_cipher *child = ctx->child;
int err;
crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(child, key, keylen);
crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
return err;
}
static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
u8 *iv = walk->iv;
do {
xor(iv, src, bsize);
fn(crypto_cipher_tfm(tfm), dst, iv);
memcpy(iv, dst, bsize);
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
return nbytes;
}
static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *iv = walk->iv;
do {
xor(src, iv, bsize);
fn(crypto_cipher_tfm(tfm), src, src);
iv = src;
src += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_cbc_encrypt(struct blkcipher_desc *desc,
struct scatterlist *dst, struct scatterlist *src,
unsigned int nbytes)
{
struct blkcipher_walk walk;
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_cbc_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_cbc_encrypt_inplace(desc, &walk, child,
xor);
else
nbytes = crypto_cbc_encrypt_segment(desc, &walk, child,
xor);
err = blkcipher_walk_done(desc, &walk, nbytes);
}
return err;
}
static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_decrypt;
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
u8 *iv = walk->iv;
do {
fn(crypto_cipher_tfm(tfm), dst, src);
xor(dst, iv, bsize);
iv = src;
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_cipher *tfm,
void (*xor)(u8 *, const u8 *,
unsigned int))
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_decrypt;
int bsize = crypto_cipher_blocksize(tfm);
unsigned long alignmask = crypto_cipher_alignmask(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 stack[bsize + alignmask];
u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
memcpy(first_iv, walk->iv, bsize);
/* Start of the last block. */
src += nbytes - nbytes % bsize - bsize;
memcpy(walk->iv, src, bsize);
for (;;) {
fn(crypto_cipher_tfm(tfm), src, src);
if ((nbytes -= bsize) < bsize)
break;
xor(src, src - bsize, bsize);
src -= bsize;
}
xor(src, first_iv, bsize);
return nbytes;
}
static int crypto_cbc_decrypt(struct blkcipher_desc *desc,
struct scatterlist *dst, struct scatterlist *src,
unsigned int nbytes)
{
struct blkcipher_walk walk;
struct crypto_blkcipher *tfm = desc->tfm;
struct crypto_cbc_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_cbc_decrypt_inplace(desc, &walk, child,
xor);
else
nbytes = crypto_cbc_decrypt_segment(desc, &walk, child,
xor);
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_cbc_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_spawn *spawn = crypto_instance_ctx(inst);
struct crypto_cbc_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);
ctx->child = cipher;
return 0;
}
static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm)
{
struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
crypto_free_cipher(ctx->child);
}
static struct crypto_instance *crypto_cbc_alloc(struct rtattr **tb)
{
struct crypto_instance *inst;
struct crypto_alg *alg;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
if (err)
return ERR_PTR(err);
alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
if (IS_ERR(alg))
return ERR_PTR(PTR_ERR(alg));
inst = crypto_alloc_instance("cbc", alg);
if (IS_ERR(inst))
goto out_put_alg;
inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
inst->alg.cra_priority = alg->cra_priority;
inst->alg.cra_blocksize = alg->cra_blocksize;
inst->alg.cra_alignmask = alg->cra_alignmask;
inst->alg.cra_type = &crypto_blkcipher_type;
if (!(alg->cra_blocksize % 4))
inst->alg.cra_alignmask |= 3;
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;
inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
inst->alg.cra_init = crypto_cbc_init_tfm;
inst->alg.cra_exit = crypto_cbc_exit_tfm;
inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;
inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;
inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt;
out_put_alg:
crypto_mod_put(alg);
return inst;
}
static void crypto_cbc_free(struct crypto_instance *inst)
{
crypto_drop_spawn(crypto_instance_ctx(inst));
kfree(inst);
}
static struct crypto_template crypto_cbc_tmpl = {
.name = "cbc",
.alloc = crypto_cbc_alloc,
.free = crypto_cbc_free,
.module = THIS_MODULE,
};
static int __init crypto_cbc_module_init(void)
{
return crypto_register_template(&crypto_cbc_tmpl);
}
static void __exit crypto_cbc_module_exit(void)
{
crypto_unregister_template(&crypto_cbc_tmpl);
}
module_init(crypto_cbc_module_init);
module_exit(crypto_cbc_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CBC block cipher algorithm");
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