linux/crypto/pcbc.c

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/*
* PCBC: Propagating Cipher Block Chaining mode
*
* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* Derived from cbc.c
* - 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 <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/compiler.h>
struct crypto_pcbc_ctx {
struct crypto_cipher *child;
};
static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key,
unsigned int keylen)
{
struct crypto_pcbc_ctx *ctx = crypto_skcipher_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_skcipher_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(child, key, keylen);
crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
return err;
}
static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
struct skcipher_walk *walk,
struct crypto_cipher *tfm)
{
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 {
crypto_xor(iv, src, bsize);
crypto_cipher_encrypt_one(tfm, dst, iv);
crypto_xor_cpy(iv, dst, src, bsize);
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
return nbytes;
}
static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
struct skcipher_walk *walk,
struct crypto_cipher *tfm)
{
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *iv = walk->iv;
u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
do {
memcpy(tmpbuf, src, bsize);
crypto_xor(iv, src, bsize);
crypto_cipher_encrypt_one(tfm, src, iv);
crypto_xor_cpy(iv, tmpbuf, src, bsize);
src += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_pcbc_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
struct skcipher_walk walk;
unsigned int nbytes;
int err;
err = skcipher_walk_virt(&walk, req, false);
while ((nbytes = walk.nbytes)) {
if (walk.src.virt.addr == walk.dst.virt.addr)
nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
child);
else
nbytes = crypto_pcbc_encrypt_segment(req, &walk,
child);
err = skcipher_walk_done(&walk, nbytes);
}
return err;
}
static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
struct skcipher_walk *walk,
struct crypto_cipher *tfm)
{
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 {
crypto_cipher_decrypt_one(tfm, dst, src);
crypto_xor(dst, iv, bsize);
crypto_xor_cpy(iv, dst, src, bsize);
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
struct skcipher_walk *walk,
struct crypto_cipher *tfm)
{
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *iv = walk->iv;
u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
do {
memcpy(tmpbuf, src, bsize);
crypto_cipher_decrypt_one(tfm, src, src);
crypto_xor(src, iv, bsize);
crypto_xor_cpy(iv, src, tmpbuf, bsize);
src += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_pcbc_decrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
struct crypto_cipher *child = ctx->child;
struct skcipher_walk walk;
unsigned int nbytes;
int err;
err = skcipher_walk_virt(&walk, req, false);
while ((nbytes = walk.nbytes)) {
if (walk.src.virt.addr == walk.dst.virt.addr)
nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
child);
else
nbytes = crypto_pcbc_decrypt_segment(req, &walk,
child);
err = skcipher_walk_done(&walk, nbytes);
}
return err;
}
static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
struct crypto_cipher *cipher;
cipher = crypto_spawn_cipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
return 0;
}
static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm)
{
struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_free_cipher(ctx->child);
}
static void crypto_pcbc_free(struct skcipher_instance *inst)
{
crypto_drop_skcipher(skcipher_instance_ctx(inst));
kfree(inst);
}
static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct skcipher_instance *inst;
struct crypto_attr_type *algt;
struct crypto_spawn *spawn;
struct crypto_alg *alg;
int err;
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
return PTR_ERR(algt);
if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) &
~CRYPTO_ALG_INTERNAL)
return -EINVAL;
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER |
(algt->type & CRYPTO_ALG_INTERNAL),
CRYPTO_ALG_TYPE_MASK |
(algt->mask & CRYPTO_ALG_INTERNAL));
err = PTR_ERR(alg);
if (IS_ERR(alg))
goto err_free_inst;
spawn = skcipher_instance_ctx(inst);
err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
CRYPTO_ALG_TYPE_MASK);
if (err)
goto err_put_alg;
err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
if (err)
goto err_drop_spawn;
inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
inst->alg.base.cra_alignmask = alg->cra_alignmask;
inst->alg.ivsize = alg->cra_blocksize;
inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
inst->alg.init = crypto_pcbc_init_tfm;
inst->alg.exit = crypto_pcbc_exit_tfm;
inst->alg.setkey = crypto_pcbc_setkey;
inst->alg.encrypt = crypto_pcbc_encrypt;
inst->alg.decrypt = crypto_pcbc_decrypt;
inst->free = crypto_pcbc_free;
err = skcipher_register_instance(tmpl, inst);
if (err)
goto err_drop_spawn;
crypto_mod_put(alg);
out:
return err;
err_drop_spawn:
crypto_drop_spawn(spawn);
err_put_alg:
crypto_mod_put(alg);
err_free_inst:
kfree(inst);
goto out;
}
static struct crypto_template crypto_pcbc_tmpl = {
.name = "pcbc",
.create = crypto_pcbc_create,
.module = THIS_MODULE,
};
static int __init crypto_pcbc_module_init(void)
{
return crypto_register_template(&crypto_pcbc_tmpl);
}
static void __exit crypto_pcbc_module_exit(void)
{
crypto_unregister_template(&crypto_pcbc_tmpl);
}
module_init(crypto_pcbc_module_init);
module_exit(crypto_pcbc_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PCBC block cipher algorithm");
MODULE_ALIAS_CRYPTO("pcbc");