[mirror_ubuntu-artful-kernel.git] / crypto / cbc.c

/*
 * 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/log2.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

struct crypto_cbc_ctx {
	struct crypto_cipher *child;
};

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 (*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 {
		crypto_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 (*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 {
		crypto_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;
	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);
		else
			nbytes = crypto_cbc_encrypt_segment(desc, &walk, child);
		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 (*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);
		crypto_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 (*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 last_iv[bsize];

	/* Start of the last block. */
	src += nbytes - (nbytes & (bsize - 1)) - bsize;
	memcpy(last_iv, src, bsize);

	for (;;) {
		fn(crypto_cipher_tfm(tfm), src, src);
		if ((nbytes -= bsize) < bsize)
			break;
		crypto_xor(src, src - bsize, bsize);
		src -= bsize;
	}

	crypto_xor(src, walk->iv, bsize);
	memcpy(walk->iv, last_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;
	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);
		else
			nbytes = crypto_cbc_decrypt_segment(desc, &walk, child);
		err = blkcipher_walk_done(desc, &walk, nbytes);
	}

	return err;
}

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;

	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_CAST(alg);

	inst = ERR_PTR(-EINVAL);
	if (!is_power_of_2(alg->cra_blocksize))
		goto out_put_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;

	/* 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;

	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");
MODULE_ALIAS_CRYPTO("cbc");
Commit	Line	Data
db131ef9 HX	1	/*
	2	* CBC: Cipher Block Chaining mode
	3	*
	4	* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License as published by the Free
	8	* Software Foundation; either version 2 of the License, or (at your option)
	9	* any later version.
	10	*
	11	*/
	12
	13	#include <crypto/algapi.h>
	14	#include <linux/err.h>
	15	#include <linux/init.h>
	16	#include <linux/kernel.h>
50b6544e	17	#include <linux/log2.h>
db131ef9 HX	18	#include <linux/module.h>
	19	#include <linux/scatterlist.h>
	20	#include <linux/slab.h>
	21
	22	struct crypto_cbc_ctx {
	23	struct crypto_cipher *child;
db131ef9 HX	24	};
	25
	26	static int crypto_cbc_setkey(struct crypto_tfm parent, const u8 key,
	27	unsigned int keylen)
	28	{
	29	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent);
	30	struct crypto_cipher *child = ctx->child;
	31	int err;
	32
	33	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	34	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
	35	CRYPTO_TFM_REQ_MASK);
	36	err = crypto_cipher_setkey(child, key, keylen);
	37	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
	38	CRYPTO_TFM_RES_MASK);
	39	return err;
	40	}
	41
	42	static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,
	43	struct blkcipher_walk *walk,
3c7f076d	44	struct crypto_cipher *tfm)
db131ef9 HX	45	{
	46	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	47	crypto_cipher_alg(tfm)->cia_encrypt;
	48	int bsize = crypto_cipher_blocksize(tfm);
	49	unsigned int nbytes = walk->nbytes;
	50	u8 *src = walk->src.virt.addr;
	51	u8 *dst = walk->dst.virt.addr;
	52	u8 *iv = walk->iv;
	53
	54	do {
3c7f076d	55	crypto_xor(iv, src, bsize);
db131ef9 HX	56	fn(crypto_cipher_tfm(tfm), dst, iv);
	57	memcpy(iv, dst, bsize);
	58
	59	src += bsize;
	60	dst += bsize;
	61	} while ((nbytes -= bsize) >= bsize);
	62
	63	return nbytes;
	64	}
	65
	66	static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
	67	struct blkcipher_walk *walk,
3c7f076d	68	struct crypto_cipher *tfm)
db131ef9 HX	69	{
	70	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	71	crypto_cipher_alg(tfm)->cia_encrypt;
	72	int bsize = crypto_cipher_blocksize(tfm);
	73	unsigned int nbytes = walk->nbytes;
	74	u8 *src = walk->src.virt.addr;
	75	u8 *iv = walk->iv;
	76
	77	do {
3c7f076d	78	crypto_xor(src, iv, bsize);
db131ef9 HX	79	fn(crypto_cipher_tfm(tfm), src, src);
	80	iv = src;
	81
	82	src += bsize;
	83	} while ((nbytes -= bsize) >= bsize);
	84
	85	memcpy(walk->iv, iv, bsize);
	86
	87	return nbytes;
	88	}
	89
	90	static int crypto_cbc_encrypt(struct blkcipher_desc *desc,
	91	struct scatterlist dst, struct scatterlist src,
	92	unsigned int nbytes)
	93	{
	94	struct blkcipher_walk walk;
	95	struct crypto_blkcipher *tfm = desc->tfm;
	96	struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
	97	struct crypto_cipher *child = ctx->child;
db131ef9 HX	98	int err;
	99
	100	blkcipher_walk_init(&walk, dst, src, nbytes);
	101	err = blkcipher_walk_virt(desc, &walk);
	102
	103	while ((nbytes = walk.nbytes)) {
	104	if (walk.src.virt.addr == walk.dst.virt.addr)
3c7f076d	105	nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child);
db131ef9	106	else
3c7f076d	107	nbytes = crypto_cbc_encrypt_segment(desc, &walk, child);
db131ef9 HX	108	err = blkcipher_walk_done(desc, &walk, nbytes);
	109	}
	110
	111	return err;
	112	}
	113
	114	static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
	115	struct blkcipher_walk *walk,
3c7f076d	116	struct crypto_cipher *tfm)
db131ef9 HX	117	{
	118	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	119	crypto_cipher_alg(tfm)->cia_decrypt;
	120	int bsize = crypto_cipher_blocksize(tfm);
	121	unsigned int nbytes = walk->nbytes;
	122	u8 *src = walk->src.virt.addr;
	123	u8 *dst = walk->dst.virt.addr;
	124	u8 *iv = walk->iv;
	125
	126	do {
	127	fn(crypto_cipher_tfm(tfm), dst, src);
3c7f076d	128	crypto_xor(dst, iv, bsize);
db131ef9 HX	129	iv = src;
	130
	131	src += bsize;
	132	dst += bsize;
	133	} while ((nbytes -= bsize) >= bsize);
	134
	135	memcpy(walk->iv, iv, bsize);
	136
	137	return nbytes;
	138	}
	139
	140	static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
	141	struct blkcipher_walk *walk,
3c7f076d	142	struct crypto_cipher *tfm)
db131ef9 HX	143	{
	144	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	145	crypto_cipher_alg(tfm)->cia_decrypt;
	146	int bsize = crypto_cipher_blocksize(tfm);
db131ef9 HX	147	unsigned int nbytes = walk->nbytes;
db131ef9 HX	148	u8 *src = walk->src.virt.addr;
50b6544e	149	u8 last_iv[bsize];
db131ef9 HX	150
db131ef9 HX	151	/* Start of the last block. */
50b6544e HX	152	src += nbytes - (nbytes & (bsize - 1)) - bsize;
50b6544e HX	153	memcpy(last_iv, src, bsize);
db131ef9 HX	154
	155	for (;;) {
	156	fn(crypto_cipher_tfm(tfm), src, src);
	157	if ((nbytes -= bsize) < bsize)
	158	break;
3c7f076d	159	crypto_xor(src, src - bsize, bsize);
db131ef9 HX	160	src -= bsize;
	161	}
	162
50b6544e HX	163	crypto_xor(src, walk->iv, bsize);
50b6544e HX	164	memcpy(walk->iv, last_iv, bsize);
db131ef9 HX	165
	166	return nbytes;
	167	}
	168
	169	static int crypto_cbc_decrypt(struct blkcipher_desc *desc,
	170	struct scatterlist dst, struct scatterlist src,
	171	unsigned int nbytes)
	172	{
	173	struct blkcipher_walk walk;
	174	struct crypto_blkcipher *tfm = desc->tfm;
	175	struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
	176	struct crypto_cipher *child = ctx->child;
db131ef9 HX	177	int err;
	178
	179	blkcipher_walk_init(&walk, dst, src, nbytes);
	180	err = blkcipher_walk_virt(desc, &walk);
	181
	182	while ((nbytes = walk.nbytes)) {
	183	if (walk.src.virt.addr == walk.dst.virt.addr)
3c7f076d	184	nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child);
db131ef9	185	else
3c7f076d	186	nbytes = crypto_cbc_decrypt_segment(desc, &walk, child);
db131ef9 HX	187	err = blkcipher_walk_done(desc, &walk, nbytes);
	188	}
	189
	190	return err;
	191	}
	192
db131ef9 HX	193	static int crypto_cbc_init_tfm(struct crypto_tfm *tfm)
	194	{
	195	struct crypto_instance inst = (void )tfm->__crt_alg;
	196	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	197	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
2e306ee0	198	struct crypto_cipher *cipher;
db131ef9	199
2e306ee0 HX	200	cipher = crypto_spawn_cipher(spawn);
	201	if (IS_ERR(cipher))
	202	return PTR_ERR(cipher);
db131ef9	203
2e306ee0	204	ctx->child = cipher;
db131ef9 HX	205	return 0;
	206	}
	207
	208	static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm)
	209	{
	210	struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
	211	crypto_free_cipher(ctx->child);
	212	}
	213
ebc610e5	214	static struct crypto_instance crypto_cbc_alloc(struct rtattr *tb)
db131ef9 HX	215	{
	216	struct crypto_instance *inst;
	217	struct crypto_alg *alg;
ebc610e5 HX	218	int err;
	219
	220	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	221	if (err)
	222	return ERR_PTR(err);
db131ef9	223
ebc610e5 HX	224	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
ebc610e5 HX	225	CRYPTO_ALG_TYPE_MASK);
db131ef9	226	if (IS_ERR(alg))
e231c2ee	227	return ERR_CAST(alg);
db131ef9	228
50b6544e HX	229	inst = ERR_PTR(-EINVAL);
	230	if (!is_power_of_2(alg->cra_blocksize))
	231	goto out_put_alg;
	232
db131ef9 HX	233	inst = crypto_alloc_instance("cbc", alg);
	234	if (IS_ERR(inst))
	235	goto out_put_alg;
	236
	237	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	238	inst->alg.cra_priority = alg->cra_priority;
	239	inst->alg.cra_blocksize = alg->cra_blocksize;
	240	inst->alg.cra_alignmask = alg->cra_alignmask;
	241	inst->alg.cra_type = &crypto_blkcipher_type;
	242
3c7f076d HX	243	/* We access the data as u32s when xoring. */
	244	inst->alg.cra_alignmask \|= __alignof__(u32) - 1;
	245
db131ef9 HX	246	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	247	inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
	248	inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
	249
	250	inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
	251
	252	inst->alg.cra_init = crypto_cbc_init_tfm;
	253	inst->alg.cra_exit = crypto_cbc_exit_tfm;
	254
	255	inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;
	256	inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;
	257	inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt;
	258
	259	out_put_alg:
	260	crypto_mod_put(alg);
	261	return inst;
	262	}
	263
	264	static void crypto_cbc_free(struct crypto_instance *inst)
	265	{
	266	crypto_drop_spawn(crypto_instance_ctx(inst));
	267	kfree(inst);
	268	}
	269
	270	static struct crypto_template crypto_cbc_tmpl = {
	271	.name = "cbc",
	272	.alloc = crypto_cbc_alloc,
	273	.free = crypto_cbc_free,
	274	.module = THIS_MODULE,
	275	};
	276
	277	static int __init crypto_cbc_module_init(void)
	278	{
	279	return crypto_register_template(&crypto_cbc_tmpl);
	280	}
	281
	282	static void __exit crypto_cbc_module_exit(void)
	283	{
	284	crypto_unregister_template(&crypto_cbc_tmpl);
	285	}
	286
	287	module_init(crypto_cbc_module_init);
	288	module_exit(crypto_cbc_module_exit);
	289
	290	MODULE_LICENSE("GPL");
	291	MODULE_DESCRIPTION("CBC block cipher algorithm");
4943ba16	292	MODULE_ALIAS_CRYPTO("cbc");