[linux-block.git] / crypto / cbc.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * CBC: Cipher Block Chaining mode
 *
 * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <crypto/algapi.h>
#include <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/module.h>

static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
				      struct crypto_skcipher *skcipher)
{
	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
	unsigned int nbytes = walk->nbytes;
	u8 *src = walk->src.virt.addr;
	u8 *dst = walk->dst.virt.addr;
	struct crypto_cipher *cipher;
	struct crypto_tfm *tfm;
	u8 *iv = walk->iv;

	cipher = skcipher_cipher_simple(skcipher);
	tfm = crypto_cipher_tfm(cipher);
	fn = crypto_cipher_alg(cipher)->cia_encrypt;

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

		src += bsize;
		dst += bsize;
	} while ((nbytes -= bsize) >= bsize);

	return nbytes;
}

static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
				      struct crypto_skcipher *skcipher)
{
	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
	unsigned int nbytes = walk->nbytes;
	u8 *src = walk->src.virt.addr;
	struct crypto_cipher *cipher;
	struct crypto_tfm *tfm;
	u8 *iv = walk->iv;

	cipher = skcipher_cipher_simple(skcipher);
	tfm = crypto_cipher_tfm(cipher);
	fn = crypto_cipher_alg(cipher)->cia_encrypt;

	do {
		crypto_xor(src, iv, bsize);
		fn(tfm, src, src);
		iv = src;

		src += bsize;
	} while ((nbytes -= bsize) >= bsize);

	memcpy(walk->iv, iv, bsize);

	return nbytes;
}

static int crypto_cbc_encrypt(struct skcipher_request *req)
{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct skcipher_walk walk;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while (walk.nbytes) {
		if (walk.src.virt.addr == walk.dst.virt.addr)
			err = crypto_cbc_encrypt_inplace(&walk, skcipher);
		else
			err = crypto_cbc_encrypt_segment(&walk, skcipher);
		err = skcipher_walk_done(&walk, err);
	}

	return err;
}

static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
				      struct crypto_skcipher *skcipher)
{
	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
	unsigned int nbytes = walk->nbytes;
	u8 *src = walk->src.virt.addr;
	u8 *dst = walk->dst.virt.addr;
	struct crypto_cipher *cipher;
	struct crypto_tfm *tfm;
	u8 *iv = walk->iv;

	cipher = skcipher_cipher_simple(skcipher);
	tfm = crypto_cipher_tfm(cipher);
	fn = crypto_cipher_alg(cipher)->cia_decrypt;

	do {
		fn(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 skcipher_walk *walk,
				      struct crypto_skcipher *skcipher)
{
	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
	unsigned int nbytes = walk->nbytes;
	u8 *src = walk->src.virt.addr;
	u8 last_iv[MAX_CIPHER_BLOCKSIZE];
	struct crypto_cipher *cipher;
	struct crypto_tfm *tfm;

	cipher = skcipher_cipher_simple(skcipher);
	tfm = crypto_cipher_tfm(cipher);
	fn = crypto_cipher_alg(cipher)->cia_decrypt;

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

	for (;;) {
		fn(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 skcipher_request *req)
{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct skcipher_walk walk;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while (walk.nbytes) {
		if (walk.src.virt.addr == walk.dst.virt.addr)
			err = crypto_cbc_decrypt_inplace(&walk, skcipher);
		else
			err = crypto_cbc_decrypt_segment(&walk, skcipher);
		err = skcipher_walk_done(&walk, err);
	}

	return err;
}

static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct skcipher_instance *inst;
	struct crypto_alg *alg;
	int err;

	inst = skcipher_alloc_instance_simple(tmpl, tb);
	if (IS_ERR(inst))
		return PTR_ERR(inst);

	alg = skcipher_ialg_simple(inst);

	err = -EINVAL;
	if (!is_power_of_2(alg->cra_blocksize))
		goto out_free_inst;

	inst->alg.encrypt = crypto_cbc_encrypt;
	inst->alg.decrypt = crypto_cbc_decrypt;

	err = skcipher_register_instance(tmpl, inst);
	if (err) {
out_free_inst:
		inst->free(inst);
	}

	return err;
}

static struct crypto_template crypto_cbc_tmpl = {
	.name = "cbc",
	.create = crypto_cbc_create,
	.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);
}

subsys_initcall(crypto_cbc_module_init);
module_exit(crypto_cbc_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CBC block cipher mode of operation");
MODULE_ALIAS_CRYPTO("cbc");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
db131ef9 HX	2	/*
	3	* CBC: Cipher Block Chaining mode
	4	*
cc868d82	5	* Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
db131ef9 HX	6	*/
db131ef9 HX	7
e6c2e65c	8	#include <crypto/algapi.h>
79c65d17	9	#include <crypto/internal/skcipher.h>
db131ef9 HX	10	#include <linux/err.h>
	11	#include <linux/init.h>
	12	#include <linux/kernel.h>
50b6544e	13	#include <linux/log2.h>
db131ef9	14	#include <linux/module.h>
db131ef9	15
5f254dd4 HX	16	static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
5f254dd4 HX	17	struct crypto_skcipher *skcipher)
79c65d17	18	{
5f254dd4 HX	19	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	20	void (fn)(struct crypto_tfm , u8 , const u8 );
	21	unsigned int nbytes = walk->nbytes;
	22	u8 *src = walk->src.virt.addr;
	23	u8 *dst = walk->dst.virt.addr;
	24	struct crypto_cipher *cipher;
	25	struct crypto_tfm *tfm;
	26	u8 *iv = walk->iv;
	27
	28	cipher = skcipher_cipher_simple(skcipher);
	29	tfm = crypto_cipher_tfm(cipher);
	30	fn = crypto_cipher_alg(cipher)->cia_encrypt;
	31
	32	do {
	33	crypto_xor(iv, src, bsize);
	34	fn(tfm, dst, iv);
	35	memcpy(iv, dst, bsize);
	36
	37	src += bsize;
	38	dst += bsize;
	39	} while ((nbytes -= bsize) >= bsize);
	40
	41	return nbytes;
	42	}
	43
	44	static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
	45	struct crypto_skcipher *skcipher)
	46	{
	47	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	48	void (fn)(struct crypto_tfm , u8 , const u8 );
	49	unsigned int nbytes = walk->nbytes;
	50	u8 *src = walk->src.virt.addr;
	51	struct crypto_cipher *cipher;
	52	struct crypto_tfm *tfm;
	53	u8 *iv = walk->iv;
	54
	55	cipher = skcipher_cipher_simple(skcipher);
	56	tfm = crypto_cipher_tfm(cipher);
	57	fn = crypto_cipher_alg(cipher)->cia_encrypt;
	58
	59	do {
	60	crypto_xor(src, iv, bsize);
	61	fn(tfm, src, src);
	62	iv = src;
	63
	64	src += bsize;
	65	} while ((nbytes -= bsize) >= bsize);
	66
	67	memcpy(walk->iv, iv, bsize);
	68
	69	return nbytes;
79c65d17 HX	70	}
	71
	72	static int crypto_cbc_encrypt(struct skcipher_request *req)
db131ef9	73	{
5f254dd4 HX	74	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	75	struct skcipher_walk walk;
	76	int err;
	77
	78	err = skcipher_walk_virt(&walk, req, false);
	79
	80	while (walk.nbytes) {
	81	if (walk.src.virt.addr == walk.dst.virt.addr)
	82	err = crypto_cbc_encrypt_inplace(&walk, skcipher);
	83	else
	84	err = crypto_cbc_encrypt_segment(&walk, skcipher);
	85	err = skcipher_walk_done(&walk, err);
	86	}
	87
	88	return err;
	89	}
	90
	91	static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
	92	struct crypto_skcipher *skcipher)
	93	{
	94	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	95	void (fn)(struct crypto_tfm , u8 , const u8 );
	96	unsigned int nbytes = walk->nbytes;
	97	u8 *src = walk->src.virt.addr;
	98	u8 *dst = walk->dst.virt.addr;
	99	struct crypto_cipher *cipher;
	100	struct crypto_tfm *tfm;
	101	u8 *iv = walk->iv;
	102
	103	cipher = skcipher_cipher_simple(skcipher);
	104	tfm = crypto_cipher_tfm(cipher);
	105	fn = crypto_cipher_alg(cipher)->cia_decrypt;
	106
	107	do {
	108	fn(tfm, dst, src);
	109	crypto_xor(dst, iv, bsize);
	110	iv = src;
	111
	112	src += bsize;
	113	dst += bsize;
	114	} while ((nbytes -= bsize) >= bsize);
	115
	116	memcpy(walk->iv, iv, bsize);
	117
	118	return nbytes;
79c65d17 HX	119	}
79c65d17 HX	120
5f254dd4 HX	121	static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk,
5f254dd4 HX	122	struct crypto_skcipher *skcipher)
79c65d17	123	{
5f254dd4 HX	124	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
	125	void (fn)(struct crypto_tfm , u8 , const u8 );
	126	unsigned int nbytes = walk->nbytes;
	127	u8 *src = walk->src.virt.addr;
	128	u8 last_iv[MAX_CIPHER_BLOCKSIZE];
	129	struct crypto_cipher *cipher;
	130	struct crypto_tfm *tfm;
	131
	132	cipher = skcipher_cipher_simple(skcipher);
	133	tfm = crypto_cipher_tfm(cipher);
	134	fn = crypto_cipher_alg(cipher)->cia_decrypt;
	135
	136	/* Start of the last block. */
	137	src += nbytes - (nbytes & (bsize - 1)) - bsize;
	138	memcpy(last_iv, src, bsize);
	139
	140	for (;;) {
	141	fn(tfm, src, src);
	142	if ((nbytes -= bsize) < bsize)
	143	break;
	144	crypto_xor(src, src - bsize, bsize);
	145	src -= bsize;
	146	}
	147
	148	crypto_xor(src, walk->iv, bsize);
	149	memcpy(walk->iv, last_iv, bsize);
	150
	151	return nbytes;
79c65d17 HX	152	}
	153
	154	static int crypto_cbc_decrypt(struct skcipher_request *req)
	155	{
5f254dd4	156	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
79c65d17	157	struct skcipher_walk walk;
db131ef9 HX	158	int err;
db131ef9 HX	159
79c65d17	160	err = skcipher_walk_virt(&walk, req, false);
db131ef9	161
79c65d17	162	while (walk.nbytes) {
5f254dd4 HX	163	if (walk.src.virt.addr == walk.dst.virt.addr)
	164	err = crypto_cbc_decrypt_inplace(&walk, skcipher);
	165	else
	166	err = crypto_cbc_decrypt_segment(&walk, skcipher);
79c65d17	167	err = skcipher_walk_done(&walk, err);
db131ef9 HX	168	}
	169
	170	return err;
	171	}
	172
79c65d17 HX	173	static int crypto_cbc_create(struct crypto_template tmpl, struct rtattr *tb)
	174	{
	175	struct skcipher_instance *inst;
db131ef9	176	struct crypto_alg *alg;
ebc610e5 HX	177	int err;
ebc610e5 HX	178
b3c16bfc	179	inst = skcipher_alloc_instance_simple(tmpl, tb);
a5a84a9d EB	180	if (IS_ERR(inst))
a5a84a9d EB	181	return PTR_ERR(inst);
50b6544e	182
b3c16bfc HX	183	alg = skcipher_ialg_simple(inst);
b3c16bfc HX	184
79c65d17 HX	185	err = -EINVAL;
79c65d17 HX	186	if (!is_power_of_2(alg->cra_blocksize))
a5a84a9d	187	goto out_free_inst;
db131ef9	188
79c65d17 HX	189	inst->alg.encrypt = crypto_cbc_encrypt;
79c65d17 HX	190	inst->alg.decrypt = crypto_cbc_decrypt;
db131ef9	191
79c65d17	192	err = skcipher_register_instance(tmpl, inst);
b3c16bfc	193	if (err) {
a5a84a9d	194	out_free_inst:
b3c16bfc HX	195	inst->free(inst);
	196	}
	197
a5a84a9d	198	return err;
db131ef9 HX	199	}
	200
	201	static struct crypto_template crypto_cbc_tmpl = {
	202	.name = "cbc",
79c65d17	203	.create = crypto_cbc_create,
db131ef9 HX	204	.module = THIS_MODULE,
	205	};
	206
	207	static int __init crypto_cbc_module_init(void)
	208	{
	209	return crypto_register_template(&crypto_cbc_tmpl);
	210	}
	211
	212	static void __exit crypto_cbc_module_exit(void)
	213	{
	214	crypto_unregister_template(&crypto_cbc_tmpl);
	215	}
	216
c4741b23	217	subsys_initcall(crypto_cbc_module_init);
db131ef9 HX	218	module_exit(crypto_cbc_module_exit);
	219
	220	MODULE_LICENSE("GPL");
a5a84a9d	221	MODULE_DESCRIPTION("CBC block cipher mode of operation");
4943ba16	222	MODULE_ALIAS_CRYPTO("cbc");