1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * CBC: Cipher Block Chaining mode
  4 *
  5 * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
  6 */
  7
  8#include <crypto/algapi.h>
  9#include <crypto/internal/cipher.h>
 10#include <crypto/internal/skcipher.h>
 11#include <linux/err.h>
 12#include <linux/init.h>
 13#include <linux/kernel.h>
 14#include <linux/log2.h>
 15#include <linux/module.h>
 16
 17static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
 18				      struct crypto_skcipher *skcipher)
 
 19{
 20	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
 21	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 22	unsigned int nbytes = walk->nbytes;
 23	u8 *src = walk->src.virt.addr;
 24	u8 *dst = walk->dst.virt.addr;
 25	struct crypto_cipher *cipher;
 26	struct crypto_tfm *tfm;
 27	u8 *iv = walk->iv;
 28
 29	cipher = skcipher_cipher_simple(skcipher);
 30	tfm = crypto_cipher_tfm(cipher);
 31	fn = crypto_cipher_alg(cipher)->cia_encrypt;
 32
 33	do {
 34		crypto_xor(iv, src, bsize);
 35		fn(tfm, dst, iv);
 36		memcpy(iv, dst, bsize);
 37
 38		src += bsize;
 39		dst += bsize;
 40	} while ((nbytes -= bsize) >= bsize);
 41
 42	return nbytes;
 43}
 44
 45static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
 46				      struct crypto_skcipher *skcipher)
 47{
 48	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
 49	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 50	unsigned int nbytes = walk->nbytes;
 51	u8 *src = walk->src.virt.addr;
 52	struct crypto_cipher *cipher;
 53	struct crypto_tfm *tfm;
 54	u8 *iv = walk->iv;
 55
 56	cipher = skcipher_cipher_simple(skcipher);
 57	tfm = crypto_cipher_tfm(cipher);
 58	fn = crypto_cipher_alg(cipher)->cia_encrypt;
 59
 60	do {
 61		crypto_xor(src, iv, bsize);
 62		fn(tfm, src, src);
 63		iv = src;
 64
 65		src += bsize;
 66	} while ((nbytes -= bsize) >= bsize);
 67
 68	memcpy(walk->iv, iv, bsize);
 69
 
 70	return nbytes;
 71}
 72
 73static int crypto_cbc_encrypt(struct skcipher_request *req)
 
 74{
 75	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 76	struct skcipher_walk walk;
 77	int err;
 78
 79	err = skcipher_walk_virt(&walk, req, false);
 80
 81	while (walk.nbytes) {
 82		if (walk.src.virt.addr == walk.dst.virt.addr)
 83			err = crypto_cbc_encrypt_inplace(&walk, skcipher);
 84		else
 85			err = crypto_cbc_encrypt_segment(&walk, skcipher);
 86		err = skcipher_walk_done(&walk, err);
 87	}
 88
 89	return err;
 90}
 91
 92static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
 93				      struct crypto_skcipher *skcipher)
 
 94{
 95	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
 96	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 97	unsigned int nbytes = walk->nbytes;
 98	u8 *src = walk->src.virt.addr;
 99	u8 *dst = walk->dst.virt.addr;
100	struct crypto_cipher *cipher;
101	struct crypto_tfm *tfm;
102	u8 *iv = walk->iv;
103
104	cipher = skcipher_cipher_simple(skcipher);
105	tfm = crypto_cipher_tfm(cipher);
106	fn = crypto_cipher_alg(cipher)->cia_decrypt;
107
108	do {
109		fn(tfm, dst, src);
110		crypto_xor(dst, iv, bsize);
111		iv = src;
112
113		src += bsize;
114		dst += bsize;
115	} while ((nbytes -= bsize) >= bsize);
116
117	memcpy(walk->iv, iv, bsize);
118
 
119	return nbytes;
120}
121
122static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk,
123				      struct crypto_skcipher *skcipher)
124{
125	unsigned int bsize = crypto_skcipher_blocksize(skcipher);
126	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
127	unsigned int nbytes = walk->nbytes;
128	u8 *src = walk->src.virt.addr;
129	u8 last_iv[MAX_CIPHER_BLOCKSIZE];
130	struct crypto_cipher *cipher;
131	struct crypto_tfm *tfm;
132
133	cipher = skcipher_cipher_simple(skcipher);
134	tfm = crypto_cipher_tfm(cipher);
135	fn = crypto_cipher_alg(cipher)->cia_decrypt;
136
137	/* Start of the last block. */
138	src += nbytes - (nbytes & (bsize - 1)) - bsize;
139	memcpy(last_iv, src, bsize);
140
141	for (;;) {
142		fn(tfm, src, src);
143		if ((nbytes -= bsize) < bsize)
144			break;
145		crypto_xor(src, src - bsize, bsize);
146		src -= bsize;
147	}
148
149	crypto_xor(src, walk->iv, bsize);
150	memcpy(walk->iv, last_iv, bsize);
151
 
152	return nbytes;
153}
154
155static int crypto_cbc_decrypt(struct skcipher_request *req)
 
156{
157	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
158	struct skcipher_walk walk;
159	int err;
 
 
 
 
 
 
160
161	err = skcipher_walk_virt(&walk, req, false);
162
163	while (walk.nbytes) {
164		if (walk.src.virt.addr == walk.dst.virt.addr)
165			err = crypto_cbc_decrypt_inplace(&walk, skcipher);
166		else
167			err = crypto_cbc_decrypt_segment(&walk, skcipher);
168		err = skcipher_walk_done(&walk, err);
169	}
170
171	return err;
172}
173
174static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
175{
176	struct skcipher_instance *inst;
177	struct crypto_alg *alg;
178	int err;
179
180	inst = skcipher_alloc_instance_simple(tmpl, tb);
181	if (IS_ERR(inst))
182		return PTR_ERR(inst);
183
184	alg = skcipher_ialg_simple(inst);
185
186	err = -EINVAL;
187	if (!is_power_of_2(alg->cra_blocksize))
 
 
 
188		goto out_free_inst;
189
190	inst->alg.encrypt = crypto_cbc_encrypt;
191	inst->alg.decrypt = crypto_cbc_decrypt;
192
193	err = skcipher_register_instance(tmpl, inst);
194	if (err) {
195out_free_inst:
196		inst->free(inst);
197	}
198
199	return err;
200}
201
202static struct crypto_template crypto_cbc_tmpl = {
203	.name = "cbc",
204	.create = crypto_cbc_create,
205	.module = THIS_MODULE,
206};
207
208static int __init crypto_cbc_module_init(void)
209{
210	return crypto_register_template(&crypto_cbc_tmpl);
211}
212
213static void __exit crypto_cbc_module_exit(void)
214{
215	crypto_unregister_template(&crypto_cbc_tmpl);
216}
217
218subsys_initcall(crypto_cbc_module_init);
219module_exit(crypto_cbc_module_exit);
220
221MODULE_LICENSE("GPL");
222MODULE_DESCRIPTION("CBC block cipher mode of operation");
223MODULE_ALIAS_CRYPTO("cbc");

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * CBC: Cipher Block Chaining mode
  4 *
  5 * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
  6 */
  7
 
 
  8#include <crypto/internal/skcipher.h>
  9#include <linux/err.h>
 10#include <linux/init.h>
 11#include <linux/kernel.h>
 12#include <linux/log2.h>
 13#include <linux/module.h>
 14
 15static int crypto_cbc_encrypt_segment(struct crypto_lskcipher *tfm,
 16				      const u8 *src, u8 *dst, unsigned nbytes,
 17				      u8 *iv)
 18{
 19	unsigned int bsize = crypto_lskcipher_blocksize(tfm);
 
 
 
 
 
 
 
 
 
 
 
 20
 21	for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize) {
 22		crypto_xor(iv, src, bsize);
 23		crypto_lskcipher_encrypt(tfm, iv, dst, bsize, NULL);
 24		memcpy(iv, dst, bsize);
 25	}
 
 
 
 26
 27	return nbytes;
 28}
 29
 30static int crypto_cbc_encrypt_inplace(struct crypto_lskcipher *tfm,
 31				      u8 *src, unsigned nbytes, u8 *oiv)
 32{
 33	unsigned int bsize = crypto_lskcipher_blocksize(tfm);
 34	u8 *iv = oiv;
 35
 36	if (nbytes < bsize)
 37		goto out;
 
 
 
 
 
 
 38
 39	do {
 40		crypto_xor(src, iv, bsize);
 41		crypto_lskcipher_encrypt(tfm, src, src, bsize, NULL);
 42		iv = src;
 43
 44		src += bsize;
 45	} while ((nbytes -= bsize) >= bsize);
 46
 47	memcpy(oiv, iv, bsize);
 48
 49out:
 50	return nbytes;
 51}
 52
 53static int crypto_cbc_encrypt(struct crypto_lskcipher *tfm, const u8 *src,
 54			      u8 *dst, unsigned len, u8 *iv, u32 flags)
 55{
 56	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
 57	bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;
 58	struct crypto_lskcipher *cipher = *ctx;
 59	int rem;
 
 60
 61	if (src == dst)
 62		rem = crypto_cbc_encrypt_inplace(cipher, dst, len, iv);
 63	else
 64		rem = crypto_cbc_encrypt_segment(cipher, src, dst, len, iv);
 
 
 
 65
 66	return rem && final ? -EINVAL : rem;
 67}
 68
 69static int crypto_cbc_decrypt_segment(struct crypto_lskcipher *tfm,
 70				      const u8 *src, u8 *dst, unsigned nbytes,
 71				      u8 *oiv)
 72{
 73	unsigned int bsize = crypto_lskcipher_blocksize(tfm);
 74	const u8 *iv = oiv;
 75
 76	if (nbytes < bsize)
 77		goto out;
 
 
 
 
 
 
 
 78
 79	do {
 80		crypto_lskcipher_decrypt(tfm, src, dst, bsize, NULL);
 81		crypto_xor(dst, iv, bsize);
 82		iv = src;
 83
 84		src += bsize;
 85		dst += bsize;
 86	} while ((nbytes -= bsize) >= bsize);
 87
 88	memcpy(oiv, iv, bsize);
 89
 90out:
 91	return nbytes;
 92}
 93
 94static int crypto_cbc_decrypt_inplace(struct crypto_lskcipher *tfm,
 95				      u8 *src, unsigned nbytes, u8 *iv)
 96{
 97	unsigned int bsize = crypto_lskcipher_blocksize(tfm);
 
 
 
 98	u8 last_iv[MAX_CIPHER_BLOCKSIZE];
 
 
 99
100	if (nbytes < bsize)
101		goto out;
 
102
103	/* Start of the last block. */
104	src += nbytes - (nbytes & (bsize - 1)) - bsize;
105	memcpy(last_iv, src, bsize);
106
107	for (;;) {
108		crypto_lskcipher_decrypt(tfm, src, src, bsize, NULL);
109		if ((nbytes -= bsize) < bsize)
110			break;
111		crypto_xor(src, src - bsize, bsize);
112		src -= bsize;
113	}
114
115	crypto_xor(src, iv, bsize);
116	memcpy(iv, last_iv, bsize);
117
118out:
119	return nbytes;
120}
121
122static int crypto_cbc_decrypt(struct crypto_lskcipher *tfm, const u8 *src,
123			      u8 *dst, unsigned len, u8 *iv, u32 flags)
124{
125	struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm);
126	bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL;
127	struct crypto_lskcipher *cipher = *ctx;
128	int rem;
129
130	if (src == dst)
131		rem = crypto_cbc_decrypt_inplace(cipher, dst, len, iv);
132	else
133		rem = crypto_cbc_decrypt_segment(cipher, src, dst, len, iv);
134
135	return rem && final ? -EINVAL : rem;
 
 
 
 
 
 
 
 
 
 
136}
137
138static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
139{
140	struct lskcipher_instance *inst;
 
141	int err;
142
143	inst = lskcipher_alloc_instance_simple(tmpl, tb);
144	if (IS_ERR(inst))
145		return PTR_ERR(inst);
146
 
 
147	err = -EINVAL;
148	if (!is_power_of_2(inst->alg.co.base.cra_blocksize))
149		goto out_free_inst;
150
151	if (inst->alg.co.statesize)
152		goto out_free_inst;
153
154	inst->alg.encrypt = crypto_cbc_encrypt;
155	inst->alg.decrypt = crypto_cbc_decrypt;
156
157	err = lskcipher_register_instance(tmpl, inst);
158	if (err) {
159out_free_inst:
160		inst->free(inst);
161	}
162
163	return err;
164}
165
166static struct crypto_template crypto_cbc_tmpl = {
167	.name = "cbc",
168	.create = crypto_cbc_create,
169	.module = THIS_MODULE,
170};
171
172static int __init crypto_cbc_module_init(void)
173{
174	return crypto_register_template(&crypto_cbc_tmpl);
175}
176
177static void __exit crypto_cbc_module_exit(void)
178{
179	crypto_unregister_template(&crypto_cbc_tmpl);
180}
181
182subsys_initcall(crypto_cbc_module_init);
183module_exit(crypto_cbc_module_exit);
184
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("CBC block cipher mode of operation");
187MODULE_ALIAS_CRYPTO("cbc");