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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");
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/cbc.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 inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
18 const u8 *src, u8 *dst)
19{
20 crypto_cipher_encrypt_one(skcipher_cipher_simple(tfm), dst, src);
21}
22
23static int crypto_cbc_encrypt(struct skcipher_request *req)
24{
25 return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
26}
27
28static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
29 const u8 *src, u8 *dst)
30{
31 crypto_cipher_decrypt_one(skcipher_cipher_simple(tfm), dst, src);
32}
33
34static int crypto_cbc_decrypt(struct skcipher_request *req)
35{
36 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
37 struct skcipher_walk walk;
38 int err;
39
40 err = skcipher_walk_virt(&walk, req, false);
41
42 while (walk.nbytes) {
43 err = crypto_cbc_decrypt_blocks(&walk, tfm,
44 crypto_cbc_decrypt_one);
45 err = skcipher_walk_done(&walk, err);
46 }
47
48 return err;
49}
50
51static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
52{
53 struct skcipher_instance *inst;
54 struct crypto_alg *alg;
55 int err;
56
57 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
58 if (IS_ERR(inst))
59 return PTR_ERR(inst);
60
61 err = -EINVAL;
62 if (!is_power_of_2(alg->cra_blocksize))
63 goto out_free_inst;
64
65 inst->alg.encrypt = crypto_cbc_encrypt;
66 inst->alg.decrypt = crypto_cbc_decrypt;
67
68 err = skcipher_register_instance(tmpl, inst);
69 if (err)
70 goto out_free_inst;
71 goto out_put_alg;
72
73out_free_inst:
74 inst->free(inst);
75out_put_alg:
76 crypto_mod_put(alg);
77 return err;
78}
79
80static struct crypto_template crypto_cbc_tmpl = {
81 .name = "cbc",
82 .create = crypto_cbc_create,
83 .module = THIS_MODULE,
84};
85
86static int __init crypto_cbc_module_init(void)
87{
88 return crypto_register_template(&crypto_cbc_tmpl);
89}
90
91static void __exit crypto_cbc_module_exit(void)
92{
93 crypto_unregister_template(&crypto_cbc_tmpl);
94}
95
96subsys_initcall(crypto_cbc_module_init);
97module_exit(crypto_cbc_module_exit);
98
99MODULE_LICENSE("GPL");
100MODULE_DESCRIPTION("CBC block cipher mode of operation");
101MODULE_ALIAS_CRYPTO("cbc");