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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/*
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>
17#include <linux/log2.h>
18#include <linux/module.h>
19#include <linux/scatterlist.h>
20#include <linux/slab.h>
21
22struct crypto_cbc_ctx {
23 struct crypto_cipher *child;
24};
25
26static 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
42static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,
43 struct blkcipher_walk *walk,
44 struct crypto_cipher *tfm)
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 {
55 crypto_xor(iv, src, bsize);
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
66static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
67 struct blkcipher_walk *walk,
68 struct crypto_cipher *tfm)
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 {
78 crypto_xor(src, iv, bsize);
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
90static 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;
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)
105 nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child);
106 else
107 nbytes = crypto_cbc_encrypt_segment(desc, &walk, child);
108 err = blkcipher_walk_done(desc, &walk, nbytes);
109 }
110
111 return err;
112}
113
114static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
115 struct blkcipher_walk *walk,
116 struct crypto_cipher *tfm)
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);
128 crypto_xor(dst, iv, bsize);
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
140static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
141 struct blkcipher_walk *walk,
142 struct crypto_cipher *tfm)
143{
144 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
145 crypto_cipher_alg(tfm)->cia_decrypt;
146 int bsize = crypto_cipher_blocksize(tfm);
147 unsigned int nbytes = walk->nbytes;
148 u8 *src = walk->src.virt.addr;
149 u8 last_iv[bsize];
150
151 /* Start of the last block. */
152 src += nbytes - (nbytes & (bsize - 1)) - bsize;
153 memcpy(last_iv, src, bsize);
154
155 for (;;) {
156 fn(crypto_cipher_tfm(tfm), src, src);
157 if ((nbytes -= bsize) < bsize)
158 break;
159 crypto_xor(src, src - bsize, bsize);
160 src -= bsize;
161 }
162
163 crypto_xor(src, walk->iv, bsize);
164 memcpy(walk->iv, last_iv, bsize);
165
166 return nbytes;
167}
168
169static 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;
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)
184 nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child);
185 else
186 nbytes = crypto_cbc_decrypt_segment(desc, &walk, child);
187 err = blkcipher_walk_done(desc, &walk, nbytes);
188 }
189
190 return err;
191}
192
193static 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);
198 struct crypto_cipher *cipher;
199
200 cipher = crypto_spawn_cipher(spawn);
201 if (IS_ERR(cipher))
202 return PTR_ERR(cipher);
203
204 ctx->child = cipher;
205 return 0;
206}
207
208static 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
214static struct crypto_instance *crypto_cbc_alloc(struct rtattr **tb)
215{
216 struct crypto_instance *inst;
217 struct crypto_alg *alg;
218 int err;
219
220 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
221 if (err)
222 return ERR_PTR(err);
223
224 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
225 CRYPTO_ALG_TYPE_MASK);
226 if (IS_ERR(alg))
227 return ERR_CAST(alg);
228
229 inst = ERR_PTR(-EINVAL);
230 if (!is_power_of_2(alg->cra_blocksize))
231 goto out_put_alg;
232
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
243 /* We access the data as u32s when xoring. */
244 inst->alg.cra_alignmask |= __alignof__(u32) - 1;
245
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
259out_put_alg:
260 crypto_mod_put(alg);
261 return inst;
262}
263
264static void crypto_cbc_free(struct crypto_instance *inst)
265{
266 crypto_drop_spawn(crypto_instance_ctx(inst));
267 kfree(inst);
268}
269
270static 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
277static int __init crypto_cbc_module_init(void)
278{
279 return crypto_register_template(&crypto_cbc_tmpl);
280}
281
282static void __exit crypto_cbc_module_exit(void)
283{
284 crypto_unregister_template(&crypto_cbc_tmpl);
285}
286
287module_init(crypto_cbc_module_init);
288module_exit(crypto_cbc_module_exit);
289
290MODULE_LICENSE("GPL");
291MODULE_DESCRIPTION("CBC block cipher algorithm");
292MODULE_ALIAS_CRYPTO("cbc");