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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) 2006-2016 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 <crypto/cbc.h>
15#include <crypto/internal/skcipher.h>
16#include <linux/err.h>
17#include <linux/init.h>
18#include <linux/kernel.h>
19#include <linux/log2.h>
20#include <linux/module.h>
21#include <linux/slab.h>
22
23struct crypto_cbc_ctx {
24 struct crypto_cipher *child;
25};
26
27static int crypto_cbc_setkey(struct crypto_skcipher *parent, const u8 *key,
28 unsigned int keylen)
29{
30 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(parent);
31 struct crypto_cipher *child = ctx->child;
32 int err;
33
34 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
35 crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
36 CRYPTO_TFM_REQ_MASK);
37 err = crypto_cipher_setkey(child, key, keylen);
38 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
39 CRYPTO_TFM_RES_MASK);
40 return err;
41}
42
43static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
44 const u8 *src, u8 *dst)
45{
46 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
47
48 crypto_cipher_encrypt_one(ctx->child, dst, src);
49}
50
51static int crypto_cbc_encrypt(struct skcipher_request *req)
52{
53 return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
54}
55
56static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
57 const u8 *src, u8 *dst)
58{
59 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
60
61 crypto_cipher_decrypt_one(ctx->child, dst, src);
62}
63
64static int crypto_cbc_decrypt(struct skcipher_request *req)
65{
66 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
67 struct skcipher_walk walk;
68 int err;
69
70 err = skcipher_walk_virt(&walk, req, false);
71
72 while (walk.nbytes) {
73 err = crypto_cbc_decrypt_blocks(&walk, tfm,
74 crypto_cbc_decrypt_one);
75 err = skcipher_walk_done(&walk, err);
76 }
77
78 return err;
79}
80
81static int crypto_cbc_init_tfm(struct crypto_skcipher *tfm)
82{
83 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
84 struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
85 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
86 struct crypto_cipher *cipher;
87
88 cipher = crypto_spawn_cipher(spawn);
89 if (IS_ERR(cipher))
90 return PTR_ERR(cipher);
91
92 ctx->child = cipher;
93 return 0;
94}
95
96static void crypto_cbc_exit_tfm(struct crypto_skcipher *tfm)
97{
98 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
99
100 crypto_free_cipher(ctx->child);
101}
102
103static void crypto_cbc_free(struct skcipher_instance *inst)
104{
105 crypto_drop_skcipher(skcipher_instance_ctx(inst));
106 kfree(inst);
107}
108
109static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
110{
111 struct skcipher_instance *inst;
112 struct crypto_attr_type *algt;
113 struct crypto_spawn *spawn;
114 struct crypto_alg *alg;
115 u32 mask;
116 int err;
117
118 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
119 if (err)
120 return err;
121
122 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
123 if (!inst)
124 return -ENOMEM;
125
126 algt = crypto_get_attr_type(tb);
127 err = PTR_ERR(algt);
128 if (IS_ERR(algt))
129 goto err_free_inst;
130
131 mask = CRYPTO_ALG_TYPE_MASK |
132 crypto_requires_off(algt->type, algt->mask,
133 CRYPTO_ALG_NEED_FALLBACK);
134
135 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, mask);
136 err = PTR_ERR(alg);
137 if (IS_ERR(alg))
138 goto err_free_inst;
139
140 spawn = skcipher_instance_ctx(inst);
141 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
142 CRYPTO_ALG_TYPE_MASK);
143 crypto_mod_put(alg);
144 if (err)
145 goto err_free_inst;
146
147 err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
148 if (err)
149 goto err_drop_spawn;
150
151 err = -EINVAL;
152 if (!is_power_of_2(alg->cra_blocksize))
153 goto err_drop_spawn;
154
155 inst->alg.base.cra_priority = alg->cra_priority;
156 inst->alg.base.cra_blocksize = alg->cra_blocksize;
157 inst->alg.base.cra_alignmask = alg->cra_alignmask;
158
159 inst->alg.ivsize = alg->cra_blocksize;
160 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
161 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
162
163 inst->alg.base.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
164
165 inst->alg.init = crypto_cbc_init_tfm;
166 inst->alg.exit = crypto_cbc_exit_tfm;
167
168 inst->alg.setkey = crypto_cbc_setkey;
169 inst->alg.encrypt = crypto_cbc_encrypt;
170 inst->alg.decrypt = crypto_cbc_decrypt;
171
172 inst->free = crypto_cbc_free;
173
174 err = skcipher_register_instance(tmpl, inst);
175 if (err)
176 goto err_drop_spawn;
177
178out:
179 return err;
180
181err_drop_spawn:
182 crypto_drop_spawn(spawn);
183err_free_inst:
184 kfree(inst);
185 goto out;
186}
187
188static struct crypto_template crypto_cbc_tmpl = {
189 .name = "cbc",
190 .create = crypto_cbc_create,
191 .module = THIS_MODULE,
192};
193
194static int __init crypto_cbc_module_init(void)
195{
196 return crypto_register_template(&crypto_cbc_tmpl);
197}
198
199static void __exit crypto_cbc_module_exit(void)
200{
201 crypto_unregister_template(&crypto_cbc_tmpl);
202}
203
204module_init(crypto_cbc_module_init);
205module_exit(crypto_cbc_module_exit);
206
207MODULE_LICENSE("GPL");
208MODULE_DESCRIPTION("CBC block cipher algorithm");
209MODULE_ALIAS_CRYPTO("cbc");