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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/cbc.h>
14#include <crypto/internal/skcipher.h>
15#include <linux/err.h>
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/log2.h>
19#include <linux/module.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_skcipher *parent, const u8 *key,
27 unsigned int keylen)
28{
29 struct crypto_cbc_ctx *ctx = crypto_skcipher_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_skcipher_get_flags(parent) &
35 CRYPTO_TFM_REQ_MASK);
36 err = crypto_cipher_setkey(child, key, keylen);
37 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
38 CRYPTO_TFM_RES_MASK);
39 return err;
40}
41
42static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
43 const u8 *src, u8 *dst)
44{
45 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
46
47 crypto_cipher_encrypt_one(ctx->child, dst, src);
48}
49
50static int crypto_cbc_encrypt(struct skcipher_request *req)
51{
52 return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
53}
54
55static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
56 const u8 *src, u8 *dst)
57{
58 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
59
60 crypto_cipher_decrypt_one(ctx->child, dst, src);
61}
62
63static int crypto_cbc_decrypt(struct skcipher_request *req)
64{
65 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
66 struct skcipher_walk walk;
67 int err;
68
69 err = skcipher_walk_virt(&walk, req, false);
70
71 while (walk.nbytes) {
72 err = crypto_cbc_decrypt_blocks(&walk, tfm,
73 crypto_cbc_decrypt_one);
74 err = skcipher_walk_done(&walk, err);
75 }
76
77 return err;
78}
79
80static int crypto_cbc_init_tfm(struct crypto_skcipher *tfm)
81{
82 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
83 struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
84 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
85 struct crypto_cipher *cipher;
86
87 cipher = crypto_spawn_cipher(spawn);
88 if (IS_ERR(cipher))
89 return PTR_ERR(cipher);
90
91 ctx->child = cipher;
92 return 0;
93}
94
95static void crypto_cbc_exit_tfm(struct crypto_skcipher *tfm)
96{
97 struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
98
99 crypto_free_cipher(ctx->child);
100}
101
102static void crypto_cbc_free(struct skcipher_instance *inst)
103{
104 crypto_drop_skcipher(skcipher_instance_ctx(inst));
105 kfree(inst);
106}
107
108static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
109{
110 struct skcipher_instance *inst;
111 struct crypto_spawn *spawn;
112 struct crypto_alg *alg;
113 int err;
114
115 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
116 if (err)
117 return err;
118
119 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
120 if (!inst)
121 return -ENOMEM;
122
123 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
124 CRYPTO_ALG_TYPE_MASK);
125 err = PTR_ERR(alg);
126 if (IS_ERR(alg))
127 goto err_free_inst;
128
129 spawn = skcipher_instance_ctx(inst);
130 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
131 CRYPTO_ALG_TYPE_MASK);
132 crypto_mod_put(alg);
133 if (err)
134 goto err_free_inst;
135
136 err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
137 if (err)
138 goto err_drop_spawn;
139
140 err = -EINVAL;
141 if (!is_power_of_2(alg->cra_blocksize))
142 goto err_drop_spawn;
143
144 inst->alg.base.cra_priority = alg->cra_priority;
145 inst->alg.base.cra_blocksize = alg->cra_blocksize;
146 inst->alg.base.cra_alignmask = alg->cra_alignmask;
147
148 /* We access the data as u32s when xoring. */
149 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
150
151 inst->alg.ivsize = alg->cra_blocksize;
152 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
153 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
154
155 inst->alg.base.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
156
157 inst->alg.init = crypto_cbc_init_tfm;
158 inst->alg.exit = crypto_cbc_exit_tfm;
159
160 inst->alg.setkey = crypto_cbc_setkey;
161 inst->alg.encrypt = crypto_cbc_encrypt;
162 inst->alg.decrypt = crypto_cbc_decrypt;
163
164 inst->free = crypto_cbc_free;
165
166 err = skcipher_register_instance(tmpl, inst);
167 if (err)
168 goto err_drop_spawn;
169
170out:
171 return err;
172
173err_drop_spawn:
174 crypto_drop_spawn(spawn);
175err_free_inst:
176 kfree(inst);
177 goto out;
178}
179
180static struct crypto_template crypto_cbc_tmpl = {
181 .name = "cbc",
182 .create = crypto_cbc_create,
183 .module = THIS_MODULE,
184};
185
186static int __init crypto_cbc_module_init(void)
187{
188 return crypto_register_template(&crypto_cbc_tmpl);
189}
190
191static void __exit crypto_cbc_module_exit(void)
192{
193 crypto_unregister_template(&crypto_cbc_tmpl);
194}
195
196module_init(crypto_cbc_module_init);
197module_exit(crypto_cbc_module_exit);
198
199MODULE_LICENSE("GPL");
200MODULE_DESCRIPTION("CBC block cipher algorithm");
201MODULE_ALIAS_CRYPTO("cbc");