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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
22 struct crypto_cbc_ctx {
23 struct crypto_cipher *child;
24 };
25
26 static 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
42 static 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
50 static int crypto_cbc_encrypt(struct skcipher_request *req)
51 {
52 return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
53 }
54
55 static 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
63 static 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
80 static 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
95 static 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
102 static void crypto_cbc_free(struct skcipher_instance *inst)
103 {
104 crypto_drop_skcipher(skcipher_instance_ctx(inst));
105 kfree(inst);
106 }
107
108 static 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
170 out:
171 return err;
172
173 err_drop_spawn:
174 crypto_drop_spawn(spawn);
175 err_free_inst:
176 kfree(inst);
177 goto out;
178 }
179
180 static struct crypto_template crypto_cbc_tmpl = {
181 .name = "cbc",
182 .create = crypto_cbc_create,
183 .module = THIS_MODULE,
184 };
185
186 static int __init crypto_cbc_module_init(void)
187 {
188 return crypto_register_template(&crypto_cbc_tmpl);
189 }
190
191 static void __exit crypto_cbc_module_exit(void)
192 {
193 crypto_unregister_template(&crypto_cbc_tmpl);
194 }
195
196 module_init(crypto_cbc_module_init);
197 module_exit(crypto_cbc_module_exit);
198
199 MODULE_LICENSE("GPL");
200 MODULE_DESCRIPTION("CBC block cipher algorithm");
201 MODULE_ALIAS_CRYPTO("cbc");