Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
db131ef9 HX |
2 | /* |
3 | * CBC: Cipher Block Chaining mode | |
4 | * | |
cc868d82 | 5 | * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au> |
db131ef9 HX |
6 | */ |
7 | ||
79c65d17 | 8 | #include <crypto/internal/skcipher.h> |
db131ef9 HX |
9 | #include <linux/err.h> |
10 | #include <linux/init.h> | |
11 | #include <linux/kernel.h> | |
50b6544e | 12 | #include <linux/log2.h> |
db131ef9 | 13 | #include <linux/module.h> |
db131ef9 | 14 | |
705b52fe HX |
15 | static int crypto_cbc_encrypt_segment(struct crypto_lskcipher *tfm, |
16 | const u8 *src, u8 *dst, unsigned nbytes, | |
17 | u8 *iv) | |
79c65d17 | 18 | { |
705b52fe | 19 | unsigned int bsize = crypto_lskcipher_blocksize(tfm); |
5f254dd4 | 20 | |
705b52fe | 21 | for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize) { |
5f254dd4 | 22 | crypto_xor(iv, src, bsize); |
705b52fe | 23 | crypto_lskcipher_encrypt(tfm, iv, dst, bsize, NULL); |
5f254dd4 | 24 | memcpy(iv, dst, bsize); |
705b52fe | 25 | } |
5f254dd4 HX |
26 | |
27 | return nbytes; | |
28 | } | |
29 | ||
705b52fe HX |
30 | static int crypto_cbc_encrypt_inplace(struct crypto_lskcipher *tfm, |
31 | u8 *src, unsigned nbytes, u8 *oiv) | |
5f254dd4 | 32 | { |
705b52fe HX |
33 | unsigned int bsize = crypto_lskcipher_blocksize(tfm); |
34 | u8 *iv = oiv; | |
35 | ||
36 | if (nbytes < bsize) | |
37 | goto out; | |
5f254dd4 HX |
38 | |
39 | do { | |
40 | crypto_xor(src, iv, bsize); | |
705b52fe | 41 | crypto_lskcipher_encrypt(tfm, src, src, bsize, NULL); |
5f254dd4 HX |
42 | iv = src; |
43 | ||
44 | src += bsize; | |
45 | } while ((nbytes -= bsize) >= bsize); | |
46 | ||
705b52fe | 47 | memcpy(oiv, iv, bsize); |
5f254dd4 | 48 | |
705b52fe | 49 | out: |
5f254dd4 | 50 | return nbytes; |
79c65d17 HX |
51 | } |
52 | ||
705b52fe HX |
53 | static int crypto_cbc_encrypt(struct crypto_lskcipher *tfm, const u8 *src, |
54 | u8 *dst, unsigned len, u8 *iv, bool final) | |
db131ef9 | 55 | { |
705b52fe HX |
56 | struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm); |
57 | struct crypto_lskcipher *cipher = *ctx; | |
58 | int rem; | |
5f254dd4 | 59 | |
705b52fe HX |
60 | if (src == dst) |
61 | rem = crypto_cbc_encrypt_inplace(cipher, dst, len, iv); | |
62 | else | |
63 | rem = crypto_cbc_encrypt_segment(cipher, src, dst, len, iv); | |
5f254dd4 | 64 | |
705b52fe | 65 | return rem && final ? -EINVAL : rem; |
5f254dd4 HX |
66 | } |
67 | ||
705b52fe HX |
68 | static int crypto_cbc_decrypt_segment(struct crypto_lskcipher *tfm, |
69 | const u8 *src, u8 *dst, unsigned nbytes, | |
70 | u8 *oiv) | |
5f254dd4 | 71 | { |
705b52fe HX |
72 | unsigned int bsize = crypto_lskcipher_blocksize(tfm); |
73 | const u8 *iv = oiv; | |
74 | ||
75 | if (nbytes < bsize) | |
76 | goto out; | |
5f254dd4 HX |
77 | |
78 | do { | |
705b52fe | 79 | crypto_lskcipher_decrypt(tfm, src, dst, bsize, NULL); |
5f254dd4 HX |
80 | crypto_xor(dst, iv, bsize); |
81 | iv = src; | |
82 | ||
83 | src += bsize; | |
84 | dst += bsize; | |
85 | } while ((nbytes -= bsize) >= bsize); | |
86 | ||
705b52fe | 87 | memcpy(oiv, iv, bsize); |
5f254dd4 | 88 | |
705b52fe | 89 | out: |
5f254dd4 | 90 | return nbytes; |
79c65d17 HX |
91 | } |
92 | ||
705b52fe HX |
93 | static int crypto_cbc_decrypt_inplace(struct crypto_lskcipher *tfm, |
94 | u8 *src, unsigned nbytes, u8 *iv) | |
79c65d17 | 95 | { |
705b52fe | 96 | unsigned int bsize = crypto_lskcipher_blocksize(tfm); |
5f254dd4 | 97 | u8 last_iv[MAX_CIPHER_BLOCKSIZE]; |
5f254dd4 | 98 | |
705b52fe HX |
99 | if (nbytes < bsize) |
100 | goto out; | |
5f254dd4 HX |
101 | |
102 | /* Start of the last block. */ | |
103 | src += nbytes - (nbytes & (bsize - 1)) - bsize; | |
104 | memcpy(last_iv, src, bsize); | |
105 | ||
106 | for (;;) { | |
705b52fe | 107 | crypto_lskcipher_decrypt(tfm, src, src, bsize, NULL); |
5f254dd4 HX |
108 | if ((nbytes -= bsize) < bsize) |
109 | break; | |
110 | crypto_xor(src, src - bsize, bsize); | |
111 | src -= bsize; | |
112 | } | |
113 | ||
705b52fe HX |
114 | crypto_xor(src, iv, bsize); |
115 | memcpy(iv, last_iv, bsize); | |
5f254dd4 | 116 | |
705b52fe | 117 | out: |
5f254dd4 | 118 | return nbytes; |
79c65d17 HX |
119 | } |
120 | ||
705b52fe HX |
121 | static int crypto_cbc_decrypt(struct crypto_lskcipher *tfm, const u8 *src, |
122 | u8 *dst, unsigned len, u8 *iv, bool final) | |
79c65d17 | 123 | { |
705b52fe HX |
124 | struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm); |
125 | struct crypto_lskcipher *cipher = *ctx; | |
126 | int rem; | |
db131ef9 | 127 | |
705b52fe HX |
128 | if (src == dst) |
129 | rem = crypto_cbc_decrypt_inplace(cipher, dst, len, iv); | |
130 | else | |
131 | rem = crypto_cbc_decrypt_segment(cipher, src, dst, len, iv); | |
db131ef9 | 132 | |
705b52fe | 133 | return rem && final ? -EINVAL : rem; |
db131ef9 HX |
134 | } |
135 | ||
79c65d17 HX |
136 | static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) |
137 | { | |
705b52fe | 138 | struct lskcipher_instance *inst; |
ebc610e5 HX |
139 | int err; |
140 | ||
705b52fe | 141 | inst = lskcipher_alloc_instance_simple(tmpl, tb); |
a5a84a9d EB |
142 | if (IS_ERR(inst)) |
143 | return PTR_ERR(inst); | |
50b6544e | 144 | |
79c65d17 | 145 | err = -EINVAL; |
705b52fe | 146 | if (!is_power_of_2(inst->alg.co.base.cra_blocksize)) |
a5a84a9d | 147 | goto out_free_inst; |
db131ef9 | 148 | |
79c65d17 HX |
149 | inst->alg.encrypt = crypto_cbc_encrypt; |
150 | inst->alg.decrypt = crypto_cbc_decrypt; | |
db131ef9 | 151 | |
705b52fe | 152 | err = lskcipher_register_instance(tmpl, inst); |
b3c16bfc | 153 | if (err) { |
a5a84a9d | 154 | out_free_inst: |
b3c16bfc HX |
155 | inst->free(inst); |
156 | } | |
157 | ||
a5a84a9d | 158 | return err; |
db131ef9 HX |
159 | } |
160 | ||
161 | static struct crypto_template crypto_cbc_tmpl = { | |
162 | .name = "cbc", | |
79c65d17 | 163 | .create = crypto_cbc_create, |
db131ef9 HX |
164 | .module = THIS_MODULE, |
165 | }; | |
166 | ||
167 | static int __init crypto_cbc_module_init(void) | |
168 | { | |
169 | return crypto_register_template(&crypto_cbc_tmpl); | |
170 | } | |
171 | ||
172 | static void __exit crypto_cbc_module_exit(void) | |
173 | { | |
174 | crypto_unregister_template(&crypto_cbc_tmpl); | |
175 | } | |
176 | ||
c4741b23 | 177 | subsys_initcall(crypto_cbc_module_init); |
db131ef9 HX |
178 | module_exit(crypto_cbc_module_exit); |
179 | ||
180 | MODULE_LICENSE("GPL"); | |
a5a84a9d | 181 | MODULE_DESCRIPTION("CBC block cipher mode of operation"); |
4943ba16 | 182 | MODULE_ALIAS_CRYPTO("cbc"); |