1 /*
2 * CBC: Cipher Block Chaining mode
3 *
4 * Copyright (c) 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 #ifndef _CRYPTO_CBC_H
14 #define _CRYPTO_CBC_H
15
16 #include <crypto/internal/skcipher.h>
17 #include <linux/string.h>
18 #include <linux/types.h>
19
crypto_cbc_encrypt_segment(struct skcipher_walk * walk,struct crypto_skcipher * tfm,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))20 static inline int crypto_cbc_encrypt_segment(
21 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
22 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
23 {
24 unsigned int bsize = crypto_skcipher_blocksize(tfm);
25 unsigned int nbytes = walk->nbytes;
26 u8 *src = walk->src.virt.addr;
27 u8 *dst = walk->dst.virt.addr;
28 u8 *iv = walk->iv;
29
30 do {
31 crypto_xor(iv, src, bsize);
32 fn(tfm, iv, dst);
33 memcpy(iv, dst, bsize);
34
35 src += bsize;
36 dst += bsize;
37 } while ((nbytes -= bsize) >= bsize);
38
39 return nbytes;
40 }
41
crypto_cbc_encrypt_inplace(struct skcipher_walk * walk,struct crypto_skcipher * tfm,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))42 static inline int crypto_cbc_encrypt_inplace(
43 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
44 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
45 {
46 unsigned int bsize = crypto_skcipher_blocksize(tfm);
47 unsigned int nbytes = walk->nbytes;
48 u8 *src = walk->src.virt.addr;
49 u8 *iv = walk->iv;
50
51 do {
52 crypto_xor(src, iv, bsize);
53 fn(tfm, src, src);
54 iv = src;
55
56 src += bsize;
57 } while ((nbytes -= bsize) >= bsize);
58
59 memcpy(walk->iv, iv, bsize);
60
61 return nbytes;
62 }
63
crypto_cbc_encrypt_walk(struct skcipher_request * req,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))64 static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req,
65 void (*fn)(struct crypto_skcipher *,
66 const u8 *, u8 *))
67 {
68 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
69 struct skcipher_walk walk;
70 int err;
71
72 err = skcipher_walk_virt(&walk, req, false);
73
74 while (walk.nbytes) {
75 if (walk.src.virt.addr == walk.dst.virt.addr)
76 err = crypto_cbc_encrypt_inplace(&walk, tfm, fn);
77 else
78 err = crypto_cbc_encrypt_segment(&walk, tfm, fn);
79 err = skcipher_walk_done(&walk, err);
80 }
81
82 return err;
83 }
84
crypto_cbc_decrypt_segment(struct skcipher_walk * walk,struct crypto_skcipher * tfm,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))85 static inline int crypto_cbc_decrypt_segment(
86 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
87 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
88 {
89 unsigned int bsize = crypto_skcipher_blocksize(tfm);
90 unsigned int nbytes = walk->nbytes;
91 u8 *src = walk->src.virt.addr;
92 u8 *dst = walk->dst.virt.addr;
93 u8 *iv = walk->iv;
94
95 do {
96 fn(tfm, src, dst);
97 crypto_xor(dst, iv, bsize);
98 iv = src;
99
100 src += bsize;
101 dst += bsize;
102 } while ((nbytes -= bsize) >= bsize);
103
104 memcpy(walk->iv, iv, bsize);
105
106 return nbytes;
107 }
108
crypto_cbc_decrypt_inplace(struct skcipher_walk * walk,struct crypto_skcipher * tfm,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))109 static inline int crypto_cbc_decrypt_inplace(
110 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
111 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
112 {
113 unsigned int bsize = crypto_skcipher_blocksize(tfm);
114 unsigned int nbytes = walk->nbytes;
115 u8 *src = walk->src.virt.addr;
116 u8 last_iv[bsize];
117
118 /* Start of the last block. */
119 src += nbytes - (nbytes & (bsize - 1)) - bsize;
120 memcpy(last_iv, src, bsize);
121
122 for (;;) {
123 fn(tfm, src, src);
124 if ((nbytes -= bsize) < bsize)
125 break;
126 crypto_xor(src, src - bsize, bsize);
127 src -= bsize;
128 }
129
130 crypto_xor(src, walk->iv, bsize);
131 memcpy(walk->iv, last_iv, bsize);
132
133 return nbytes;
134 }
135
crypto_cbc_decrypt_blocks(struct skcipher_walk * walk,struct crypto_skcipher * tfm,void (* fn)(struct crypto_skcipher *,const u8 *,u8 *))136 static inline int crypto_cbc_decrypt_blocks(
137 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
138 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
139 {
140 if (walk->src.virt.addr == walk->dst.virt.addr)
141 return crypto_cbc_decrypt_inplace(walk, tfm, fn);
142 else
143 return crypto_cbc_decrypt_segment(walk, tfm, fn);
144 }
145
146 #endif /* _CRYPTO_CBC_H */
147
