Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * CBC: Cipher Block Chaining mode
4 *
5 * Copyright (c) 2016 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8#ifndef _CRYPTO_CBC_H
9#define _CRYPTO_CBC_H
10
11#include <crypto/internal/skcipher.h>
12#include <linux/string.h>
13#include <linux/types.h>
14
15static inline int crypto_cbc_encrypt_segment(
16 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
17 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
18{
19 unsigned int bsize = crypto_skcipher_blocksize(tfm);
20 unsigned int nbytes = walk->nbytes;
21 u8 *src = walk->src.virt.addr;
22 u8 *dst = walk->dst.virt.addr;
23 u8 *iv = walk->iv;
24
25 do {
26 crypto_xor(iv, src, bsize);
27 fn(tfm, iv, dst);
28 memcpy(iv, dst, bsize);
29
30 src += bsize;
31 dst += bsize;
32 } while ((nbytes -= bsize) >= bsize);
33
34 return nbytes;
35}
36
37static inline int crypto_cbc_encrypt_inplace(
38 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
39 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
40{
41 unsigned int bsize = crypto_skcipher_blocksize(tfm);
42 unsigned int nbytes = walk->nbytes;
43 u8 *src = walk->src.virt.addr;
44 u8 *iv = walk->iv;
45
46 do {
47 crypto_xor(src, iv, bsize);
48 fn(tfm, src, src);
49 iv = src;
50
51 src += bsize;
52 } while ((nbytes -= bsize) >= bsize);
53
54 memcpy(walk->iv, iv, bsize);
55
56 return nbytes;
57}
58
59static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req,
60 void (*fn)(struct crypto_skcipher *,
61 const u8 *, u8 *))
62{
63 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
64 struct skcipher_walk walk;
65 int err;
66
67 err = skcipher_walk_virt(&walk, req, false);
68
69 while (walk.nbytes) {
70 if (walk.src.virt.addr == walk.dst.virt.addr)
71 err = crypto_cbc_encrypt_inplace(&walk, tfm, fn);
72 else
73 err = crypto_cbc_encrypt_segment(&walk, tfm, fn);
74 err = skcipher_walk_done(&walk, err);
75 }
76
77 return err;
78}
79
80static inline int crypto_cbc_decrypt_segment(
81 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
82 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
83{
84 unsigned int bsize = crypto_skcipher_blocksize(tfm);
85 unsigned int nbytes = walk->nbytes;
86 u8 *src = walk->src.virt.addr;
87 u8 *dst = walk->dst.virt.addr;
88 u8 *iv = walk->iv;
89
90 do {
91 fn(tfm, src, dst);
92 crypto_xor(dst, iv, bsize);
93 iv = src;
94
95 src += bsize;
96 dst += bsize;
97 } while ((nbytes -= bsize) >= bsize);
98
99 memcpy(walk->iv, iv, bsize);
100
101 return nbytes;
102}
103
104static inline int crypto_cbc_decrypt_inplace(
105 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
106 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
107{
108 unsigned int bsize = crypto_skcipher_blocksize(tfm);
109 unsigned int nbytes = walk->nbytes;
110 u8 *src = walk->src.virt.addr;
111 u8 last_iv[MAX_CIPHER_BLOCKSIZE];
112
113 /* Start of the last block. */
114 src += nbytes - (nbytes & (bsize - 1)) - bsize;
115 memcpy(last_iv, src, bsize);
116
117 for (;;) {
118 fn(tfm, src, src);
119 if ((nbytes -= bsize) < bsize)
120 break;
121 crypto_xor(src, src - bsize, bsize);
122 src -= bsize;
123 }
124
125 crypto_xor(src, walk->iv, bsize);
126 memcpy(walk->iv, last_iv, bsize);
127
128 return nbytes;
129}
130
131static inline int crypto_cbc_decrypt_blocks(
132 struct skcipher_walk *walk, struct crypto_skcipher *tfm,
133 void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
134{
135 if (walk->src.virt.addr == walk->dst.virt.addr)
136 return crypto_cbc_decrypt_inplace(walk, tfm, fn);
137 else
138 return crypto_cbc_decrypt_segment(walk, tfm, fn);
139}
140
141#endif /* _CRYPTO_CBC_H */