1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* CBC: Cipher Block Chaining mode
*
* Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
*/
#include <crypto/algapi.h>
#include <crypto/internal/cipher.h>
#include <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/module.h>
static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
struct crypto_skcipher *skcipher)
{
unsigned int bsize = crypto_skcipher_blocksize(skcipher);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
struct crypto_cipher *cipher;
struct crypto_tfm *tfm;
u8 *iv = walk->iv;
cipher = skcipher_cipher_simple(skcipher);
tfm = crypto_cipher_tfm(cipher);
fn = crypto_cipher_alg(cipher)->cia_encrypt;
do {
crypto_xor(iv, src, bsize);
fn(tfm, dst, iv);
memcpy(iv, dst, bsize);
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
return nbytes;
}
static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
struct crypto_skcipher *skcipher)
{
unsigned int bsize = crypto_skcipher_blocksize(skcipher);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
struct crypto_cipher *cipher;
struct crypto_tfm *tfm;
u8 *iv = walk->iv;
cipher = skcipher_cipher_simple(skcipher);
tfm = crypto_cipher_tfm(cipher);
fn = crypto_cipher_alg(cipher)->cia_encrypt;
do {
crypto_xor(src, iv, bsize);
fn(tfm, src, src);
iv = src;
src += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_cbc_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
struct skcipher_walk walk;
int err;
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes) {
if (walk.src.virt.addr == walk.dst.virt.addr)
err = crypto_cbc_encrypt_inplace(&walk, skcipher);
else
err = crypto_cbc_encrypt_segment(&walk, skcipher);
err = skcipher_walk_done(&walk, err);
}
return err;
}
static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
struct crypto_skcipher *skcipher)
{
unsigned int bsize = crypto_skcipher_blocksize(skcipher);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
struct crypto_cipher *cipher;
struct crypto_tfm *tfm;
u8 *iv = walk->iv;
cipher = skcipher_cipher_simple(skcipher);
tfm = crypto_cipher_tfm(cipher);
fn = crypto_cipher_alg(cipher)->cia_decrypt;
do {
fn(tfm, dst, src);
crypto_xor(dst, iv, bsize);
iv = src;
src += bsize;
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
memcpy(walk->iv, iv, bsize);
return nbytes;
}
static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk,
struct crypto_skcipher *skcipher)
{
unsigned int bsize = crypto_skcipher_blocksize(skcipher);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 last_iv[MAX_CIPHER_BLOCKSIZE];
struct crypto_cipher *cipher;
struct crypto_tfm *tfm;
cipher = skcipher_cipher_simple(skcipher);
tfm = crypto_cipher_tfm(cipher);
fn = crypto_cipher_alg(cipher)->cia_decrypt;
/* Start of the last block. */
src += nbytes - (nbytes & (bsize - 1)) - bsize;
memcpy(last_iv, src, bsize);
for (;;) {
fn(tfm, src, src);
if ((nbytes -= bsize) < bsize)
break;
crypto_xor(src, src - bsize, bsize);
src -= bsize;
}
crypto_xor(src, walk->iv, bsize);
memcpy(walk->iv, last_iv, bsize);
return nbytes;
}
static int crypto_cbc_decrypt(struct skcipher_request *req)
{
struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
struct skcipher_walk walk;
int err;
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes) {
if (walk.src.virt.addr == walk.dst.virt.addr)
err = crypto_cbc_decrypt_inplace(&walk, skcipher);
else
err = crypto_cbc_decrypt_segment(&walk, skcipher);
err = skcipher_walk_done(&walk, err);
}
return err;
}
static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct skcipher_instance *inst;
struct crypto_alg *alg;
int err;
inst = skcipher_alloc_instance_simple(tmpl, tb);
if (IS_ERR(inst))
return PTR_ERR(inst);
alg = skcipher_ialg_simple(inst);
err = -EINVAL;
if (!is_power_of_2(alg->cra_blocksize))
goto out_free_inst;
inst->alg.encrypt = crypto_cbc_encrypt;
inst->alg.decrypt = crypto_cbc_decrypt;
err = skcipher_register_instance(tmpl, inst);
if (err) {
out_free_inst:
inst->free(inst);
}
return err;
}
static struct crypto_template crypto_cbc_tmpl = {
.name = "cbc",
.create = crypto_cbc_create,
.module = THIS_MODULE,
};
static int __init crypto_cbc_module_init(void)
{
return crypto_register_template(&crypto_cbc_tmpl);
}
static void __exit crypto_cbc_module_exit(void)
{
crypto_unregister_template(&crypto_cbc_tmpl);
}
subsys_initcall(crypto_cbc_module_init);
module_exit(crypto_cbc_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CBC block cipher mode of operation");
MODULE_ALIAS_CRYPTO("cbc");
|
