1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PCBC: Propagating Cipher Block Chaining mode
4 *
5 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
7 *
8 * Derived from cbc.c
9 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 */
11
12#include <crypto/algapi.h>
13#include <crypto/internal/cipher.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/module.h>
19
20static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
21 struct skcipher_walk *walk,
22 struct crypto_cipher *tfm)
23{
24 int bsize = crypto_cipher_blocksize(tfm);
25 const u8 *src = walk->src.virt.addr;
26 unsigned int nbytes = walk->nbytes;
27 u8 *dst = walk->dst.virt.addr;
28 u8 * const iv = walk->iv;
29
30 do {
31 crypto_xor(dst: iv, src, size: bsize);
32 crypto_cipher_encrypt_one(tfm, dst, src: iv);
33 crypto_xor_cpy(dst: iv, src1: dst, src2: src, size: bsize);
34
35 src += bsize;
36 dst += bsize;
37 } while ((nbytes -= bsize) >= bsize);
38
39 return nbytes;
40}
41
42static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
43 struct skcipher_walk *walk,
44 struct crypto_cipher *tfm)
45{
46 int bsize = crypto_cipher_blocksize(tfm);
47 unsigned int nbytes = walk->nbytes;
48 u8 *dst = walk->dst.virt.addr;
49 u8 * const iv = walk->iv;
50 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
51
52 do {
53 memcpy(tmpbuf, dst, bsize);
54 crypto_xor(dst: iv, src: dst, size: bsize);
55 crypto_cipher_encrypt_one(tfm, dst, src: iv);
56 crypto_xor_cpy(dst: iv, src1: tmpbuf, src2: dst, size: bsize);
57
58 dst += bsize;
59 } while ((nbytes -= bsize) >= bsize);
60
61 return nbytes;
62}
63
64static int crypto_pcbc_encrypt(struct skcipher_request *req)
65{
66 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
67 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
68 struct skcipher_walk walk;
69 unsigned int nbytes;
70 int err;
71
72 err = skcipher_walk_virt(walk: &walk, req, atomic: false);
73
74 while (walk.nbytes) {
75 if (walk.src.virt.addr == walk.dst.virt.addr)
76 nbytes = crypto_pcbc_encrypt_inplace(req, walk: &walk,
77 tfm: cipher);
78 else
79 nbytes = crypto_pcbc_encrypt_segment(req, walk: &walk,
80 tfm: cipher);
81 err = skcipher_walk_done(walk: &walk, res: nbytes);
82 }
83
84 return err;
85}
86
87static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
88 struct skcipher_walk *walk,
89 struct crypto_cipher *tfm)
90{
91 int bsize = crypto_cipher_blocksize(tfm);
92 const u8 *src = walk->src.virt.addr;
93 unsigned int nbytes = walk->nbytes;
94 u8 *dst = walk->dst.virt.addr;
95 u8 * const iv = walk->iv;
96
97 do {
98 crypto_cipher_decrypt_one(tfm, dst, src);
99 crypto_xor(dst, src: iv, size: bsize);
100 crypto_xor_cpy(dst: iv, src1: dst, src2: src, size: bsize);
101
102 src += bsize;
103 dst += bsize;
104 } while ((nbytes -= bsize) >= bsize);
105
106 return nbytes;
107}
108
109static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
110 struct skcipher_walk *walk,
111 struct crypto_cipher *tfm)
112{
113 int bsize = crypto_cipher_blocksize(tfm);
114 unsigned int nbytes = walk->nbytes;
115 u8 *dst = walk->dst.virt.addr;
116 u8 * const iv = walk->iv;
117 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
118
119 do {
120 memcpy(tmpbuf, dst, bsize);
121 crypto_cipher_decrypt_one(tfm, dst, src: dst);
122 crypto_xor(dst, src: iv, size: bsize);
123 crypto_xor_cpy(dst: iv, src1: dst, src2: tmpbuf, size: bsize);
124
125 dst += bsize;
126 } while ((nbytes -= bsize) >= bsize);
127
128 return nbytes;
129}
130
131static int crypto_pcbc_decrypt(struct skcipher_request *req)
132{
133 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
134 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
135 struct skcipher_walk walk;
136 unsigned int nbytes;
137 int err;
138
139 err = skcipher_walk_virt(walk: &walk, req, atomic: false);
140
141 while (walk.nbytes) {
142 if (walk.src.virt.addr == walk.dst.virt.addr)
143 nbytes = crypto_pcbc_decrypt_inplace(req, walk: &walk,
144 tfm: cipher);
145 else
146 nbytes = crypto_pcbc_decrypt_segment(req, walk: &walk,
147 tfm: cipher);
148 err = skcipher_walk_done(walk: &walk, res: nbytes);
149 }
150
151 return err;
152}
153
154static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
155{
156 struct skcipher_instance *inst;
157 int err;
158
159 inst = skcipher_alloc_instance_simple(tmpl, tb);
160 if (IS_ERR(ptr: inst))
161 return PTR_ERR(ptr: inst);
162
163 inst->alg.encrypt = crypto_pcbc_encrypt;
164 inst->alg.decrypt = crypto_pcbc_decrypt;
165
166 err = skcipher_register_instance(tmpl, inst);
167 if (err)
168 inst->free(inst);
169
170 return err;
171}
172
173static struct crypto_template crypto_pcbc_tmpl = {
174 .name = "pcbc",
175 .create = crypto_pcbc_create,
176 .module = THIS_MODULE,
177};
178
179static int __init crypto_pcbc_module_init(void)
180{
181 return crypto_register_template(tmpl: &crypto_pcbc_tmpl);
182}
183
184static void __exit crypto_pcbc_module_exit(void)
185{
186 crypto_unregister_template(tmpl: &crypto_pcbc_tmpl);
187}
188
189module_init(crypto_pcbc_module_init);
190module_exit(crypto_pcbc_module_exit);
191
192MODULE_LICENSE("GPL");
193MODULE_DESCRIPTION("PCBC block cipher mode of operation");
194MODULE_ALIAS_CRYPTO("pcbc");
195MODULE_IMPORT_NS("CRYPTO_INTERNAL");
196

source code of linux/crypto/pcbc.c

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