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
20 static 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 unsigned int nbytes = walk->nbytes;
26 u8 *src = walk->src.virt.addr;
27 u8 *dst = walk->dst.virt.addr;
28 u8 * const iv = walk->iv;
29
30 do {
31 crypto_xor(iv, src, bsize);
32 crypto_cipher_encrypt_one(tfm, dst, iv);
33 crypto_xor_cpy(iv, dst, src, bsize);
34
35 src += bsize;
36 dst += bsize;
37 } while ((nbytes -= bsize) >= bsize);
38
39 return nbytes;
40 }
41
42 static 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 *src = walk->src.virt.addr;
49 u8 * const iv = walk->iv;
50 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
51
52 do {
53 memcpy(tmpbuf, src, bsize);
54 crypto_xor(iv, src, bsize);
55 crypto_cipher_encrypt_one(tfm, src, iv);
56 crypto_xor_cpy(iv, tmpbuf, src, bsize);
57
58 src += bsize;
59 } while ((nbytes -= bsize) >= bsize);
60
61 return nbytes;
62 }
63
64 static 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, req, false);
73
74 while (walk.nbytes) {
75 if (walk.src.virt.addr == walk.dst.virt.addr)
76 nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
77 cipher);
78 else
79 nbytes = crypto_pcbc_encrypt_segment(req, &walk,
80 cipher);
81 err = skcipher_walk_done(&walk, nbytes);
82 }
83
84 return err;
85 }
86
87 static 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 unsigned int nbytes = walk->nbytes;
93 u8 *src = walk->src.virt.addr;
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, iv, bsize);
100 crypto_xor_cpy(iv, dst, src, bsize);
101
102 src += bsize;
103 dst += bsize;
104 } while ((nbytes -= bsize) >= bsize);
105
106 return nbytes;
107 }
108
109 static 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 *src = walk->src.virt.addr;
116 u8 * const iv = walk->iv;
117 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
118
119 do {
120 memcpy(tmpbuf, src, bsize);
121 crypto_cipher_decrypt_one(tfm, src, src);
122 crypto_xor(src, iv, bsize);
123 crypto_xor_cpy(iv, src, tmpbuf, bsize);
124
125 src += bsize;
126 } while ((nbytes -= bsize) >= bsize);
127
128 return nbytes;
129 }
130
131 static 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, req, false);
140
141 while (walk.nbytes) {
142 if (walk.src.virt.addr == walk.dst.virt.addr)
143 nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
144 cipher);
145 else
146 nbytes = crypto_pcbc_decrypt_segment(req, &walk,
147 cipher);
148 err = skcipher_walk_done(&walk, nbytes);
149 }
150
151 return err;
152 }
153
154 static 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(inst))
161 return PTR_ERR(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
173 static struct crypto_template crypto_pcbc_tmpl = {
174 .name = "pcbc",
175 .create = crypto_pcbc_create,
176 .module = THIS_MODULE,
177 };
178
179 static int __init crypto_pcbc_module_init(void)
180 {
181 return crypto_register_template(&crypto_pcbc_tmpl);
182 }
183
184 static void __exit crypto_pcbc_module_exit(void)
185 {
186 crypto_unregister_template(&crypto_pcbc_tmpl);
187 }
188
189 subsys_initcall(crypto_pcbc_module_init);
190 module_exit(crypto_pcbc_module_exit);
191
192 MODULE_LICENSE("GPL");
193 MODULE_DESCRIPTION("PCBC block cipher mode of operation");
194 MODULE_ALIAS_CRYPTO("pcbc");
195 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
196
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