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/skcipher.h>
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18
crypto_pcbc_encrypt_segment(struct skcipher_request * req,struct skcipher_walk * walk,struct crypto_cipher * tfm)19 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
20 struct skcipher_walk *walk,
21 struct crypto_cipher *tfm)
22 {
23 int bsize = crypto_cipher_blocksize(tfm);
24 unsigned int nbytes = walk->nbytes;
25 u8 *src = walk->src.virt.addr;
26 u8 *dst = walk->dst.virt.addr;
27 u8 * const iv = walk->iv;
28
29 do {
30 crypto_xor(iv, src, bsize);
31 crypto_cipher_encrypt_one(tfm, dst, iv);
32 crypto_xor_cpy(iv, dst, src, bsize);
33
34 src += bsize;
35 dst += bsize;
36 } while ((nbytes -= bsize) >= bsize);
37
38 return nbytes;
39 }
40
crypto_pcbc_encrypt_inplace(struct skcipher_request * req,struct skcipher_walk * walk,struct crypto_cipher * tfm)41 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
42 struct skcipher_walk *walk,
43 struct crypto_cipher *tfm)
44 {
45 int bsize = crypto_cipher_blocksize(tfm);
46 unsigned int nbytes = walk->nbytes;
47 u8 *src = walk->src.virt.addr;
48 u8 * const iv = walk->iv;
49 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
50
51 do {
52 memcpy(tmpbuf, src, bsize);
53 crypto_xor(iv, src, bsize);
54 crypto_cipher_encrypt_one(tfm, src, iv);
55 crypto_xor_cpy(iv, tmpbuf, src, bsize);
56
57 src += bsize;
58 } while ((nbytes -= bsize) >= bsize);
59
60 return nbytes;
61 }
62
crypto_pcbc_encrypt(struct skcipher_request * req)63 static int crypto_pcbc_encrypt(struct skcipher_request *req)
64 {
65 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
66 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
67 struct skcipher_walk walk;
68 unsigned int nbytes;
69 int err;
70
71 err = skcipher_walk_virt(&walk, req, false);
72
73 while ((nbytes = walk.nbytes)) {
74 if (walk.src.virt.addr == walk.dst.virt.addr)
75 nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
76 cipher);
77 else
78 nbytes = crypto_pcbc_encrypt_segment(req, &walk,
79 cipher);
80 err = skcipher_walk_done(&walk, nbytes);
81 }
82
83 return err;
84 }
85
crypto_pcbc_decrypt_segment(struct skcipher_request * req,struct skcipher_walk * walk,struct crypto_cipher * tfm)86 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
87 struct skcipher_walk *walk,
88 struct crypto_cipher *tfm)
89 {
90 int bsize = crypto_cipher_blocksize(tfm);
91 unsigned int nbytes = walk->nbytes;
92 u8 *src = walk->src.virt.addr;
93 u8 *dst = walk->dst.virt.addr;
94 u8 * const iv = walk->iv;
95
96 do {
97 crypto_cipher_decrypt_one(tfm, dst, src);
98 crypto_xor(dst, iv, bsize);
99 crypto_xor_cpy(iv, dst, src, bsize);
100
101 src += bsize;
102 dst += bsize;
103 } while ((nbytes -= bsize) >= bsize);
104
105 return nbytes;
106 }
107
crypto_pcbc_decrypt_inplace(struct skcipher_request * req,struct skcipher_walk * walk,struct crypto_cipher * tfm)108 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
109 struct skcipher_walk *walk,
110 struct crypto_cipher *tfm)
111 {
112 int bsize = crypto_cipher_blocksize(tfm);
113 unsigned int nbytes = walk->nbytes;
114 u8 *src = walk->src.virt.addr;
115 u8 * const iv = walk->iv;
116 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
117
118 do {
119 memcpy(tmpbuf, src, bsize);
120 crypto_cipher_decrypt_one(tfm, src, src);
121 crypto_xor(src, iv, bsize);
122 crypto_xor_cpy(iv, src, tmpbuf, bsize);
123
124 src += bsize;
125 } while ((nbytes -= bsize) >= bsize);
126
127 return nbytes;
128 }
129
crypto_pcbc_decrypt(struct skcipher_request * req)130 static int crypto_pcbc_decrypt(struct skcipher_request *req)
131 {
132 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
133 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
134 struct skcipher_walk walk;
135 unsigned int nbytes;
136 int err;
137
138 err = skcipher_walk_virt(&walk, req, false);
139
140 while ((nbytes = walk.nbytes)) {
141 if (walk.src.virt.addr == walk.dst.virt.addr)
142 nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
143 cipher);
144 else
145 nbytes = crypto_pcbc_decrypt_segment(req, &walk,
146 cipher);
147 err = skcipher_walk_done(&walk, nbytes);
148 }
149
150 return err;
151 }
152
crypto_pcbc_create(struct crypto_template * tmpl,struct rtattr ** tb)153 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
154 {
155 struct skcipher_instance *inst;
156 struct crypto_alg *alg;
157 int err;
158
159 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
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 crypto_mod_put(alg);
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
crypto_pcbc_module_init(void)179 static int __init crypto_pcbc_module_init(void)
180 {
181 return crypto_register_template(&crypto_pcbc_tmpl);
182 }
183
crypto_pcbc_module_exit(void)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