1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * PCBC: Propagating Cipher Block Chaining mode
5 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
9 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
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>
20 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
21 struct skcipher_walk *walk,
22 struct crypto_cipher *tfm)
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;
31 crypto_xor(iv, src, bsize);
32 crypto_cipher_encrypt_one(tfm, dst, iv);
33 crypto_xor_cpy(iv, dst, src, bsize);
37 } while ((nbytes -= bsize) >= bsize);
42 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
43 struct skcipher_walk *walk,
44 struct crypto_cipher *tfm)
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];
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);
59 } while ((nbytes -= bsize) >= bsize);
64 static int crypto_pcbc_encrypt(struct skcipher_request *req)
66 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
67 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
68 struct skcipher_walk walk;
72 err = skcipher_walk_virt(&walk, req, false);
74 while ((nbytes = walk.nbytes)) {
75 if (walk.src.virt.addr == walk.dst.virt.addr)
76 nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
79 nbytes = crypto_pcbc_encrypt_segment(req, &walk,
81 err = skcipher_walk_done(&walk, nbytes);
87 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
88 struct skcipher_walk *walk,
89 struct crypto_cipher *tfm)
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;
98 crypto_cipher_decrypt_one(tfm, dst, src);
99 crypto_xor(dst, iv, bsize);
100 crypto_xor_cpy(iv, dst, src, bsize);
104 } while ((nbytes -= bsize) >= bsize);
109 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
110 struct skcipher_walk *walk,
111 struct crypto_cipher *tfm)
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));
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);
126 } while ((nbytes -= bsize) >= bsize);
131 static int crypto_pcbc_decrypt(struct skcipher_request *req)
133 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
134 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
135 struct skcipher_walk walk;
139 err = skcipher_walk_virt(&walk, req, false);
141 while ((nbytes = walk.nbytes)) {
142 if (walk.src.virt.addr == walk.dst.virt.addr)
143 nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
146 nbytes = crypto_pcbc_decrypt_segment(req, &walk,
148 err = skcipher_walk_done(&walk, nbytes);
154 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
156 struct skcipher_instance *inst;
159 inst = skcipher_alloc_instance_simple(tmpl, tb);
161 return PTR_ERR(inst);
163 inst->alg.encrypt = crypto_pcbc_encrypt;
164 inst->alg.decrypt = crypto_pcbc_decrypt;
166 err = skcipher_register_instance(tmpl, inst);
173 static struct crypto_template crypto_pcbc_tmpl = {
175 .create = crypto_pcbc_create,
176 .module = THIS_MODULE,
179 static int __init crypto_pcbc_module_init(void)
181 return crypto_register_template(&crypto_pcbc_tmpl);
184 static void __exit crypto_pcbc_module_exit(void)
186 crypto_unregister_template(&crypto_pcbc_tmpl);
189 subsys_initcall(crypto_pcbc_module_init);
190 module_exit(crypto_pcbc_module_exit);
192 MODULE_LICENSE("GPL");
193 MODULE_DESCRIPTION("PCBC block cipher mode of operation");
194 MODULE_ALIAS_CRYPTO("pcbc");
195 MODULE_IMPORT_NS(CRYPTO_INTERNAL);