2 * PCBC: Propagating Cipher Block Chaining mode
4 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the Free
12 * Software Foundation; either version 2 of the License, or (at your option)
17 #include <crypto/algapi.h>
18 #include <crypto/internal/skcipher.h>
19 #include <linux/err.h>
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/slab.h>
24 #include <linux/compiler.h>
26 struct crypto_pcbc_ctx {
27 struct crypto_cipher *child;
30 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key,
33 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent);
34 struct crypto_cipher *child = ctx->child;
37 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
38 crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
40 err = crypto_cipher_setkey(child, key, keylen);
41 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
46 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
47 struct skcipher_walk *walk,
48 struct crypto_cipher *tfm)
50 int bsize = crypto_cipher_blocksize(tfm);
51 unsigned int nbytes = walk->nbytes;
52 u8 *src = walk->src.virt.addr;
53 u8 *dst = walk->dst.virt.addr;
57 crypto_xor(iv, src, bsize);
58 crypto_cipher_encrypt_one(tfm, dst, iv);
59 crypto_xor_cpy(iv, dst, src, bsize);
63 } while ((nbytes -= bsize) >= bsize);
68 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
69 struct skcipher_walk *walk,
70 struct crypto_cipher *tfm)
72 int bsize = crypto_cipher_blocksize(tfm);
73 unsigned int nbytes = walk->nbytes;
74 u8 *src = walk->src.virt.addr;
76 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
79 memcpy(tmpbuf, src, bsize);
80 crypto_xor(iv, src, bsize);
81 crypto_cipher_encrypt_one(tfm, src, iv);
82 crypto_xor_cpy(iv, tmpbuf, src, bsize);
85 } while ((nbytes -= bsize) >= bsize);
87 memcpy(walk->iv, iv, bsize);
92 static int crypto_pcbc_encrypt(struct skcipher_request *req)
94 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
95 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
96 struct crypto_cipher *child = ctx->child;
97 struct skcipher_walk walk;
101 err = skcipher_walk_virt(&walk, req, false);
103 while ((nbytes = walk.nbytes)) {
104 if (walk.src.virt.addr == walk.dst.virt.addr)
105 nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
108 nbytes = crypto_pcbc_encrypt_segment(req, &walk,
110 err = skcipher_walk_done(&walk, nbytes);
116 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
117 struct skcipher_walk *walk,
118 struct crypto_cipher *tfm)
120 int bsize = crypto_cipher_blocksize(tfm);
121 unsigned int nbytes = walk->nbytes;
122 u8 *src = walk->src.virt.addr;
123 u8 *dst = walk->dst.virt.addr;
127 crypto_cipher_decrypt_one(tfm, dst, src);
128 crypto_xor(dst, iv, bsize);
129 crypto_xor_cpy(iv, dst, src, bsize);
133 } while ((nbytes -= bsize) >= bsize);
135 memcpy(walk->iv, iv, bsize);
140 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
141 struct skcipher_walk *walk,
142 struct crypto_cipher *tfm)
144 int bsize = crypto_cipher_blocksize(tfm);
145 unsigned int nbytes = walk->nbytes;
146 u8 *src = walk->src.virt.addr;
148 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
151 memcpy(tmpbuf, src, bsize);
152 crypto_cipher_decrypt_one(tfm, src, src);
153 crypto_xor(src, iv, bsize);
154 crypto_xor_cpy(iv, src, tmpbuf, bsize);
157 } while ((nbytes -= bsize) >= bsize);
159 memcpy(walk->iv, iv, bsize);
164 static int crypto_pcbc_decrypt(struct skcipher_request *req)
166 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
167 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
168 struct crypto_cipher *child = ctx->child;
169 struct skcipher_walk walk;
173 err = skcipher_walk_virt(&walk, req, false);
175 while ((nbytes = walk.nbytes)) {
176 if (walk.src.virt.addr == walk.dst.virt.addr)
177 nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
180 nbytes = crypto_pcbc_decrypt_segment(req, &walk,
182 err = skcipher_walk_done(&walk, nbytes);
188 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm)
190 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
191 struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
192 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
193 struct crypto_cipher *cipher;
195 cipher = crypto_spawn_cipher(spawn);
197 return PTR_ERR(cipher);
203 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm)
205 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
207 crypto_free_cipher(ctx->child);
210 static void crypto_pcbc_free(struct skcipher_instance *inst)
212 crypto_drop_skcipher(skcipher_instance_ctx(inst));
216 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
218 struct skcipher_instance *inst;
219 struct crypto_attr_type *algt;
220 struct crypto_spawn *spawn;
221 struct crypto_alg *alg;
224 algt = crypto_get_attr_type(tb);
226 return PTR_ERR(algt);
228 if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) &
229 ~CRYPTO_ALG_INTERNAL)
232 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
236 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER |
237 (algt->type & CRYPTO_ALG_INTERNAL),
238 CRYPTO_ALG_TYPE_MASK |
239 (algt->mask & CRYPTO_ALG_INTERNAL));
244 spawn = skcipher_instance_ctx(inst);
245 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
246 CRYPTO_ALG_TYPE_MASK);
250 err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
254 inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
255 inst->alg.base.cra_priority = alg->cra_priority;
256 inst->alg.base.cra_blocksize = alg->cra_blocksize;
257 inst->alg.base.cra_alignmask = alg->cra_alignmask;
259 inst->alg.ivsize = alg->cra_blocksize;
260 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
261 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
263 inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
265 inst->alg.init = crypto_pcbc_init_tfm;
266 inst->alg.exit = crypto_pcbc_exit_tfm;
268 inst->alg.setkey = crypto_pcbc_setkey;
269 inst->alg.encrypt = crypto_pcbc_encrypt;
270 inst->alg.decrypt = crypto_pcbc_decrypt;
272 inst->free = crypto_pcbc_free;
274 err = skcipher_register_instance(tmpl, inst);
283 crypto_drop_spawn(spawn);
291 static struct crypto_template crypto_pcbc_tmpl = {
293 .create = crypto_pcbc_create,
294 .module = THIS_MODULE,
297 static int __init crypto_pcbc_module_init(void)
299 return crypto_register_template(&crypto_pcbc_tmpl);
302 static void __exit crypto_pcbc_module_exit(void)
304 crypto_unregister_template(&crypto_pcbc_tmpl);
307 module_init(crypto_pcbc_module_init);
308 module_exit(crypto_pcbc_module_exit);
310 MODULE_LICENSE("GPL");
311 MODULE_DESCRIPTION("PCBC block cipher algorithm");
312 MODULE_ALIAS_CRYPTO("pcbc");