1 /*
2 * PCBC: Propagating Cipher Block Chaining mode
3 *
4 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * Derived from cbc.c
8 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
9 *
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)
13 * any later version.
14 *
15 */
16
17 #include <crypto/algapi.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/scatterlist.h>
23 #include <linux/slab.h>
24
25 struct crypto_pcbc_ctx {
26 struct crypto_cipher *child;
27 };
28
crypto_pcbc_setkey(struct crypto_tfm * parent,const u8 * key,unsigned int keylen)29 static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
30 unsigned int keylen)
31 {
32 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(parent);
33 struct crypto_cipher *child = ctx->child;
34 int err;
35
36 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
37 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
38 CRYPTO_TFM_REQ_MASK);
39 err = crypto_cipher_setkey(child, key, keylen);
40 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
41 CRYPTO_TFM_RES_MASK);
42 return err;
43 }
44
crypto_pcbc_encrypt_segment(struct blkcipher_desc * desc,struct blkcipher_walk * walk,struct crypto_cipher * tfm)45 static int crypto_pcbc_encrypt_segment(struct blkcipher_desc *desc,
46 struct blkcipher_walk *walk,
47 struct crypto_cipher *tfm)
48 {
49 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
50 crypto_cipher_alg(tfm)->cia_encrypt;
51 int bsize = crypto_cipher_blocksize(tfm);
52 unsigned int nbytes = walk->nbytes;
53 u8 *src = walk->src.virt.addr;
54 u8 *dst = walk->dst.virt.addr;
55 u8 * const iv = walk->iv;
56
57 do {
58 crypto_xor(iv, src, bsize);
59 fn(crypto_cipher_tfm(tfm), dst, iv);
60 memcpy(iv, dst, bsize);
61 crypto_xor(iv, src, bsize);
62
63 src += bsize;
64 dst += bsize;
65 } while ((nbytes -= bsize) >= bsize);
66
67 return nbytes;
68 }
69
crypto_pcbc_encrypt_inplace(struct blkcipher_desc * desc,struct blkcipher_walk * walk,struct crypto_cipher * tfm)70 static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,
71 struct blkcipher_walk *walk,
72 struct crypto_cipher *tfm)
73 {
74 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
75 crypto_cipher_alg(tfm)->cia_encrypt;
76 int bsize = crypto_cipher_blocksize(tfm);
77 unsigned int nbytes = walk->nbytes;
78 u8 *src = walk->src.virt.addr;
79 u8 * const iv = walk->iv;
80 u8 tmpbuf[bsize];
81
82 do {
83 memcpy(tmpbuf, src, bsize);
84 crypto_xor(iv, src, bsize);
85 fn(crypto_cipher_tfm(tfm), src, iv);
86 memcpy(iv, tmpbuf, bsize);
87 crypto_xor(iv, src, bsize);
88
89 src += bsize;
90 } while ((nbytes -= bsize) >= bsize);
91
92 return nbytes;
93 }
94
crypto_pcbc_encrypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)95 static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,
96 struct scatterlist *dst, struct scatterlist *src,
97 unsigned int nbytes)
98 {
99 struct blkcipher_walk walk;
100 struct crypto_blkcipher *tfm = desc->tfm;
101 struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
102 struct crypto_cipher *child = ctx->child;
103 int err;
104
105 blkcipher_walk_init(&walk, dst, src, nbytes);
106 err = blkcipher_walk_virt(desc, &walk);
107
108 while ((nbytes = walk.nbytes)) {
109 if (walk.src.virt.addr == walk.dst.virt.addr)
110 nbytes = crypto_pcbc_encrypt_inplace(desc, &walk,
111 child);
112 else
113 nbytes = crypto_pcbc_encrypt_segment(desc, &walk,
114 child);
115 err = blkcipher_walk_done(desc, &walk, nbytes);
116 }
117
118 return err;
119 }
120
crypto_pcbc_decrypt_segment(struct blkcipher_desc * desc,struct blkcipher_walk * walk,struct crypto_cipher * tfm)121 static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,
122 struct blkcipher_walk *walk,
123 struct crypto_cipher *tfm)
124 {
125 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
126 crypto_cipher_alg(tfm)->cia_decrypt;
127 int bsize = crypto_cipher_blocksize(tfm);
128 unsigned int nbytes = walk->nbytes;
129 u8 *src = walk->src.virt.addr;
130 u8 *dst = walk->dst.virt.addr;
131 u8 * const iv = walk->iv;
132
133 do {
134 fn(crypto_cipher_tfm(tfm), dst, src);
135 crypto_xor(dst, iv, bsize);
136 memcpy(iv, src, bsize);
137 crypto_xor(iv, dst, bsize);
138
139 src += bsize;
140 dst += bsize;
141 } while ((nbytes -= bsize) >= bsize);
142
143 return nbytes;
144 }
145
crypto_pcbc_decrypt_inplace(struct blkcipher_desc * desc,struct blkcipher_walk * walk,struct crypto_cipher * tfm)146 static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
147 struct blkcipher_walk *walk,
148 struct crypto_cipher *tfm)
149 {
150 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
151 crypto_cipher_alg(tfm)->cia_decrypt;
152 int bsize = crypto_cipher_blocksize(tfm);
153 unsigned int nbytes = walk->nbytes;
154 u8 *src = walk->src.virt.addr;
155 u8 * const iv = walk->iv;
156 u8 tmpbuf[bsize];
157
158 do {
159 memcpy(tmpbuf, src, bsize);
160 fn(crypto_cipher_tfm(tfm), src, src);
161 crypto_xor(src, iv, bsize);
162 memcpy(iv, tmpbuf, bsize);
163 crypto_xor(iv, src, bsize);
164
165 src += bsize;
166 } while ((nbytes -= bsize) >= bsize);
167
168 return nbytes;
169 }
170
crypto_pcbc_decrypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)171 static int crypto_pcbc_decrypt(struct blkcipher_desc *desc,
172 struct scatterlist *dst, struct scatterlist *src,
173 unsigned int nbytes)
174 {
175 struct blkcipher_walk walk;
176 struct crypto_blkcipher *tfm = desc->tfm;
177 struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
178 struct crypto_cipher *child = ctx->child;
179 int err;
180
181 blkcipher_walk_init(&walk, dst, src, nbytes);
182 err = blkcipher_walk_virt(desc, &walk);
183
184 while ((nbytes = walk.nbytes)) {
185 if (walk.src.virt.addr == walk.dst.virt.addr)
186 nbytes = crypto_pcbc_decrypt_inplace(desc, &walk,
187 child);
188 else
189 nbytes = crypto_pcbc_decrypt_segment(desc, &walk,
190 child);
191 err = blkcipher_walk_done(desc, &walk, nbytes);
192 }
193
194 return err;
195 }
196
crypto_pcbc_init_tfm(struct crypto_tfm * tfm)197 static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
198 {
199 struct crypto_instance *inst = (void *)tfm->__crt_alg;
200 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
201 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
202 struct crypto_cipher *cipher;
203
204 cipher = crypto_spawn_cipher(spawn);
205 if (IS_ERR(cipher))
206 return PTR_ERR(cipher);
207
208 ctx->child = cipher;
209 return 0;
210 }
211
crypto_pcbc_exit_tfm(struct crypto_tfm * tfm)212 static void crypto_pcbc_exit_tfm(struct crypto_tfm *tfm)
213 {
214 struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
215 crypto_free_cipher(ctx->child);
216 }
217
crypto_pcbc_alloc(struct rtattr ** tb)218 static struct crypto_instance *crypto_pcbc_alloc(struct rtattr **tb)
219 {
220 struct crypto_instance *inst;
221 struct crypto_alg *alg;
222 int err;
223
224 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
225 if (err)
226 return ERR_PTR(err);
227
228 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
229 CRYPTO_ALG_TYPE_MASK);
230 if (IS_ERR(alg))
231 return ERR_CAST(alg);
232
233 inst = crypto_alloc_instance("pcbc", alg);
234 if (IS_ERR(inst))
235 goto out_put_alg;
236
237 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
238 inst->alg.cra_priority = alg->cra_priority;
239 inst->alg.cra_blocksize = alg->cra_blocksize;
240 inst->alg.cra_alignmask = alg->cra_alignmask;
241 inst->alg.cra_type = &crypto_blkcipher_type;
242
243 /* We access the data as u32s when xoring. */
244 inst->alg.cra_alignmask |= __alignof__(u32) - 1;
245
246 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
247 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
248 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
249
250 inst->alg.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
251
252 inst->alg.cra_init = crypto_pcbc_init_tfm;
253 inst->alg.cra_exit = crypto_pcbc_exit_tfm;
254
255 inst->alg.cra_blkcipher.setkey = crypto_pcbc_setkey;
256 inst->alg.cra_blkcipher.encrypt = crypto_pcbc_encrypt;
257 inst->alg.cra_blkcipher.decrypt = crypto_pcbc_decrypt;
258
259 out_put_alg:
260 crypto_mod_put(alg);
261 return inst;
262 }
263
crypto_pcbc_free(struct crypto_instance * inst)264 static void crypto_pcbc_free(struct crypto_instance *inst)
265 {
266 crypto_drop_spawn(crypto_instance_ctx(inst));
267 kfree(inst);
268 }
269
270 static struct crypto_template crypto_pcbc_tmpl = {
271 .name = "pcbc",
272 .alloc = crypto_pcbc_alloc,
273 .free = crypto_pcbc_free,
274 .module = THIS_MODULE,
275 };
276
crypto_pcbc_module_init(void)277 static int __init crypto_pcbc_module_init(void)
278 {
279 return crypto_register_template(&crypto_pcbc_tmpl);
280 }
281
crypto_pcbc_module_exit(void)282 static void __exit crypto_pcbc_module_exit(void)
283 {
284 crypto_unregister_template(&crypto_pcbc_tmpl);
285 }
286
287 module_init(crypto_pcbc_module_init);
288 module_exit(crypto_pcbc_module_exit);
289
290 MODULE_LICENSE("GPL");
291 MODULE_DESCRIPTION("PCBC block cipher algorithm");
292 MODULE_ALIAS_CRYPTO("pcbc");
293