[CRYPTO] cipher: Added block ciphers for CBC/ECB
[linux-3.10.git] / crypto / cbc.c
1 /*
2  * CBC: Cipher Block Chaining mode
3  *
4  * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  */
12
13 #include <crypto/algapi.h>
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/scatterlist.h>
19 #include <linux/slab.h>
20
21 struct crypto_cbc_ctx {
22         struct crypto_cipher *child;
23         void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
24 };
25
26 static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key,
27                              unsigned int keylen)
28 {
29         struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent);
30         struct crypto_cipher *child = ctx->child;
31         int err;
32
33         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
34         crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
35                                        CRYPTO_TFM_REQ_MASK);
36         err = crypto_cipher_setkey(child, key, keylen);
37         crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
38                                      CRYPTO_TFM_RES_MASK);
39         return err;
40 }
41
42 static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc,
43                                       struct blkcipher_walk *walk,
44                                       struct crypto_cipher *tfm,
45                                       void (*xor)(u8 *, const u8 *,
46                                                   unsigned int))
47 {
48         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
49                 crypto_cipher_alg(tfm)->cia_encrypt;
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;
54         u8 *iv = walk->iv;
55
56         do {
57                 xor(iv, src, bsize);
58                 fn(crypto_cipher_tfm(tfm), dst, iv);
59                 memcpy(iv, dst, bsize);
60
61                 src += bsize;
62                 dst += bsize;
63         } while ((nbytes -= bsize) >= bsize);
64
65         return nbytes;
66 }
67
68 static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
69                                       struct blkcipher_walk *walk,
70                                       struct crypto_cipher *tfm,
71                                       void (*xor)(u8 *, const u8 *,
72                                                   unsigned int))
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 *iv = walk->iv;
80
81         do {
82                 xor(src, iv, bsize);
83                 fn(crypto_cipher_tfm(tfm), src, src);
84                 iv = src;
85
86                 src += bsize;
87         } while ((nbytes -= bsize) >= bsize);
88
89         memcpy(walk->iv, iv, bsize);
90
91         return nbytes;
92 }
93
94 static int crypto_cbc_encrypt(struct blkcipher_desc *desc,
95                               struct scatterlist *dst, struct scatterlist *src,
96                               unsigned int nbytes)
97 {
98         struct blkcipher_walk walk;
99         struct crypto_blkcipher *tfm = desc->tfm;
100         struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
101         struct crypto_cipher *child = ctx->child;
102         void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
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_cbc_encrypt_inplace(desc, &walk, child,
111                                                             xor);
112                 else
113                         nbytes = crypto_cbc_encrypt_segment(desc, &walk, child,
114                                                             xor);
115                 err = blkcipher_walk_done(desc, &walk, nbytes);
116         }
117
118         return err;
119 }
120
121 static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
122                                       struct blkcipher_walk *walk,
123                                       struct crypto_cipher *tfm,
124                                       void (*xor)(u8 *, const u8 *,
125                                                   unsigned int))
126 {
127         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
128                 crypto_cipher_alg(tfm)->cia_decrypt;
129         int bsize = crypto_cipher_blocksize(tfm);
130         unsigned int nbytes = walk->nbytes;
131         u8 *src = walk->src.virt.addr;
132         u8 *dst = walk->dst.virt.addr;
133         u8 *iv = walk->iv;
134
135         do {
136                 fn(crypto_cipher_tfm(tfm), dst, src);
137                 xor(dst, iv, bsize);
138                 iv = src;
139
140                 src += bsize;
141                 dst += bsize;
142         } while ((nbytes -= bsize) >= bsize);
143
144         memcpy(walk->iv, iv, bsize);
145
146         return nbytes;
147 }
148
149 static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
150                                       struct blkcipher_walk *walk,
151                                       struct crypto_cipher *tfm,
152                                       void (*xor)(u8 *, const u8 *,
153                                                   unsigned int))
154 {
155         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
156                 crypto_cipher_alg(tfm)->cia_decrypt;
157         int bsize = crypto_cipher_blocksize(tfm);
158         unsigned long alignmask = crypto_cipher_alignmask(tfm);
159         unsigned int nbytes = walk->nbytes;
160         u8 *src = walk->src.virt.addr;
161         u8 stack[bsize + alignmask];
162         u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
163
164         memcpy(first_iv, walk->iv, bsize);
165
166         /* Start of the last block. */
167         src += nbytes - nbytes % bsize - bsize;
168         memcpy(walk->iv, src, bsize);
169
170         for (;;) {
171                 fn(crypto_cipher_tfm(tfm), src, src);
172                 if ((nbytes -= bsize) < bsize)
173                         break;
174                 xor(src, src - bsize, bsize);
175                 src -= bsize;
176         }
177
178         xor(src, first_iv, bsize);
179
180         return nbytes;
181 }
182
183 static int crypto_cbc_decrypt(struct blkcipher_desc *desc,
184                               struct scatterlist *dst, struct scatterlist *src,
185                               unsigned int nbytes)
186 {
187         struct blkcipher_walk walk;
188         struct crypto_blkcipher *tfm = desc->tfm;
189         struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
190         struct crypto_cipher *child = ctx->child;
191         void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
192         int err;
193
194         blkcipher_walk_init(&walk, dst, src, nbytes);
195         err = blkcipher_walk_virt(desc, &walk);
196
197         while ((nbytes = walk.nbytes)) {
198                 if (walk.src.virt.addr == walk.dst.virt.addr)
199                         nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child,
200                                                             xor);
201                 else
202                         nbytes = crypto_cbc_decrypt_segment(desc, &walk, child,
203                                                             xor);
204                 err = blkcipher_walk_done(desc, &walk, nbytes);
205         }
206
207         return err;
208 }
209
210 static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
211 {
212         do {
213                 *a++ ^= *b++;
214         } while (--bs);
215 }
216
217 static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
218 {
219         u32 *a = (u32 *)dst;
220         u32 *b = (u32 *)src;
221
222         do {
223                 *a++ ^= *b++;
224         } while ((bs -= 4));
225 }
226
227 static void xor_64(u8 *a, const u8 *b, unsigned int bs)
228 {
229         ((u32 *)a)[0] ^= ((u32 *)b)[0];
230         ((u32 *)a)[1] ^= ((u32 *)b)[1];
231 }
232
233 static void xor_128(u8 *a, const u8 *b, unsigned int bs)
234 {
235         ((u32 *)a)[0] ^= ((u32 *)b)[0];
236         ((u32 *)a)[1] ^= ((u32 *)b)[1];
237         ((u32 *)a)[2] ^= ((u32 *)b)[2];
238         ((u32 *)a)[3] ^= ((u32 *)b)[3];
239 }
240
241 static int crypto_cbc_init_tfm(struct crypto_tfm *tfm)
242 {
243         struct crypto_instance *inst = (void *)tfm->__crt_alg;
244         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
245         struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
246
247         switch (crypto_tfm_alg_blocksize(tfm)) {
248         case 8:
249                 ctx->xor = xor_64;
250                 break;
251
252         case 16:
253                 ctx->xor = xor_128;
254                 break;
255
256         default:
257                 if (crypto_tfm_alg_blocksize(tfm) % 4)
258                         ctx->xor = xor_byte;
259                 else
260                         ctx->xor = xor_quad;
261         }
262
263         tfm = crypto_spawn_tfm(spawn);
264         if (IS_ERR(tfm))
265                 return PTR_ERR(tfm);
266
267         ctx->child = crypto_cipher_cast(tfm);
268         return 0;
269 }
270
271 static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm)
272 {
273         struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
274         crypto_free_cipher(ctx->child);
275 }
276
277 static struct crypto_instance *crypto_cbc_alloc(void *param, unsigned int len)
278 {
279         struct crypto_instance *inst;
280         struct crypto_alg *alg;
281
282         alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
283                                   CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
284         if (IS_ERR(alg))
285                 return ERR_PTR(PTR_ERR(alg));
286
287         inst = crypto_alloc_instance("cbc", alg);
288         if (IS_ERR(inst))
289                 goto out_put_alg;
290
291         inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
292         inst->alg.cra_priority = alg->cra_priority;
293         inst->alg.cra_blocksize = alg->cra_blocksize;
294         inst->alg.cra_alignmask = alg->cra_alignmask;
295         inst->alg.cra_type = &crypto_blkcipher_type;
296
297         if (!(alg->cra_blocksize % 4))
298                 inst->alg.cra_alignmask |= 3;
299         inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
300         inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
301         inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
302
303         inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
304
305         inst->alg.cra_init = crypto_cbc_init_tfm;
306         inst->alg.cra_exit = crypto_cbc_exit_tfm;
307
308         inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;
309         inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;
310         inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt;
311
312 out_put_alg:
313         crypto_mod_put(alg);
314         return inst;
315 }
316
317 static void crypto_cbc_free(struct crypto_instance *inst)
318 {
319         crypto_drop_spawn(crypto_instance_ctx(inst));
320         kfree(inst);
321 }
322
323 static struct crypto_template crypto_cbc_tmpl = {
324         .name = "cbc",
325         .alloc = crypto_cbc_alloc,
326         .free = crypto_cbc_free,
327         .module = THIS_MODULE,
328 };
329
330 static int __init crypto_cbc_module_init(void)
331 {
332         return crypto_register_template(&crypto_cbc_tmpl);
333 }
334
335 static void __exit crypto_cbc_module_exit(void)
336 {
337         crypto_unregister_template(&crypto_cbc_tmpl);
338 }
339
340 module_init(crypto_cbc_module_init);
341 module_exit(crypto_cbc_module_exit);
342
343 MODULE_LICENSE("GPL");
344 MODULE_DESCRIPTION("CBC block cipher algorithm");