[CRYPTO] Handle unaligned iv from encrypt_iv/decrypt_iv
[linux-2.6.git] / crypto / cipher.c
1 /*
2  * Cryptographic API.
3  *
4  * Cipher operations.
5  *
6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License as published by the Free
11  * Software Foundation; either version 2 of the License, or (at your option) 
12  * any later version.
13  *
14  */
15 #include <linux/compiler.h>
16 #include <linux/kernel.h>
17 #include <linux/crypto.h>
18 #include <linux/errno.h>
19 #include <linux/mm.h>
20 #include <linux/slab.h>
21 #include <linux/string.h>
22 #include <asm/scatterlist.h>
23 #include "internal.h"
24 #include "scatterwalk.h"
25
26 static inline void xor_64(u8 *a, const u8 *b)
27 {
28         ((u32 *)a)[0] ^= ((u32 *)b)[0];
29         ((u32 *)a)[1] ^= ((u32 *)b)[1];
30 }
31
32 static inline void xor_128(u8 *a, const u8 *b)
33 {
34         ((u32 *)a)[0] ^= ((u32 *)b)[0];
35         ((u32 *)a)[1] ^= ((u32 *)b)[1];
36         ((u32 *)a)[2] ^= ((u32 *)b)[2];
37         ((u32 *)a)[3] ^= ((u32 *)b)[3];
38 }
39
40 static unsigned int crypt_slow(const struct cipher_desc *desc,
41                                struct scatter_walk *in,
42                                struct scatter_walk *out, unsigned int bsize)
43 {
44         unsigned int alignmask = crypto_tfm_alg_alignmask(desc->tfm);
45         u8 buffer[bsize * 2 + alignmask];
46         u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
47         u8 *dst = src + bsize;
48         unsigned int n;
49
50         n = scatterwalk_copychunks(src, in, bsize, 0);
51         scatterwalk_advance(in, n);
52
53         desc->prfn(desc, dst, src, bsize);
54
55         n = scatterwalk_copychunks(dst, out, bsize, 1);
56         scatterwalk_advance(out, n);
57
58         return bsize;
59 }
60
61 static inline unsigned int crypt_fast(const struct cipher_desc *desc,
62                                       struct scatter_walk *in,
63                                       struct scatter_walk *out,
64                                       unsigned int nbytes, u8 *tmp)
65 {
66         u8 *src, *dst;
67
68         src = in->data;
69         dst = scatterwalk_samebuf(in, out) ? src : out->data;
70
71         if (tmp) {
72                 memcpy(tmp, in->data, nbytes);
73                 src = tmp;
74                 dst = tmp;
75         }
76
77         nbytes = desc->prfn(desc, dst, src, nbytes);
78
79         if (tmp)
80                 memcpy(out->data, tmp, nbytes);
81
82         scatterwalk_advance(in, nbytes);
83         scatterwalk_advance(out, nbytes);
84
85         return nbytes;
86 }
87
88 /* 
89  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
90  * multiple page boundaries by using temporary blocks.  In user context,
91  * the kernel is given a chance to schedule us once per page.
92  */
93 static int crypt(const struct cipher_desc *desc,
94                  struct scatterlist *dst,
95                  struct scatterlist *src,
96                  unsigned int nbytes)
97 {
98         struct scatter_walk walk_in, walk_out;
99         struct crypto_tfm *tfm = desc->tfm;
100         const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
101         unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
102         unsigned long buffer = 0;
103
104         if (!nbytes)
105                 return 0;
106
107         if (nbytes % bsize) {
108                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
109                 return -EINVAL;
110         }
111
112         scatterwalk_start(&walk_in, src);
113         scatterwalk_start(&walk_out, dst);
114
115         for(;;) {
116                 unsigned int n = nbytes;
117                 u8 *tmp = NULL;
118
119                 if (!scatterwalk_aligned(&walk_in, alignmask) ||
120                     !scatterwalk_aligned(&walk_out, alignmask)) {
121                         if (!buffer) {
122                                 buffer = __get_free_page(GFP_ATOMIC);
123                                 if (!buffer)
124                                         n = 0;
125                         }
126                         tmp = (u8 *)buffer;
127                 }
128
129                 scatterwalk_map(&walk_in, 0);
130                 scatterwalk_map(&walk_out, 1);
131
132                 n = scatterwalk_clamp(&walk_in, n);
133                 n = scatterwalk_clamp(&walk_out, n);
134
135                 if (likely(n >= bsize))
136                         n = crypt_fast(desc, &walk_in, &walk_out, n, tmp);
137                 else
138                         n = crypt_slow(desc, &walk_in, &walk_out, bsize);
139
140                 nbytes -= n;
141
142                 scatterwalk_done(&walk_in, 0, nbytes);
143                 scatterwalk_done(&walk_out, 1, nbytes);
144
145                 if (!nbytes)
146                         break;
147
148                 crypto_yield(tfm);
149         }
150
151         if (buffer)
152                 free_page(buffer);
153
154         return 0;
155 }
156
157 static int crypt_iv_unaligned(struct cipher_desc *desc,
158                               struct scatterlist *dst,
159                               struct scatterlist *src,
160                               unsigned int nbytes)
161 {
162         struct crypto_tfm *tfm = desc->tfm;
163         unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
164         u8 *iv = desc->info;
165
166         if (unlikely(((unsigned long)iv & alignmask))) {
167                 unsigned int ivsize = tfm->crt_cipher.cit_ivsize;
168                 u8 buffer[ivsize + alignmask];
169                 u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
170                 int err;
171
172                 desc->info = memcpy(tmp, iv, ivsize);
173                 err = crypt(desc, dst, src, nbytes);
174                 memcpy(iv, tmp, ivsize);
175
176                 return err;
177         }
178
179         return crypt(desc, dst, src, nbytes);
180 }
181
182 static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
183                                         u8 *dst, const u8 *src,
184                                         unsigned int nbytes)
185 {
186         struct crypto_tfm *tfm = desc->tfm;
187         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
188         int bsize = crypto_tfm_alg_blocksize(tfm);
189
190         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
191         u8 *iv = desc->info;
192         unsigned int done = 0;
193
194         do {
195                 xor(iv, src);
196                 fn(crypto_tfm_ctx(tfm), dst, iv);
197                 memcpy(iv, dst, bsize);
198
199                 src += bsize;
200                 dst += bsize;
201         } while ((done += bsize) < nbytes);
202
203         return done;
204 }
205
206 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
207                                         u8 *dst, const u8 *src,
208                                         unsigned int nbytes)
209 {
210         struct crypto_tfm *tfm = desc->tfm;
211         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
212         int bsize = crypto_tfm_alg_blocksize(tfm);
213
214         u8 stack[src == dst ? bsize : 0];
215         u8 *buf = stack;
216         u8 **dst_p = src == dst ? &buf : &dst;
217
218         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
219         u8 *iv = desc->info;
220         unsigned int done = 0;
221
222         do {
223                 u8 *tmp_dst = *dst_p;
224
225                 fn(crypto_tfm_ctx(tfm), tmp_dst, src);
226                 xor(tmp_dst, iv);
227                 memcpy(iv, src, bsize);
228                 if (tmp_dst != dst)
229                         memcpy(dst, tmp_dst, bsize);
230
231                 src += bsize;
232                 dst += bsize;
233         } while ((done += bsize) < nbytes);
234
235         return done;
236 }
237
238 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
239                                 const u8 *src, unsigned int nbytes)
240 {
241         struct crypto_tfm *tfm = desc->tfm;
242         int bsize = crypto_tfm_alg_blocksize(tfm);
243         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
244         unsigned int done = 0;
245
246         do {
247                 fn(crypto_tfm_ctx(tfm), dst, src);
248
249                 src += bsize;
250                 dst += bsize;
251         } while ((done += bsize) < nbytes);
252
253         return done;
254 }
255
256 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
257 {
258         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
259         
260         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
261                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
262                 return -EINVAL;
263         } else
264                 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
265                                        &tfm->crt_flags);
266 }
267
268 static int ecb_encrypt(struct crypto_tfm *tfm,
269                        struct scatterlist *dst,
270                        struct scatterlist *src, unsigned int nbytes)
271 {
272         struct cipher_desc desc;
273         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
274
275         desc.tfm = tfm;
276         desc.crfn = cipher->cia_encrypt;
277         desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
278
279         return crypt(&desc, dst, src, nbytes);
280 }
281
282 static int ecb_decrypt(struct crypto_tfm *tfm,
283                        struct scatterlist *dst,
284                        struct scatterlist *src,
285                        unsigned int nbytes)
286 {
287         struct cipher_desc desc;
288         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
289
290         desc.tfm = tfm;
291         desc.crfn = cipher->cia_decrypt;
292         desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
293
294         return crypt(&desc, dst, src, nbytes);
295 }
296
297 static int cbc_encrypt(struct crypto_tfm *tfm,
298                        struct scatterlist *dst,
299                        struct scatterlist *src,
300                        unsigned int nbytes)
301 {
302         struct cipher_desc desc;
303         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
304
305         desc.tfm = tfm;
306         desc.crfn = cipher->cia_encrypt;
307         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
308         desc.info = tfm->crt_cipher.cit_iv;
309
310         return crypt(&desc, dst, src, nbytes);
311 }
312
313 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
314                           struct scatterlist *dst,
315                           struct scatterlist *src,
316                           unsigned int nbytes, u8 *iv)
317 {
318         struct cipher_desc desc;
319         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
320
321         desc.tfm = tfm;
322         desc.crfn = cipher->cia_encrypt;
323         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
324         desc.info = iv;
325
326         return crypt_iv_unaligned(&desc, dst, src, nbytes);
327 }
328
329 static int cbc_decrypt(struct crypto_tfm *tfm,
330                        struct scatterlist *dst,
331                        struct scatterlist *src,
332                        unsigned int nbytes)
333 {
334         struct cipher_desc desc;
335         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
336
337         desc.tfm = tfm;
338         desc.crfn = cipher->cia_decrypt;
339         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
340         desc.info = tfm->crt_cipher.cit_iv;
341
342         return crypt(&desc, dst, src, nbytes);
343 }
344
345 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
346                           struct scatterlist *dst,
347                           struct scatterlist *src,
348                           unsigned int nbytes, u8 *iv)
349 {
350         struct cipher_desc desc;
351         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
352
353         desc.tfm = tfm;
354         desc.crfn = cipher->cia_decrypt;
355         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
356         desc.info = iv;
357
358         return crypt_iv_unaligned(&desc, dst, src, nbytes);
359 }
360
361 static int nocrypt(struct crypto_tfm *tfm,
362                    struct scatterlist *dst,
363                    struct scatterlist *src,
364                    unsigned int nbytes)
365 {
366         return -ENOSYS;
367 }
368
369 static int nocrypt_iv(struct crypto_tfm *tfm,
370                       struct scatterlist *dst,
371                       struct scatterlist *src,
372                       unsigned int nbytes, u8 *iv)
373 {
374         return -ENOSYS;
375 }
376
377 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
378 {
379         u32 mode = flags & CRYPTO_TFM_MODE_MASK;
380         
381         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
382         if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
383                 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
384         
385         return 0;
386 }
387
388 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
389 {
390         int ret = 0;
391         struct cipher_tfm *ops = &tfm->crt_cipher;
392
393         ops->cit_setkey = setkey;
394
395         switch (tfm->crt_cipher.cit_mode) {
396         case CRYPTO_TFM_MODE_ECB:
397                 ops->cit_encrypt = ecb_encrypt;
398                 ops->cit_decrypt = ecb_decrypt;
399                 break;
400                 
401         case CRYPTO_TFM_MODE_CBC:
402                 ops->cit_encrypt = cbc_encrypt;
403                 ops->cit_decrypt = cbc_decrypt;
404                 ops->cit_encrypt_iv = cbc_encrypt_iv;
405                 ops->cit_decrypt_iv = cbc_decrypt_iv;
406                 break;
407                 
408         case CRYPTO_TFM_MODE_CFB:
409                 ops->cit_encrypt = nocrypt;
410                 ops->cit_decrypt = nocrypt;
411                 ops->cit_encrypt_iv = nocrypt_iv;
412                 ops->cit_decrypt_iv = nocrypt_iv;
413                 break;
414         
415         case CRYPTO_TFM_MODE_CTR:
416                 ops->cit_encrypt = nocrypt;
417                 ops->cit_decrypt = nocrypt;
418                 ops->cit_encrypt_iv = nocrypt_iv;
419                 ops->cit_decrypt_iv = nocrypt_iv;
420                 break;
421
422         default:
423                 BUG();
424         }
425         
426         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
427                 unsigned int align;
428                 unsigned long addr;
429                 
430                 switch (crypto_tfm_alg_blocksize(tfm)) {
431                 case 8:
432                         ops->cit_xor_block = xor_64;
433                         break;
434                         
435                 case 16:
436                         ops->cit_xor_block = xor_128;
437                         break;
438                         
439                 default:
440                         printk(KERN_WARNING "%s: block size %u not supported\n",
441                                crypto_tfm_alg_name(tfm),
442                                crypto_tfm_alg_blocksize(tfm));
443                         ret = -EINVAL;
444                         goto out;
445                 }
446                 
447                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
448                 align = crypto_tfm_alg_alignmask(tfm) + 1;
449                 addr = (unsigned long)crypto_tfm_ctx(tfm);
450                 addr = ALIGN(addr, align);
451                 addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
452                 ops->cit_iv = (void *)addr;
453         }
454
455 out:    
456         return ret;
457 }
458
459 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
460 {
461 }