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[linux-3.10.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 long 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->crt_flags);
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 long 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)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
191         u8 *iv = desc->info;
192         unsigned int done = 0;
193
194         nbytes -= bsize;
195
196         do {
197                 xor(iv, src);
198                 fn(tfm, dst, iv);
199                 memcpy(iv, dst, bsize);
200
201                 src += bsize;
202                 dst += bsize;
203         } while ((done += bsize) <= nbytes);
204
205         return done;
206 }
207
208 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
209                                         u8 *dst, const u8 *src,
210                                         unsigned int nbytes)
211 {
212         struct crypto_tfm *tfm = desc->tfm;
213         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
214         int bsize = crypto_tfm_alg_blocksize(tfm);
215         unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
216
217         u8 stack[src == dst ? bsize + alignmask : 0];
218         u8 *buf = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
219         u8 **dst_p = src == dst ? &buf : &dst;
220
221         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
222         u8 *iv = desc->info;
223         unsigned int done = 0;
224
225         nbytes -= bsize;
226
227         do {
228                 u8 *tmp_dst = *dst_p;
229
230                 fn(tfm, tmp_dst, src);
231                 xor(tmp_dst, iv);
232                 memcpy(iv, src, bsize);
233                 if (tmp_dst != dst)
234                         memcpy(dst, tmp_dst, bsize);
235
236                 src += bsize;
237                 dst += bsize;
238         } while ((done += bsize) <= nbytes);
239
240         return done;
241 }
242
243 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
244                                 const u8 *src, unsigned int nbytes)
245 {
246         struct crypto_tfm *tfm = desc->tfm;
247         int bsize = crypto_tfm_alg_blocksize(tfm);
248         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
249         unsigned int done = 0;
250
251         nbytes -= bsize;
252
253         do {
254                 fn(tfm, dst, src);
255
256                 src += bsize;
257                 dst += bsize;
258         } while ((done += bsize) <= nbytes);
259
260         return done;
261 }
262
263 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
264 {
265         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
266         
267         tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
268         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
269                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
270                 return -EINVAL;
271         } else
272                 return cia->cia_setkey(tfm, key, keylen);
273 }
274
275 static int ecb_encrypt(struct crypto_tfm *tfm,
276                        struct scatterlist *dst,
277                        struct scatterlist *src, unsigned int nbytes)
278 {
279         struct cipher_desc desc;
280         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
281
282         desc.tfm = tfm;
283         desc.crfn = cipher->cia_encrypt;
284         desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
285
286         return crypt(&desc, dst, src, nbytes);
287 }
288
289 static int ecb_decrypt(struct crypto_tfm *tfm,
290                        struct scatterlist *dst,
291                        struct scatterlist *src,
292                        unsigned int nbytes)
293 {
294         struct cipher_desc desc;
295         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
296
297         desc.tfm = tfm;
298         desc.crfn = cipher->cia_decrypt;
299         desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
300
301         return crypt(&desc, dst, src, nbytes);
302 }
303
304 static int cbc_encrypt(struct crypto_tfm *tfm,
305                        struct scatterlist *dst,
306                        struct scatterlist *src,
307                        unsigned int nbytes)
308 {
309         struct cipher_desc desc;
310         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
311
312         desc.tfm = tfm;
313         desc.crfn = cipher->cia_encrypt;
314         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
315         desc.info = tfm->crt_cipher.cit_iv;
316
317         return crypt(&desc, dst, src, nbytes);
318 }
319
320 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
321                           struct scatterlist *dst,
322                           struct scatterlist *src,
323                           unsigned int nbytes, u8 *iv)
324 {
325         struct cipher_desc desc;
326         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
327
328         desc.tfm = tfm;
329         desc.crfn = cipher->cia_encrypt;
330         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
331         desc.info = iv;
332
333         return crypt_iv_unaligned(&desc, dst, src, nbytes);
334 }
335
336 static int cbc_decrypt(struct crypto_tfm *tfm,
337                        struct scatterlist *dst,
338                        struct scatterlist *src,
339                        unsigned int nbytes)
340 {
341         struct cipher_desc desc;
342         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
343
344         desc.tfm = tfm;
345         desc.crfn = cipher->cia_decrypt;
346         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
347         desc.info = tfm->crt_cipher.cit_iv;
348
349         return crypt(&desc, dst, src, nbytes);
350 }
351
352 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
353                           struct scatterlist *dst,
354                           struct scatterlist *src,
355                           unsigned int nbytes, u8 *iv)
356 {
357         struct cipher_desc desc;
358         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
359
360         desc.tfm = tfm;
361         desc.crfn = cipher->cia_decrypt;
362         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
363         desc.info = iv;
364
365         return crypt_iv_unaligned(&desc, dst, src, nbytes);
366 }
367
368 static int nocrypt(struct crypto_tfm *tfm,
369                    struct scatterlist *dst,
370                    struct scatterlist *src,
371                    unsigned int nbytes)
372 {
373         return -ENOSYS;
374 }
375
376 static int nocrypt_iv(struct crypto_tfm *tfm,
377                       struct scatterlist *dst,
378                       struct scatterlist *src,
379                       unsigned int nbytes, u8 *iv)
380 {
381         return -ENOSYS;
382 }
383
384 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
385 {
386         u32 mode = flags & CRYPTO_TFM_MODE_MASK;
387         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
388         return 0;
389 }
390
391 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
392 {
393         int ret = 0;
394         struct cipher_tfm *ops = &tfm->crt_cipher;
395
396         ops->cit_setkey = setkey;
397
398         switch (tfm->crt_cipher.cit_mode) {
399         case CRYPTO_TFM_MODE_ECB:
400                 ops->cit_encrypt = ecb_encrypt;
401                 ops->cit_decrypt = ecb_decrypt;
402                 ops->cit_encrypt_iv = nocrypt_iv;
403                 ops->cit_decrypt_iv = nocrypt_iv;
404                 break;
405                 
406         case CRYPTO_TFM_MODE_CBC:
407                 ops->cit_encrypt = cbc_encrypt;
408                 ops->cit_decrypt = cbc_decrypt;
409                 ops->cit_encrypt_iv = cbc_encrypt_iv;
410                 ops->cit_decrypt_iv = cbc_decrypt_iv;
411                 break;
412                 
413         case CRYPTO_TFM_MODE_CFB:
414                 ops->cit_encrypt = nocrypt;
415                 ops->cit_decrypt = nocrypt;
416                 ops->cit_encrypt_iv = nocrypt_iv;
417                 ops->cit_decrypt_iv = nocrypt_iv;
418                 break;
419         
420         case CRYPTO_TFM_MODE_CTR:
421                 ops->cit_encrypt = nocrypt;
422                 ops->cit_decrypt = nocrypt;
423                 ops->cit_encrypt_iv = nocrypt_iv;
424                 ops->cit_decrypt_iv = nocrypt_iv;
425                 break;
426
427         default:
428                 BUG();
429         }
430         
431         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
432                 unsigned long align;
433                 unsigned long addr;
434                 
435                 switch (crypto_tfm_alg_blocksize(tfm)) {
436                 case 8:
437                         ops->cit_xor_block = xor_64;
438                         break;
439                         
440                 case 16:
441                         ops->cit_xor_block = xor_128;
442                         break;
443                         
444                 default:
445                         printk(KERN_WARNING "%s: block size %u not supported\n",
446                                crypto_tfm_alg_name(tfm),
447                                crypto_tfm_alg_blocksize(tfm));
448                         ret = -EINVAL;
449                         goto out;
450                 }
451                 
452                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
453                 align = crypto_tfm_alg_alignmask(tfm) + 1;
454                 addr = (unsigned long)crypto_tfm_ctx(tfm);
455                 addr = ALIGN(addr, align);
456                 addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
457                 ops->cit_iv = (void *)addr;
458         }
459
460 out:    
461         return ret;
462 }
463
464 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
465 {
466 }