[CRYPTO] cipher: Added block cipher type
[linux-2.6.git] / crypto / blkcipher.c
1 /*
2  * Block chaining cipher operations.
3  * 
4  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
5  * multiple page boundaries by using temporary blocks.  In user context,
6  * the kernel is given a chance to schedule us once per page.
7  *
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 <linux/crypto.h>
18 #include <linux/errno.h>
19 #include <linux/kernel.h>
20 #include <linux/io.h>
21 #include <linux/module.h>
22 #include <linux/scatterlist.h>
23 #include <linux/seq_file.h>
24 #include <linux/slab.h>
25 #include <linux/string.h>
26
27 #include "internal.h"
28 #include "scatterwalk.h"
29
30 enum {
31         BLKCIPHER_WALK_PHYS = 1 << 0,
32         BLKCIPHER_WALK_SLOW = 1 << 1,
33         BLKCIPHER_WALK_COPY = 1 << 2,
34         BLKCIPHER_WALK_DIFF = 1 << 3,
35 };
36
37 static int blkcipher_walk_next(struct blkcipher_desc *desc,
38                                struct blkcipher_walk *walk);
39 static int blkcipher_walk_first(struct blkcipher_desc *desc,
40                                 struct blkcipher_walk *walk);
41
42 static inline void blkcipher_map_src(struct blkcipher_walk *walk)
43 {
44         walk->src.virt.addr = scatterwalk_map(&walk->in, 0);
45 }
46
47 static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
48 {
49         walk->dst.virt.addr = scatterwalk_map(&walk->out, 1);
50 }
51
52 static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
53 {
54         scatterwalk_unmap(walk->src.virt.addr, 0);
55 }
56
57 static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
58 {
59         scatterwalk_unmap(walk->dst.virt.addr, 1);
60 }
61
62 static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
63 {
64         if (offset_in_page(start + len) < len)
65                 return (u8 *)((unsigned long)(start + len) & PAGE_MASK);
66         return start;
67 }
68
69 static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm,
70                                                struct blkcipher_walk *walk,
71                                                unsigned int bsize)
72 {
73         u8 *addr;
74         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
75
76         addr = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
77         addr = blkcipher_get_spot(addr, bsize);
78         scatterwalk_copychunks(addr, &walk->out, bsize, 1);
79         return bsize;
80 }
81
82 static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
83                                                unsigned int n)
84 {
85         n = walk->nbytes - n;
86
87         if (walk->flags & BLKCIPHER_WALK_COPY) {
88                 blkcipher_map_dst(walk);
89                 memcpy(walk->dst.virt.addr, walk->page, n);
90                 blkcipher_unmap_dst(walk);
91         } else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
92                 blkcipher_unmap_src(walk);
93                 if (walk->flags & BLKCIPHER_WALK_DIFF)
94                         blkcipher_unmap_dst(walk);
95         }
96
97         scatterwalk_advance(&walk->in, n);
98         scatterwalk_advance(&walk->out, n);
99
100         return n;
101 }
102
103 int blkcipher_walk_done(struct blkcipher_desc *desc,
104                         struct blkcipher_walk *walk, int err)
105 {
106         struct crypto_blkcipher *tfm = desc->tfm;
107         unsigned int nbytes = 0;
108
109         if (likely(err >= 0)) {
110                 unsigned int bsize = crypto_blkcipher_blocksize(tfm);
111                 unsigned int n;
112
113                 if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
114                         n = blkcipher_done_fast(walk, err);
115                 else
116                         n = blkcipher_done_slow(tfm, walk, bsize);
117
118                 nbytes = walk->total - n;
119                 err = 0;
120         }
121
122         scatterwalk_done(&walk->in, 0, nbytes);
123         scatterwalk_done(&walk->out, 1, nbytes);
124
125         walk->total = nbytes;
126         walk->nbytes = nbytes;
127
128         if (nbytes) {
129                 crypto_yield(desc->flags);
130                 return blkcipher_walk_next(desc, walk);
131         }
132
133         if (walk->iv != desc->info)
134                 memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
135         if (walk->buffer != walk->page)
136                 kfree(walk->buffer);
137         if (walk->page)
138                 free_page((unsigned long)walk->page);
139
140         return err;
141 }
142 EXPORT_SYMBOL_GPL(blkcipher_walk_done);
143
144 static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
145                                       struct blkcipher_walk *walk,
146                                       unsigned int bsize,
147                                       unsigned int alignmask)
148 {
149         unsigned int n;
150
151         if (walk->buffer)
152                 goto ok;
153
154         walk->buffer = walk->page;
155         if (walk->buffer)
156                 goto ok;
157
158         n = bsize * 2 + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
159         walk->buffer = kmalloc(n, GFP_ATOMIC);
160         if (!walk->buffer)
161                 return blkcipher_walk_done(desc, walk, -ENOMEM);
162
163 ok:
164         walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
165                                           alignmask + 1);
166         walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
167         walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr + bsize,
168                                                  bsize);
169
170         scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
171
172         walk->nbytes = bsize;
173         walk->flags |= BLKCIPHER_WALK_SLOW;
174
175         return 0;
176 }
177
178 static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
179 {
180         u8 *tmp = walk->page;
181
182         blkcipher_map_src(walk);
183         memcpy(tmp, walk->src.virt.addr, walk->nbytes);
184         blkcipher_unmap_src(walk);
185
186         walk->src.virt.addr = tmp;
187         walk->dst.virt.addr = tmp;
188
189         return 0;
190 }
191
192 static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
193                                       struct blkcipher_walk *walk)
194 {
195         unsigned long diff;
196
197         walk->src.phys.page = scatterwalk_page(&walk->in);
198         walk->src.phys.offset = offset_in_page(walk->in.offset);
199         walk->dst.phys.page = scatterwalk_page(&walk->out);
200         walk->dst.phys.offset = offset_in_page(walk->out.offset);
201
202         if (walk->flags & BLKCIPHER_WALK_PHYS)
203                 return 0;
204
205         diff = walk->src.phys.offset - walk->dst.phys.offset;
206         diff |= walk->src.virt.page - walk->dst.virt.page;
207
208         blkcipher_map_src(walk);
209         walk->dst.virt.addr = walk->src.virt.addr;
210
211         if (diff) {
212                 walk->flags |= BLKCIPHER_WALK_DIFF;
213                 blkcipher_map_dst(walk);
214         }
215
216         return 0;
217 }
218
219 static int blkcipher_walk_next(struct blkcipher_desc *desc,
220                                struct blkcipher_walk *walk)
221 {
222         struct crypto_blkcipher *tfm = desc->tfm;
223         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
224         unsigned int bsize = crypto_blkcipher_blocksize(tfm);
225         unsigned int n;
226         int err;
227
228         n = walk->total;
229         if (unlikely(n < bsize)) {
230                 desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
231                 return blkcipher_walk_done(desc, walk, -EINVAL);
232         }
233
234         walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
235                          BLKCIPHER_WALK_DIFF);
236         if (!scatterwalk_aligned(&walk->in, alignmask) ||
237             !scatterwalk_aligned(&walk->out, alignmask)) {
238                 walk->flags |= BLKCIPHER_WALK_COPY;
239                 if (!walk->page) {
240                         walk->page = (void *)__get_free_page(GFP_ATOMIC);
241                         if (!walk->page)
242                                 n = 0;
243                 }
244         }
245
246         n = scatterwalk_clamp(&walk->in, n);
247         n = scatterwalk_clamp(&walk->out, n);
248
249         if (unlikely(n < bsize)) {
250                 err = blkcipher_next_slow(desc, walk, bsize, alignmask);
251                 goto set_phys_lowmem;
252         }
253
254         walk->nbytes = n;
255         if (walk->flags & BLKCIPHER_WALK_COPY) {
256                 err = blkcipher_next_copy(walk);
257                 goto set_phys_lowmem;
258         }
259
260         return blkcipher_next_fast(desc, walk);
261
262 set_phys_lowmem:
263         if (walk->flags & BLKCIPHER_WALK_PHYS) {
264                 walk->src.phys.page = virt_to_page(walk->src.virt.addr);
265                 walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
266                 walk->src.phys.offset &= PAGE_SIZE - 1;
267                 walk->dst.phys.offset &= PAGE_SIZE - 1;
268         }
269         return err;
270 }
271
272 static inline int blkcipher_copy_iv(struct blkcipher_walk *walk,
273                                     struct crypto_blkcipher *tfm,
274                                     unsigned int alignmask)
275 {
276         unsigned bs = crypto_blkcipher_blocksize(tfm);
277         unsigned int ivsize = crypto_blkcipher_ivsize(tfm);
278         unsigned int size = bs * 2 + ivsize + max(bs, ivsize) - (alignmask + 1);
279         u8 *iv;
280
281         size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
282         walk->buffer = kmalloc(size, GFP_ATOMIC);
283         if (!walk->buffer)
284                 return -ENOMEM;
285
286         iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
287         iv = blkcipher_get_spot(iv, bs) + bs;
288         iv = blkcipher_get_spot(iv, bs) + bs;
289         iv = blkcipher_get_spot(iv, ivsize);
290
291         walk->iv = memcpy(iv, walk->iv, ivsize);
292         return 0;
293 }
294
295 int blkcipher_walk_virt(struct blkcipher_desc *desc,
296                         struct blkcipher_walk *walk)
297 {
298         walk->flags &= ~BLKCIPHER_WALK_PHYS;
299         return blkcipher_walk_first(desc, walk);
300 }
301 EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
302
303 int blkcipher_walk_phys(struct blkcipher_desc *desc,
304                         struct blkcipher_walk *walk)
305 {
306         walk->flags |= BLKCIPHER_WALK_PHYS;
307         return blkcipher_walk_first(desc, walk);
308 }
309 EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
310
311 static int blkcipher_walk_first(struct blkcipher_desc *desc,
312                                 struct blkcipher_walk *walk)
313 {
314         struct crypto_blkcipher *tfm = desc->tfm;
315         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
316
317         walk->nbytes = walk->total;
318         if (unlikely(!walk->total))
319                 return 0;
320
321         walk->buffer = NULL;
322         walk->iv = desc->info;
323         if (unlikely(((unsigned long)walk->iv & alignmask))) {
324                 int err = blkcipher_copy_iv(walk, tfm, alignmask);
325                 if (err)
326                         return err;
327         }
328
329         scatterwalk_start(&walk->in, walk->in.sg);
330         scatterwalk_start(&walk->out, walk->out.sg);
331         walk->page = NULL;
332
333         return blkcipher_walk_next(desc, walk);
334 }
335
336 static int setkey(struct crypto_tfm *tfm, const u8 *key,
337                   unsigned int keylen)
338 {
339         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
340
341         if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
342                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
343                 return -EINVAL;
344         }
345
346         return cipher->setkey(tfm, key, keylen);
347 }
348
349 static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg)
350 {
351         struct blkcipher_alg *cipher = &alg->cra_blkcipher;
352         unsigned int len = alg->cra_ctxsize;
353
354         if (cipher->ivsize) {
355                 len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
356                 len += cipher->ivsize;
357         }
358
359         return len;
360 }
361
362 static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm)
363 {
364         struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
365         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
366         unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
367         unsigned long addr;
368
369         if (alg->ivsize > PAGE_SIZE / 8)
370                 return -EINVAL;
371
372         crt->setkey = setkey;
373         crt->encrypt = alg->encrypt;
374         crt->decrypt = alg->decrypt;
375
376         addr = (unsigned long)crypto_tfm_ctx(tfm);
377         addr = ALIGN(addr, align);
378         addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
379         crt->iv = (void *)addr;
380
381         return 0;
382 }
383
384 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
385         __attribute_used__;
386 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
387 {
388         seq_printf(m, "type         : blkcipher\n");
389         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
390         seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
391         seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
392         seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
393 }
394
395 const struct crypto_type crypto_blkcipher_type = {
396         .ctxsize = crypto_blkcipher_ctxsize,
397         .init = crypto_init_blkcipher_ops,
398 #ifdef CONFIG_PROC_FS
399         .show = crypto_blkcipher_show,
400 #endif
401 };
402 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
403
404 MODULE_LICENSE("GPL");
405 MODULE_DESCRIPTION("Generic block chaining cipher type");