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Linux/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 <crypto/aead.h>
 18 #include <crypto/internal/skcipher.h>
 19 #include <crypto/scatterwalk.h>
 20 #include <linux/errno.h>
 21 #include <linux/hardirq.h>
 22 #include <linux/kernel.h>
 23 #include <linux/module.h>
 24 #include <linux/seq_file.h>
 25 #include <linux/slab.h>
 26 #include <linux/string.h>
 27 #include <linux/cryptouser.h>
 28 #include <net/netlink.h>
 29 
 30 #include "internal.h"
 31 
 32 enum {
 33         BLKCIPHER_WALK_PHYS = 1 << 0,
 34         BLKCIPHER_WALK_SLOW = 1 << 1,
 35         BLKCIPHER_WALK_COPY = 1 << 2,
 36         BLKCIPHER_WALK_DIFF = 1 << 3,
 37 };
 38 
 39 static int blkcipher_walk_next(struct blkcipher_desc *desc,
 40                                struct blkcipher_walk *walk);
 41 static int blkcipher_walk_first(struct blkcipher_desc *desc,
 42                                 struct blkcipher_walk *walk);
 43 
 44 static inline void blkcipher_map_src(struct blkcipher_walk *walk)
 45 {
 46         walk->src.virt.addr = scatterwalk_map(&walk->in);
 47 }
 48 
 49 static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
 50 {
 51         walk->dst.virt.addr = scatterwalk_map(&walk->out);
 52 }
 53 
 54 static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
 55 {
 56         scatterwalk_unmap(walk->src.virt.addr);
 57 }
 58 
 59 static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
 60 {
 61         scatterwalk_unmap(walk->dst.virt.addr);
 62 }
 63 
 64 /* Get a spot of the specified length that does not straddle a page.
 65  * The caller needs to ensure that there is enough space for this operation.
 66  */
 67 static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
 68 {
 69         u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);
 70         return max(start, end_page);
 71 }
 72 
 73 static inline unsigned int blkcipher_done_slow(struct blkcipher_walk *walk,
 74                                                unsigned int bsize)
 75 {
 76         u8 *addr;
 77 
 78         addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
 79         addr = blkcipher_get_spot(addr, bsize);
 80         scatterwalk_copychunks(addr, &walk->out, bsize, 1);
 81         return bsize;
 82 }
 83 
 84 static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
 85                                                unsigned int 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                 if (walk->flags & BLKCIPHER_WALK_DIFF)
 93                         blkcipher_unmap_dst(walk);
 94                 blkcipher_unmap_src(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         unsigned int nbytes = 0;
107 
108         if (likely(err >= 0)) {
109                 unsigned int n = walk->nbytes - err;
110 
111                 if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
112                         n = blkcipher_done_fast(walk, n);
113                 else if (WARN_ON(err)) {
114                         err = -EINVAL;
115                         goto err;
116                 } else
117                         n = blkcipher_done_slow(walk, n);
118 
119                 nbytes = walk->total - n;
120                 err = 0;
121         }
122 
123         scatterwalk_done(&walk->in, 0, nbytes);
124         scatterwalk_done(&walk->out, 1, nbytes);
125 
126 err:
127         walk->total = nbytes;
128         walk->nbytes = nbytes;
129 
130         if (nbytes) {
131                 crypto_yield(desc->flags);
132                 return blkcipher_walk_next(desc, walk);
133         }
134 
135         if (walk->iv != desc->info)
136                 memcpy(desc->info, walk->iv, walk->ivsize);
137         if (walk->buffer != walk->page)
138                 kfree(walk->buffer);
139         if (walk->page)
140                 free_page((unsigned long)walk->page);
141 
142         return err;
143 }
144 EXPORT_SYMBOL_GPL(blkcipher_walk_done);
145 
146 static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
147                                       struct blkcipher_walk *walk,
148                                       unsigned int bsize,
149                                       unsigned int alignmask)
150 {
151         unsigned int n;
152         unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);
153 
154         if (walk->buffer)
155                 goto ok;
156 
157         walk->buffer = walk->page;
158         if (walk->buffer)
159                 goto ok;
160 
161         n = aligned_bsize * 3 - (alignmask + 1) +
162             (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
163         walk->buffer = kmalloc(n, GFP_ATOMIC);
164         if (!walk->buffer)
165                 return blkcipher_walk_done(desc, walk, -ENOMEM);
166 
167 ok:
168         walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
169                                           alignmask + 1);
170         walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
171         walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr +
172                                                  aligned_bsize, bsize);
173 
174         scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
175 
176         walk->nbytes = bsize;
177         walk->flags |= BLKCIPHER_WALK_SLOW;
178 
179         return 0;
180 }
181 
182 static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
183 {
184         u8 *tmp = walk->page;
185 
186         blkcipher_map_src(walk);
187         memcpy(tmp, walk->src.virt.addr, walk->nbytes);
188         blkcipher_unmap_src(walk);
189 
190         walk->src.virt.addr = tmp;
191         walk->dst.virt.addr = tmp;
192 
193         return 0;
194 }
195 
196 static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
197                                       struct blkcipher_walk *walk)
198 {
199         unsigned long diff;
200 
201         walk->src.phys.page = scatterwalk_page(&walk->in);
202         walk->src.phys.offset = offset_in_page(walk->in.offset);
203         walk->dst.phys.page = scatterwalk_page(&walk->out);
204         walk->dst.phys.offset = offset_in_page(walk->out.offset);
205 
206         if (walk->flags & BLKCIPHER_WALK_PHYS)
207                 return 0;
208 
209         diff = walk->src.phys.offset - walk->dst.phys.offset;
210         diff |= walk->src.virt.page - walk->dst.virt.page;
211 
212         blkcipher_map_src(walk);
213         walk->dst.virt.addr = walk->src.virt.addr;
214 
215         if (diff) {
216                 walk->flags |= BLKCIPHER_WALK_DIFF;
217                 blkcipher_map_dst(walk);
218         }
219 
220         return 0;
221 }
222 
223 static int blkcipher_walk_next(struct blkcipher_desc *desc,
224                                struct blkcipher_walk *walk)
225 {
226         unsigned int bsize;
227         unsigned int n;
228         int err;
229 
230         n = walk->total;
231         if (unlikely(n < walk->cipher_blocksize)) {
232                 desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
233                 return blkcipher_walk_done(desc, walk, -EINVAL);
234         }
235 
236         bsize = min(walk->walk_blocksize, n);
237 
238         walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
239                          BLKCIPHER_WALK_DIFF);
240         if (!scatterwalk_aligned(&walk->in, walk->alignmask) ||
241             !scatterwalk_aligned(&walk->out, walk->alignmask)) {
242                 walk->flags |= BLKCIPHER_WALK_COPY;
243                 if (!walk->page) {
244                         walk->page = (void *)__get_free_page(GFP_ATOMIC);
245                         if (!walk->page)
246                                 n = 0;
247                 }
248         }
249 
250         n = scatterwalk_clamp(&walk->in, n);
251         n = scatterwalk_clamp(&walk->out, n);
252 
253         if (unlikely(n < bsize)) {
254                 err = blkcipher_next_slow(desc, walk, bsize, walk->alignmask);
255                 goto set_phys_lowmem;
256         }
257 
258         walk->nbytes = n;
259         if (walk->flags & BLKCIPHER_WALK_COPY) {
260                 err = blkcipher_next_copy(walk);
261                 goto set_phys_lowmem;
262         }
263 
264         return blkcipher_next_fast(desc, walk);
265 
266 set_phys_lowmem:
267         if (walk->flags & BLKCIPHER_WALK_PHYS) {
268                 walk->src.phys.page = virt_to_page(walk->src.virt.addr);
269                 walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
270                 walk->src.phys.offset &= PAGE_SIZE - 1;
271                 walk->dst.phys.offset &= PAGE_SIZE - 1;
272         }
273         return err;
274 }
275 
276 static inline int blkcipher_copy_iv(struct blkcipher_walk *walk)
277 {
278         unsigned bs = walk->walk_blocksize;
279         unsigned aligned_bs = ALIGN(bs, walk->alignmask + 1);
280         unsigned int size = aligned_bs * 2 +
281                             walk->ivsize + max(aligned_bs, walk->ivsize) -
282                             (walk->alignmask + 1);
283         u8 *iv;
284 
285         size += walk->alignmask & ~(crypto_tfm_ctx_alignment() - 1);
286         walk->buffer = kmalloc(size, GFP_ATOMIC);
287         if (!walk->buffer)
288                 return -ENOMEM;
289 
290         iv = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
291         iv = blkcipher_get_spot(iv, bs) + aligned_bs;
292         iv = blkcipher_get_spot(iv, bs) + aligned_bs;
293         iv = blkcipher_get_spot(iv, walk->ivsize);
294 
295         walk->iv = memcpy(iv, walk->iv, walk->ivsize);
296         return 0;
297 }
298 
299 int blkcipher_walk_virt(struct blkcipher_desc *desc,
300                         struct blkcipher_walk *walk)
301 {
302         walk->flags &= ~BLKCIPHER_WALK_PHYS;
303         walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
304         walk->cipher_blocksize = walk->walk_blocksize;
305         walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
306         walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
307         return blkcipher_walk_first(desc, walk);
308 }
309 EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
310 
311 int blkcipher_walk_phys(struct blkcipher_desc *desc,
312                         struct blkcipher_walk *walk)
313 {
314         walk->flags |= BLKCIPHER_WALK_PHYS;
315         walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
316         walk->cipher_blocksize = walk->walk_blocksize;
317         walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
318         walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
319         return blkcipher_walk_first(desc, walk);
320 }
321 EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
322 
323 static int blkcipher_walk_first(struct blkcipher_desc *desc,
324                                 struct blkcipher_walk *walk)
325 {
326         if (WARN_ON_ONCE(in_irq()))
327                 return -EDEADLK;
328 
329         walk->iv = desc->info;
330         walk->nbytes = walk->total;
331         if (unlikely(!walk->total))
332                 return 0;
333 
334         walk->buffer = NULL;
335         if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
336                 int err = blkcipher_copy_iv(walk);
337                 if (err)
338                         return err;
339         }
340 
341         scatterwalk_start(&walk->in, walk->in.sg);
342         scatterwalk_start(&walk->out, walk->out.sg);
343         walk->page = NULL;
344 
345         return blkcipher_walk_next(desc, walk);
346 }
347 
348 int blkcipher_walk_virt_block(struct blkcipher_desc *desc,
349                               struct blkcipher_walk *walk,
350                               unsigned int blocksize)
351 {
352         walk->flags &= ~BLKCIPHER_WALK_PHYS;
353         walk->walk_blocksize = blocksize;
354         walk->cipher_blocksize = crypto_blkcipher_blocksize(desc->tfm);
355         walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
356         walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);
357         return blkcipher_walk_first(desc, walk);
358 }
359 EXPORT_SYMBOL_GPL(blkcipher_walk_virt_block);
360 
361 int blkcipher_aead_walk_virt_block(struct blkcipher_desc *desc,
362                                    struct blkcipher_walk *walk,
363                                    struct crypto_aead *tfm,
364                                    unsigned int blocksize)
365 {
366         walk->flags &= ~BLKCIPHER_WALK_PHYS;
367         walk->walk_blocksize = blocksize;
368         walk->cipher_blocksize = crypto_aead_blocksize(tfm);
369         walk->ivsize = crypto_aead_ivsize(tfm);
370         walk->alignmask = crypto_aead_alignmask(tfm);
371         return blkcipher_walk_first(desc, walk);
372 }
373 EXPORT_SYMBOL_GPL(blkcipher_aead_walk_virt_block);
374 
375 static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
376                             unsigned int keylen)
377 {
378         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
379         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
380         int ret;
381         u8 *buffer, *alignbuffer;
382         unsigned long absize;
383 
384         absize = keylen + alignmask;
385         buffer = kmalloc(absize, GFP_ATOMIC);
386         if (!buffer)
387                 return -ENOMEM;
388 
389         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
390         memcpy(alignbuffer, key, keylen);
391         ret = cipher->setkey(tfm, alignbuffer, keylen);
392         memset(alignbuffer, 0, keylen);
393         kfree(buffer);
394         return ret;
395 }
396 
397 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
398 {
399         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
400         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
401 
402         if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
403                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
404                 return -EINVAL;
405         }
406 
407         if ((unsigned long)key & alignmask)
408                 return setkey_unaligned(tfm, key, keylen);
409 
410         return cipher->setkey(tfm, key, keylen);
411 }
412 
413 static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
414                         unsigned int keylen)
415 {
416         return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);
417 }
418 
419 static int async_encrypt(struct ablkcipher_request *req)
420 {
421         struct crypto_tfm *tfm = req->base.tfm;
422         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
423         struct blkcipher_desc desc = {
424                 .tfm = __crypto_blkcipher_cast(tfm),
425                 .info = req->info,
426                 .flags = req->base.flags,
427         };
428 
429 
430         return alg->encrypt(&desc, req->dst, req->src, req->nbytes);
431 }
432 
433 static int async_decrypt(struct ablkcipher_request *req)
434 {
435         struct crypto_tfm *tfm = req->base.tfm;
436         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
437         struct blkcipher_desc desc = {
438                 .tfm = __crypto_blkcipher_cast(tfm),
439                 .info = req->info,
440                 .flags = req->base.flags,
441         };
442 
443         return alg->decrypt(&desc, req->dst, req->src, req->nbytes);
444 }
445 
446 static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,
447                                              u32 mask)
448 {
449         struct blkcipher_alg *cipher = &alg->cra_blkcipher;
450         unsigned int len = alg->cra_ctxsize;
451 
452         if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK &&
453             cipher->ivsize) {
454                 len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
455                 len += cipher->ivsize;
456         }
457 
458         return len;
459 }
460 
461 static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
462 {
463         struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
464         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
465 
466         crt->setkey = async_setkey;
467         crt->encrypt = async_encrypt;
468         crt->decrypt = async_decrypt;
469         crt->base = __crypto_ablkcipher_cast(tfm);
470         crt->ivsize = alg->ivsize;
471 
472         return 0;
473 }
474 
475 static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)
476 {
477         struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
478         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
479         unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
480         unsigned long addr;
481 
482         crt->setkey = setkey;
483         crt->encrypt = alg->encrypt;
484         crt->decrypt = alg->decrypt;
485 
486         addr = (unsigned long)crypto_tfm_ctx(tfm);
487         addr = ALIGN(addr, align);
488         addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
489         crt->iv = (void *)addr;
490 
491         return 0;
492 }
493 
494 static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
495 {
496         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
497 
498         if (alg->ivsize > PAGE_SIZE / 8)
499                 return -EINVAL;
500 
501         if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK)
502                 return crypto_init_blkcipher_ops_sync(tfm);
503         else
504                 return crypto_init_blkcipher_ops_async(tfm);
505 }
506 
507 #ifdef CONFIG_NET
508 static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
509 {
510         struct crypto_report_blkcipher rblkcipher;
511 
512         strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
513         strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
514                 sizeof(rblkcipher.geniv));
515 
516         rblkcipher.blocksize = alg->cra_blocksize;
517         rblkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
518         rblkcipher.max_keysize = alg->cra_blkcipher.max_keysize;
519         rblkcipher.ivsize = alg->cra_blkcipher.ivsize;
520 
521         if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
522                     sizeof(struct crypto_report_blkcipher), &rblkcipher))
523                 goto nla_put_failure;
524         return 0;
525 
526 nla_put_failure:
527         return -EMSGSIZE;
528 }
529 #else
530 static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
531 {
532         return -ENOSYS;
533 }
534 #endif
535 
536 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
537         __attribute__ ((unused));
538 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
539 {
540         seq_printf(m, "type         : blkcipher\n");
541         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
542         seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
543         seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
544         seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
545         seq_printf(m, "geniv        : %s\n", alg->cra_blkcipher.geniv ?:
546                                              "<default>");
547 }
548 
549 const struct crypto_type crypto_blkcipher_type = {
550         .ctxsize = crypto_blkcipher_ctxsize,
551         .init = crypto_init_blkcipher_ops,
552 #ifdef CONFIG_PROC_FS
553         .show = crypto_blkcipher_show,
554 #endif
555         .report = crypto_blkcipher_report,
556 };
557 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
558 
559 MODULE_LICENSE("GPL");
560 MODULE_DESCRIPTION("Generic block chaining cipher type");
561 

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