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1 /*
2  * Synchronous Cryptographic Hash operations.
3  *
4  * Copyright (c) 2008 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/scatterwalk.h>
14 #include <crypto/internal/hash.h>
15 #include <linux/err.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/seq_file.h>
20 #include <linux/cryptouser.h>
21 #include <net/netlink.h>
22
23 #include "internal.h"
24
25 static const struct crypto_type crypto_shash_type;
26
27 static int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
28                            unsigned int keylen)
29 {
30         return -ENOSYS;
31 }
32
33 static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
34                                   unsigned int keylen)
35 {
36         struct shash_alg *shash = crypto_shash_alg(tfm);
37         unsigned long alignmask = crypto_shash_alignmask(tfm);
38         unsigned long absize;
39         u8 *buffer, *alignbuffer;
40         int err;
41
42         absize = keylen + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
43         buffer = kmalloc(absize, GFP_KERNEL);
44         if (!buffer)
45                 return -ENOMEM;
46
47         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
48         memcpy(alignbuffer, key, keylen);
49         err = shash->setkey(tfm, alignbuffer, keylen);
50         kzfree(buffer);
51         return err;
52 }
53
54 int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
55                         unsigned int keylen)
56 {
57         struct shash_alg *shash = crypto_shash_alg(tfm);
58         unsigned long alignmask = crypto_shash_alignmask(tfm);
59
60         if ((unsigned long)key & alignmask)
61                 return shash_setkey_unaligned(tfm, key, keylen);
62
63         return shash->setkey(tfm, key, keylen);
64 }
65 EXPORT_SYMBOL_GPL(crypto_shash_setkey);
66
67 static inline unsigned int shash_align_buffer_size(unsigned len,
68                                                    unsigned long mask)
69 {
70         typedef u8 __attribute__ ((aligned)) u8_aligned;
71         return len + (mask & ~(__alignof__(u8_aligned) - 1));
72 }
73
74 static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
75                                   unsigned int len)
76 {
77         struct crypto_shash *tfm = desc->tfm;
78         struct shash_alg *shash = crypto_shash_alg(tfm);
79         unsigned long alignmask = crypto_shash_alignmask(tfm);
80         unsigned int unaligned_len = alignmask + 1 -
81                                      ((unsigned long)data & alignmask);
82         u8 ubuf[shash_align_buffer_size(unaligned_len, alignmask)]
83                 __attribute__ ((aligned));
84         u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
85         int err;
86
87         if (unaligned_len > len)
88                 unaligned_len = len;
89
90         memcpy(buf, data, unaligned_len);
91         err = shash->update(desc, buf, unaligned_len);
92         memset(buf, 0, unaligned_len);
93
94         return err ?:
95                shash->update(desc, data + unaligned_len, len - unaligned_len);
96 }
97
98 int crypto_shash_update(struct shash_desc *desc, const u8 *data,
99                         unsigned int len)
100 {
101         struct crypto_shash *tfm = desc->tfm;
102         struct shash_alg *shash = crypto_shash_alg(tfm);
103         unsigned long alignmask = crypto_shash_alignmask(tfm);
104
105         if ((unsigned long)data & alignmask)
106                 return shash_update_unaligned(desc, data, len);
107
108         return shash->update(desc, data, len);
109 }
110 EXPORT_SYMBOL_GPL(crypto_shash_update);
111
112 static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
113 {
114         struct crypto_shash *tfm = desc->tfm;
115         unsigned long alignmask = crypto_shash_alignmask(tfm);
116         struct shash_alg *shash = crypto_shash_alg(tfm);
117         unsigned int ds = crypto_shash_digestsize(tfm);
118         u8 ubuf[shash_align_buffer_size(ds, alignmask)]
119                 __attribute__ ((aligned));
120         u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
121         int err;
122
123         err = shash->final(desc, buf);
124         if (err)
125                 goto out;
126
127         memcpy(out, buf, ds);
128
129 out:
130         memset(buf, 0, ds);
131         return err;
132 }
133
134 int crypto_shash_final(struct shash_desc *desc, u8 *out)
135 {
136         struct crypto_shash *tfm = desc->tfm;
137         struct shash_alg *shash = crypto_shash_alg(tfm);
138         unsigned long alignmask = crypto_shash_alignmask(tfm);
139
140         if ((unsigned long)out & alignmask)
141                 return shash_final_unaligned(desc, out);
142
143         return shash->final(desc, out);
144 }
145 EXPORT_SYMBOL_GPL(crypto_shash_final);
146
147 static int shash_finup_unaligned(struct shash_desc *desc, const u8 *data,
148                                  unsigned int len, u8 *out)
149 {
150         return crypto_shash_update(desc, data, len) ?:
151                crypto_shash_final(desc, out);
152 }
153
154 int crypto_shash_finup(struct shash_desc *desc, const u8 *data,
155                        unsigned int len, u8 *out)
156 {
157         struct crypto_shash *tfm = desc->tfm;
158         struct shash_alg *shash = crypto_shash_alg(tfm);
159         unsigned long alignmask = crypto_shash_alignmask(tfm);
160
161         if (((unsigned long)data | (unsigned long)out) & alignmask)
162                 return shash_finup_unaligned(desc, data, len, out);
163
164         return shash->finup(desc, data, len, out);
165 }
166 EXPORT_SYMBOL_GPL(crypto_shash_finup);
167
168 static int shash_digest_unaligned(struct shash_desc *desc, const u8 *data,
169                                   unsigned int len, u8 *out)
170 {
171         return crypto_shash_init(desc) ?:
172                crypto_shash_finup(desc, data, len, out);
173 }
174
175 int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
176                         unsigned int len, u8 *out)
177 {
178         struct crypto_shash *tfm = desc->tfm;
179         struct shash_alg *shash = crypto_shash_alg(tfm);
180         unsigned long alignmask = crypto_shash_alignmask(tfm);
181
182         if (((unsigned long)data | (unsigned long)out) & alignmask)
183                 return shash_digest_unaligned(desc, data, len, out);
184
185         return shash->digest(desc, data, len, out);
186 }
187 EXPORT_SYMBOL_GPL(crypto_shash_digest);
188
189 static int shash_default_export(struct shash_desc *desc, void *out)
190 {
191         memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));
192         return 0;
193 }
194
195 static int shash_default_import(struct shash_desc *desc, const void *in)
196 {
197         memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(desc->tfm));
198         return 0;
199 }
200
201 static int shash_async_setkey(struct crypto_ahash *tfm, const u8 *key,
202                               unsigned int keylen)
203 {
204         struct crypto_shash **ctx = crypto_ahash_ctx(tfm);
205
206         return crypto_shash_setkey(*ctx, key, keylen);
207 }
208
209 static int shash_async_init(struct ahash_request *req)
210 {
211         struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
212         struct shash_desc *desc = ahash_request_ctx(req);
213
214         desc->tfm = *ctx;
215         desc->flags = req->base.flags;
216
217         return crypto_shash_init(desc);
218 }
219
220 int shash_ahash_update(struct ahash_request *req, struct shash_desc *desc)
221 {
222         struct crypto_hash_walk walk;
223         int nbytes;
224
225         for (nbytes = crypto_hash_walk_first(req, &walk); nbytes > 0;
226              nbytes = crypto_hash_walk_done(&walk, nbytes))
227                 nbytes = crypto_shash_update(desc, walk.data, nbytes);
228
229         return nbytes;
230 }
231 EXPORT_SYMBOL_GPL(shash_ahash_update);
232
233 static int shash_async_update(struct ahash_request *req)
234 {
235         return shash_ahash_update(req, ahash_request_ctx(req));
236 }
237
238 static int shash_async_final(struct ahash_request *req)
239 {
240         return crypto_shash_final(ahash_request_ctx(req), req->result);
241 }
242
243 int shash_ahash_finup(struct ahash_request *req, struct shash_desc *desc)
244 {
245         struct crypto_hash_walk walk;
246         int nbytes;
247
248         nbytes = crypto_hash_walk_first(req, &walk);
249         if (!nbytes)
250                 return crypto_shash_final(desc, req->result);
251
252         do {
253                 nbytes = crypto_hash_walk_last(&walk) ?
254                          crypto_shash_finup(desc, walk.data, nbytes,
255                                             req->result) :
256                          crypto_shash_update(desc, walk.data, nbytes);
257                 nbytes = crypto_hash_walk_done(&walk, nbytes);
258         } while (nbytes > 0);
259
260         return nbytes;
261 }
262 EXPORT_SYMBOL_GPL(shash_ahash_finup);
263
264 static int shash_async_finup(struct ahash_request *req)
265 {
266         struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
267         struct shash_desc *desc = ahash_request_ctx(req);
268
269         desc->tfm = *ctx;
270         desc->flags = req->base.flags;
271
272         return shash_ahash_finup(req, desc);
273 }
274
275 int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc)
276 {
277         struct scatterlist *sg = req->src;
278         unsigned int offset = sg->offset;
279         unsigned int nbytes = req->nbytes;
280         int err;
281
282         if (nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset)) {
283                 void *data;
284
285                 data = kmap_atomic(sg_page(sg));
286                 err = crypto_shash_digest(desc, data + offset, nbytes,
287                                           req->result);
288                 kunmap_atomic(data);
289                 crypto_yield(desc->flags);
290         } else
291                 err = crypto_shash_init(desc) ?:
292                       shash_ahash_finup(req, desc);
293
294         return err;
295 }
296 EXPORT_SYMBOL_GPL(shash_ahash_digest);
297
298 static int shash_async_digest(struct ahash_request *req)
299 {
300         struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
301         struct shash_desc *desc = ahash_request_ctx(req);
302
303         desc->tfm = *ctx;
304         desc->flags = req->base.flags;
305
306         return shash_ahash_digest(req, desc);
307 }
308
309 static int shash_async_export(struct ahash_request *req, void *out)
310 {
311         return crypto_shash_export(ahash_request_ctx(req), out);
312 }
313
314 static int shash_async_import(struct ahash_request *req, const void *in)
315 {
316         struct crypto_shash **ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
317         struct shash_desc *desc = ahash_request_ctx(req);
318
319         desc->tfm = *ctx;
320         desc->flags = req->base.flags;
321
322         return crypto_shash_import(desc, in);
323 }
324
325 static void crypto_exit_shash_ops_async(struct crypto_tfm *tfm)
326 {
327         struct crypto_shash **ctx = crypto_tfm_ctx(tfm);
328
329         crypto_free_shash(*ctx);
330 }
331
332 int crypto_init_shash_ops_async(struct crypto_tfm *tfm)
333 {
334         struct crypto_alg *calg = tfm->__crt_alg;
335         struct shash_alg *alg = __crypto_shash_alg(calg);
336         struct crypto_ahash *crt = __crypto_ahash_cast(tfm);
337         struct crypto_shash **ctx = crypto_tfm_ctx(tfm);
338         struct crypto_shash *shash;
339
340         if (!crypto_mod_get(calg))
341                 return -EAGAIN;
342
343         shash = crypto_create_tfm(calg, &crypto_shash_type);
344         if (IS_ERR(shash)) {
345                 crypto_mod_put(calg);
346                 return PTR_ERR(shash);
347         }
348
349         *ctx = shash;
350         tfm->exit = crypto_exit_shash_ops_async;
351
352         crt->init = shash_async_init;
353         crt->update = shash_async_update;
354         crt->final = shash_async_final;
355         crt->finup = shash_async_finup;
356         crt->digest = shash_async_digest;
357         crt->setkey = shash_async_setkey;
358
359         crt->has_setkey = alg->setkey != shash_no_setkey;
360
361         if (alg->export)
362                 crt->export = shash_async_export;
363         if (alg->import)
364                 crt->import = shash_async_import;
365
366         crt->reqsize = sizeof(struct shash_desc) + crypto_shash_descsize(shash);
367
368         return 0;
369 }
370
371 static int shash_compat_setkey(struct crypto_hash *tfm, const u8 *key,
372                                unsigned int keylen)
373 {
374         struct shash_desc **descp = crypto_hash_ctx(tfm);
375         struct shash_desc *desc = *descp;
376
377         return crypto_shash_setkey(desc->tfm, key, keylen);
378 }
379
380 static int shash_compat_init(struct hash_desc *hdesc)
381 {
382         struct shash_desc **descp = crypto_hash_ctx(hdesc->tfm);
383         struct shash_desc *desc = *descp;
384
385         desc->flags = hdesc->flags;
386
387         return crypto_shash_init(desc);
388 }
389
390 static int shash_compat_update(struct hash_desc *hdesc, struct scatterlist *sg,
391                                unsigned int len)
392 {
393         struct shash_desc **descp = crypto_hash_ctx(hdesc->tfm);
394         struct shash_desc *desc = *descp;
395         struct crypto_hash_walk walk;
396         int nbytes;
397
398         for (nbytes = crypto_hash_walk_first_compat(hdesc, &walk, sg, len);
399              nbytes > 0; nbytes = crypto_hash_walk_done(&walk, nbytes))
400                 nbytes = crypto_shash_update(desc, walk.data, nbytes);
401
402         return nbytes;
403 }
404
405 static int shash_compat_final(struct hash_desc *hdesc, u8 *out)
406 {
407         struct shash_desc **descp = crypto_hash_ctx(hdesc->tfm);
408
409         return crypto_shash_final(*descp, out);
410 }
411
412 static int shash_compat_digest(struct hash_desc *hdesc, struct scatterlist *sg,
413                                unsigned int nbytes, u8 *out)
414 {
415         unsigned int offset = sg->offset;
416         int err;
417
418         if (nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset)) {
419                 struct shash_desc **descp = crypto_hash_ctx(hdesc->tfm);
420                 struct shash_desc *desc = *descp;
421                 void *data;
422
423                 desc->flags = hdesc->flags;
424
425                 data = kmap_atomic(sg_page(sg));
426                 err = crypto_shash_digest(desc, data + offset, nbytes, out);
427                 kunmap_atomic(data);
428                 crypto_yield(desc->flags);
429                 goto out;
430         }
431
432         err = shash_compat_init(hdesc);
433         if (err)
434                 goto out;
435
436         err = shash_compat_update(hdesc, sg, nbytes);
437         if (err)
438                 goto out;
439
440         err = shash_compat_final(hdesc, out);
441
442 out:
443         return err;
444 }
445
446 static void crypto_exit_shash_ops_compat(struct crypto_tfm *tfm)
447 {
448         struct shash_desc **descp = crypto_tfm_ctx(tfm);
449         struct shash_desc *desc = *descp;
450
451         crypto_free_shash(desc->tfm);
452         kzfree(desc);
453 }
454
455 static int crypto_init_shash_ops_compat(struct crypto_tfm *tfm)
456 {
457         struct hash_tfm *crt = &tfm->crt_hash;
458         struct crypto_alg *calg = tfm->__crt_alg;
459         struct shash_alg *alg = __crypto_shash_alg(calg);
460         struct shash_desc **descp = crypto_tfm_ctx(tfm);
461         struct crypto_shash *shash;
462         struct shash_desc *desc;
463
464         if (!crypto_mod_get(calg))
465                 return -EAGAIN;
466
467         shash = crypto_create_tfm(calg, &crypto_shash_type);
468         if (IS_ERR(shash)) {
469                 crypto_mod_put(calg);
470                 return PTR_ERR(shash);
471         }
472
473         desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(shash),
474                        GFP_KERNEL);
475         if (!desc) {
476                 crypto_free_shash(shash);
477                 return -ENOMEM;
478         }
479
480         *descp = desc;
481         desc->tfm = shash;
482         tfm->exit = crypto_exit_shash_ops_compat;
483
484         crt->init = shash_compat_init;
485         crt->update = shash_compat_update;
486         crt->final  = shash_compat_final;
487         crt->digest = shash_compat_digest;
488         crt->setkey = shash_compat_setkey;
489
490         crt->digestsize = alg->digestsize;
491
492         return 0;
493 }
494
495 static int crypto_init_shash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
496 {
497         switch (mask & CRYPTO_ALG_TYPE_MASK) {
498         case CRYPTO_ALG_TYPE_HASH_MASK:
499                 return crypto_init_shash_ops_compat(tfm);
500         }
501
502         return -EINVAL;
503 }
504
505 static unsigned int crypto_shash_ctxsize(struct crypto_alg *alg, u32 type,
506                                          u32 mask)
507 {
508         switch (mask & CRYPTO_ALG_TYPE_MASK) {
509         case CRYPTO_ALG_TYPE_HASH_MASK:
510                 return sizeof(struct shash_desc *);
511         }
512
513         return 0;
514 }
515
516 static int crypto_shash_init_tfm(struct crypto_tfm *tfm)
517 {
518         struct crypto_shash *hash = __crypto_shash_cast(tfm);
519
520         hash->descsize = crypto_shash_alg(hash)->descsize;
521         return 0;
522 }
523
524 #ifdef CONFIG_NET
525 static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
526 {
527         struct crypto_report_hash rhash;
528         struct shash_alg *salg = __crypto_shash_alg(alg);
529
530         strncpy(rhash.type, "shash", sizeof(rhash.type));
531
532         rhash.blocksize = alg->cra_blocksize;
533         rhash.digestsize = salg->digestsize;
534
535         if (nla_put(skb, CRYPTOCFGA_REPORT_HASH,
536                     sizeof(struct crypto_report_hash), &rhash))
537                 goto nla_put_failure;
538         return 0;
539
540 nla_put_failure:
541         return -EMSGSIZE;
542 }
543 #else
544 static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
545 {
546         return -ENOSYS;
547 }
548 #endif
549
550 static void crypto_shash_show(struct seq_file *m, struct crypto_alg *alg)
551         __attribute__ ((unused));
552 static void crypto_shash_show(struct seq_file *m, struct crypto_alg *alg)
553 {
554         struct shash_alg *salg = __crypto_shash_alg(alg);
555
556         seq_printf(m, "type         : shash\n");
557         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
558         seq_printf(m, "digestsize   : %u\n", salg->digestsize);
559 }
560
561 static const struct crypto_type crypto_shash_type = {
562         .ctxsize = crypto_shash_ctxsize,
563         .extsize = crypto_alg_extsize,
564         .init = crypto_init_shash_ops,
565         .init_tfm = crypto_shash_init_tfm,
566 #ifdef CONFIG_PROC_FS
567         .show = crypto_shash_show,
568 #endif
569         .report = crypto_shash_report,
570         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
571         .maskset = CRYPTO_ALG_TYPE_MASK,
572         .type = CRYPTO_ALG_TYPE_SHASH,
573         .tfmsize = offsetof(struct crypto_shash, base),
574 };
575
576 struct crypto_shash *crypto_alloc_shash(const char *alg_name, u32 type,
577                                         u32 mask)
578 {
579         return crypto_alloc_tfm(alg_name, &crypto_shash_type, type, mask);
580 }
581 EXPORT_SYMBOL_GPL(crypto_alloc_shash);
582
583 static int shash_prepare_alg(struct shash_alg *alg)
584 {
585         struct crypto_alg *base = &alg->base;
586
587         if (alg->digestsize > PAGE_SIZE / 8 ||
588             alg->descsize > PAGE_SIZE / 8 ||
589             alg->statesize > PAGE_SIZE / 8)
590                 return -EINVAL;
591
592         base->cra_type = &crypto_shash_type;
593         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
594         base->cra_flags |= CRYPTO_ALG_TYPE_SHASH;
595
596         if (!alg->finup)
597                 alg->finup = shash_finup_unaligned;
598         if (!alg->digest)
599                 alg->digest = shash_digest_unaligned;
600         if (!alg->export) {
601                 alg->export = shash_default_export;
602                 alg->import = shash_default_import;
603                 alg->statesize = alg->descsize;
604         }
605         if (!alg->setkey)
606                 alg->setkey = shash_no_setkey;
607
608         return 0;
609 }
610
611 int crypto_register_shash(struct shash_alg *alg)
612 {
613         struct crypto_alg *base = &alg->base;
614         int err;
615
616         err = shash_prepare_alg(alg);
617         if (err)
618                 return err;
619
620         return crypto_register_alg(base);
621 }
622 EXPORT_SYMBOL_GPL(crypto_register_shash);
623
624 int crypto_unregister_shash(struct shash_alg *alg)
625 {
626         return crypto_unregister_alg(&alg->base);
627 }
628 EXPORT_SYMBOL_GPL(crypto_unregister_shash);
629
630 int crypto_register_shashes(struct shash_alg *algs, int count)
631 {
632         int i, ret;
633
634         for (i = 0; i < count; i++) {
635                 ret = crypto_register_shash(&algs[i]);
636                 if (ret)
637                         goto err;
638         }
639
640         return 0;
641
642 err:
643         for (--i; i >= 0; --i)
644                 crypto_unregister_shash(&algs[i]);
645
646         return ret;
647 }
648 EXPORT_SYMBOL_GPL(crypto_register_shashes);
649
650 int crypto_unregister_shashes(struct shash_alg *algs, int count)
651 {
652         int i, ret;
653
654         for (i = count - 1; i >= 0; --i) {
655                 ret = crypto_unregister_shash(&algs[i]);
656                 if (ret)
657                         pr_err("Failed to unregister %s %s: %d\n",
658                                algs[i].base.cra_driver_name,
659                                algs[i].base.cra_name, ret);
660         }
661
662         return 0;
663 }
664 EXPORT_SYMBOL_GPL(crypto_unregister_shashes);
665
666 int shash_register_instance(struct crypto_template *tmpl,
667                             struct shash_instance *inst)
668 {
669         int err;
670
671         err = shash_prepare_alg(&inst->alg);
672         if (err)
673                 return err;
674
675         return crypto_register_instance(tmpl, shash_crypto_instance(inst));
676 }
677 EXPORT_SYMBOL_GPL(shash_register_instance);
678
679 void shash_free_instance(struct crypto_instance *inst)
680 {
681         crypto_drop_spawn(crypto_instance_ctx(inst));
682         kfree(shash_instance(inst));
683 }
684 EXPORT_SYMBOL_GPL(shash_free_instance);
685
686 int crypto_init_shash_spawn(struct crypto_shash_spawn *spawn,
687                             struct shash_alg *alg,
688                             struct crypto_instance *inst)
689 {
690         return crypto_init_spawn2(&spawn->base, &alg->base, inst,
691                                   &crypto_shash_type);
692 }
693 EXPORT_SYMBOL_GPL(crypto_init_shash_spawn);
694
695 struct shash_alg *shash_attr_alg(struct rtattr *rta, u32 type, u32 mask)
696 {
697         struct crypto_alg *alg;
698
699         alg = crypto_attr_alg2(rta, &crypto_shash_type, type, mask);
700         return IS_ERR(alg) ? ERR_CAST(alg) :
701                container_of(alg, struct shash_alg, base);
702 }
703 EXPORT_SYMBOL_GPL(shash_attr_alg);
704
705 MODULE_LICENSE("GPL");
706 MODULE_DESCRIPTION("Synchronous cryptographic hash type");