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