crypto/api.c

   1 /*
   2  * Scatterlist Cryptographic API.
   3  *
   4  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   5  * Copyright (c) 2002 David S. Miller (davem@redhat.com)
   6  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
   7  *
   8  * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
   9  * and Nettle, by Niels Möller.
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License as published by the Free
  13  * Software Foundation; either version 2 of the License, or (at your option)
  14  * any later version.
  15  *
  16  */
  17
  18 #include <linux/err.h>
  19 #include <linux/errno.h>
  20 #include <linux/kernel.h>
  21 #include <linux/kmod.h>
  22 #include <linux/module.h>
  23 #include <linux/param.h>
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26 #include <linux/string.h>
  27 #include "internal.h"
  28
  29 LIST_HEAD(crypto_alg_list);
  30 EXPORT_SYMBOL_GPL(crypto_alg_list);
  31 DECLARE_RWSEM(crypto_alg_sem);
  32 EXPORT_SYMBOL_GPL(crypto_alg_sem);
  33
  34 BLOCKING_NOTIFIER_HEAD(crypto_chain);
  35 EXPORT_SYMBOL_GPL(crypto_chain);
  36
  37 static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
  38 {
  39         atomic_inc(&alg->cra_refcnt);
  40         return alg;
  41 }
  42
  43 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
  44 {
  45         return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
  46 }
  47 EXPORT_SYMBOL_GPL(crypto_mod_get);
  48
  49 void crypto_mod_put(struct crypto_alg *alg)
  50 {
  51         struct module *module = alg->cra_module;
  52
  53         crypto_alg_put(alg);
  54         module_put(module);
  55 }
  56 EXPORT_SYMBOL_GPL(crypto_mod_put);
  57
  58 static inline int crypto_is_test_larval(struct crypto_larval *larval)
  59 {
  60         return larval->alg.cra_driver_name[0];
  61 }
  62
  63 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
  64                                               u32 mask)
  65 {
  66         struct crypto_alg *q, *alg = NULL;
  67         int best = -2;
  68
  69         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  70                 int exact, fuzzy;
  71
  72                 if (crypto_is_moribund(q))
  73                         continue;
  74
  75                 if ((q->cra_flags ^ type) & mask)
  76                         continue;
  77
  78                 if (crypto_is_larval(q) &&
  79                     !crypto_is_test_larval((struct crypto_larval *)q) &&
  80                     ((struct crypto_larval *)q)->mask != mask)
  81                         continue;
  82
  83                 exact = !strcmp(q->cra_driver_name, name);
  84                 fuzzy = !strcmp(q->cra_name, name);
  85                 if (!exact && !(fuzzy && q->cra_priority > best))
  86                         continue;
  87
  88                 if (unlikely(!crypto_mod_get(q)))
  89                         continue;
  90
  91                 best = q->cra_priority;
  92                 if (alg)
  93                         crypto_mod_put(alg);
  94                 alg = q;
  95
  96                 if (exact)
  97                         break;
  98         }
  99
 100         return alg;
 101 }
 102
 103 static void crypto_larval_destroy(struct crypto_alg *alg)
 104 {
 105         struct crypto_larval *larval = (void *)alg;
 106
 107         BUG_ON(!crypto_is_larval(alg));
 108         if (larval->adult)
 109                 crypto_mod_put(larval->adult);
 110         kfree(larval);
 111 }
 112
 113 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
 114 {
 115         struct crypto_larval *larval;
 116
 117         larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 118         if (!larval)
 119                 return ERR_PTR(-ENOMEM);
 120
 121         larval->mask = mask;
 122         larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
 123         larval->alg.cra_priority = -1;
 124         larval->alg.cra_destroy = crypto_larval_destroy;
 125
 126         strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
 127         init_completion(&larval->completion);
 128
 129         return larval;
 130 }
 131 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
 132
 133 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
 134                                             u32 mask)
 135 {
 136         struct crypto_alg *alg;
 137         struct crypto_larval *larval;
 138
 139         larval = crypto_larval_alloc(name, type, mask);
 140         if (IS_ERR(larval))
 141                 return ERR_CAST(larval);
 142
 143         atomic_set(&larval->alg.cra_refcnt, 2);
 144
 145         down_write(&crypto_alg_sem);
 146         alg = __crypto_alg_lookup(name, type, mask);
 147         if (!alg) {
 148                 alg = &larval->alg;
 149                 list_add(&alg->cra_list, &crypto_alg_list);
 150         }
 151         up_write(&crypto_alg_sem);
 152
 153         if (alg != &larval->alg)
 154                 kfree(larval);
 155
 156         return alg;
 157 }
 158
 159 void crypto_larval_kill(struct crypto_alg *alg)
 160 {
 161         struct crypto_larval *larval = (void *)alg;
 162
 163         down_write(&crypto_alg_sem);
 164         list_del(&alg->cra_list);
 165         up_write(&crypto_alg_sem);
 166         complete_all(&larval->completion);
 167         crypto_alg_put(alg);
 168 }
 169 EXPORT_SYMBOL_GPL(crypto_larval_kill);
 170
 171 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 172 {
 173         struct crypto_larval *larval = (void *)alg;
 174         long timeout;
 175
 176         timeout = wait_for_completion_interruptible_timeout(
 177                 &larval->completion, 60 * HZ);
 178
 179         alg = larval->adult;
 180         if (timeout < 0)
 181                 alg = ERR_PTR(-EINTR);
 182         else if (!timeout)
 183                 alg = ERR_PTR(-ETIMEDOUT);
 184         else if (!alg)
 185                 alg = ERR_PTR(-ENOENT);
 186         else if (crypto_is_test_larval(larval) &&
 187                  !(alg->cra_flags & CRYPTO_ALG_TESTED))
 188                 alg = ERR_PTR(-EAGAIN);
 189         else if (!crypto_mod_get(alg))
 190                 alg = ERR_PTR(-EAGAIN);
 191         crypto_mod_put(&larval->alg);
 192
 193         return alg;
 194 }
 195
 196 struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
 197 {
 198         struct crypto_alg *alg;
 199
 200         down_read(&crypto_alg_sem);
 201         alg = __crypto_alg_lookup(name, type, mask);
 202         up_read(&crypto_alg_sem);
 203
 204         return alg;
 205 }
 206 EXPORT_SYMBOL_GPL(crypto_alg_lookup);
 207
 208 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
 209 {
 210         struct crypto_alg *alg;
 211
 212         if (!name)
 213                 return ERR_PTR(-ENOENT);
 214
 215         mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 216         type &= mask;
 217
 218         alg = crypto_alg_lookup(name, type, mask);
 219         if (!alg) {
 220                 char tmp[CRYPTO_MAX_ALG_NAME];
 221
 222                 request_module(name);
 223
 224                 if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
 225                       CRYPTO_ALG_NEED_FALLBACK) &&
 226                     snprintf(tmp, sizeof(tmp), "%s-all", name) < sizeof(tmp))
 227                         request_module(tmp);
 228
 229                 alg = crypto_alg_lookup(name, type, mask);
 230         }
 231
 232         if (alg)
 233                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 234
 235         return crypto_larval_add(name, type, mask);
 236 }
 237 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
 238
 239 int crypto_probing_notify(unsigned long val, void *v)
 240 {
 241         int ok;
 242
 243         ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 244         if (ok == NOTIFY_DONE) {
 245                 request_module("cryptomgr");
 246                 ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 247         }
 248
 249         return ok;
 250 }
 251 EXPORT_SYMBOL_GPL(crypto_probing_notify);
 252
 253 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 254 {
 255         struct crypto_alg *alg;
 256         struct crypto_alg *larval;
 257         int ok;
 258
 259         if (!((type | mask) & CRYPTO_ALG_TESTED)) {
 260                 type |= CRYPTO_ALG_TESTED;
 261                 mask |= CRYPTO_ALG_TESTED;
 262         }
 263
 264         larval = crypto_larval_lookup(name, type, mask);
 265         if (IS_ERR(larval) || !crypto_is_larval(larval))
 266                 return larval;
 267
 268         ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 269
 270         if (ok == NOTIFY_STOP)
 271                 alg = crypto_larval_wait(larval);
 272         else {
 273                 crypto_mod_put(larval);
 274                 alg = ERR_PTR(-ENOENT);
 275         }
 276         crypto_larval_kill(larval);
 277         return alg;
 278 }
 279 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 280
 281 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 282 {
 283         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 284
 285         if (type_obj)
 286                 return type_obj->init(tfm, type, mask);
 287
 288         switch (crypto_tfm_alg_type(tfm)) {
 289         case CRYPTO_ALG_TYPE_CIPHER:
 290                 return crypto_init_cipher_ops(tfm);
 291
 292         case CRYPTO_ALG_TYPE_DIGEST:
 293                 if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
 294                     CRYPTO_ALG_TYPE_HASH_MASK)
 295                         return crypto_init_digest_ops_async(tfm);
 296                 else
 297                         return crypto_init_digest_ops(tfm);
 298
 299         case CRYPTO_ALG_TYPE_COMPRESS:
 300                 return crypto_init_compress_ops(tfm);
 301
 302         default:
 303                 break;
 304         }
 305
 306         BUG();
 307         return -EINVAL;
 308 }
 309
 310 static void crypto_exit_ops(struct crypto_tfm *tfm)
 311 {
 312         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 313
 314         if (type) {
 315                 if (tfm->exit)
 316                         tfm->exit(tfm);
 317                 return;
 318         }
 319
 320         switch (crypto_tfm_alg_type(tfm)) {
 321         case CRYPTO_ALG_TYPE_CIPHER:
 322                 crypto_exit_cipher_ops(tfm);
 323                 break;
 324
 325         case CRYPTO_ALG_TYPE_DIGEST:
 326                 crypto_exit_digest_ops(tfm);
 327                 break;
 328
 329         case CRYPTO_ALG_TYPE_COMPRESS:
 330                 crypto_exit_compress_ops(tfm);
 331                 break;
 332
 333         default:
 334                 BUG();
 335
 336         }
 337 }
 338
 339 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 340 {
 341         const struct crypto_type *type_obj = alg->cra_type;
 342         unsigned int len;
 343
 344         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 345         if (type_obj)
 346                 return len + type_obj->ctxsize(alg, type, mask);
 347
 348         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 349         default:
 350                 BUG();
 351
 352         case CRYPTO_ALG_TYPE_CIPHER:
 353                 len += crypto_cipher_ctxsize(alg);
 354                 break;
 355
 356         case CRYPTO_ALG_TYPE_DIGEST:
 357                 len += crypto_digest_ctxsize(alg);
 358                 break;
 359
 360         case CRYPTO_ALG_TYPE_COMPRESS:
 361                 len += crypto_compress_ctxsize(alg);
 362                 break;
 363         }
 364
 365         return len;
 366 }
 367
 368 void crypto_shoot_alg(struct crypto_alg *alg)
 369 {
 370         down_write(&crypto_alg_sem);
 371         alg->cra_flags |= CRYPTO_ALG_DYING;
 372         up_write(&crypto_alg_sem);
 373 }
 374 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 375
 376 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 377                                       u32 mask)
 378 {
 379         struct crypto_tfm *tfm = NULL;
 380         unsigned int tfm_size;
 381         int err = -ENOMEM;
 382
 383         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 384         tfm = kzalloc(tfm_size, GFP_KERNEL);
 385         if (tfm == NULL)
 386                 goto out_err;
 387
 388         tfm->__crt_alg = alg;
 389
 390         err = crypto_init_ops(tfm, type, mask);
 391         if (err)
 392                 goto out_free_tfm;
 393
 394         if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 395                 goto cra_init_failed;
 396
 397         goto out;
 398
 399 cra_init_failed:
 400         crypto_exit_ops(tfm);
 401 out_free_tfm:
 402         if (err == -EAGAIN)
 403                 crypto_shoot_alg(alg);
 404         kfree(tfm);
 405 out_err:
 406         tfm = ERR_PTR(err);
 407 out:
 408         return tfm;
 409 }
 410 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 411
 412 /*
 413  *      crypto_alloc_base - Locate algorithm and allocate transform
 414  *      @alg_name: Name of algorithm
 415  *      @type: Type of algorithm
 416  *      @mask: Mask for type comparison
 417  *
 418  *      This function should not be used by new algorithm types.
 419  *      Plesae use crypto_alloc_tfm instead.
 420  *
 421  *      crypto_alloc_base() will first attempt to locate an already loaded
 422  *      algorithm.  If that fails and the kernel supports dynamically loadable
 423  *      modules, it will then attempt to load a module of the same name or
 424  *      alias.  If that fails it will send a query to any loaded crypto manager
 425  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 426  *      algorithm which is then associated with the new transform.
 427  *
 428  *      The returned transform is of a non-determinate type.  Most people
 429  *      should use one of the more specific allocation functions such as
 430  *      crypto_alloc_blkcipher.
 431  *
 432  *      In case of error the return value is an error pointer.
 433  */
 434 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 435 {
 436         struct crypto_tfm *tfm;
 437         int err;
 438
 439         for (;;) {
 440                 struct crypto_alg *alg;
 441
 442                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 443                 if (IS_ERR(alg)) {
 444                         err = PTR_ERR(alg);
 445                         goto err;
 446                 }
 447
 448                 tfm = __crypto_alloc_tfm(alg, type, mask);
 449                 if (!IS_ERR(tfm))
 450                         return tfm;
 451
 452                 crypto_mod_put(alg);
 453                 err = PTR_ERR(tfm);
 454
 455 err:
 456                 if (err != -EAGAIN)
 457                         break;
 458                 if (signal_pending(current)) {
 459                         err = -EINTR;
 460                         break;
 461                 }
 462         }
 463
 464         return ERR_PTR(err);
 465 }
 466 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 467
 468 void *crypto_create_tfm(struct crypto_alg *alg,
 469                         const struct crypto_type *frontend)
 470 {
 471         char *mem;
 472         struct crypto_tfm *tfm = NULL;
 473         unsigned int tfmsize;
 474         unsigned int total;
 475         int err = -ENOMEM;
 476
 477         tfmsize = frontend->tfmsize;
 478         total = tfmsize + sizeof(*tfm) + frontend->extsize(alg, frontend);
 479
 480         mem = kzalloc(total, GFP_KERNEL);
 481         if (mem == NULL)
 482                 goto out_err;
 483
 484         tfm = (struct crypto_tfm *)(mem + tfmsize);
 485         tfm->__crt_alg = alg;
 486
 487         err = frontend->init_tfm(tfm, frontend);
 488         if (err)
 489                 goto out_free_tfm;
 490
 491         if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 492                 goto cra_init_failed;
 493
 494         goto out;
 495
 496 cra_init_failed:
 497         crypto_exit_ops(tfm);
 498 out_free_tfm:
 499         if (err == -EAGAIN)
 500                 crypto_shoot_alg(alg);
 501         kfree(mem);
 502 out_err:
 503         mem = ERR_PTR(err);
 504 out:
 505         return mem;
 506 }
 507 EXPORT_SYMBOL_GPL(crypto_create_tfm);
 508
 509 /*
 510  *      crypto_alloc_tfm - Locate algorithm and allocate transform
 511  *      @alg_name: Name of algorithm
 512  *      @frontend: Frontend algorithm type
 513  *      @type: Type of algorithm
 514  *      @mask: Mask for type comparison
 515  *
 516  *      crypto_alloc_tfm() will first attempt to locate an already loaded
 517  *      algorithm.  If that fails and the kernel supports dynamically loadable
 518  *      modules, it will then attempt to load a module of the same name or
 519  *      alias.  If that fails it will send a query to any loaded crypto manager
 520  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 521  *      algorithm which is then associated with the new transform.
 522  *
 523  *      The returned transform is of a non-determinate type.  Most people
 524  *      should use one of the more specific allocation functions such as
 525  *      crypto_alloc_blkcipher.
 526  *
 527  *      In case of error the return value is an error pointer.
 528  */
 529 void *crypto_alloc_tfm(const char *alg_name,
 530                        const struct crypto_type *frontend, u32 type, u32 mask)
 531 {
 532         struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
 533         void *tfm;
 534         int err;
 535
 536         type &= frontend->maskclear;
 537         mask &= frontend->maskclear;
 538         type |= frontend->type;
 539         mask |= frontend->maskset;
 540
 541         lookup = frontend->lookup ?: crypto_alg_mod_lookup;
 542
 543         for (;;) {
 544                 struct crypto_alg *alg;
 545
 546                 alg = lookup(alg_name, type, mask);
 547                 if (IS_ERR(alg)) {
 548                         err = PTR_ERR(alg);
 549                         goto err;
 550                 }
 551
 552                 tfm = crypto_create_tfm(alg, frontend);
 553                 if (!IS_ERR(tfm))
 554                         return tfm;
 555
 556                 crypto_mod_put(alg);
 557                 err = PTR_ERR(tfm);
 558
 559 err:
 560                 if (err != -EAGAIN)
 561                         break;
 562                 if (signal_pending(current)) {
 563                         err = -EINTR;
 564                         break;
 565                 }
 566         }
 567
 568         return ERR_PTR(err);
 569 }
 570 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 571
 572 /*
 573  *      crypto_destroy_tfm - Free crypto transform
 574  *      @mem: Start of tfm slab
 575  *      @tfm: Transform to free
 576  *
 577  *      This function frees up the transform and any associated resources,
 578  *      then drops the refcount on the associated algorithm.
 579  */
 580 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
 581 {
 582         struct crypto_alg *alg;
 583         int size;
 584
 585         if (unlikely(!mem))
 586                 return;
 587
 588         alg = tfm->__crt_alg;
 589         size = ksize(mem);
 590
 591         if (!tfm->exit && alg->cra_exit)
 592                 alg->cra_exit(tfm);
 593         crypto_exit_ops(tfm);
 594         crypto_mod_put(alg);
 595         memset(mem, 0, size);
 596         kfree(mem);
 597 }
 598 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
 599
 600 int crypto_has_alg(const char *name, u32 type, u32 mask)
 601 {
 602         int ret = 0;
 603         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 604
 605         if (!IS_ERR(alg)) {
 606                 crypto_mod_put(alg);
 607                 ret = 1;
 608         }
 609
 610         return ret;
 611 }
 612 EXPORT_SYMBOL_GPL(crypto_has_alg);
 613
 614 MODULE_DESCRIPTION("Cryptographic core API");
 615 MODULE_LICENSE("GPL");