crypto/api.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Scatterlist Cryptographic API.
   4  *
   5  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   6  * Copyright (c) 2002 David S. Miller (davem@redhat.com)
   7  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
  10  * and Nettle, by Niels Möller.
  11  */
  12
  13 #include <linux/err.h>
  14 #include <linux/errno.h>
  15 #include <linux/kernel.h>
  16 #include <linux/kmod.h>
  17 #include <linux/module.h>
  18 #include <linux/param.h>
  19 #include <linux/sched/signal.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.h>
  22 #include <linux/completion.h>
  23 #include "internal.h"
  24
  25 LIST_HEAD(crypto_alg_list);
  26 EXPORT_SYMBOL_GPL(crypto_alg_list);
  27 DECLARE_RWSEM(crypto_alg_sem);
  28 EXPORT_SYMBOL_GPL(crypto_alg_sem);
  29
  30 BLOCKING_NOTIFIER_HEAD(crypto_chain);
  31 EXPORT_SYMBOL_GPL(crypto_chain);
  32
  33 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
  34
  35 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
  36 {
  37         return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
  38 }
  39 EXPORT_SYMBOL_GPL(crypto_mod_get);
  40
  41 void crypto_mod_put(struct crypto_alg *alg)
  42 {
  43         struct module *module = alg->cra_module;
  44
  45         crypto_alg_put(alg);
  46         module_put(module);
  47 }
  48 EXPORT_SYMBOL_GPL(crypto_mod_put);
  49
  50 static inline int crypto_is_test_larval(struct crypto_larval *larval)
  51 {
  52         return larval->alg.cra_driver_name[0];
  53 }
  54
  55 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
  56                                               u32 mask)
  57 {
  58         struct crypto_alg *q, *alg = NULL;
  59         int best = -2;
  60
  61         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  62                 int exact, fuzzy;
  63
  64                 if (crypto_is_moribund(q))
  65                         continue;
  66
  67                 if ((q->cra_flags ^ type) & mask)
  68                         continue;
  69
  70                 if (crypto_is_larval(q) &&
  71                     !crypto_is_test_larval((struct crypto_larval *)q) &&
  72                     ((struct crypto_larval *)q)->mask != mask)
  73                         continue;
  74
  75                 exact = !strcmp(q->cra_driver_name, name);
  76                 fuzzy = !strcmp(q->cra_name, name);
  77                 if (!exact && !(fuzzy && q->cra_priority > best))
  78                         continue;
  79
  80                 if (unlikely(!crypto_mod_get(q)))
  81                         continue;
  82
  83                 best = q->cra_priority;
  84                 if (alg)
  85                         crypto_mod_put(alg);
  86                 alg = q;
  87
  88                 if (exact)
  89                         break;
  90         }
  91
  92         return alg;
  93 }
  94
  95 static void crypto_larval_destroy(struct crypto_alg *alg)
  96 {
  97         struct crypto_larval *larval = (void *)alg;
  98
  99         BUG_ON(!crypto_is_larval(alg));
 100         if (!IS_ERR_OR_NULL(larval->adult))
 101                 crypto_mod_put(larval->adult);
 102         kfree(larval);
 103 }
 104
 105 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
 106 {
 107         struct crypto_larval *larval;
 108
 109         larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 110         if (!larval)
 111                 return ERR_PTR(-ENOMEM);
 112
 113         larval->mask = mask;
 114         larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
 115         larval->alg.cra_priority = -1;
 116         larval->alg.cra_destroy = crypto_larval_destroy;
 117
 118         strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
 119         init_completion(&larval->completion);
 120
 121         return larval;
 122 }
 123 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
 124
 125 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
 126                                             u32 mask)
 127 {
 128         struct crypto_alg *alg;
 129         struct crypto_larval *larval;
 130
 131         larval = crypto_larval_alloc(name, type, mask);
 132         if (IS_ERR(larval))
 133                 return ERR_CAST(larval);
 134
 135         refcount_set(&larval->alg.cra_refcnt, 2);
 136
 137         down_write(&crypto_alg_sem);
 138         alg = __crypto_alg_lookup(name, type, mask);
 139         if (!alg) {
 140                 alg = &larval->alg;
 141                 list_add(&alg->cra_list, &crypto_alg_list);
 142         }
 143         up_write(&crypto_alg_sem);
 144
 145         if (alg != &larval->alg) {
 146                 kfree(larval);
 147                 if (crypto_is_larval(alg))
 148                         alg = crypto_larval_wait(alg);
 149         }
 150
 151         return alg;
 152 }
 153
 154 void crypto_larval_kill(struct crypto_alg *alg)
 155 {
 156         struct crypto_larval *larval = (void *)alg;
 157
 158         down_write(&crypto_alg_sem);
 159         list_del(&alg->cra_list);
 160         up_write(&crypto_alg_sem);
 161         complete_all(&larval->completion);
 162         crypto_alg_put(alg);
 163 }
 164 EXPORT_SYMBOL_GPL(crypto_larval_kill);
 165
 166 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 167 {
 168         struct crypto_larval *larval = (void *)alg;
 169         long timeout;
 170
 171         timeout = wait_for_completion_killable_timeout(
 172                 &larval->completion, 60 * HZ);
 173
 174         alg = larval->adult;
 175         if (timeout < 0)
 176                 alg = ERR_PTR(-EINTR);
 177         else if (!timeout)
 178                 alg = ERR_PTR(-ETIMEDOUT);
 179         else if (!alg)
 180                 alg = ERR_PTR(-ENOENT);
 181         else if (IS_ERR(alg))
 182                 ;
 183         else if (crypto_is_test_larval(larval) &&
 184                  !(alg->cra_flags & CRYPTO_ALG_TESTED))
 185                 alg = ERR_PTR(-EAGAIN);
 186         else if (!crypto_mod_get(alg))
 187                 alg = ERR_PTR(-EAGAIN);
 188         crypto_mod_put(&larval->alg);
 189
 190         return alg;
 191 }
 192
 193 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 194                                             u32 mask)
 195 {
 196         struct crypto_alg *alg;
 197         u32 test = 0;
 198
 199         if (!((type | mask) & CRYPTO_ALG_TESTED))
 200                 test |= CRYPTO_ALG_TESTED;
 201
 202         down_read(&crypto_alg_sem);
 203         alg = __crypto_alg_lookup(name, type | test, mask | test);
 204         if (!alg && test) {
 205                 alg = __crypto_alg_lookup(name, type, mask);
 206                 if (alg && !crypto_is_larval(alg)) {
 207                         /* Test failed */
 208                         crypto_mod_put(alg);
 209                         alg = ERR_PTR(-ELIBBAD);
 210                 }
 211         }
 212         up_read(&crypto_alg_sem);
 213
 214         return alg;
 215 }
 216
 217 static struct crypto_alg *crypto_larval_lookup(const char *name, u32 type,
 218                                                u32 mask)
 219 {
 220         struct crypto_alg *alg;
 221
 222         if (!name)
 223                 return ERR_PTR(-ENOENT);
 224
 225         type &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 226         mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 227
 228         alg = crypto_alg_lookup(name, type, mask);
 229         if (!alg && !(mask & CRYPTO_NOLOAD)) {
 230                 request_module("crypto-%s", name);
 231
 232                 if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
 233                       CRYPTO_ALG_NEED_FALLBACK))
 234                         request_module("crypto-%s-all", name);
 235
 236                 alg = crypto_alg_lookup(name, type, mask);
 237         }
 238
 239         if (!IS_ERR_OR_NULL(alg) && crypto_is_larval(alg))
 240                 alg = crypto_larval_wait(alg);
 241         else if (!alg)
 242                 alg = crypto_larval_add(name, type, mask);
 243
 244         return alg;
 245 }
 246
 247 int crypto_probing_notify(unsigned long val, void *v)
 248 {
 249         int ok;
 250
 251         ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 252         if (ok == NOTIFY_DONE) {
 253                 request_module("cryptomgr");
 254                 ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 255         }
 256
 257         return ok;
 258 }
 259 EXPORT_SYMBOL_GPL(crypto_probing_notify);
 260
 261 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 262 {
 263         struct crypto_alg *alg;
 264         struct crypto_alg *larval;
 265         int ok;
 266
 267         /*
 268          * If the internal flag is set for a cipher, require a caller to
 269          * to invoke the cipher with the internal flag to use that cipher.
 270          * Also, if a caller wants to allocate a cipher that may or may
 271          * not be an internal cipher, use type | CRYPTO_ALG_INTERNAL and
 272          * !(mask & CRYPTO_ALG_INTERNAL).
 273          */
 274         if (!((type | mask) & CRYPTO_ALG_INTERNAL))
 275                 mask |= CRYPTO_ALG_INTERNAL;
 276
 277         larval = crypto_larval_lookup(name, type, mask);
 278         if (IS_ERR(larval) || !crypto_is_larval(larval))
 279                 return larval;
 280
 281         ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 282
 283         if (ok == NOTIFY_STOP)
 284                 alg = crypto_larval_wait(larval);
 285         else {
 286                 crypto_mod_put(larval);
 287                 alg = ERR_PTR(-ENOENT);
 288         }
 289         crypto_larval_kill(larval);
 290         return alg;
 291 }
 292 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 293
 294 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 295 {
 296         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 297
 298         if (type_obj)
 299                 return type_obj->init(tfm, type, mask);
 300         return 0;
 301 }
 302
 303 static void crypto_exit_ops(struct crypto_tfm *tfm)
 304 {
 305         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 306
 307         if (type && tfm->exit)
 308                 tfm->exit(tfm);
 309 }
 310
 311 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 312 {
 313         const struct crypto_type *type_obj = alg->cra_type;
 314         unsigned int len;
 315
 316         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 317         if (type_obj)
 318                 return len + type_obj->ctxsize(alg, type, mask);
 319
 320         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 321         default:
 322                 BUG();
 323
 324         case CRYPTO_ALG_TYPE_CIPHER:
 325                 len += crypto_cipher_ctxsize(alg);
 326                 break;
 327
 328         case CRYPTO_ALG_TYPE_COMPRESS:
 329                 len += crypto_compress_ctxsize(alg);
 330                 break;
 331         }
 332
 333         return len;
 334 }
 335
 336 static void crypto_shoot_alg(struct crypto_alg *alg)
 337 {
 338         down_write(&crypto_alg_sem);
 339         alg->cra_flags |= CRYPTO_ALG_DYING;
 340         up_write(&crypto_alg_sem);
 341 }
 342
 343 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 344                                       u32 mask)
 345 {
 346         struct crypto_tfm *tfm = NULL;
 347         unsigned int tfm_size;
 348         int err = -ENOMEM;
 349
 350         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 351         tfm = kzalloc(tfm_size, GFP_KERNEL);
 352         if (tfm == NULL)
 353                 goto out_err;
 354
 355         tfm->__crt_alg = alg;
 356
 357         err = crypto_init_ops(tfm, type, mask);
 358         if (err)
 359                 goto out_free_tfm;
 360
 361         if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 362                 goto cra_init_failed;
 363
 364         goto out;
 365
 366 cra_init_failed:
 367         crypto_exit_ops(tfm);
 368 out_free_tfm:
 369         if (err == -EAGAIN)
 370                 crypto_shoot_alg(alg);
 371         kfree(tfm);
 372 out_err:
 373         tfm = ERR_PTR(err);
 374 out:
 375         return tfm;
 376 }
 377 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 378
 379 /*
 380  *      crypto_alloc_base - Locate algorithm and allocate transform
 381  *      @alg_name: Name of algorithm
 382  *      @type: Type of algorithm
 383  *      @mask: Mask for type comparison
 384  *
 385  *      This function should not be used by new algorithm types.
 386  *      Please use crypto_alloc_tfm instead.
 387  *
 388  *      crypto_alloc_base() will first attempt to locate an already loaded
 389  *      algorithm.  If that fails and the kernel supports dynamically loadable
 390  *      modules, it will then attempt to load a module of the same name or
 391  *      alias.  If that fails it will send a query to any loaded crypto manager
 392  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 393  *      algorithm which is then associated with the new transform.
 394  *
 395  *      The returned transform is of a non-determinate type.  Most people
 396  *      should use one of the more specific allocation functions such as
 397  *      crypto_alloc_skcipher().
 398  *
 399  *      In case of error the return value is an error pointer.
 400  */
 401 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 402 {
 403         struct crypto_tfm *tfm;
 404         int err;
 405
 406         for (;;) {
 407                 struct crypto_alg *alg;
 408
 409                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 410                 if (IS_ERR(alg)) {
 411                         err = PTR_ERR(alg);
 412                         goto err;
 413                 }
 414
 415                 tfm = __crypto_alloc_tfm(alg, type, mask);
 416                 if (!IS_ERR(tfm))
 417                         return tfm;
 418
 419                 crypto_mod_put(alg);
 420                 err = PTR_ERR(tfm);
 421
 422 err:
 423                 if (err != -EAGAIN)
 424                         break;
 425                 if (fatal_signal_pending(current)) {
 426                         err = -EINTR;
 427                         break;
 428                 }
 429         }
 430
 431         return ERR_PTR(err);
 432 }
 433 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 434
 435 void *crypto_create_tfm(struct crypto_alg *alg,
 436                         const struct crypto_type *frontend)
 437 {
 438         char *mem;
 439         struct crypto_tfm *tfm = NULL;
 440         unsigned int tfmsize;
 441         unsigned int total;
 442         int err = -ENOMEM;
 443
 444         tfmsize = frontend->tfmsize;
 445         total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
 446
 447         mem = kzalloc(total, GFP_KERNEL);
 448         if (mem == NULL)
 449                 goto out_err;
 450
 451         tfm = (struct crypto_tfm *)(mem + tfmsize);
 452         tfm->__crt_alg = alg;
 453
 454         err = frontend->init_tfm(tfm);
 455         if (err)
 456                 goto out_free_tfm;
 457
 458         if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 459                 goto cra_init_failed;
 460
 461         goto out;
 462
 463 cra_init_failed:
 464         crypto_exit_ops(tfm);
 465 out_free_tfm:
 466         if (err == -EAGAIN)
 467                 crypto_shoot_alg(alg);
 468         kfree(mem);
 469 out_err:
 470         mem = ERR_PTR(err);
 471 out:
 472         return mem;
 473 }
 474 EXPORT_SYMBOL_GPL(crypto_create_tfm);
 475
 476 struct crypto_alg *crypto_find_alg(const char *alg_name,
 477                                    const struct crypto_type *frontend,
 478                                    u32 type, u32 mask)
 479 {
 480         if (frontend) {
 481                 type &= frontend->maskclear;
 482                 mask &= frontend->maskclear;
 483                 type |= frontend->type;
 484                 mask |= frontend->maskset;
 485         }
 486
 487         return crypto_alg_mod_lookup(alg_name, type, mask);
 488 }
 489 EXPORT_SYMBOL_GPL(crypto_find_alg);
 490
 491 /*
 492  *      crypto_alloc_tfm - Locate algorithm and allocate transform
 493  *      @alg_name: Name of algorithm
 494  *      @frontend: Frontend algorithm type
 495  *      @type: Type of algorithm
 496  *      @mask: Mask for type comparison
 497  *
 498  *      crypto_alloc_tfm() will first attempt to locate an already loaded
 499  *      algorithm.  If that fails and the kernel supports dynamically loadable
 500  *      modules, it will then attempt to load a module of the same name or
 501  *      alias.  If that fails it will send a query to any loaded crypto manager
 502  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 503  *      algorithm which is then associated with the new transform.
 504  *
 505  *      The returned transform is of a non-determinate type.  Most people
 506  *      should use one of the more specific allocation functions such as
 507  *      crypto_alloc_skcipher().
 508  *
 509  *      In case of error the return value is an error pointer.
 510  */
 511 void *crypto_alloc_tfm(const char *alg_name,
 512                        const struct crypto_type *frontend, u32 type, u32 mask)
 513 {
 514         void *tfm;
 515         int err;
 516
 517         for (;;) {
 518                 struct crypto_alg *alg;
 519
 520                 alg = crypto_find_alg(alg_name, frontend, type, mask);
 521                 if (IS_ERR(alg)) {
 522                         err = PTR_ERR(alg);
 523                         goto err;
 524                 }
 525
 526                 tfm = crypto_create_tfm(alg, frontend);
 527                 if (!IS_ERR(tfm))
 528                         return tfm;
 529
 530                 crypto_mod_put(alg);
 531                 err = PTR_ERR(tfm);
 532
 533 err:
 534                 if (err != -EAGAIN)
 535                         break;
 536                 if (fatal_signal_pending(current)) {
 537                         err = -EINTR;
 538                         break;
 539                 }
 540         }
 541
 542         return ERR_PTR(err);
 543 }
 544 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 545
 546 /*
 547  *      crypto_destroy_tfm - Free crypto transform
 548  *      @mem: Start of tfm slab
 549  *      @tfm: Transform to free
 550  *
 551  *      This function frees up the transform and any associated resources,
 552  *      then drops the refcount on the associated algorithm.
 553  */
 554 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
 555 {
 556         struct crypto_alg *alg;
 557
 558         if (unlikely(!mem))
 559                 return;
 560
 561         alg = tfm->__crt_alg;
 562
 563         if (!tfm->exit && alg->cra_exit)
 564                 alg->cra_exit(tfm);
 565         crypto_exit_ops(tfm);
 566         crypto_mod_put(alg);
 567         kzfree(mem);
 568 }
 569 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
 570
 571 int crypto_has_alg(const char *name, u32 type, u32 mask)
 572 {
 573         int ret = 0;
 574         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 575
 576         if (!IS_ERR(alg)) {
 577                 crypto_mod_put(alg);
 578                 ret = 1;
 579         }
 580
 581         return ret;
 582 }
 583 EXPORT_SYMBOL_GPL(crypto_has_alg);
 584
 585 void crypto_req_done(struct crypto_async_request *req, int err)
 586 {
 587         struct crypto_wait *wait = req->data;
 588
 589         if (err == -EINPROGRESS)
 590                 return;
 591
 592         wait->err = err;
 593         complete(&wait->completion);
 594 }
 595 EXPORT_SYMBOL_GPL(crypto_req_done);
 596
 597 MODULE_DESCRIPTION("Cryptographic core API");
 598 MODULE_LICENSE("GPL");
 599 MODULE_SOFTDEP("pre: cryptomgr");