linux/crypto/api.c
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   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
  29LIST_HEAD(crypto_alg_list);
  30EXPORT_SYMBOL_GPL(crypto_alg_list);
  31DECLARE_RWSEM(crypto_alg_sem);
  32EXPORT_SYMBOL_GPL(crypto_alg_sem);
  33
  34BLOCKING_NOTIFIER_HEAD(crypto_chain);
  35EXPORT_SYMBOL_GPL(crypto_chain);
  36
  37static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
  38{
  39        atomic_inc(&alg->cra_refcnt);
  40        return alg;
  41}
  42
  43struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
  44{
  45        return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
  46}
  47EXPORT_SYMBOL_GPL(crypto_mod_get);
  48
  49void 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}
  56EXPORT_SYMBOL_GPL(crypto_mod_put);
  57
  58static inline int crypto_is_test_larval(struct crypto_larval *larval)
  59{
  60        return larval->alg.cra_driver_name[0];
  61}
  62
  63static 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
 103static 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
 113struct 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}
 131EXPORT_SYMBOL_GPL(crypto_larval_alloc);
 132
 133static 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
 159void 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}
 169EXPORT_SYMBOL_GPL(crypto_larval_kill);
 170
 171static 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
 196struct 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}
 206EXPORT_SYMBOL_GPL(crypto_alg_lookup);
 207
 208struct 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                request_module("%s", name);
 221
 222                if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
 223                      CRYPTO_ALG_NEED_FALLBACK))
 224                        request_module("%s-all", name);
 225
 226                alg = crypto_alg_lookup(name, type, mask);
 227        }
 228
 229        if (alg)
 230                return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 231
 232        return crypto_larval_add(name, type, mask);
 233}
 234EXPORT_SYMBOL_GPL(crypto_larval_lookup);
 235
 236int crypto_probing_notify(unsigned long val, void *v)
 237{
 238        int ok;
 239
 240        ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 241        if (ok == NOTIFY_DONE) {
 242                request_module("cryptomgr");
 243                ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 244        }
 245
 246        return ok;
 247}
 248EXPORT_SYMBOL_GPL(crypto_probing_notify);
 249
 250struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 251{
 252        struct crypto_alg *alg;
 253        struct crypto_alg *larval;
 254        int ok;
 255
 256        if (!((type | mask) & CRYPTO_ALG_TESTED)) {
 257                type |= CRYPTO_ALG_TESTED;
 258                mask |= CRYPTO_ALG_TESTED;
 259        }
 260
 261        larval = crypto_larval_lookup(name, type, mask);
 262        if (IS_ERR(larval) || !crypto_is_larval(larval))
 263                return larval;
 264
 265        ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 266
 267        if (ok == NOTIFY_STOP)
 268                alg = crypto_larval_wait(larval);
 269        else {
 270                crypto_mod_put(larval);
 271                alg = ERR_PTR(-ENOENT);
 272        }
 273        crypto_larval_kill(larval);
 274        return alg;
 275}
 276EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 277
 278static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 279{
 280        const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 281
 282        if (type_obj)
 283                return type_obj->init(tfm, type, mask);
 284
 285        switch (crypto_tfm_alg_type(tfm)) {
 286        case CRYPTO_ALG_TYPE_CIPHER:
 287                return crypto_init_cipher_ops(tfm);
 288
 289        case CRYPTO_ALG_TYPE_COMPRESS:
 290                return crypto_init_compress_ops(tfm);
 291
 292        default:
 293                break;
 294        }
 295
 296        BUG();
 297        return -EINVAL;
 298}
 299
 300static void crypto_exit_ops(struct crypto_tfm *tfm)
 301{
 302        const struct crypto_type *type = tfm->__crt_alg->cra_type;
 303
 304        if (type) {
 305                if (tfm->exit)
 306                        tfm->exit(tfm);
 307                return;
 308        }
 309
 310        switch (crypto_tfm_alg_type(tfm)) {
 311        case CRYPTO_ALG_TYPE_CIPHER:
 312                crypto_exit_cipher_ops(tfm);
 313                break;
 314
 315        case CRYPTO_ALG_TYPE_COMPRESS:
 316                crypto_exit_compress_ops(tfm);
 317                break;
 318
 319        default:
 320                BUG();
 321        }
 322}
 323
 324static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 325{
 326        const struct crypto_type *type_obj = alg->cra_type;
 327        unsigned int len;
 328
 329        len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 330        if (type_obj)
 331                return len + type_obj->ctxsize(alg, type, mask);
 332
 333        switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 334        default:
 335                BUG();
 336
 337        case CRYPTO_ALG_TYPE_CIPHER:
 338                len += crypto_cipher_ctxsize(alg);
 339                break;
 340
 341        case CRYPTO_ALG_TYPE_COMPRESS:
 342                len += crypto_compress_ctxsize(alg);
 343                break;
 344        }
 345
 346        return len;
 347}
 348
 349void crypto_shoot_alg(struct crypto_alg *alg)
 350{
 351        down_write(&crypto_alg_sem);
 352        alg->cra_flags |= CRYPTO_ALG_DYING;
 353        up_write(&crypto_alg_sem);
 354}
 355EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 356
 357struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 358                                      u32 mask)
 359{
 360        struct crypto_tfm *tfm = NULL;
 361        unsigned int tfm_size;
 362        int err = -ENOMEM;
 363
 364        tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 365        tfm = kzalloc(tfm_size, GFP_KERNEL);
 366        if (tfm == NULL)
 367                goto out_err;
 368
 369        tfm->__crt_alg = alg;
 370
 371        err = crypto_init_ops(tfm, type, mask);
 372        if (err)
 373                goto out_free_tfm;
 374
 375        if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 376                goto cra_init_failed;
 377
 378        goto out;
 379
 380cra_init_failed:
 381        crypto_exit_ops(tfm);
 382out_free_tfm:
 383        if (err == -EAGAIN)
 384                crypto_shoot_alg(alg);
 385        kfree(tfm);
 386out_err:
 387        tfm = ERR_PTR(err);
 388out:
 389        return tfm;
 390}
 391EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 392
 393/*
 394 *      crypto_alloc_base - Locate algorithm and allocate transform
 395 *      @alg_name: Name of algorithm
 396 *      @type: Type of algorithm
 397 *      @mask: Mask for type comparison
 398 *
 399 *      This function should not be used by new algorithm types.
 400 *      Plesae use crypto_alloc_tfm instead.
 401 *
 402 *      crypto_alloc_base() will first attempt to locate an already loaded
 403 *      algorithm.  If that fails and the kernel supports dynamically loadable
 404 *      modules, it will then attempt to load a module of the same name or
 405 *      alias.  If that fails it will send a query to any loaded crypto manager
 406 *      to construct an algorithm on the fly.  A refcount is grabbed on the
 407 *      algorithm which is then associated with the new transform.
 408 *
 409 *      The returned transform is of a non-determinate type.  Most people
 410 *      should use one of the more specific allocation functions such as
 411 *      crypto_alloc_blkcipher.
 412 *
 413 *      In case of error the return value is an error pointer.
 414 */
 415struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 416{
 417        struct crypto_tfm *tfm;
 418        int err;
 419
 420        for (;;) {
 421                struct crypto_alg *alg;
 422
 423                alg = crypto_alg_mod_lookup(alg_name, type, mask);
 424                if (IS_ERR(alg)) {
 425                        err = PTR_ERR(alg);
 426                        goto err;
 427                }
 428
 429                tfm = __crypto_alloc_tfm(alg, type, mask);
 430                if (!IS_ERR(tfm))
 431                        return tfm;
 432
 433                crypto_mod_put(alg);
 434                err = PTR_ERR(tfm);
 435
 436err:
 437                if (err != -EAGAIN)
 438                        break;
 439                if (signal_pending(current)) {
 440                        err = -EINTR;
 441                        break;
 442                }
 443        }
 444
 445        return ERR_PTR(err);
 446}
 447EXPORT_SYMBOL_GPL(crypto_alloc_base);
 448
 449void *crypto_create_tfm(struct crypto_alg *alg,
 450                        const struct crypto_type *frontend)
 451{
 452        char *mem;
 453        struct crypto_tfm *tfm = NULL;
 454        unsigned int tfmsize;
 455        unsigned int total;
 456        int err = -ENOMEM;
 457
 458        tfmsize = frontend->tfmsize;
 459        total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
 460
 461        mem = kzalloc(total, GFP_KERNEL);
 462        if (mem == NULL)
 463                goto out_err;
 464
 465        tfm = (struct crypto_tfm *)(mem + tfmsize);
 466        tfm->__crt_alg = alg;
 467
 468        err = frontend->init_tfm(tfm);
 469        if (err)
 470                goto out_free_tfm;
 471
 472        if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 473                goto cra_init_failed;
 474
 475        goto out;
 476
 477cra_init_failed:
 478        crypto_exit_ops(tfm);
 479out_free_tfm:
 480        if (err == -EAGAIN)
 481                crypto_shoot_alg(alg);
 482        kfree(mem);
 483out_err:
 484        mem = ERR_PTR(err);
 485out:
 486        return mem;
 487}
 488EXPORT_SYMBOL_GPL(crypto_create_tfm);
 489
 490struct crypto_alg *crypto_find_alg(const char *alg_name,
 491                                   const struct crypto_type *frontend,
 492                                   u32 type, u32 mask)
 493{
 494        struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
 495                crypto_alg_mod_lookup;
 496
 497        if (frontend) {
 498                type &= frontend->maskclear;
 499                mask &= frontend->maskclear;
 500                type |= frontend->type;
 501                mask |= frontend->maskset;
 502
 503                if (frontend->lookup)
 504                        lookup = frontend->lookup;
 505        }
 506
 507        return lookup(alg_name, type, mask);
 508}
 509EXPORT_SYMBOL_GPL(crypto_find_alg);
 510
 511/*
 512 *      crypto_alloc_tfm - Locate algorithm and allocate transform
 513 *      @alg_name: Name of algorithm
 514 *      @frontend: Frontend algorithm type
 515 *      @type: Type of algorithm
 516 *      @mask: Mask for type comparison
 517 *
 518 *      crypto_alloc_tfm() will first attempt to locate an already loaded
 519 *      algorithm.  If that fails and the kernel supports dynamically loadable
 520 *      modules, it will then attempt to load a module of the same name or
 521 *      alias.  If that fails it will send a query to any loaded crypto manager
 522 *      to construct an algorithm on the fly.  A refcount is grabbed on the
 523 *      algorithm which is then associated with the new transform.
 524 *
 525 *      The returned transform is of a non-determinate type.  Most people
 526 *      should use one of the more specific allocation functions such as
 527 *      crypto_alloc_blkcipher.
 528 *
 529 *      In case of error the return value is an error pointer.
 530 */
 531void *crypto_alloc_tfm(const char *alg_name,
 532                       const struct crypto_type *frontend, u32 type, u32 mask)
 533{
 534        void *tfm;
 535        int err;
 536
 537        for (;;) {
 538                struct crypto_alg *alg;
 539
 540                alg = crypto_find_alg(alg_name, frontend, type, mask);
 541                if (IS_ERR(alg)) {
 542                        err = PTR_ERR(alg);
 543                        goto err;
 544                }
 545
 546                tfm = crypto_create_tfm(alg, frontend);
 547                if (!IS_ERR(tfm))
 548                        return tfm;
 549
 550                crypto_mod_put(alg);
 551                err = PTR_ERR(tfm);
 552
 553err:
 554                if (err != -EAGAIN)
 555                        break;
 556                if (signal_pending(current)) {
 557                        err = -EINTR;
 558                        break;
 559                }
 560        }
 561
 562        return ERR_PTR(err);
 563}
 564EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 565
 566/*
 567 *      crypto_destroy_tfm - Free crypto transform
 568 *      @mem: Start of tfm slab
 569 *      @tfm: Transform to free
 570 *
 571 *      This function frees up the transform and any associated resources,
 572 *      then drops the refcount on the associated algorithm.
 573 */
 574void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
 575{
 576        struct crypto_alg *alg;
 577
 578        if (unlikely(!mem))
 579                return;
 580
 581        alg = tfm->__crt_alg;
 582
 583        if (!tfm->exit && alg->cra_exit)
 584                alg->cra_exit(tfm);
 585        crypto_exit_ops(tfm);
 586        crypto_mod_put(alg);
 587        kzfree(mem);
 588}
 589EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
 590
 591int crypto_has_alg(const char *name, u32 type, u32 mask)
 592{
 593        int ret = 0;
 594        struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 595
 596        if (!IS_ERR(alg)) {
 597                crypto_mod_put(alg);
 598                ret = 1;
 599        }
 600
 601        return ret;
 602}
 603EXPORT_SYMBOL_GPL(crypto_has_alg);
 604
 605MODULE_DESCRIPTION("Cryptographic core API");
 606MODULE_LICENSE("GPL");
 607
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