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 = try_then_request_module(crypto_alg_lookup(name, type, mask),
 219                                       name);
 220         if (alg)
 221                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 222
 223         return crypto_larval_add(name, type, mask);
 224 }
 225 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
 226
 227 int crypto_probing_notify(unsigned long val, void *v)
 228 {
 229         int ok;
 230
 231         ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 232         if (ok == NOTIFY_DONE) {
 233                 request_module("cryptomgr");
 234                 ok = blocking_notifier_call_chain(&crypto_chain, val, v);
 235         }
 236
 237         return ok;
 238 }
 239 EXPORT_SYMBOL_GPL(crypto_probing_notify);
 240
 241 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 242 {
 243         struct crypto_alg *alg;
 244         struct crypto_alg *larval;
 245         int ok;
 246
 247         if (!(mask & CRYPTO_ALG_TESTED)) {
 248                 type |= CRYPTO_ALG_TESTED;
 249                 mask |= CRYPTO_ALG_TESTED;
 250         }
 251
 252         larval = crypto_larval_lookup(name, type, mask);
 253         if (IS_ERR(larval) || !crypto_is_larval(larval))
 254                 return larval;
 255
 256         ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 257
 258         if (ok == NOTIFY_STOP)
 259                 alg = crypto_larval_wait(larval);
 260         else {
 261                 crypto_mod_put(larval);
 262                 alg = ERR_PTR(-ENOENT);
 263         }
 264         crypto_larval_kill(larval);
 265         return alg;
 266 }
 267 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 268
 269 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 270 {
 271         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 272
 273         if (type_obj)
 274                 return type_obj->init(tfm, type, mask);
 275
 276         switch (crypto_tfm_alg_type(tfm)) {
 277         case CRYPTO_ALG_TYPE_CIPHER:
 278                 return crypto_init_cipher_ops(tfm);
 279
 280         case CRYPTO_ALG_TYPE_DIGEST:
 281                 if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
 282                     CRYPTO_ALG_TYPE_HASH_MASK)
 283                         return crypto_init_digest_ops_async(tfm);
 284                 else
 285                         return crypto_init_digest_ops(tfm);
 286
 287         case CRYPTO_ALG_TYPE_COMPRESS:
 288                 return crypto_init_compress_ops(tfm);
 289
 290         default:
 291                 break;
 292         }
 293
 294         BUG();
 295         return -EINVAL;
 296 }
 297
 298 static void crypto_exit_ops(struct crypto_tfm *tfm)
 299 {
 300         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 301
 302         if (type) {
 303                 if (type->exit)
 304                         type->exit(tfm);
 305                 return;
 306         }
 307
 308         switch (crypto_tfm_alg_type(tfm)) {
 309         case CRYPTO_ALG_TYPE_CIPHER:
 310                 crypto_exit_cipher_ops(tfm);
 311                 break;
 312
 313         case CRYPTO_ALG_TYPE_DIGEST:
 314                 crypto_exit_digest_ops(tfm);
 315                 break;
 316
 317         case CRYPTO_ALG_TYPE_COMPRESS:
 318                 crypto_exit_compress_ops(tfm);
 319                 break;
 320
 321         default:
 322                 BUG();
 323
 324         }
 325 }
 326
 327 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 328 {
 329         const struct crypto_type *type_obj = alg->cra_type;
 330         unsigned int len;
 331
 332         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 333         if (type_obj)
 334                 return len + type_obj->ctxsize(alg, type, mask);
 335
 336         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 337         default:
 338                 BUG();
 339
 340         case CRYPTO_ALG_TYPE_CIPHER:
 341                 len += crypto_cipher_ctxsize(alg);
 342                 break;
 343
 344         case CRYPTO_ALG_TYPE_DIGEST:
 345                 len += crypto_digest_ctxsize(alg);
 346                 break;
 347
 348         case CRYPTO_ALG_TYPE_COMPRESS:
 349                 len += crypto_compress_ctxsize(alg);
 350                 break;
 351         }
 352
 353         return len;
 354 }
 355
 356 void crypto_shoot_alg(struct crypto_alg *alg)
 357 {
 358         down_write(&crypto_alg_sem);
 359         alg->cra_flags |= CRYPTO_ALG_DYING;
 360         up_write(&crypto_alg_sem);
 361 }
 362 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 363
 364 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 365                                       u32 mask)
 366 {
 367         struct crypto_tfm *tfm = NULL;
 368         unsigned int tfm_size;
 369         int err = -ENOMEM;
 370
 371         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 372         tfm = kzalloc(tfm_size, GFP_KERNEL);
 373         if (tfm == NULL)
 374                 goto out_err;
 375
 376         tfm->__crt_alg = alg;
 377
 378         err = crypto_init_ops(tfm, type, mask);
 379         if (err)
 380                 goto out_free_tfm;
 381
 382         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 383                 if (err == -EAGAIN)
 384                         crypto_shoot_alg(alg);
 385                 goto cra_init_failed;
 386         }
 387
 388         goto out;
 389
 390 cra_init_failed:
 391         crypto_exit_ops(tfm);
 392 out_free_tfm:
 393         kfree(tfm);
 394 out_err:
 395         tfm = ERR_PTR(err);
 396 out:
 397         return tfm;
 398 }
 399 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 400
 401 /*
 402  *      crypto_alloc_base - Locate algorithm and allocate transform
 403  *      @alg_name: Name of algorithm
 404  *      @type: Type of algorithm
 405  *      @mask: Mask for type comparison
 406  *
 407  *      crypto_alloc_base() will first attempt to locate an already loaded
 408  *      algorithm.  If that fails and the kernel supports dynamically loadable
 409  *      modules, it will then attempt to load a module of the same name or
 410  *      alias.  If that fails it will send a query to any loaded crypto manager
 411  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 412  *      algorithm which is then associated with the new transform.
 413  *
 414  *      The returned transform is of a non-determinate type.  Most people
 415  *      should use one of the more specific allocation functions such as
 416  *      crypto_alloc_blkcipher.
 417  *
 418  *      In case of error the return value is an error pointer.
 419  */
 420 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 421 {
 422         struct crypto_tfm *tfm;
 423         int err;
 424
 425         for (;;) {
 426                 struct crypto_alg *alg;
 427
 428                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 429                 if (IS_ERR(alg)) {
 430                         err = PTR_ERR(alg);
 431                         goto err;
 432                 }
 433
 434                 tfm = __crypto_alloc_tfm(alg, type, mask);
 435                 if (!IS_ERR(tfm))
 436                         return tfm;
 437
 438                 crypto_mod_put(alg);
 439                 err = PTR_ERR(tfm);
 440
 441 err:
 442                 if (err != -EAGAIN)
 443                         break;
 444                 if (signal_pending(current)) {
 445                         err = -EINTR;
 446                         break;
 447                 }
 448         }
 449
 450         return ERR_PTR(err);
 451 }
 452 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 453
 454 /*
 455  *      crypto_free_tfm - Free crypto transform
 456  *      @tfm: Transform to free
 457  *
 458  *      crypto_free_tfm() frees up the transform and any associated resources,
 459  *      then drops the refcount on the associated algorithm.
 460  */
 461 void crypto_free_tfm(struct crypto_tfm *tfm)
 462 {
 463         struct crypto_alg *alg;
 464         int size;
 465
 466         if (unlikely(!tfm))
 467                 return;
 468
 469         alg = tfm->__crt_alg;
 470         size = sizeof(*tfm) + alg->cra_ctxsize;
 471
 472         if (alg->cra_exit)
 473                 alg->cra_exit(tfm);
 474         crypto_exit_ops(tfm);
 475         crypto_mod_put(alg);
 476         memset(tfm, 0, size);
 477         kfree(tfm);
 478 }
 479
 480 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 481
 482 int crypto_has_alg(const char *name, u32 type, u32 mask)
 483 {
 484         int ret = 0;
 485         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 486
 487         if (!IS_ERR(alg)) {
 488                 crypto_mod_put(alg);
 489                 ret = 1;
 490         }
 491
 492         return ret;
 493 }
 494 EXPORT_SYMBOL_GPL(crypto_has_alg);
 495
 496 MODULE_DESCRIPTION("Cryptographic core API");
 497 MODULE_LICENSE("GPL");