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         crypto_alg_put(alg);
  52         module_put(alg->cra_module);
  53 }
  54 EXPORT_SYMBOL_GPL(crypto_mod_put);
  55
  56 struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type, 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                     ((struct crypto_larval *)q)->mask != mask)
  72                         continue;
  73
  74                 exact = !strcmp(q->cra_driver_name, name);
  75                 fuzzy = !strcmp(q->cra_name, name);
  76                 if (!exact && !(fuzzy && q->cra_priority > best))
  77                         continue;
  78
  79                 if (unlikely(!crypto_mod_get(q)))
  80                         continue;
  81
  82                 best = q->cra_priority;
  83                 if (alg)
  84                         crypto_mod_put(alg);
  85                 alg = q;
  86
  87                 if (exact)
  88                         break;
  89         }
  90
  91         return alg;
  92 }
  93 EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
  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 (larval->adult)
 101                 crypto_mod_put(larval->adult);
 102         kfree(larval);
 103 }
 104
 105 static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
 106                                               u32 mask)
 107 {
 108         struct crypto_alg *alg;
 109         struct crypto_larval *larval;
 110
 111         larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 112         if (!larval)
 113                 return ERR_PTR(-ENOMEM);
 114
 115         larval->mask = mask;
 116         larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
 117         larval->alg.cra_priority = -1;
 118         larval->alg.cra_destroy = crypto_larval_destroy;
 119
 120         atomic_set(&larval->alg.cra_refcnt, 2);
 121         strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
 122         init_completion(&larval->completion);
 123
 124         down_write(&crypto_alg_sem);
 125         alg = __crypto_alg_lookup(name, type, mask);
 126         if (!alg) {
 127                 alg = &larval->alg;
 128                 list_add(&alg->cra_list, &crypto_alg_list);
 129         }
 130         up_write(&crypto_alg_sem);
 131
 132         if (alg != &larval->alg)
 133                 kfree(larval);
 134
 135         return alg;
 136 }
 137
 138 static void crypto_larval_kill(struct crypto_alg *alg)
 139 {
 140         struct crypto_larval *larval = (void *)alg;
 141
 142         down_write(&crypto_alg_sem);
 143         list_del(&alg->cra_list);
 144         up_write(&crypto_alg_sem);
 145         complete(&larval->completion);
 146         crypto_alg_put(alg);
 147 }
 148
 149 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 150 {
 151         struct crypto_larval *larval = (void *)alg;
 152
 153         wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
 154         alg = larval->adult;
 155         if (alg) {
 156                 if (!crypto_mod_get(alg))
 157                         alg = ERR_PTR(-EAGAIN);
 158         } else
 159                 alg = ERR_PTR(-ENOENT);
 160         crypto_mod_put(&larval->alg);
 161
 162         return alg;
 163 }
 164
 165 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 166                                             u32 mask)
 167 {
 168         struct crypto_alg *alg;
 169
 170         down_read(&crypto_alg_sem);
 171         alg = __crypto_alg_lookup(name, type, mask);
 172         up_read(&crypto_alg_sem);
 173
 174         return alg;
 175 }
 176
 177 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 178 {
 179         struct crypto_alg *alg;
 180         struct crypto_alg *larval;
 181         int ok;
 182
 183         if (!name)
 184                 return ERR_PTR(-ENOENT);
 185
 186         mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 187         type &= mask;
 188
 189         alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
 190                                       name);
 191         if (alg)
 192                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 193
 194         larval = crypto_larval_alloc(name, type, mask);
 195         if (IS_ERR(larval) || !crypto_is_larval(larval))
 196                 return larval;
 197
 198         ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 199         if (ok == NOTIFY_DONE) {
 200                 request_module("cryptomgr");
 201                 ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 202         }
 203
 204         if (ok == NOTIFY_STOP)
 205                 alg = crypto_larval_wait(larval);
 206         else {
 207                 crypto_mod_put(larval);
 208                 alg = ERR_PTR(-ENOENT);
 209         }
 210         crypto_larval_kill(larval);
 211         return alg;
 212 }
 213 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 214
 215 static int crypto_init_flags(struct crypto_tfm *tfm, u32 flags)
 216 {
 217         tfm->crt_flags = flags & CRYPTO_TFM_REQ_MASK;
 218         flags &= ~CRYPTO_TFM_REQ_MASK;
 219
 220         switch (crypto_tfm_alg_type(tfm)) {
 221         case CRYPTO_ALG_TYPE_CIPHER:
 222                 return crypto_init_cipher_flags(tfm, flags);
 223
 224         case CRYPTO_ALG_TYPE_DIGEST:
 225                 return crypto_init_digest_flags(tfm, flags);
 226
 227         case CRYPTO_ALG_TYPE_COMPRESS:
 228                 return crypto_init_compress_flags(tfm, flags);
 229         }
 230
 231         return 0;
 232 }
 233
 234 static int crypto_init_ops(struct crypto_tfm *tfm)
 235 {
 236         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 237
 238         if (type)
 239                 return type->init(tfm);
 240
 241         switch (crypto_tfm_alg_type(tfm)) {
 242         case CRYPTO_ALG_TYPE_CIPHER:
 243                 return crypto_init_cipher_ops(tfm);
 244
 245         case CRYPTO_ALG_TYPE_DIGEST:
 246                 return crypto_init_digest_ops(tfm);
 247
 248         case CRYPTO_ALG_TYPE_COMPRESS:
 249                 return crypto_init_compress_ops(tfm);
 250
 251         default:
 252                 break;
 253         }
 254
 255         BUG();
 256         return -EINVAL;
 257 }
 258
 259 static void crypto_exit_ops(struct crypto_tfm *tfm)
 260 {
 261         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 262
 263         if (type) {
 264                 if (type->exit)
 265                         type->exit(tfm);
 266                 return;
 267         }
 268
 269         switch (crypto_tfm_alg_type(tfm)) {
 270         case CRYPTO_ALG_TYPE_CIPHER:
 271                 crypto_exit_cipher_ops(tfm);
 272                 break;
 273
 274         case CRYPTO_ALG_TYPE_DIGEST:
 275                 crypto_exit_digest_ops(tfm);
 276                 break;
 277
 278         case CRYPTO_ALG_TYPE_COMPRESS:
 279                 crypto_exit_compress_ops(tfm);
 280                 break;
 281
 282         default:
 283                 BUG();
 284
 285         }
 286 }
 287
 288 static unsigned int crypto_ctxsize(struct crypto_alg *alg, int flags)
 289 {
 290         const struct crypto_type *type = alg->cra_type;
 291         unsigned int len;
 292
 293         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 294         if (type)
 295                 return len + type->ctxsize(alg);
 296
 297         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 298         default:
 299                 BUG();
 300
 301         case CRYPTO_ALG_TYPE_CIPHER:
 302                 len += crypto_cipher_ctxsize(alg, flags);
 303                 break;
 304
 305         case CRYPTO_ALG_TYPE_DIGEST:
 306                 len += crypto_digest_ctxsize(alg, flags);
 307                 break;
 308
 309         case CRYPTO_ALG_TYPE_COMPRESS:
 310                 len += crypto_compress_ctxsize(alg, flags);
 311                 break;
 312         }
 313
 314         return len;
 315 }
 316
 317 void crypto_shoot_alg(struct crypto_alg *alg)
 318 {
 319         down_write(&crypto_alg_sem);
 320         alg->cra_flags |= CRYPTO_ALG_DYING;
 321         up_write(&crypto_alg_sem);
 322 }
 323 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 324
 325 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 flags)
 326 {
 327         struct crypto_tfm *tfm = NULL;
 328         unsigned int tfm_size;
 329         int err = -ENOMEM;
 330
 331         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, flags);
 332         tfm = kzalloc(tfm_size, GFP_KERNEL);
 333         if (tfm == NULL)
 334                 goto out_err;
 335
 336         tfm->__crt_alg = alg;
 337
 338         err = crypto_init_flags(tfm, flags);
 339         if (err)
 340                 goto out_free_tfm;
 341
 342         err = crypto_init_ops(tfm);
 343         if (err)
 344                 goto out_free_tfm;
 345
 346         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 347                 if (err == -EAGAIN)
 348                         crypto_shoot_alg(alg);
 349                 goto cra_init_failed;
 350         }
 351
 352         goto out;
 353
 354 cra_init_failed:
 355         crypto_exit_ops(tfm);
 356 out_free_tfm:
 357         kfree(tfm);
 358 out_err:
 359         tfm = ERR_PTR(err);
 360 out:
 361         return tfm;
 362 }
 363 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 364
 365 struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 366 {
 367         struct crypto_tfm *tfm = NULL;
 368         int err;
 369
 370         do {
 371                 struct crypto_alg *alg;
 372
 373                 alg = crypto_alg_mod_lookup(name, 0, CRYPTO_ALG_ASYNC);
 374                 err = PTR_ERR(alg);
 375                 if (IS_ERR(alg))
 376                         continue;
 377
 378                 tfm = __crypto_alloc_tfm(alg, flags);
 379                 err = 0;
 380                 if (IS_ERR(tfm)) {
 381                         crypto_mod_put(alg);
 382                         err = PTR_ERR(tfm);
 383                         tfm = NULL;
 384                 }
 385         } while (err == -EAGAIN && !signal_pending(current));
 386
 387         return tfm;
 388 }
 389
 390 /*
 391  *      crypto_alloc_base - Locate algorithm and allocate transform
 392  *      @alg_name: Name of algorithm
 393  *      @type: Type of algorithm
 394  *      @mask: Mask for type comparison
 395  *
 396  *      crypto_alloc_base() will first attempt to locate an already loaded
 397  *      algorithm.  If that fails and the kernel supports dynamically loadable
 398  *      modules, it will then attempt to load a module of the same name or
 399  *      alias.  If that fails it will send a query to any loaded crypto manager
 400  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 401  *      algorithm which is then associated with the new transform.
 402  *
 403  *      The returned transform is of a non-determinate type.  Most people
 404  *      should use one of the more specific allocation functions such as
 405  *      crypto_alloc_blkcipher.
 406  *
 407  *      In case of error the return value is an error pointer.
 408  */
 409 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 410 {
 411         struct crypto_tfm *tfm;
 412         int err;
 413
 414         for (;;) {
 415                 struct crypto_alg *alg;
 416
 417                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 418                 if (IS_ERR(alg)) {
 419                         err = PTR_ERR(alg);
 420                         goto err;
 421                 }
 422
 423                 tfm = __crypto_alloc_tfm(alg, 0);
 424                 if (!IS_ERR(tfm))
 425                         return tfm;
 426
 427                 crypto_mod_put(alg);
 428                 err = PTR_ERR(tfm);
 429
 430 err:
 431                 if (err != -EAGAIN)
 432                         break;
 433                 if (signal_pending(current)) {
 434                         err = -EINTR;
 435                         break;
 436                 }
 437         }
 438
 439         return ERR_PTR(err);
 440 }
 441 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 442
 443 /*
 444  *      crypto_free_tfm - Free crypto transform
 445  *      @tfm: Transform to free
 446  *
 447  *      crypto_free_tfm() frees up the transform and any associated resources,
 448  *      then drops the refcount on the associated algorithm.
 449  */
 450 void crypto_free_tfm(struct crypto_tfm *tfm)
 451 {
 452         struct crypto_alg *alg;
 453         int size;
 454
 455         if (unlikely(!tfm))
 456                 return;
 457
 458         alg = tfm->__crt_alg;
 459         size = sizeof(*tfm) + alg->cra_ctxsize;
 460
 461         if (alg->cra_exit)
 462                 alg->cra_exit(tfm);
 463         crypto_exit_ops(tfm);
 464         crypto_mod_put(alg);
 465         memset(tfm, 0, size);
 466         kfree(tfm);
 467 }
 468
 469 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 470 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 471
 472 int crypto_has_alg(const char *name, u32 type, u32 mask)
 473 {
 474         int ret = 0;
 475         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 476
 477         if (!IS_ERR(alg)) {
 478                 crypto_mod_put(alg);
 479                 ret = 1;
 480         }
 481
 482         return ret;
 483 }
 484 EXPORT_SYMBOL_GPL(crypto_has_alg);