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_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 216 {
 217         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 218
 219         if (type_obj)
 220                 return type_obj->init(tfm, type, mask);
 221
 222         switch (crypto_tfm_alg_type(tfm)) {
 223         case CRYPTO_ALG_TYPE_CIPHER:
 224                 return crypto_init_cipher_ops(tfm);
 225
 226         case CRYPTO_ALG_TYPE_DIGEST:
 227                 return crypto_init_digest_ops(tfm);
 228
 229         case CRYPTO_ALG_TYPE_COMPRESS:
 230                 return crypto_init_compress_ops(tfm);
 231
 232         default:
 233                 break;
 234         }
 235
 236         BUG();
 237         return -EINVAL;
 238 }
 239
 240 static void crypto_exit_ops(struct crypto_tfm *tfm)
 241 {
 242         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 243
 244         if (type) {
 245                 if (type->exit)
 246                         type->exit(tfm);
 247                 return;
 248         }
 249
 250         switch (crypto_tfm_alg_type(tfm)) {
 251         case CRYPTO_ALG_TYPE_CIPHER:
 252                 crypto_exit_cipher_ops(tfm);
 253                 break;
 254
 255         case CRYPTO_ALG_TYPE_DIGEST:
 256                 crypto_exit_digest_ops(tfm);
 257                 break;
 258
 259         case CRYPTO_ALG_TYPE_COMPRESS:
 260                 crypto_exit_compress_ops(tfm);
 261                 break;
 262
 263         default:
 264                 BUG();
 265
 266         }
 267 }
 268
 269 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 270 {
 271         const struct crypto_type *type_obj = alg->cra_type;
 272         unsigned int len;
 273
 274         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 275         if (type_obj)
 276                 return len + type_obj->ctxsize(alg, type, mask);
 277
 278         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 279         default:
 280                 BUG();
 281
 282         case CRYPTO_ALG_TYPE_CIPHER:
 283                 len += crypto_cipher_ctxsize(alg);
 284                 break;
 285
 286         case CRYPTO_ALG_TYPE_DIGEST:
 287                 len += crypto_digest_ctxsize(alg);
 288                 break;
 289
 290         case CRYPTO_ALG_TYPE_COMPRESS:
 291                 len += crypto_compress_ctxsize(alg);
 292                 break;
 293         }
 294
 295         return len;
 296 }
 297
 298 void crypto_shoot_alg(struct crypto_alg *alg)
 299 {
 300         down_write(&crypto_alg_sem);
 301         alg->cra_flags |= CRYPTO_ALG_DYING;
 302         up_write(&crypto_alg_sem);
 303 }
 304 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 305
 306 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 307                                       u32 mask)
 308 {
 309         struct crypto_tfm *tfm = NULL;
 310         unsigned int tfm_size;
 311         int err = -ENOMEM;
 312
 313         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 314         tfm = kzalloc(tfm_size, GFP_KERNEL);
 315         if (tfm == NULL)
 316                 goto out_err;
 317
 318         tfm->__crt_alg = alg;
 319
 320         err = crypto_init_ops(tfm, type, mask);
 321         if (err)
 322                 goto out_free_tfm;
 323
 324         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 325                 if (err == -EAGAIN)
 326                         crypto_shoot_alg(alg);
 327                 goto cra_init_failed;
 328         }
 329
 330         goto out;
 331
 332 cra_init_failed:
 333         crypto_exit_ops(tfm);
 334 out_free_tfm:
 335         kfree(tfm);
 336 out_err:
 337         tfm = ERR_PTR(err);
 338 out:
 339         return tfm;
 340 }
 341 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 342
 343 /*
 344  *      crypto_alloc_base - Locate algorithm and allocate transform
 345  *      @alg_name: Name of algorithm
 346  *      @type: Type of algorithm
 347  *      @mask: Mask for type comparison
 348  *
 349  *      crypto_alloc_base() will first attempt to locate an already loaded
 350  *      algorithm.  If that fails and the kernel supports dynamically loadable
 351  *      modules, it will then attempt to load a module of the same name or
 352  *      alias.  If that fails it will send a query to any loaded crypto manager
 353  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 354  *      algorithm which is then associated with the new transform.
 355  *
 356  *      The returned transform is of a non-determinate type.  Most people
 357  *      should use one of the more specific allocation functions such as
 358  *      crypto_alloc_blkcipher.
 359  *
 360  *      In case of error the return value is an error pointer.
 361  */
 362 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 363 {
 364         struct crypto_tfm *tfm;
 365         int err;
 366
 367         for (;;) {
 368                 struct crypto_alg *alg;
 369
 370                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 371                 if (IS_ERR(alg)) {
 372                         err = PTR_ERR(alg);
 373                         goto err;
 374                 }
 375
 376                 tfm = __crypto_alloc_tfm(alg, type, mask);
 377                 if (!IS_ERR(tfm))
 378                         return tfm;
 379
 380                 crypto_mod_put(alg);
 381                 err = PTR_ERR(tfm);
 382
 383 err:
 384                 if (err != -EAGAIN)
 385                         break;
 386                 if (signal_pending(current)) {
 387                         err = -EINTR;
 388                         break;
 389                 }
 390         }
 391
 392         return ERR_PTR(err);
 393 }
 394 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 395
 396 /*
 397  *      crypto_free_tfm - Free crypto transform
 398  *      @tfm: Transform to free
 399  *
 400  *      crypto_free_tfm() frees up the transform and any associated resources,
 401  *      then drops the refcount on the associated algorithm.
 402  */
 403 void crypto_free_tfm(struct crypto_tfm *tfm)
 404 {
 405         struct crypto_alg *alg;
 406         int size;
 407
 408         if (unlikely(!tfm))
 409                 return;
 410
 411         alg = tfm->__crt_alg;
 412         size = sizeof(*tfm) + alg->cra_ctxsize;
 413
 414         if (alg->cra_exit)
 415                 alg->cra_exit(tfm);
 416         crypto_exit_ops(tfm);
 417         crypto_mod_put(alg);
 418         memset(tfm, 0, size);
 419         kfree(tfm);
 420 }
 421
 422 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 423
 424 int crypto_has_alg(const char *name, u32 type, u32 mask)
 425 {
 426         int ret = 0;
 427         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 428
 429         if (!IS_ERR(alg)) {
 430                 crypto_mod_put(alg);
 431                 ret = 1;
 432         }
 433
 434         return ret;
 435 }
 436 EXPORT_SYMBOL_GPL(crypto_has_alg);