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 struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type, u32 mask)
  59 {
  60         struct crypto_alg *q, *alg = NULL;
  61         int best = -2;
  62
  63         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  64                 int exact, fuzzy;
  65
  66                 if (crypto_is_moribund(q))
  67                         continue;
  68
  69                 if ((q->cra_flags ^ type) & mask)
  70                         continue;
  71
  72                 if (crypto_is_larval(q) &&
  73                     ((struct crypto_larval *)q)->mask != mask)
  74                         continue;
  75
  76                 exact = !strcmp(q->cra_driver_name, name);
  77                 fuzzy = !strcmp(q->cra_name, name);
  78                 if (!exact && !(fuzzy && q->cra_priority > best))
  79                         continue;
  80
  81                 if (unlikely(!crypto_mod_get(q)))
  82                         continue;
  83
  84                 best = q->cra_priority;
  85                 if (alg)
  86                         crypto_mod_put(alg);
  87                 alg = q;
  88
  89                 if (exact)
  90                         break;
  91         }
  92
  93         return alg;
  94 }
  95 EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
  96
  97 static void crypto_larval_destroy(struct crypto_alg *alg)
  98 {
  99         struct crypto_larval *larval = (void *)alg;
 100
 101         BUG_ON(!crypto_is_larval(alg));
 102         if (larval->adult)
 103                 crypto_mod_put(larval->adult);
 104         kfree(larval);
 105 }
 106
 107 static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
 108                                               u32 mask)
 109 {
 110         struct crypto_alg *alg;
 111         struct crypto_larval *larval;
 112
 113         larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 114         if (!larval)
 115                 return ERR_PTR(-ENOMEM);
 116
 117         larval->mask = mask;
 118         larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
 119         larval->alg.cra_priority = -1;
 120         larval->alg.cra_destroy = crypto_larval_destroy;
 121
 122         atomic_set(&larval->alg.cra_refcnt, 2);
 123         strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
 124         init_completion(&larval->completion);
 125
 126         down_write(&crypto_alg_sem);
 127         alg = __crypto_alg_lookup(name, type, mask);
 128         if (!alg) {
 129                 alg = &larval->alg;
 130                 list_add(&alg->cra_list, &crypto_alg_list);
 131         }
 132         up_write(&crypto_alg_sem);
 133
 134         if (alg != &larval->alg)
 135                 kfree(larval);
 136
 137         return alg;
 138 }
 139
 140 void crypto_larval_kill(struct crypto_alg *alg)
 141 {
 142         struct crypto_larval *larval = (void *)alg;
 143
 144         down_write(&crypto_alg_sem);
 145         list_del(&alg->cra_list);
 146         up_write(&crypto_alg_sem);
 147         complete_all(&larval->completion);
 148         crypto_alg_put(alg);
 149 }
 150 EXPORT_SYMBOL_GPL(crypto_larval_kill);
 151
 152 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 153 {
 154         struct crypto_larval *larval = (void *)alg;
 155
 156         wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
 157         alg = larval->adult;
 158         if (alg) {
 159                 if (!crypto_mod_get(alg))
 160                         alg = ERR_PTR(-EAGAIN);
 161         } else
 162                 alg = ERR_PTR(-ENOENT);
 163         crypto_mod_put(&larval->alg);
 164
 165         return alg;
 166 }
 167
 168 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 169                                             u32 mask)
 170 {
 171         struct crypto_alg *alg;
 172
 173         down_read(&crypto_alg_sem);
 174         alg = __crypto_alg_lookup(name, type, mask);
 175         up_read(&crypto_alg_sem);
 176
 177         return alg;
 178 }
 179
 180 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
 181 {
 182         struct crypto_alg *alg;
 183
 184         if (!name)
 185                 return ERR_PTR(-ENOENT);
 186
 187         mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 188         type &= mask;
 189
 190         alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
 191                                       name);
 192         if (alg)
 193                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 194
 195         return crypto_larval_alloc(name, type, mask);
 196 }
 197 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
 198
 199 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 200 {
 201         struct crypto_alg *alg;
 202         struct crypto_alg *larval;
 203         int ok;
 204
 205         larval = crypto_larval_lookup(name, type, mask);
 206         if (IS_ERR(larval) || !crypto_is_larval(larval))
 207                 return larval;
 208
 209         ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 210         if (ok == NOTIFY_DONE) {
 211                 request_module("cryptomgr");
 212                 ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 213         }
 214
 215         if (ok == NOTIFY_STOP)
 216                 alg = crypto_larval_wait(larval);
 217         else {
 218                 crypto_mod_put(larval);
 219                 alg = ERR_PTR(-ENOENT);
 220         }
 221         crypto_larval_kill(larval);
 222         return alg;
 223 }
 224 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 225
 226 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 227 {
 228         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 229
 230         if (type_obj)
 231                 return type_obj->init(tfm, type, mask);
 232
 233         switch (crypto_tfm_alg_type(tfm)) {
 234         case CRYPTO_ALG_TYPE_CIPHER:
 235                 return crypto_init_cipher_ops(tfm);
 236
 237         case CRYPTO_ALG_TYPE_DIGEST:
 238                 if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
 239                     CRYPTO_ALG_TYPE_HASH_MASK)
 240                         return crypto_init_digest_ops_async(tfm);
 241                 else
 242                         return crypto_init_digest_ops(tfm);
 243
 244         case CRYPTO_ALG_TYPE_COMPRESS:
 245                 return crypto_init_compress_ops(tfm);
 246
 247         default:
 248                 break;
 249         }
 250
 251         BUG();
 252         return -EINVAL;
 253 }
 254
 255 static void crypto_exit_ops(struct crypto_tfm *tfm)
 256 {
 257         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 258
 259         if (type) {
 260                 if (type->exit)
 261                         type->exit(tfm);
 262                 return;
 263         }
 264
 265         switch (crypto_tfm_alg_type(tfm)) {
 266         case CRYPTO_ALG_TYPE_CIPHER:
 267                 crypto_exit_cipher_ops(tfm);
 268                 break;
 269
 270         case CRYPTO_ALG_TYPE_DIGEST:
 271                 crypto_exit_digest_ops(tfm);
 272                 break;
 273
 274         case CRYPTO_ALG_TYPE_COMPRESS:
 275                 crypto_exit_compress_ops(tfm);
 276                 break;
 277
 278         default:
 279                 BUG();
 280
 281         }
 282 }
 283
 284 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 285 {
 286         const struct crypto_type *type_obj = alg->cra_type;
 287         unsigned int len;
 288
 289         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 290         if (type_obj)
 291                 return len + type_obj->ctxsize(alg, type, mask);
 292
 293         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 294         default:
 295                 BUG();
 296
 297         case CRYPTO_ALG_TYPE_CIPHER:
 298                 len += crypto_cipher_ctxsize(alg);
 299                 break;
 300
 301         case CRYPTO_ALG_TYPE_DIGEST:
 302                 len += crypto_digest_ctxsize(alg);
 303                 break;
 304
 305         case CRYPTO_ALG_TYPE_COMPRESS:
 306                 len += crypto_compress_ctxsize(alg);
 307                 break;
 308         }
 309
 310         return len;
 311 }
 312
 313 void crypto_shoot_alg(struct crypto_alg *alg)
 314 {
 315         down_write(&crypto_alg_sem);
 316         alg->cra_flags |= CRYPTO_ALG_DYING;
 317         up_write(&crypto_alg_sem);
 318 }
 319 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 320
 321 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 322                                       u32 mask)
 323 {
 324         struct crypto_tfm *tfm = NULL;
 325         unsigned int tfm_size;
 326         int err = -ENOMEM;
 327
 328         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 329         tfm = kzalloc(tfm_size, GFP_KERNEL);
 330         if (tfm == NULL)
 331                 goto out_err;
 332
 333         tfm->__crt_alg = alg;
 334
 335         err = crypto_init_ops(tfm, type, mask);
 336         if (err)
 337                 goto out_free_tfm;
 338
 339         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 340                 if (err == -EAGAIN)
 341                         crypto_shoot_alg(alg);
 342                 goto cra_init_failed;
 343         }
 344
 345         goto out;
 346
 347 cra_init_failed:
 348         crypto_exit_ops(tfm);
 349 out_free_tfm:
 350         kfree(tfm);
 351 out_err:
 352         tfm = ERR_PTR(err);
 353 out:
 354         return tfm;
 355 }
 356 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 357
 358 /*
 359  *      crypto_alloc_base - Locate algorithm and allocate transform
 360  *      @alg_name: Name of algorithm
 361  *      @type: Type of algorithm
 362  *      @mask: Mask for type comparison
 363  *
 364  *      crypto_alloc_base() will first attempt to locate an already loaded
 365  *      algorithm.  If that fails and the kernel supports dynamically loadable
 366  *      modules, it will then attempt to load a module of the same name or
 367  *      alias.  If that fails it will send a query to any loaded crypto manager
 368  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 369  *      algorithm which is then associated with the new transform.
 370  *
 371  *      The returned transform is of a non-determinate type.  Most people
 372  *      should use one of the more specific allocation functions such as
 373  *      crypto_alloc_blkcipher.
 374  *
 375  *      In case of error the return value is an error pointer.
 376  */
 377 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 378 {
 379         struct crypto_tfm *tfm;
 380         int err;
 381
 382         for (;;) {
 383                 struct crypto_alg *alg;
 384
 385                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 386                 if (IS_ERR(alg)) {
 387                         err = PTR_ERR(alg);
 388                         goto err;
 389                 }
 390
 391                 tfm = __crypto_alloc_tfm(alg, type, mask);
 392                 if (!IS_ERR(tfm))
 393                         return tfm;
 394
 395                 crypto_mod_put(alg);
 396                 err = PTR_ERR(tfm);
 397
 398 err:
 399                 if (err != -EAGAIN)
 400                         break;
 401                 if (signal_pending(current)) {
 402                         err = -EINTR;
 403                         break;
 404                 }
 405         }
 406
 407         return ERR_PTR(err);
 408 }
 409 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 410
 411 /*
 412  *      crypto_free_tfm - Free crypto transform
 413  *      @tfm: Transform to free
 414  *
 415  *      crypto_free_tfm() frees up the transform and any associated resources,
 416  *      then drops the refcount on the associated algorithm.
 417  */
 418 void crypto_free_tfm(struct crypto_tfm *tfm)
 419 {
 420         struct crypto_alg *alg;
 421         int size;
 422
 423         if (unlikely(!tfm))
 424                 return;
 425
 426         alg = tfm->__crt_alg;
 427         size = sizeof(*tfm) + alg->cra_ctxsize;
 428
 429         if (alg->cra_exit)
 430                 alg->cra_exit(tfm);
 431         crypto_exit_ops(tfm);
 432         crypto_mod_put(alg);
 433         memset(tfm, 0, size);
 434         kfree(tfm);
 435 }
 436
 437 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 438
 439 int crypto_has_alg(const char *name, u32 type, u32 mask)
 440 {
 441         int ret = 0;
 442         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 443
 444         if (!IS_ERR(alg)) {
 445                 crypto_mod_put(alg);
 446                 ret = 1;
 447         }
 448
 449         return ret;
 450 }
 451 EXPORT_SYMBOL_GPL(crypto_has_alg);
 452
 453 MODULE_DESCRIPTION("Cryptographic core API");
 454 MODULE_LICENSE("GPL");