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 static 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
 151 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 152 {
 153         struct crypto_larval *larval = (void *)alg;
 154
 155         wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
 156         alg = larval->adult;
 157         if (alg) {
 158                 if (!crypto_mod_get(alg))
 159                         alg = ERR_PTR(-EAGAIN);
 160         } else
 161                 alg = ERR_PTR(-ENOENT);
 162         crypto_mod_put(&larval->alg);
 163
 164         return alg;
 165 }
 166
 167 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 168                                             u32 mask)
 169 {
 170         struct crypto_alg *alg;
 171
 172         down_read(&crypto_alg_sem);
 173         alg = __crypto_alg_lookup(name, type, mask);
 174         up_read(&crypto_alg_sem);
 175
 176         return alg;
 177 }
 178
 179 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 180 {
 181         struct crypto_alg *alg;
 182         struct crypto_alg *larval;
 183         int ok;
 184
 185         if (!name)
 186                 return ERR_PTR(-ENOENT);
 187
 188         mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 189         type &= mask;
 190
 191         alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
 192                                       name);
 193         if (alg)
 194                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 195
 196         larval = crypto_larval_alloc(name, type, mask);
 197         if (IS_ERR(larval) || !crypto_is_larval(larval))
 198                 return larval;
 199
 200         ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 201         if (ok == NOTIFY_DONE) {
 202                 request_module("cryptomgr");
 203                 ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
 204         }
 205
 206         if (ok == NOTIFY_STOP)
 207                 alg = crypto_larval_wait(larval);
 208         else {
 209                 crypto_mod_put(larval);
 210                 alg = ERR_PTR(-ENOENT);
 211         }
 212         crypto_larval_kill(larval);
 213         return alg;
 214 }
 215 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
 216
 217 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 218 {
 219         const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
 220
 221         if (type_obj)
 222                 return type_obj->init(tfm, type, mask);
 223
 224         switch (crypto_tfm_alg_type(tfm)) {
 225         case CRYPTO_ALG_TYPE_CIPHER:
 226                 return crypto_init_cipher_ops(tfm);
 227
 228         case CRYPTO_ALG_TYPE_DIGEST:
 229                 return crypto_init_digest_ops(tfm);
 230
 231         case CRYPTO_ALG_TYPE_COMPRESS:
 232                 return crypto_init_compress_ops(tfm);
 233
 234         default:
 235                 break;
 236         }
 237
 238         BUG();
 239         return -EINVAL;
 240 }
 241
 242 static void crypto_exit_ops(struct crypto_tfm *tfm)
 243 {
 244         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 245
 246         if (type) {
 247                 if (type->exit)
 248                         type->exit(tfm);
 249                 return;
 250         }
 251
 252         switch (crypto_tfm_alg_type(tfm)) {
 253         case CRYPTO_ALG_TYPE_CIPHER:
 254                 crypto_exit_cipher_ops(tfm);
 255                 break;
 256
 257         case CRYPTO_ALG_TYPE_DIGEST:
 258                 crypto_exit_digest_ops(tfm);
 259                 break;
 260
 261         case CRYPTO_ALG_TYPE_COMPRESS:
 262                 crypto_exit_compress_ops(tfm);
 263                 break;
 264
 265         default:
 266                 BUG();
 267
 268         }
 269 }
 270
 271 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 272 {
 273         const struct crypto_type *type_obj = alg->cra_type;
 274         unsigned int len;
 275
 276         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 277         if (type_obj)
 278                 return len + type_obj->ctxsize(alg, type, mask);
 279
 280         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 281         default:
 282                 BUG();
 283
 284         case CRYPTO_ALG_TYPE_CIPHER:
 285                 len += crypto_cipher_ctxsize(alg);
 286                 break;
 287
 288         case CRYPTO_ALG_TYPE_DIGEST:
 289                 len += crypto_digest_ctxsize(alg);
 290                 break;
 291
 292         case CRYPTO_ALG_TYPE_COMPRESS:
 293                 len += crypto_compress_ctxsize(alg);
 294                 break;
 295         }
 296
 297         return len;
 298 }
 299
 300 void crypto_shoot_alg(struct crypto_alg *alg)
 301 {
 302         down_write(&crypto_alg_sem);
 303         alg->cra_flags |= CRYPTO_ALG_DYING;
 304         up_write(&crypto_alg_sem);
 305 }
 306 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 307
 308 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 309                                       u32 mask)
 310 {
 311         struct crypto_tfm *tfm = NULL;
 312         unsigned int tfm_size;
 313         int err = -ENOMEM;
 314
 315         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 316         tfm = kzalloc(tfm_size, GFP_KERNEL);
 317         if (tfm == NULL)
 318                 goto out_err;
 319
 320         tfm->__crt_alg = alg;
 321
 322         err = crypto_init_ops(tfm, type, mask);
 323         if (err)
 324                 goto out_free_tfm;
 325
 326         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 327                 if (err == -EAGAIN)
 328                         crypto_shoot_alg(alg);
 329                 goto cra_init_failed;
 330         }
 331
 332         goto out;
 333
 334 cra_init_failed:
 335         crypto_exit_ops(tfm);
 336 out_free_tfm:
 337         kfree(tfm);
 338 out_err:
 339         tfm = ERR_PTR(err);
 340 out:
 341         return tfm;
 342 }
 343 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 344
 345 /*
 346  *      crypto_alloc_base - Locate algorithm and allocate transform
 347  *      @alg_name: Name of algorithm
 348  *      @type: Type of algorithm
 349  *      @mask: Mask for type comparison
 350  *
 351  *      crypto_alloc_base() will first attempt to locate an already loaded
 352  *      algorithm.  If that fails and the kernel supports dynamically loadable
 353  *      modules, it will then attempt to load a module of the same name or
 354  *      alias.  If that fails it will send a query to any loaded crypto manager
 355  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 356  *      algorithm which is then associated with the new transform.
 357  *
 358  *      The returned transform is of a non-determinate type.  Most people
 359  *      should use one of the more specific allocation functions such as
 360  *      crypto_alloc_blkcipher.
 361  *
 362  *      In case of error the return value is an error pointer.
 363  */
 364 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 365 {
 366         struct crypto_tfm *tfm;
 367         int err;
 368
 369         for (;;) {
 370                 struct crypto_alg *alg;
 371
 372                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 373                 if (IS_ERR(alg)) {
 374                         err = PTR_ERR(alg);
 375                         goto err;
 376                 }
 377
 378                 tfm = __crypto_alloc_tfm(alg, type, mask);
 379                 if (!IS_ERR(tfm))
 380                         return tfm;
 381
 382                 crypto_mod_put(alg);
 383                 err = PTR_ERR(tfm);
 384
 385 err:
 386                 if (err != -EAGAIN)
 387                         break;
 388                 if (signal_pending(current)) {
 389                         err = -EINTR;
 390                         break;
 391                 }
 392         }
 393
 394         return ERR_PTR(err);
 395 }
 396 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 397
 398 /*
 399  *      crypto_free_tfm - Free crypto transform
 400  *      @tfm: Transform to free
 401  *
 402  *      crypto_free_tfm() frees up the transform and any associated resources,
 403  *      then drops the refcount on the associated algorithm.
 404  */
 405 void crypto_free_tfm(struct crypto_tfm *tfm)
 406 {
 407         struct crypto_alg *alg;
 408         int size;
 409
 410         if (unlikely(!tfm))
 411                 return;
 412
 413         alg = tfm->__crt_alg;
 414         size = sizeof(*tfm) + alg->cra_ctxsize;
 415
 416         if (alg->cra_exit)
 417                 alg->cra_exit(tfm);
 418         crypto_exit_ops(tfm);
 419         crypto_mod_put(alg);
 420         memset(tfm, 0, size);
 421         kfree(tfm);
 422 }
 423
 424 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 425
 426 int crypto_has_alg(const char *name, u32 type, u32 mask)
 427 {
 428         int ret = 0;
 429         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 430
 431         if (!IS_ERR(alg)) {
 432                 crypto_mod_put(alg);
 433                 ret = 1;
 434         }
 435
 436         return ret;
 437 }
 438 EXPORT_SYMBOL_GPL(crypto_has_alg);