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                 return crypto_init_digest_ops(tfm);
 239
 240         case CRYPTO_ALG_TYPE_COMPRESS:
 241                 return crypto_init_compress_ops(tfm);
 242
 243         default:
 244                 break;
 245         }
 246
 247         BUG();
 248         return -EINVAL;
 249 }
 250
 251 static void crypto_exit_ops(struct crypto_tfm *tfm)
 252 {
 253         const struct crypto_type *type = tfm->__crt_alg->cra_type;
 254
 255         if (type) {
 256                 if (type->exit)
 257                         type->exit(tfm);
 258                 return;
 259         }
 260
 261         switch (crypto_tfm_alg_type(tfm)) {
 262         case CRYPTO_ALG_TYPE_CIPHER:
 263                 crypto_exit_cipher_ops(tfm);
 264                 break;
 265
 266         case CRYPTO_ALG_TYPE_DIGEST:
 267                 crypto_exit_digest_ops(tfm);
 268                 break;
 269
 270         case CRYPTO_ALG_TYPE_COMPRESS:
 271                 crypto_exit_compress_ops(tfm);
 272                 break;
 273
 274         default:
 275                 BUG();
 276
 277         }
 278 }
 279
 280 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
 281 {
 282         const struct crypto_type *type_obj = alg->cra_type;
 283         unsigned int len;
 284
 285         len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 286         if (type_obj)
 287                 return len + type_obj->ctxsize(alg, type, mask);
 288
 289         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 290         default:
 291                 BUG();
 292
 293         case CRYPTO_ALG_TYPE_CIPHER:
 294                 len += crypto_cipher_ctxsize(alg);
 295                 break;
 296
 297         case CRYPTO_ALG_TYPE_DIGEST:
 298                 len += crypto_digest_ctxsize(alg);
 299                 break;
 300
 301         case CRYPTO_ALG_TYPE_COMPRESS:
 302                 len += crypto_compress_ctxsize(alg);
 303                 break;
 304         }
 305
 306         return len;
 307 }
 308
 309 void crypto_shoot_alg(struct crypto_alg *alg)
 310 {
 311         down_write(&crypto_alg_sem);
 312         alg->cra_flags |= CRYPTO_ALG_DYING;
 313         up_write(&crypto_alg_sem);
 314 }
 315 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
 316
 317 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 318                                       u32 mask)
 319 {
 320         struct crypto_tfm *tfm = NULL;
 321         unsigned int tfm_size;
 322         int err = -ENOMEM;
 323
 324         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
 325         tfm = kzalloc(tfm_size, GFP_KERNEL);
 326         if (tfm == NULL)
 327                 goto out_err;
 328
 329         tfm->__crt_alg = alg;
 330
 331         err = crypto_init_ops(tfm, type, mask);
 332         if (err)
 333                 goto out_free_tfm;
 334
 335         if (alg->cra_init && (err = alg->cra_init(tfm))) {
 336                 if (err == -EAGAIN)
 337                         crypto_shoot_alg(alg);
 338                 goto cra_init_failed;
 339         }
 340
 341         goto out;
 342
 343 cra_init_failed:
 344         crypto_exit_ops(tfm);
 345 out_free_tfm:
 346         kfree(tfm);
 347 out_err:
 348         tfm = ERR_PTR(err);
 349 out:
 350         return tfm;
 351 }
 352 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
 353
 354 /*
 355  *      crypto_alloc_base - Locate algorithm and allocate transform
 356  *      @alg_name: Name of algorithm
 357  *      @type: Type of algorithm
 358  *      @mask: Mask for type comparison
 359  *
 360  *      crypto_alloc_base() will first attempt to locate an already loaded
 361  *      algorithm.  If that fails and the kernel supports dynamically loadable
 362  *      modules, it will then attempt to load a module of the same name or
 363  *      alias.  If that fails it will send a query to any loaded crypto manager
 364  *      to construct an algorithm on the fly.  A refcount is grabbed on the
 365  *      algorithm which is then associated with the new transform.
 366  *
 367  *      The returned transform is of a non-determinate type.  Most people
 368  *      should use one of the more specific allocation functions such as
 369  *      crypto_alloc_blkcipher.
 370  *
 371  *      In case of error the return value is an error pointer.
 372  */
 373 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
 374 {
 375         struct crypto_tfm *tfm;
 376         int err;
 377
 378         for (;;) {
 379                 struct crypto_alg *alg;
 380
 381                 alg = crypto_alg_mod_lookup(alg_name, type, mask);
 382                 if (IS_ERR(alg)) {
 383                         err = PTR_ERR(alg);
 384                         goto err;
 385                 }
 386
 387                 tfm = __crypto_alloc_tfm(alg, type, mask);
 388                 if (!IS_ERR(tfm))
 389                         return tfm;
 390
 391                 crypto_mod_put(alg);
 392                 err = PTR_ERR(tfm);
 393
 394 err:
 395                 if (err != -EAGAIN)
 396                         break;
 397                 if (signal_pending(current)) {
 398                         err = -EINTR;
 399                         break;
 400                 }
 401         }
 402
 403         return ERR_PTR(err);
 404 }
 405 EXPORT_SYMBOL_GPL(crypto_alloc_base);
 406
 407 /*
 408  *      crypto_free_tfm - Free crypto transform
 409  *      @tfm: Transform to free
 410  *
 411  *      crypto_free_tfm() frees up the transform and any associated resources,
 412  *      then drops the refcount on the associated algorithm.
 413  */
 414 void crypto_free_tfm(struct crypto_tfm *tfm)
 415 {
 416         struct crypto_alg *alg;
 417         int size;
 418
 419         if (unlikely(!tfm))
 420                 return;
 421
 422         alg = tfm->__crt_alg;
 423         size = sizeof(*tfm) + alg->cra_ctxsize;
 424
 425         if (alg->cra_exit)
 426                 alg->cra_exit(tfm);
 427         crypto_exit_ops(tfm);
 428         crypto_mod_put(alg);
 429         memset(tfm, 0, size);
 430         kfree(tfm);
 431 }
 432
 433 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 434
 435 int crypto_has_alg(const char *name, u32 type, u32 mask)
 436 {
 437         int ret = 0;
 438         struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
 439
 440         if (!IS_ERR(alg)) {
 441                 crypto_mod_put(alg);
 442                 ret = 1;
 443         }
 444
 445         return ret;
 446 }
 447 EXPORT_SYMBOL_GPL(crypto_has_alg);