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/errno.h>
  19 #include <linux/kernel.h>
  20 #include <linux/kmod.h>
  21 #include <linux/param.h>
  22 #include <linux/slab.h>
  23 #include <linux/string.h>
  24 #include "internal.h"
  25
  26 LIST_HEAD(crypto_alg_list);
  27 EXPORT_SYMBOL_GPL(crypto_alg_list);
  28 DECLARE_RWSEM(crypto_alg_sem);
  29 EXPORT_SYMBOL_GPL(crypto_alg_sem);
  30
  31 BLOCKING_NOTIFIER_HEAD(crypto_chain);
  32 EXPORT_SYMBOL_GPL(crypto_chain);
  33
  34 static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
  35 {
  36         atomic_inc(&alg->cra_refcnt);
  37         return alg;
  38 }
  39
  40 static inline void crypto_alg_put(struct crypto_alg *alg)
  41 {
  42         if (atomic_dec_and_test(&alg->cra_refcnt) && alg->cra_destroy)
  43                 alg->cra_destroy(alg);
  44 }
  45
  46 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
  47 {
  48         return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
  49 }
  50 EXPORT_SYMBOL_GPL(crypto_mod_get);
  51
  52 void crypto_mod_put(struct crypto_alg *alg)
  53 {
  54         crypto_alg_put(alg);
  55         module_put(alg->cra_module);
  56 }
  57 EXPORT_SYMBOL_GPL(crypto_mod_put);
  58
  59 struct crypto_alg *__crypto_alg_lookup(const char *name)
  60 {
  61         struct crypto_alg *q, *alg = NULL;
  62         int best = -2;
  63
  64         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  65                 int exact, fuzzy;
  66
  67                 exact = !strcmp(q->cra_driver_name, name);
  68                 fuzzy = !strcmp(q->cra_name, name);
  69                 if (!exact && !(fuzzy && q->cra_priority > best))
  70                         continue;
  71
  72                 if (unlikely(!crypto_mod_get(q)))
  73                         continue;
  74
  75                 best = q->cra_priority;
  76                 if (alg)
  77                         crypto_mod_put(alg);
  78                 alg = q;
  79
  80                 if (exact)
  81                         break;
  82         }
  83
  84         return alg;
  85 }
  86 EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
  87
  88 static void crypto_larval_destroy(struct crypto_alg *alg)
  89 {
  90         struct crypto_larval *larval = (void *)alg;
  91
  92         BUG_ON(!crypto_is_larval(alg));
  93         if (larval->adult)
  94                 crypto_mod_put(larval->adult);
  95         kfree(larval);
  96 }
  97
  98 static struct crypto_alg *crypto_larval_alloc(const char *name)
  99 {
 100         struct crypto_alg *alg;
 101         struct crypto_larval *larval;
 102
 103         larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 104         if (!larval)
 105                 return NULL;
 106
 107         larval->alg.cra_flags = CRYPTO_ALG_LARVAL;
 108         larval->alg.cra_priority = -1;
 109         larval->alg.cra_destroy = crypto_larval_destroy;
 110
 111         atomic_set(&larval->alg.cra_refcnt, 2);
 112         strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
 113         init_completion(&larval->completion);
 114
 115         down_write(&crypto_alg_sem);
 116         alg = __crypto_alg_lookup(name);
 117         if (!alg) {
 118                 alg = &larval->alg;
 119                 list_add(&alg->cra_list, &crypto_alg_list);
 120         }
 121         up_write(&crypto_alg_sem);
 122
 123         if (alg != &larval->alg)
 124                 kfree(larval);
 125
 126         return alg;
 127 }
 128
 129 static void crypto_larval_kill(struct crypto_alg *alg)
 130 {
 131         struct crypto_larval *larval = (void *)alg;
 132
 133         down_write(&crypto_alg_sem);
 134         list_del(&alg->cra_list);
 135         up_write(&crypto_alg_sem);
 136         complete(&larval->completion);
 137         crypto_alg_put(alg);
 138 }
 139
 140 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 141 {
 142         struct crypto_larval *larval = (void *)alg;
 143
 144         wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
 145         alg = larval->adult;
 146         if (alg && !crypto_mod_get(alg))
 147                 alg = NULL;
 148         crypto_mod_put(&larval->alg);
 149
 150         return alg;
 151 }
 152
 153 static struct crypto_alg *crypto_alg_lookup(const char *name)
 154 {
 155         struct crypto_alg *alg;
 156
 157         if (!name)
 158                 return NULL;
 159
 160         down_read(&crypto_alg_sem);
 161         alg = __crypto_alg_lookup(name);
 162         up_read(&crypto_alg_sem);
 163
 164         return alg;
 165 }
 166
 167 /* A far more intelligent version of this is planned.  For now, just
 168  * try an exact match on the name of the algorithm. */
 169 static struct crypto_alg *crypto_alg_mod_lookup(const char *name)
 170 {
 171         struct crypto_alg *alg;
 172         struct crypto_alg *larval;
 173
 174         alg = try_then_request_module(crypto_alg_lookup(name), name);
 175         if (alg)
 176                 return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 177
 178         larval = crypto_larval_alloc(name);
 179         if (!larval || !crypto_is_larval(larval))
 180                 return larval;
 181
 182         if (crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval) == NOTIFY_STOP)
 183                 alg = crypto_larval_wait(larval);
 184         else {
 185                 crypto_mod_put(larval);
 186                 alg = NULL;
 187         }
 188         crypto_larval_kill(larval);
 189         return alg;
 190 }
 191
 192 static int crypto_init_flags(struct crypto_tfm *tfm, u32 flags)
 193 {
 194         tfm->crt_flags = flags & CRYPTO_TFM_REQ_MASK;
 195         flags &= ~CRYPTO_TFM_REQ_MASK;
 196
 197         switch (crypto_tfm_alg_type(tfm)) {
 198         case CRYPTO_ALG_TYPE_CIPHER:
 199                 return crypto_init_cipher_flags(tfm, flags);
 200
 201         case CRYPTO_ALG_TYPE_DIGEST:
 202                 return crypto_init_digest_flags(tfm, flags);
 203
 204         case CRYPTO_ALG_TYPE_COMPRESS:
 205                 return crypto_init_compress_flags(tfm, flags);
 206
 207         default:
 208                 break;
 209         }
 210
 211         BUG();
 212         return -EINVAL;
 213 }
 214
 215 static int crypto_init_ops(struct crypto_tfm *tfm)
 216 {
 217         switch (crypto_tfm_alg_type(tfm)) {
 218         case CRYPTO_ALG_TYPE_CIPHER:
 219                 return crypto_init_cipher_ops(tfm);
 220
 221         case CRYPTO_ALG_TYPE_DIGEST:
 222                 return crypto_init_digest_ops(tfm);
 223
 224         case CRYPTO_ALG_TYPE_COMPRESS:
 225                 return crypto_init_compress_ops(tfm);
 226
 227         default:
 228                 break;
 229         }
 230
 231         BUG();
 232         return -EINVAL;
 233 }
 234
 235 static void crypto_exit_ops(struct crypto_tfm *tfm)
 236 {
 237         switch (crypto_tfm_alg_type(tfm)) {
 238         case CRYPTO_ALG_TYPE_CIPHER:
 239                 crypto_exit_cipher_ops(tfm);
 240                 break;
 241
 242         case CRYPTO_ALG_TYPE_DIGEST:
 243                 crypto_exit_digest_ops(tfm);
 244                 break;
 245
 246         case CRYPTO_ALG_TYPE_COMPRESS:
 247                 crypto_exit_compress_ops(tfm);
 248                 break;
 249
 250         default:
 251                 BUG();
 252
 253         }
 254 }
 255
 256 static unsigned int crypto_ctxsize(struct crypto_alg *alg, int flags)
 257 {
 258         unsigned int len;
 259
 260         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 261         default:
 262                 BUG();
 263
 264         case CRYPTO_ALG_TYPE_CIPHER:
 265                 len = crypto_cipher_ctxsize(alg, flags);
 266                 break;
 267
 268         case CRYPTO_ALG_TYPE_DIGEST:
 269                 len = crypto_digest_ctxsize(alg, flags);
 270                 break;
 271
 272         case CRYPTO_ALG_TYPE_COMPRESS:
 273                 len = crypto_compress_ctxsize(alg, flags);
 274                 break;
 275         }
 276
 277         return len + (alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 278 }
 279
 280 struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 281 {
 282         struct crypto_tfm *tfm = NULL;
 283         struct crypto_alg *alg;
 284         unsigned int tfm_size;
 285
 286         alg = crypto_alg_mod_lookup(name);
 287         if (alg == NULL)
 288                 goto out;
 289
 290         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, flags);
 291         tfm = kzalloc(tfm_size, GFP_KERNEL);
 292         if (tfm == NULL)
 293                 goto out_put;
 294
 295         tfm->__crt_alg = alg;
 296
 297         if (crypto_init_flags(tfm, flags))
 298                 goto out_free_tfm;
 299
 300         if (crypto_init_ops(tfm))
 301                 goto out_free_tfm;
 302
 303         if (alg->cra_init && alg->cra_init(tfm))
 304                 goto cra_init_failed;
 305
 306         goto out;
 307
 308 cra_init_failed:
 309         crypto_exit_ops(tfm);
 310 out_free_tfm:
 311         kfree(tfm);
 312         tfm = NULL;
 313 out_put:
 314         crypto_mod_put(alg);
 315 out:
 316         return tfm;
 317 }
 318
 319 void crypto_free_tfm(struct crypto_tfm *tfm)
 320 {
 321         struct crypto_alg *alg;
 322         int size;
 323
 324         if (unlikely(!tfm))
 325                 return;
 326
 327         alg = tfm->__crt_alg;
 328         size = sizeof(*tfm) + alg->cra_ctxsize;
 329
 330         if (alg->cra_exit)
 331                 alg->cra_exit(tfm);
 332         crypto_exit_ops(tfm);
 333         crypto_mod_put(alg);
 334         memset(tfm, 0, size);
 335         kfree(tfm);
 336 }
 337
 338 int crypto_alg_available(const char *name, u32 flags)
 339 {
 340         int ret = 0;
 341         struct crypto_alg *alg = crypto_alg_mod_lookup(name);
 342
 343         if (alg) {
 344                 crypto_mod_put(alg);
 345                 ret = 1;
 346         }
 347
 348         return ret;
 349 }
 350
 351 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 352 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 353 EXPORT_SYMBOL_GPL(crypto_alg_available);