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/compiler.h>
  19 #include <linux/init.h>
  20 #include <linux/crypto.h>
  21 #include <linux/errno.h>
  22 #include <linux/kernel.h>
  23 #include <linux/kmod.h>
  24 #include <linux/rwsem.h>
  25 #include <linux/slab.h>
  26 #include <linux/string.h>
  27 #include "internal.h"
  28
  29 LIST_HEAD(crypto_alg_list);
  30 DECLARE_RWSEM(crypto_alg_sem);
  31
  32 static inline int crypto_alg_get(struct crypto_alg *alg)
  33 {
  34         return try_module_get(alg->cra_module);
  35 }
  36
  37 static inline void crypto_alg_put(struct crypto_alg *alg)
  38 {
  39         module_put(alg->cra_module);
  40 }
  41
  42 static struct crypto_alg *crypto_alg_lookup(const char *name)
  43 {
  44         struct crypto_alg *q, *alg = NULL;
  45         int best = -1;
  46
  47         if (!name)
  48                 return NULL;
  49
  50         down_read(&crypto_alg_sem);
  51
  52         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  53                 int exact, fuzzy;
  54
  55                 exact = !strcmp(q->cra_driver_name, name);
  56                 fuzzy = !strcmp(q->cra_name, name);
  57                 if (!exact && !(fuzzy && q->cra_priority > best))
  58                         continue;
  59
  60                 if (unlikely(!crypto_alg_get(q)))
  61                         continue;
  62
  63                 best = q->cra_priority;
  64                 if (alg)
  65                         crypto_alg_put(alg);
  66                 alg = q;
  67
  68                 if (exact)
  69                         break;
  70         }
  71
  72         up_read(&crypto_alg_sem);
  73         return alg;
  74 }
  75
  76 /* A far more intelligent version of this is planned.  For now, just
  77  * try an exact match on the name of the algorithm. */
  78 static inline struct crypto_alg *crypto_alg_mod_lookup(const char *name)
  79 {
  80         return try_then_request_module(crypto_alg_lookup(name), name);
  81 }
  82
  83 static int crypto_init_flags(struct crypto_tfm *tfm, u32 flags)
  84 {
  85         tfm->crt_flags = flags & CRYPTO_TFM_REQ_MASK;
  86         flags &= ~CRYPTO_TFM_REQ_MASK;
  87
  88         switch (crypto_tfm_alg_type(tfm)) {
  89         case CRYPTO_ALG_TYPE_CIPHER:
  90                 return crypto_init_cipher_flags(tfm, flags);
  91
  92         case CRYPTO_ALG_TYPE_DIGEST:
  93                 return crypto_init_digest_flags(tfm, flags);
  94
  95         case CRYPTO_ALG_TYPE_COMPRESS:
  96                 return crypto_init_compress_flags(tfm, flags);
  97
  98         default:
  99                 break;
 100         }
 101
 102         BUG();
 103         return -EINVAL;
 104 }
 105
 106 static int crypto_init_ops(struct crypto_tfm *tfm)
 107 {
 108         switch (crypto_tfm_alg_type(tfm)) {
 109         case CRYPTO_ALG_TYPE_CIPHER:
 110                 return crypto_init_cipher_ops(tfm);
 111
 112         case CRYPTO_ALG_TYPE_DIGEST:
 113                 return crypto_init_digest_ops(tfm);
 114
 115         case CRYPTO_ALG_TYPE_COMPRESS:
 116                 return crypto_init_compress_ops(tfm);
 117
 118         default:
 119                 break;
 120         }
 121
 122         BUG();
 123         return -EINVAL;
 124 }
 125
 126 static void crypto_exit_ops(struct crypto_tfm *tfm)
 127 {
 128         switch (crypto_tfm_alg_type(tfm)) {
 129         case CRYPTO_ALG_TYPE_CIPHER:
 130                 crypto_exit_cipher_ops(tfm);
 131                 break;
 132
 133         case CRYPTO_ALG_TYPE_DIGEST:
 134                 crypto_exit_digest_ops(tfm);
 135                 break;
 136
 137         case CRYPTO_ALG_TYPE_COMPRESS:
 138                 crypto_exit_compress_ops(tfm);
 139                 break;
 140
 141         default:
 142                 BUG();
 143
 144         }
 145 }
 146
 147 static unsigned int crypto_ctxsize(struct crypto_alg *alg, int flags)
 148 {
 149         unsigned int len;
 150
 151         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 152         default:
 153                 BUG();
 154
 155         case CRYPTO_ALG_TYPE_CIPHER:
 156                 len = crypto_cipher_ctxsize(alg, flags);
 157                 break;
 158
 159         case CRYPTO_ALG_TYPE_DIGEST:
 160                 len = crypto_digest_ctxsize(alg, flags);
 161                 break;
 162
 163         case CRYPTO_ALG_TYPE_COMPRESS:
 164                 len = crypto_compress_ctxsize(alg, flags);
 165                 break;
 166         }
 167
 168         return len + (alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 169 }
 170
 171 struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 172 {
 173         struct crypto_tfm *tfm = NULL;
 174         struct crypto_alg *alg;
 175         unsigned int tfm_size;
 176
 177         alg = crypto_alg_mod_lookup(name);
 178         if (alg == NULL)
 179                 goto out;
 180
 181         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, flags);
 182         tfm = kzalloc(tfm_size, GFP_KERNEL);
 183         if (tfm == NULL)
 184                 goto out_put;
 185
 186         tfm->__crt_alg = alg;
 187
 188         if (crypto_init_flags(tfm, flags))
 189                 goto out_free_tfm;
 190
 191         if (crypto_init_ops(tfm))
 192                 goto out_free_tfm;
 193
 194         if (alg->cra_init && alg->cra_init(tfm))
 195                 goto cra_init_failed;
 196
 197         goto out;
 198
 199 cra_init_failed:
 200         crypto_exit_ops(tfm);
 201 out_free_tfm:
 202         kfree(tfm);
 203         tfm = NULL;
 204 out_put:
 205         crypto_alg_put(alg);
 206 out:
 207         return tfm;
 208 }
 209
 210 void crypto_free_tfm(struct crypto_tfm *tfm)
 211 {
 212         struct crypto_alg *alg;
 213         int size;
 214
 215         if (unlikely(!tfm))
 216                 return;
 217
 218         alg = tfm->__crt_alg;
 219         size = sizeof(*tfm) + alg->cra_ctxsize;
 220
 221         if (alg->cra_exit)
 222                 alg->cra_exit(tfm);
 223         crypto_exit_ops(tfm);
 224         crypto_alg_put(alg);
 225         memset(tfm, 0, size);
 226         kfree(tfm);
 227 }
 228
 229 static inline int crypto_set_driver_name(struct crypto_alg *alg)
 230 {
 231         static const char suffix[] = "-generic";
 232         char *driver_name = alg->cra_driver_name;
 233         int len;
 234
 235         if (*driver_name)
 236                 return 0;
 237
 238         len = strlcpy(driver_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);
 239         if (len + sizeof(suffix) > CRYPTO_MAX_ALG_NAME)
 240                 return -ENAMETOOLONG;
 241
 242         memcpy(driver_name + len, suffix, sizeof(suffix));
 243         return 0;
 244 }
 245
 246 int crypto_register_alg(struct crypto_alg *alg)
 247 {
 248         int ret;
 249         struct crypto_alg *q;
 250
 251         if (alg->cra_alignmask & (alg->cra_alignmask + 1))
 252                 return -EINVAL;
 253
 254         if (alg->cra_alignmask & alg->cra_blocksize)
 255                 return -EINVAL;
 256
 257         if (alg->cra_blocksize > PAGE_SIZE / 8)
 258                 return -EINVAL;
 259
 260         if (alg->cra_priority < 0)
 261                 return -EINVAL;
 262
 263         ret = crypto_set_driver_name(alg);
 264         if (unlikely(ret))
 265                 return ret;
 266
 267         down_write(&crypto_alg_sem);
 268
 269         list_for_each_entry(q, &crypto_alg_list, cra_list) {
 270                 if (q == alg) {
 271                         ret = -EEXIST;
 272                         goto out;
 273                 }
 274         }
 275
 276         list_add(&alg->cra_list, &crypto_alg_list);
 277 out:
 278         up_write(&crypto_alg_sem);
 279         return ret;
 280 }
 281
 282 int crypto_unregister_alg(struct crypto_alg *alg)
 283 {
 284         int ret = -ENOENT;
 285         struct crypto_alg *q;
 286
 287         BUG_ON(!alg->cra_module);
 288
 289         down_write(&crypto_alg_sem);
 290         list_for_each_entry(q, &crypto_alg_list, cra_list) {
 291                 if (alg == q) {
 292                         list_del(&alg->cra_list);
 293                         ret = 0;
 294                         goto out;
 295                 }
 296         }
 297 out:
 298         up_write(&crypto_alg_sem);
 299         return ret;
 300 }
 301
 302 int crypto_alg_available(const char *name, u32 flags)
 303 {
 304         int ret = 0;
 305         struct crypto_alg *alg = crypto_alg_mod_lookup(name);
 306
 307         if (alg) {
 308                 crypto_alg_put(alg);
 309                 ret = 1;
 310         }
 311
 312         return ret;
 313 }
 314
 315 static int __init init_crypto(void)
 316 {
 317         printk(KERN_INFO "Initializing Cryptographic API\n");
 318         crypto_init_proc();
 319         return 0;
 320 }
 321
 322 __initcall(init_crypto);
 323
 324 EXPORT_SYMBOL_GPL(crypto_register_alg);
 325 EXPORT_SYMBOL_GPL(crypto_unregister_alg);
 326 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 327 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 328 EXPORT_SYMBOL_GPL(crypto_alg_available);