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  *
   7  * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
   8  * and Nettle, by Niels Möller.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  *
  15  */
  16
  17 #include <linux/compiler.h>
  18 #include <linux/init.h>
  19 #include <linux/crypto.h>
  20 #include <linux/errno.h>
  21 #include <linux/kmod.h>
  22 #include <linux/rwsem.h>
  23 #include <linux/slab.h>
  24 #include "internal.h"
  25
  26 LIST_HEAD(crypto_alg_list);
  27 DECLARE_RWSEM(crypto_alg_sem);
  28
  29 static inline int crypto_alg_get(struct crypto_alg *alg)
  30 {
  31         return try_module_get(alg->cra_module);
  32 }
  33
  34 static inline void crypto_alg_put(struct crypto_alg *alg)
  35 {
  36         module_put(alg->cra_module);
  37 }
  38
  39 static struct crypto_alg *crypto_alg_lookup(const char *name)
  40 {
  41         struct crypto_alg *q, *alg = NULL;
  42
  43         if (!name)
  44                 return NULL;
  45
  46         down_read(&crypto_alg_sem);
  47
  48         list_for_each_entry(q, &crypto_alg_list, cra_list) {
  49                 if (!(strcmp(q->cra_name, name))) {
  50                         if (crypto_alg_get(q))
  51                                 alg = q;
  52                         break;
  53                 }
  54         }
  55
  56         up_read(&crypto_alg_sem);
  57         return alg;
  58 }
  59
  60 /* A far more intelligent version of this is planned.  For now, just
  61  * try an exact match on the name of the algorithm. */
  62 static inline struct crypto_alg *crypto_alg_mod_lookup(const char *name)
  63 {
  64         return try_then_request_module(crypto_alg_lookup(name), name);
  65 }
  66
  67 static int crypto_init_flags(struct crypto_tfm *tfm, u32 flags)
  68 {
  69         tfm->crt_flags = flags & CRYPTO_TFM_REQ_MASK;
  70         flags &= ~CRYPTO_TFM_REQ_MASK;
  71
  72         switch (crypto_tfm_alg_type(tfm)) {
  73         case CRYPTO_ALG_TYPE_CIPHER:
  74                 return crypto_init_cipher_flags(tfm, flags);
  75
  76         case CRYPTO_ALG_TYPE_DIGEST:
  77                 return crypto_init_digest_flags(tfm, flags);
  78
  79         case CRYPTO_ALG_TYPE_COMPRESS:
  80                 return crypto_init_compress_flags(tfm, flags);
  81
  82         default:
  83                 break;
  84         }
  85
  86         BUG();
  87         return -EINVAL;
  88 }
  89
  90 static int crypto_init_ops(struct crypto_tfm *tfm)
  91 {
  92         switch (crypto_tfm_alg_type(tfm)) {
  93         case CRYPTO_ALG_TYPE_CIPHER:
  94                 return crypto_init_cipher_ops(tfm);
  95
  96         case CRYPTO_ALG_TYPE_DIGEST:
  97                 return crypto_init_digest_ops(tfm);
  98
  99         case CRYPTO_ALG_TYPE_COMPRESS:
 100                 return crypto_init_compress_ops(tfm);
 101
 102         default:
 103                 break;
 104         }
 105
 106         BUG();
 107         return -EINVAL;
 108 }
 109
 110 static void crypto_exit_ops(struct crypto_tfm *tfm)
 111 {
 112         switch (crypto_tfm_alg_type(tfm)) {
 113         case CRYPTO_ALG_TYPE_CIPHER:
 114                 crypto_exit_cipher_ops(tfm);
 115                 break;
 116
 117         case CRYPTO_ALG_TYPE_DIGEST:
 118                 crypto_exit_digest_ops(tfm);
 119                 break;
 120
 121         case CRYPTO_ALG_TYPE_COMPRESS:
 122                 crypto_exit_compress_ops(tfm);
 123                 break;
 124
 125         default:
 126                 BUG();
 127
 128         }
 129 }
 130
 131 static unsigned int crypto_ctxsize(struct crypto_alg *alg, int flags)
 132 {
 133         unsigned int len;
 134
 135         switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
 136         default:
 137                 BUG();
 138
 139         case CRYPTO_ALG_TYPE_CIPHER:
 140                 len = crypto_cipher_ctxsize(alg, flags);
 141                 break;
 142
 143         case CRYPTO_ALG_TYPE_DIGEST:
 144                 len = crypto_digest_ctxsize(alg, flags);
 145                 break;
 146
 147         case CRYPTO_ALG_TYPE_COMPRESS:
 148                 len = crypto_compress_ctxsize(alg, flags);
 149                 break;
 150         }
 151
 152         return len + alg->cra_alignmask;
 153 }
 154
 155 struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 156 {
 157         struct crypto_tfm *tfm = NULL;
 158         struct crypto_alg *alg;
 159         unsigned int tfm_size;
 160
 161         alg = crypto_alg_mod_lookup(name);
 162         if (alg == NULL)
 163                 goto out;
 164
 165         tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, flags);
 166         tfm = kmalloc(tfm_size, GFP_KERNEL);
 167         if (tfm == NULL)
 168                 goto out_put;
 169
 170         memset(tfm, 0, tfm_size);
 171
 172         tfm->__crt_alg = alg;
 173
 174         if (crypto_init_flags(tfm, flags))
 175                 goto out_free_tfm;
 176
 177         if (crypto_init_ops(tfm)) {
 178                 crypto_exit_ops(tfm);
 179                 goto out_free_tfm;
 180         }
 181
 182         goto out;
 183
 184 out_free_tfm:
 185         kfree(tfm);
 186         tfm = NULL;
 187 out_put:
 188         crypto_alg_put(alg);
 189 out:
 190         return tfm;
 191 }
 192
 193 void crypto_free_tfm(struct crypto_tfm *tfm)
 194 {
 195         struct crypto_alg *alg;
 196         int size;
 197
 198         if (unlikely(!tfm))
 199                 return;
 200
 201         alg = tfm->__crt_alg;
 202         size = sizeof(*tfm) + alg->cra_ctxsize;
 203
 204         crypto_exit_ops(tfm);
 205         crypto_alg_put(alg);
 206         memset(tfm, 0, size);
 207         kfree(tfm);
 208 }
 209
 210 int crypto_register_alg(struct crypto_alg *alg)
 211 {
 212         int ret = 0;
 213         struct crypto_alg *q;
 214
 215         if (alg->cra_alignmask & (alg->cra_alignmask + 1))
 216                 return -EINVAL;
 217
 218         if (alg->cra_alignmask & alg->cra_blocksize)
 219                 return -EINVAL;
 220
 221         if (alg->cra_blocksize > PAGE_SIZE)
 222                 return -EINVAL;
 223
 224         down_write(&crypto_alg_sem);
 225
 226         list_for_each_entry(q, &crypto_alg_list, cra_list) {
 227                 if (!(strcmp(q->cra_name, alg->cra_name))) {
 228                         ret = -EEXIST;
 229                         goto out;
 230                 }
 231         }
 232
 233         list_add_tail(&alg->cra_list, &crypto_alg_list);
 234 out:
 235         up_write(&crypto_alg_sem);
 236         return ret;
 237 }
 238
 239 int crypto_unregister_alg(struct crypto_alg *alg)
 240 {
 241         int ret = -ENOENT;
 242         struct crypto_alg *q;
 243
 244         BUG_ON(!alg->cra_module);
 245
 246         down_write(&crypto_alg_sem);
 247         list_for_each_entry(q, &crypto_alg_list, cra_list) {
 248                 if (alg == q) {
 249                         list_del(&alg->cra_list);
 250                         ret = 0;
 251                         goto out;
 252                 }
 253         }
 254 out:
 255         up_write(&crypto_alg_sem);
 256         return ret;
 257 }
 258
 259 int crypto_alg_available(const char *name, u32 flags)
 260 {
 261         int ret = 0;
 262         struct crypto_alg *alg = crypto_alg_mod_lookup(name);
 263
 264         if (alg) {
 265                 crypto_alg_put(alg);
 266                 ret = 1;
 267         }
 268
 269         return ret;
 270 }
 271
 272 static int __init init_crypto(void)
 273 {
 274         printk(KERN_INFO "Initializing Cryptographic API\n");
 275         crypto_init_proc();
 276         return 0;
 277 }
 278
 279 __initcall(init_crypto);
 280
 281 EXPORT_SYMBOL_GPL(crypto_register_alg);
 282 EXPORT_SYMBOL_GPL(crypto_unregister_alg);
 283 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 284 EXPORT_SYMBOL_GPL(crypto_free_tfm);
 285 EXPORT_SYMBOL_GPL(crypto_alg_available);