crypto/crypto_null.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Null algorithms, aka Much Ado About Nothing.
   5  *
   6  * These are needed for IPsec, and may be useful in general for
   7  * testing & debugging.
   8  *
   9  * The null cipher is compliant with RFC2410.
  10  *
  11  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  */
  19
  20 #include <crypto/null.h>
  21 #include <crypto/internal/hash.h>
  22 #include <crypto/internal/skcipher.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/mm.h>
  26 #include <linux/string.h>
  27
  28 static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
  29 static struct crypto_sync_skcipher *crypto_default_null_skcipher;
  30 static int crypto_default_null_skcipher_refcnt;
  31
  32 static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  33                          unsigned int slen, u8 *dst, unsigned int *dlen)
  34 {
  35         if (slen > *dlen)
  36                 return -EINVAL;
  37         memcpy(dst, src, slen);
  38         *dlen = slen;
  39         return 0;
  40 }
  41
  42 static int null_init(struct shash_desc *desc)
  43 {
  44         return 0;
  45 }
  46
  47 static int null_update(struct shash_desc *desc, const u8 *data,
  48                        unsigned int len)
  49 {
  50         return 0;
  51 }
  52
  53 static int null_final(struct shash_desc *desc, u8 *out)
  54 {
  55         return 0;
  56 }
  57
  58 static int null_digest(struct shash_desc *desc, const u8 *data,
  59                        unsigned int len, u8 *out)
  60 {
  61         return 0;
  62 }
  63
  64 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  65                             unsigned int keylen)
  66 { return 0; }
  67
  68 static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
  69                                 unsigned int keylen)
  70 { return 0; }
  71
  72 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  73                        unsigned int keylen)
  74 { return 0; }
  75
  76 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  77 {
  78         memcpy(dst, src, NULL_BLOCK_SIZE);
  79 }
  80
  81 static int null_skcipher_crypt(struct skcipher_request *req)
  82 {
  83         struct skcipher_walk walk;
  84         int err;
  85
  86         err = skcipher_walk_virt(&walk, req, false);
  87
  88         while (walk.nbytes) {
  89                 if (walk.src.virt.addr != walk.dst.virt.addr)
  90                         memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  91                                walk.nbytes);
  92                 err = skcipher_walk_done(&walk, 0);
  93         }
  94
  95         return err;
  96 }
  97
  98 static struct shash_alg digest_null = {
  99         .digestsize             =       NULL_DIGEST_SIZE,
 100         .setkey                 =       null_hash_setkey,
 101         .init                   =       null_init,
 102         .update                 =       null_update,
 103         .finup                  =       null_digest,
 104         .digest                 =       null_digest,
 105         .final                  =       null_final,
 106         .base                   =       {
 107                 .cra_name               =       "digest_null",
 108                 .cra_blocksize          =       NULL_BLOCK_SIZE,
 109                 .cra_module             =       THIS_MODULE,
 110         }
 111 };
 112
 113 static struct skcipher_alg skcipher_null = {
 114         .base.cra_name          =       "ecb(cipher_null)",
 115         .base.cra_driver_name   =       "ecb-cipher_null",
 116         .base.cra_priority      =       100,
 117         .base.cra_blocksize     =       NULL_BLOCK_SIZE,
 118         .base.cra_ctxsize       =       0,
 119         .base.cra_module        =       THIS_MODULE,
 120         .min_keysize            =       NULL_KEY_SIZE,
 121         .max_keysize            =       NULL_KEY_SIZE,
 122         .ivsize                 =       NULL_IV_SIZE,
 123         .setkey                 =       null_skcipher_setkey,
 124         .encrypt                =       null_skcipher_crypt,
 125         .decrypt                =       null_skcipher_crypt,
 126 };
 127
 128 static struct crypto_alg null_algs[] = { {
 129         .cra_name               =       "cipher_null",
 130         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 131         .cra_blocksize          =       NULL_BLOCK_SIZE,
 132         .cra_ctxsize            =       0,
 133         .cra_module             =       THIS_MODULE,
 134         .cra_u                  =       { .cipher = {
 135         .cia_min_keysize        =       NULL_KEY_SIZE,
 136         .cia_max_keysize        =       NULL_KEY_SIZE,
 137         .cia_setkey             =       null_setkey,
 138         .cia_encrypt            =       null_crypt,
 139         .cia_decrypt            =       null_crypt } }
 140 }, {
 141         .cra_name               =       "compress_null",
 142         .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 143         .cra_blocksize          =       NULL_BLOCK_SIZE,
 144         .cra_ctxsize            =       0,
 145         .cra_module             =       THIS_MODULE,
 146         .cra_u                  =       { .compress = {
 147         .coa_compress           =       null_compress,
 148         .coa_decompress         =       null_compress } }
 149 } };
 150
 151 MODULE_ALIAS_CRYPTO("compress_null");
 152 MODULE_ALIAS_CRYPTO("digest_null");
 153 MODULE_ALIAS_CRYPTO("cipher_null");
 154
 155 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
 156 {
 157         struct crypto_sync_skcipher *tfm;
 158
 159         mutex_lock(&crypto_default_null_skcipher_lock);
 160         tfm = crypto_default_null_skcipher;
 161
 162         if (!tfm) {
 163                 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
 164                 if (IS_ERR(tfm))
 165                         goto unlock;
 166
 167                 crypto_default_null_skcipher = tfm;
 168         }
 169
 170         crypto_default_null_skcipher_refcnt++;
 171
 172 unlock:
 173         mutex_unlock(&crypto_default_null_skcipher_lock);
 174
 175         return tfm;
 176 }
 177 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
 178
 179 void crypto_put_default_null_skcipher(void)
 180 {
 181         mutex_lock(&crypto_default_null_skcipher_lock);
 182         if (!--crypto_default_null_skcipher_refcnt) {
 183                 crypto_free_sync_skcipher(crypto_default_null_skcipher);
 184                 crypto_default_null_skcipher = NULL;
 185         }
 186         mutex_unlock(&crypto_default_null_skcipher_lock);
 187 }
 188 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
 189
 190 static int __init crypto_null_mod_init(void)
 191 {
 192         int ret = 0;
 193
 194         ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 195         if (ret < 0)
 196                 goto out;
 197
 198         ret = crypto_register_shash(&digest_null);
 199         if (ret < 0)
 200                 goto out_unregister_algs;
 201
 202         ret = crypto_register_skcipher(&skcipher_null);
 203         if (ret < 0)
 204                 goto out_unregister_shash;
 205
 206         return 0;
 207
 208 out_unregister_shash:
 209         crypto_unregister_shash(&digest_null);
 210 out_unregister_algs:
 211         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 212 out:
 213         return ret;
 214 }
 215
 216 static void __exit crypto_null_mod_fini(void)
 217 {
 218         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 219         crypto_unregister_shash(&digest_null);
 220         crypto_unregister_skcipher(&skcipher_null);
 221 }
 222
 223 subsys_initcall(crypto_null_mod_init);
 224 module_exit(crypto_null_mod_fini);
 225
 226 MODULE_LICENSE("GPL");
 227 MODULE_DESCRIPTION("Null Cryptographic Algorithms");