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 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/mm.h>
  22 #include <asm/scatterlist.h>
  23 #include <linux/crypto.h>
  24 #include <linux/string.h>
  25
  26 #define NULL_KEY_SIZE           0
  27 #define NULL_BLOCK_SIZE         1
  28 #define NULL_DIGEST_SIZE        0
  29
  30 static int null_compress(void *ctx, const u8 *src, unsigned int slen,
  31                          u8 *dst, unsigned int *dlen)
  32 {
  33         if (slen > *dlen)
  34                 return -EINVAL;
  35         memcpy(dst, src, slen);
  36         *dlen = slen;
  37         return 0;
  38 }
  39
  40 static void null_init(void *ctx)
  41 { }
  42
  43 static void null_update(void *ctx, const u8 *data, unsigned int len)
  44 { }
  45
  46 static void null_final(void *ctx, u8 *out)
  47 { }
  48
  49 static int null_setkey(void *ctx, const u8 *key,
  50                        unsigned int keylen, u32 *flags)
  51 { return 0; }
  52
  53 static void null_crypt(void *ctx, u8 *dst, const u8 *src)
  54 {
  55         memcpy(dst, src, NULL_BLOCK_SIZE);
  56 }
  57
  58 static struct crypto_alg compress_null = {
  59         .cra_name               =       "compress_null",
  60         .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
  61         .cra_blocksize          =       NULL_BLOCK_SIZE,
  62         .cra_ctxsize            =       0,
  63         .cra_module             =       THIS_MODULE,
  64         .cra_list               =       LIST_HEAD_INIT(compress_null.cra_list),
  65         .cra_u                  =       { .compress = {
  66         .coa_compress           =       null_compress,
  67         .coa_decompress         =       null_compress } }
  68 };
  69
  70 static struct crypto_alg digest_null = {
  71         .cra_name               =       "digest_null",
  72         .cra_flags              =       CRYPTO_ALG_TYPE_DIGEST,
  73         .cra_blocksize          =       NULL_BLOCK_SIZE,
  74         .cra_ctxsize            =       0,
  75         .cra_module             =       THIS_MODULE,
  76         .cra_list               =       LIST_HEAD_INIT(digest_null.cra_list),
  77         .cra_u                  =       { .digest = {
  78         .dia_digestsize         =       NULL_DIGEST_SIZE,
  79         .dia_init               =       null_init,
  80         .dia_update             =       null_update,
  81         .dia_final              =       null_final } }
  82 };
  83
  84 static struct crypto_alg cipher_null = {
  85         .cra_name               =       "cipher_null",
  86         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
  87         .cra_blocksize          =       NULL_BLOCK_SIZE,
  88         .cra_ctxsize            =       0,
  89         .cra_module             =       THIS_MODULE,
  90         .cra_list               =       LIST_HEAD_INIT(cipher_null.cra_list),
  91         .cra_u                  =       { .cipher = {
  92         .cia_min_keysize        =       NULL_KEY_SIZE,
  93         .cia_max_keysize        =       NULL_KEY_SIZE,
  94         .cia_setkey             =       null_setkey,
  95         .cia_encrypt            =       null_crypt,
  96         .cia_decrypt            =       null_crypt } }
  97 };
  98
  99 MODULE_ALIAS("compress_null");
 100 MODULE_ALIAS("digest_null");
 101 MODULE_ALIAS("cipher_null");
 102
 103 static int __init init(void)
 104 {
 105         int ret = 0;
 106
 107         ret = crypto_register_alg(&cipher_null);
 108         if (ret < 0)
 109                 goto out;
 110
 111         ret = crypto_register_alg(&digest_null);
 112         if (ret < 0) {
 113                 crypto_unregister_alg(&cipher_null);
 114                 goto out;
 115         }
 116
 117         ret = crypto_register_alg(&compress_null);
 118         if (ret < 0) {
 119                 crypto_unregister_alg(&digest_null);
 120                 crypto_unregister_alg(&cipher_null);
 121                 goto out;
 122         }
 123
 124 out:
 125         return ret;
 126 }
 127
 128 static void __exit fini(void)
 129 {
 130         crypto_unregister_alg(&compress_null);
 131         crypto_unregister_alg(&digest_null);
 132         crypto_unregister_alg(&cipher_null);
 133 }
 134
 135 module_init(init);
 136 module_exit(fini);
 137
 138 MODULE_LICENSE("GPL");
 139 MODULE_DESCRIPTION("Null Cryptographic Algorithms");