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 int null_compress(struct crypto_tfm *tfm, const u8 *src,
  29                          unsigned int slen, u8 *dst, unsigned int *dlen)
  30 {
  31         if (slen > *dlen)
  32                 return -EINVAL;
  33         memcpy(dst, src, slen);
  34         *dlen = slen;
  35         return 0;
  36 }
  37
  38 static int null_init(struct shash_desc *desc)
  39 {
  40         return 0;
  41 }
  42
  43 static int null_update(struct shash_desc *desc, const u8 *data,
  44                        unsigned int len)
  45 {
  46         return 0;
  47 }
  48
  49 static int null_final(struct shash_desc *desc, u8 *out)
  50 {
  51         return 0;
  52 }
  53
  54 static int null_digest(struct shash_desc *desc, const u8 *data,
  55                        unsigned int len, u8 *out)
  56 {
  57         return 0;
  58 }
  59
  60 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  61                             unsigned int keylen)
  62 { return 0; }
  63
  64 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  65                        unsigned int keylen)
  66 { return 0; }
  67
  68 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  69 {
  70         memcpy(dst, src, NULL_BLOCK_SIZE);
  71 }
  72
  73 static int skcipher_null_crypt(struct blkcipher_desc *desc,
  74                                struct scatterlist *dst,
  75                                struct scatterlist *src, unsigned int nbytes)
  76 {
  77         struct blkcipher_walk walk;
  78         int err;
  79
  80         blkcipher_walk_init(&walk, dst, src, nbytes);
  81         err = blkcipher_walk_virt(desc, &walk);
  82
  83         while (walk.nbytes) {
  84                 if (walk.src.virt.addr != walk.dst.virt.addr)
  85                         memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  86                                walk.nbytes);
  87                 err = blkcipher_walk_done(desc, &walk, 0);
  88         }
  89
  90         return err;
  91 }
  92
  93 static struct shash_alg digest_null = {
  94         .digestsize             =       NULL_DIGEST_SIZE,
  95         .setkey                 =       null_hash_setkey,
  96         .init                   =       null_init,
  97         .update                 =       null_update,
  98         .finup                  =       null_digest,
  99         .digest                 =       null_digest,
 100         .final                  =       null_final,
 101         .base                   =       {
 102                 .cra_name               =       "digest_null",
 103                 .cra_flags              =       CRYPTO_ALG_TYPE_SHASH,
 104                 .cra_blocksize          =       NULL_BLOCK_SIZE,
 105                 .cra_module             =       THIS_MODULE,
 106         }
 107 };
 108
 109 static struct crypto_alg null_algs[3] = { {
 110         .cra_name               =       "cipher_null",
 111         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 112         .cra_blocksize          =       NULL_BLOCK_SIZE,
 113         .cra_ctxsize            =       0,
 114         .cra_module             =       THIS_MODULE,
 115         .cra_u                  =       { .cipher = {
 116         .cia_min_keysize        =       NULL_KEY_SIZE,
 117         .cia_max_keysize        =       NULL_KEY_SIZE,
 118         .cia_setkey             =       null_setkey,
 119         .cia_encrypt            =       null_crypt,
 120         .cia_decrypt            =       null_crypt } }
 121 }, {
 122         .cra_name               =       "ecb(cipher_null)",
 123         .cra_driver_name        =       "ecb-cipher_null",
 124         .cra_priority           =       100,
 125         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 126         .cra_blocksize          =       NULL_BLOCK_SIZE,
 127         .cra_type               =       &crypto_blkcipher_type,
 128         .cra_ctxsize            =       0,
 129         .cra_module             =       THIS_MODULE,
 130         .cra_u                  =       { .blkcipher = {
 131         .min_keysize            =       NULL_KEY_SIZE,
 132         .max_keysize            =       NULL_KEY_SIZE,
 133         .ivsize                 =       NULL_IV_SIZE,
 134         .setkey                 =       null_setkey,
 135         .encrypt                =       skcipher_null_crypt,
 136         .decrypt                =       skcipher_null_crypt } }
 137 }, {
 138         .cra_name               =       "compress_null",
 139         .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 140         .cra_blocksize          =       NULL_BLOCK_SIZE,
 141         .cra_ctxsize            =       0,
 142         .cra_module             =       THIS_MODULE,
 143         .cra_u                  =       { .compress = {
 144         .coa_compress           =       null_compress,
 145         .coa_decompress         =       null_compress } }
 146 } };
 147
 148 MODULE_ALIAS_CRYPTO("compress_null");
 149 MODULE_ALIAS_CRYPTO("digest_null");
 150 MODULE_ALIAS_CRYPTO("cipher_null");
 151
 152 static int __init crypto_null_mod_init(void)
 153 {
 154         int ret = 0;
 155
 156         ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 157         if (ret < 0)
 158                 goto out;
 159
 160         ret = crypto_register_shash(&digest_null);
 161         if (ret < 0)
 162                 goto out_unregister_algs;
 163
 164         return 0;
 165
 166 out_unregister_algs:
 167         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 168 out:
 169         return ret;
 170 }
 171
 172 static void __exit crypto_null_mod_fini(void)
 173 {
 174         crypto_unregister_shash(&digest_null);
 175         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 176 }
 177
 178 module_init(crypto_null_mod_init);
 179 module_exit(crypto_null_mod_fini);
 180
 181 MODULE_LICENSE("GPL");
 182 MODULE_DESCRIPTION("Null Cryptographic Algorithms");