linux/crypto/crypto_null.c
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   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/internal/hash.h>
  21#include <crypto/internal/skcipher.h>
  22#include <linux/init.h>
  23#include <linux/module.h>
  24#include <linux/mm.h>
  25#include <linux/string.h>
  26
  27#define NULL_KEY_SIZE           0
  28#define NULL_BLOCK_SIZE         1
  29#define NULL_DIGEST_SIZE        0
  30#define NULL_IV_SIZE            0
  31
  32static 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
  42static int null_init(struct shash_desc *desc)
  43{
  44        return 0;
  45}
  46
  47static int null_update(struct shash_desc *desc, const u8 *data,
  48                       unsigned int len)
  49{
  50        return 0;
  51}
  52
  53static int null_final(struct shash_desc *desc, u8 *out)
  54{
  55        return 0;
  56}
  57
  58static int null_digest(struct shash_desc *desc, const u8 *data,
  59                       unsigned int len, u8 *out)
  60{
  61        return 0;
  62}
  63
  64static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  65                            unsigned int keylen)
  66{ return 0; }
  67
  68static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  69                       unsigned int keylen)
  70{ return 0; }
  71
  72static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  73{
  74        memcpy(dst, src, NULL_BLOCK_SIZE);
  75}
  76
  77static int skcipher_null_crypt(struct blkcipher_desc *desc,
  78                               struct scatterlist *dst,
  79                               struct scatterlist *src, unsigned int nbytes)
  80{
  81        struct blkcipher_walk walk;
  82        int err;
  83
  84        blkcipher_walk_init(&walk, dst, src, nbytes);
  85        err = blkcipher_walk_virt(desc, &walk);
  86
  87        while (walk.nbytes) {
  88                if (walk.src.virt.addr != walk.dst.virt.addr)
  89                        memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  90                               walk.nbytes);
  91                err = blkcipher_walk_done(desc, &walk, 0);
  92        }
  93
  94        return err;
  95}
  96
  97static struct shash_alg digest_null = {
  98        .digestsize             =       NULL_DIGEST_SIZE,
  99        .setkey                 =       null_hash_setkey,
 100        .init                   =       null_init,
 101        .update                 =       null_update,
 102        .finup                  =       null_digest,
 103        .digest                 =       null_digest,
 104        .final                  =       null_final,
 105        .base                   =       {
 106                .cra_name               =       "digest_null",
 107                .cra_flags              =       CRYPTO_ALG_TYPE_SHASH,
 108                .cra_blocksize          =       NULL_BLOCK_SIZE,
 109                .cra_module             =       THIS_MODULE,
 110        }
 111};
 112
 113static struct crypto_alg null_algs[3] = { {
 114        .cra_name               =       "cipher_null",
 115        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 116        .cra_blocksize          =       NULL_BLOCK_SIZE,
 117        .cra_ctxsize            =       0,
 118        .cra_module             =       THIS_MODULE,
 119        .cra_u                  =       { .cipher = {
 120        .cia_min_keysize        =       NULL_KEY_SIZE,
 121        .cia_max_keysize        =       NULL_KEY_SIZE,
 122        .cia_setkey             =       null_setkey,
 123        .cia_encrypt            =       null_crypt,
 124        .cia_decrypt            =       null_crypt } }
 125}, {
 126        .cra_name               =       "ecb(cipher_null)",
 127        .cra_driver_name        =       "ecb-cipher_null",
 128        .cra_priority           =       100,
 129        .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 130        .cra_blocksize          =       NULL_BLOCK_SIZE,
 131        .cra_type               =       &crypto_blkcipher_type,
 132        .cra_ctxsize            =       0,
 133        .cra_module             =       THIS_MODULE,
 134        .cra_u                  =       { .blkcipher = {
 135        .min_keysize            =       NULL_KEY_SIZE,
 136        .max_keysize            =       NULL_KEY_SIZE,
 137        .ivsize                 =       NULL_IV_SIZE,
 138        .setkey                 =       null_setkey,
 139        .encrypt                =       skcipher_null_crypt,
 140        .decrypt                =       skcipher_null_crypt } }
 141}, {
 142        .cra_name               =       "compress_null",
 143        .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 144        .cra_blocksize          =       NULL_BLOCK_SIZE,
 145        .cra_ctxsize            =       0,
 146        .cra_module             =       THIS_MODULE,
 147        .cra_u                  =       { .compress = {
 148        .coa_compress           =       null_compress,
 149        .coa_decompress         =       null_compress } }
 150} };
 151
 152MODULE_ALIAS("compress_null");
 153MODULE_ALIAS("digest_null");
 154MODULE_ALIAS("cipher_null");
 155
 156static int __init crypto_null_mod_init(void)
 157{
 158        int ret = 0;
 159
 160        ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 161        if (ret < 0)
 162                goto out;
 163
 164        ret = crypto_register_shash(&digest_null);
 165        if (ret < 0)
 166                goto out_unregister_algs;
 167
 168        return 0;
 169
 170out_unregister_algs:
 171        crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 172out:
 173        return ret;
 174}
 175
 176static void __exit crypto_null_mod_fini(void)
 177{
 178        crypto_unregister_shash(&digest_null);
 179        crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 180}
 181
 182module_init(crypto_null_mod_init);
 183module_exit(crypto_null_mod_fini);
 184
 185MODULE_LICENSE("GPL");
 186MODULE_DESCRIPTION("Null Cryptographic Algorithms");
 187
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