linux/crypto/crypto_null.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Cryptographic API.
   4 *
   5 * Null algorithms, aka Much Ado About Nothing.
   6 *
   7 * These are needed for IPsec, and may be useful in general for
   8 * testing & debugging.
   9 *
  10 * The null cipher is compliant with RFC2410.
  11 *
  12 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  13 */
  14
  15#include <crypto/null.h>
  16#include <crypto/internal/hash.h>
  17#include <crypto/internal/skcipher.h>
  18#include <linux/init.h>
  19#include <linux/module.h>
  20#include <linux/mm.h>
  21#include <linux/string.h>
  22
  23static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
  24static struct crypto_sync_skcipher *crypto_default_null_skcipher;
  25static int crypto_default_null_skcipher_refcnt;
  26
  27static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  28                         unsigned int slen, u8 *dst, unsigned int *dlen)
  29{
  30        if (slen > *dlen)
  31                return -EINVAL;
  32        memcpy(dst, src, slen);
  33        *dlen = slen;
  34        return 0;
  35}
  36
  37static int null_init(struct shash_desc *desc)
  38{
  39        return 0;
  40}
  41
  42static int null_update(struct shash_desc *desc, const u8 *data,
  43                       unsigned int len)
  44{
  45        return 0;
  46}
  47
  48static int null_final(struct shash_desc *desc, u8 *out)
  49{
  50        return 0;
  51}
  52
  53static int null_digest(struct shash_desc *desc, const u8 *data,
  54                       unsigned int len, u8 *out)
  55{
  56        return 0;
  57}
  58
  59static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  60                            unsigned int keylen)
  61{ return 0; }
  62
  63static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
  64                                unsigned int keylen)
  65{ return 0; }
  66
  67static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  68                       unsigned int keylen)
  69{ return 0; }
  70
  71static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  72{
  73        memcpy(dst, src, NULL_BLOCK_SIZE);
  74}
  75
  76static int null_skcipher_crypt(struct skcipher_request *req)
  77{
  78        struct skcipher_walk walk;
  79        int err;
  80
  81        err = skcipher_walk_virt(&walk, req, false);
  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 = skcipher_walk_done(&walk, 0);
  88        }
  89
  90        return err;
  91}
  92
  93static 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_driver_name        =       "digest_null-generic",
 104                .cra_blocksize          =       NULL_BLOCK_SIZE,
 105                .cra_module             =       THIS_MODULE,
 106        }
 107};
 108
 109static struct skcipher_alg skcipher_null = {
 110        .base.cra_name          =       "ecb(cipher_null)",
 111        .base.cra_driver_name   =       "ecb-cipher_null",
 112        .base.cra_priority      =       100,
 113        .base.cra_blocksize     =       NULL_BLOCK_SIZE,
 114        .base.cra_ctxsize       =       0,
 115        .base.cra_module        =       THIS_MODULE,
 116        .min_keysize            =       NULL_KEY_SIZE,
 117        .max_keysize            =       NULL_KEY_SIZE,
 118        .ivsize                 =       NULL_IV_SIZE,
 119        .setkey                 =       null_skcipher_setkey,
 120        .encrypt                =       null_skcipher_crypt,
 121        .decrypt                =       null_skcipher_crypt,
 122};
 123
 124static struct crypto_alg null_algs[] = { {
 125        .cra_name               =       "cipher_null",
 126        .cra_driver_name        =       "cipher_null-generic",
 127        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 128        .cra_blocksize          =       NULL_BLOCK_SIZE,
 129        .cra_ctxsize            =       0,
 130        .cra_module             =       THIS_MODULE,
 131        .cra_u                  =       { .cipher = {
 132        .cia_min_keysize        =       NULL_KEY_SIZE,
 133        .cia_max_keysize        =       NULL_KEY_SIZE,
 134        .cia_setkey             =       null_setkey,
 135        .cia_encrypt            =       null_crypt,
 136        .cia_decrypt            =       null_crypt } }
 137}, {
 138        .cra_name               =       "compress_null",
 139        .cra_driver_name        =       "compress_null-generic",
 140        .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 141        .cra_blocksize          =       NULL_BLOCK_SIZE,
 142        .cra_ctxsize            =       0,
 143        .cra_module             =       THIS_MODULE,
 144        .cra_u                  =       { .compress = {
 145        .coa_compress           =       null_compress,
 146        .coa_decompress         =       null_compress } }
 147} };
 148
 149MODULE_ALIAS_CRYPTO("compress_null");
 150MODULE_ALIAS_CRYPTO("digest_null");
 151MODULE_ALIAS_CRYPTO("cipher_null");
 152
 153struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
 154{
 155        struct crypto_sync_skcipher *tfm;
 156
 157        mutex_lock(&crypto_default_null_skcipher_lock);
 158        tfm = crypto_default_null_skcipher;
 159
 160        if (!tfm) {
 161                tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
 162                if (IS_ERR(tfm))
 163                        goto unlock;
 164
 165                crypto_default_null_skcipher = tfm;
 166        }
 167
 168        crypto_default_null_skcipher_refcnt++;
 169
 170unlock:
 171        mutex_unlock(&crypto_default_null_skcipher_lock);
 172
 173        return tfm;
 174}
 175EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
 176
 177void crypto_put_default_null_skcipher(void)
 178{
 179        mutex_lock(&crypto_default_null_skcipher_lock);
 180        if (!--crypto_default_null_skcipher_refcnt) {
 181                crypto_free_sync_skcipher(crypto_default_null_skcipher);
 182                crypto_default_null_skcipher = NULL;
 183        }
 184        mutex_unlock(&crypto_default_null_skcipher_lock);
 185}
 186EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
 187
 188static int __init crypto_null_mod_init(void)
 189{
 190        int ret = 0;
 191
 192        ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 193        if (ret < 0)
 194                goto out;
 195
 196        ret = crypto_register_shash(&digest_null);
 197        if (ret < 0)
 198                goto out_unregister_algs;
 199
 200        ret = crypto_register_skcipher(&skcipher_null);
 201        if (ret < 0)
 202                goto out_unregister_shash;
 203
 204        return 0;
 205
 206out_unregister_shash:
 207        crypto_unregister_shash(&digest_null);
 208out_unregister_algs:
 209        crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 210out:
 211        return ret;
 212}
 213
 214static void __exit crypto_null_mod_fini(void)
 215{
 216        crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 217        crypto_unregister_shash(&digest_null);
 218        crypto_unregister_skcipher(&skcipher_null);
 219}
 220
 221subsys_initcall(crypto_null_mod_init);
 222module_exit(crypto_null_mod_fini);
 223
 224MODULE_LICENSE("GPL");
 225MODULE_DESCRIPTION("Null Cryptographic Algorithms");
 226
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