crypto/crypto_null.c

   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
  23 static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
  24 static struct crypto_sync_skcipher *crypto_default_null_skcipher;
  25 static int crypto_default_null_skcipher_refcnt;
  26
  27 static 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
  37 static int null_init(struct shash_desc *desc)
  38 {
  39         return 0;
  40 }
  41
  42 static int null_update(struct shash_desc *desc, const u8 *data,
  43                        unsigned int len)
  44 {
  45         return 0;
  46 }
  47
  48 static int null_final(struct shash_desc *desc, u8 *out)
  49 {
  50         return 0;
  51 }
  52
  53 static int null_digest(struct shash_desc *desc, const u8 *data,
  54                        unsigned int len, u8 *out)
  55 {
  56         return 0;
  57 }
  58
  59 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  60                             unsigned int keylen)
  61 { return 0; }
  62
  63 static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
  64                                 unsigned int keylen)
  65 { return 0; }
  66
  67 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  68                        unsigned int keylen)
  69 { return 0; }
  70
  71 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  72 {
  73         memcpy(dst, src, NULL_BLOCK_SIZE);
  74 }
  75
  76 static 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
  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_blocksize          =       NULL_BLOCK_SIZE,
 104                 .cra_module             =       THIS_MODULE,
 105         }
 106 };
 107
 108 static struct skcipher_alg skcipher_null = {
 109         .base.cra_name          =       "ecb(cipher_null)",
 110         .base.cra_driver_name   =       "ecb-cipher_null",
 111         .base.cra_priority      =       100,
 112         .base.cra_blocksize     =       NULL_BLOCK_SIZE,
 113         .base.cra_ctxsize       =       0,
 114         .base.cra_module        =       THIS_MODULE,
 115         .min_keysize            =       NULL_KEY_SIZE,
 116         .max_keysize            =       NULL_KEY_SIZE,
 117         .ivsize                 =       NULL_IV_SIZE,
 118         .setkey                 =       null_skcipher_setkey,
 119         .encrypt                =       null_skcipher_crypt,
 120         .decrypt                =       null_skcipher_crypt,
 121 };
 122
 123 static struct crypto_alg null_algs[] = { {
 124         .cra_name               =       "cipher_null",
 125         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 126         .cra_blocksize          =       NULL_BLOCK_SIZE,
 127         .cra_ctxsize            =       0,
 128         .cra_module             =       THIS_MODULE,
 129         .cra_u                  =       { .cipher = {
 130         .cia_min_keysize        =       NULL_KEY_SIZE,
 131         .cia_max_keysize        =       NULL_KEY_SIZE,
 132         .cia_setkey             =       null_setkey,
 133         .cia_encrypt            =       null_crypt,
 134         .cia_decrypt            =       null_crypt } }
 135 }, {
 136         .cra_name               =       "compress_null",
 137         .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 138         .cra_blocksize          =       NULL_BLOCK_SIZE,
 139         .cra_ctxsize            =       0,
 140         .cra_module             =       THIS_MODULE,
 141         .cra_u                  =       { .compress = {
 142         .coa_compress           =       null_compress,
 143         .coa_decompress         =       null_compress } }
 144 } };
 145
 146 MODULE_ALIAS_CRYPTO("compress_null");
 147 MODULE_ALIAS_CRYPTO("digest_null");
 148 MODULE_ALIAS_CRYPTO("cipher_null");
 149
 150 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
 151 {
 152         struct crypto_sync_skcipher *tfm;
 153
 154         mutex_lock(&crypto_default_null_skcipher_lock);
 155         tfm = crypto_default_null_skcipher;
 156
 157         if (!tfm) {
 158                 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
 159                 if (IS_ERR(tfm))
 160                         goto unlock;
 161
 162                 crypto_default_null_skcipher = tfm;
 163         }
 164
 165         crypto_default_null_skcipher_refcnt++;
 166
 167 unlock:
 168         mutex_unlock(&crypto_default_null_skcipher_lock);
 169
 170         return tfm;
 171 }
 172 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
 173
 174 void crypto_put_default_null_skcipher(void)
 175 {
 176         mutex_lock(&crypto_default_null_skcipher_lock);
 177         if (!--crypto_default_null_skcipher_refcnt) {
 178                 crypto_free_sync_skcipher(crypto_default_null_skcipher);
 179                 crypto_default_null_skcipher = NULL;
 180         }
 181         mutex_unlock(&crypto_default_null_skcipher_lock);
 182 }
 183 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
 184
 185 static int __init crypto_null_mod_init(void)
 186 {
 187         int ret = 0;
 188
 189         ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 190         if (ret < 0)
 191                 goto out;
 192
 193         ret = crypto_register_shash(&digest_null);
 194         if (ret < 0)
 195                 goto out_unregister_algs;
 196
 197         ret = crypto_register_skcipher(&skcipher_null);
 198         if (ret < 0)
 199                 goto out_unregister_shash;
 200
 201         return 0;
 202
 203 out_unregister_shash:
 204         crypto_unregister_shash(&digest_null);
 205 out_unregister_algs:
 206         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 207 out:
 208         return ret;
 209 }
 210
 211 static void __exit crypto_null_mod_fini(void)
 212 {
 213         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 214         crypto_unregister_shash(&digest_null);
 215         crypto_unregister_skcipher(&skcipher_null);
 216 }
 217
 218 subsys_initcall(crypto_null_mod_init);
 219 module_exit(crypto_null_mod_fini);
 220
 221 MODULE_LICENSE("GPL");
 222 MODULE_DESCRIPTION("Null Cryptographic Algorithms");