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(struct crypto_tfm *tfm, const u8 *src, 31 unsigned int slen, 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(struct crypto_tfm *tfm) 41 { } 42 43 static void null_update(struct crypto_tfm *tfm, const u8 *data, 44 unsigned int len) 45 { } 46 47 static void null_final(struct crypto_tfm *tfm, u8 *out) 48 { } 49 50 static int null_setkey(struct crypto_tfm *tfm, const u8 *key, 51 unsigned int keylen) 52 { return 0; } 53 54 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src) 55 { 56 memcpy(dst, src, NULL_BLOCK_SIZE); 57 } 58 59 static struct crypto_alg compress_null = { 60 .cra_name = "compress_null", 61 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 62 .cra_blocksize = NULL_BLOCK_SIZE, 63 .cra_ctxsize = 0, 64 .cra_module = THIS_MODULE, 65 .cra_list = LIST_HEAD_INIT(compress_null.cra_list), 66 .cra_u = { .compress = { 67 .coa_compress = null_compress, 68 .coa_decompress = null_compress } } 69 }; 70 71 static struct crypto_alg digest_null = { 72 .cra_name = "digest_null", 73 .cra_flags = CRYPTO_ALG_TYPE_DIGEST, 74 .cra_blocksize = NULL_BLOCK_SIZE, 75 .cra_ctxsize = 0, 76 .cra_module = THIS_MODULE, 77 .cra_list = LIST_HEAD_INIT(digest_null.cra_list), 78 .cra_u = { .digest = { 79 .dia_digestsize = NULL_DIGEST_SIZE, 80 .dia_init = null_init, 81 .dia_update = null_update, 82 .dia_final = null_final } } 83 }; 84 85 static struct crypto_alg cipher_null = { 86 .cra_name = "cipher_null", 87 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 88 .cra_blocksize = NULL_BLOCK_SIZE, 89 .cra_ctxsize = 0, 90 .cra_module = THIS_MODULE, 91 .cra_list = LIST_HEAD_INIT(cipher_null.cra_list), 92 .cra_u = { .cipher = { 93 .cia_min_keysize = NULL_KEY_SIZE, 94 .cia_max_keysize = NULL_KEY_SIZE, 95 .cia_setkey = null_setkey, 96 .cia_encrypt = null_crypt, 97 .cia_decrypt = null_crypt } } 98 }; 99 100 MODULE_ALIAS("compress_null"); 101 MODULE_ALIAS("digest_null"); 102 MODULE_ALIAS("cipher_null"); 103 104 static int __init init(void) 105 { 106 int ret = 0; 107 108 ret = crypto_register_alg(&cipher_null); 109 if (ret < 0) 110 goto out; 111 112 ret = crypto_register_alg(&digest_null); 113 if (ret < 0) { 114 crypto_unregister_alg(&cipher_null); 115 goto out; 116 } 117 118 ret = crypto_register_alg(&compress_null); 119 if (ret < 0) { 120 crypto_unregister_alg(&digest_null); 121 crypto_unregister_alg(&cipher_null); 122 goto out; 123 } 124 125 out: 126 return ret; 127 } 128 129 static void __exit fini(void) 130 { 131 crypto_unregister_alg(&compress_null); 132 crypto_unregister_alg(&digest_null); 133 crypto_unregister_alg(&cipher_null); 134 } 135 136 module_init(init); 137 module_exit(fini); 138 139 MODULE_LICENSE("GPL"); 140 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 141