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 DEFINE_MUTEX(crypto_default_null_skcipher_lock); 29 static struct crypto_sync_skcipher *crypto_default_null_skcipher; 30 static int crypto_default_null_skcipher_refcnt; 31 32 static 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 42 static int null_init(struct shash_desc *desc) 43 { 44 return 0; 45 } 46 47 static int null_update(struct shash_desc *desc, const u8 *data, 48 unsigned int len) 49 { 50 return 0; 51 } 52 53 static int null_final(struct shash_desc *desc, u8 *out) 54 { 55 return 0; 56 } 57 58 static int null_digest(struct shash_desc *desc, const u8 *data, 59 unsigned int len, u8 *out) 60 { 61 return 0; 62 } 63 64 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key, 65 unsigned int keylen) 66 { return 0; } 67 68 static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key, 69 unsigned int keylen) 70 { return 0; } 71 72 static int null_setkey(struct crypto_tfm *tfm, const u8 *key, 73 unsigned int keylen) 74 { return 0; } 75 76 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src) 77 { 78 memcpy(dst, src, NULL_BLOCK_SIZE); 79 } 80 81 static int null_skcipher_crypt(struct skcipher_request *req) 82 { 83 struct skcipher_walk walk; 84 int err; 85 86 err = skcipher_walk_virt(&walk, req, false); 87 88 while (walk.nbytes) { 89 if (walk.src.virt.addr != walk.dst.virt.addr) 90 memcpy(walk.dst.virt.addr, walk.src.virt.addr, 91 walk.nbytes); 92 err = skcipher_walk_done(&walk, 0); 93 } 94 95 return err; 96 } 97 98 static struct shash_alg digest_null = { 99 .digestsize = NULL_DIGEST_SIZE, 100 .setkey = null_hash_setkey, 101 .init = null_init, 102 .update = null_update, 103 .finup = null_digest, 104 .digest = null_digest, 105 .final = null_final, 106 .base = { 107 .cra_name = "digest_null", 108 .cra_blocksize = NULL_BLOCK_SIZE, 109 .cra_module = THIS_MODULE, 110 } 111 }; 112 113 static struct skcipher_alg skcipher_null = { 114 .base.cra_name = "ecb(cipher_null)", 115 .base.cra_driver_name = "ecb-cipher_null", 116 .base.cra_priority = 100, 117 .base.cra_blocksize = NULL_BLOCK_SIZE, 118 .base.cra_ctxsize = 0, 119 .base.cra_module = THIS_MODULE, 120 .min_keysize = NULL_KEY_SIZE, 121 .max_keysize = NULL_KEY_SIZE, 122 .ivsize = NULL_IV_SIZE, 123 .setkey = null_skcipher_setkey, 124 .encrypt = null_skcipher_crypt, 125 .decrypt = null_skcipher_crypt, 126 }; 127 128 static struct crypto_alg null_algs[] = { { 129 .cra_name = "cipher_null", 130 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 131 .cra_blocksize = NULL_BLOCK_SIZE, 132 .cra_ctxsize = 0, 133 .cra_module = THIS_MODULE, 134 .cra_u = { .cipher = { 135 .cia_min_keysize = NULL_KEY_SIZE, 136 .cia_max_keysize = NULL_KEY_SIZE, 137 .cia_setkey = null_setkey, 138 .cia_encrypt = null_crypt, 139 .cia_decrypt = null_crypt } } 140 }, { 141 .cra_name = "compress_null", 142 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 143 .cra_blocksize = NULL_BLOCK_SIZE, 144 .cra_ctxsize = 0, 145 .cra_module = THIS_MODULE, 146 .cra_u = { .compress = { 147 .coa_compress = null_compress, 148 .coa_decompress = null_compress } } 149 } }; 150 151 MODULE_ALIAS_CRYPTO("compress_null"); 152 MODULE_ALIAS_CRYPTO("digest_null"); 153 MODULE_ALIAS_CRYPTO("cipher_null"); 154 155 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void) 156 { 157 struct crypto_sync_skcipher *tfm; 158 159 mutex_lock(&crypto_default_null_skcipher_lock); 160 tfm = crypto_default_null_skcipher; 161 162 if (!tfm) { 163 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0); 164 if (IS_ERR(tfm)) 165 goto unlock; 166 167 crypto_default_null_skcipher = tfm; 168 } 169 170 crypto_default_null_skcipher_refcnt++; 171 172 unlock: 173 mutex_unlock(&crypto_default_null_skcipher_lock); 174 175 return tfm; 176 } 177 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher); 178 179 void crypto_put_default_null_skcipher(void) 180 { 181 mutex_lock(&crypto_default_null_skcipher_lock); 182 if (!--crypto_default_null_skcipher_refcnt) { 183 crypto_free_sync_skcipher(crypto_default_null_skcipher); 184 crypto_default_null_skcipher = NULL; 185 } 186 mutex_unlock(&crypto_default_null_skcipher_lock); 187 } 188 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher); 189 190 static int __init crypto_null_mod_init(void) 191 { 192 int ret = 0; 193 194 ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs)); 195 if (ret < 0) 196 goto out; 197 198 ret = crypto_register_shash(&digest_null); 199 if (ret < 0) 200 goto out_unregister_algs; 201 202 ret = crypto_register_skcipher(&skcipher_null); 203 if (ret < 0) 204 goto out_unregister_shash; 205 206 return 0; 207 208 out_unregister_shash: 209 crypto_unregister_shash(&digest_null); 210 out_unregister_algs: 211 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 212 out: 213 return ret; 214 } 215 216 static void __exit crypto_null_mod_fini(void) 217 { 218 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 219 crypto_unregister_shash(&digest_null); 220 crypto_unregister_skcipher(&skcipher_null); 221 } 222 223 module_init(crypto_null_mod_init); 224 module_exit(crypto_null_mod_fini); 225 226 MODULE_LICENSE("GPL"); 227 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 228