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_driver_name = "digest_null-generic", 109 .cra_blocksize = NULL_BLOCK_SIZE, 110 .cra_module = THIS_MODULE, 111 } 112 }; 113 114 static struct skcipher_alg skcipher_null = { 115 .base.cra_name = "ecb(cipher_null)", 116 .base.cra_driver_name = "ecb-cipher_null", 117 .base.cra_priority = 100, 118 .base.cra_blocksize = NULL_BLOCK_SIZE, 119 .base.cra_ctxsize = 0, 120 .base.cra_module = THIS_MODULE, 121 .min_keysize = NULL_KEY_SIZE, 122 .max_keysize = NULL_KEY_SIZE, 123 .ivsize = NULL_IV_SIZE, 124 .setkey = null_skcipher_setkey, 125 .encrypt = null_skcipher_crypt, 126 .decrypt = null_skcipher_crypt, 127 }; 128 129 static struct crypto_alg null_algs[] = { { 130 .cra_name = "cipher_null", 131 .cra_driver_name = "cipher_null-generic", 132 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 133 .cra_blocksize = NULL_BLOCK_SIZE, 134 .cra_ctxsize = 0, 135 .cra_module = THIS_MODULE, 136 .cra_u = { .cipher = { 137 .cia_min_keysize = NULL_KEY_SIZE, 138 .cia_max_keysize = NULL_KEY_SIZE, 139 .cia_setkey = null_setkey, 140 .cia_encrypt = null_crypt, 141 .cia_decrypt = null_crypt } } 142 }, { 143 .cra_name = "compress_null", 144 .cra_driver_name = "compress_null-generic", 145 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 146 .cra_blocksize = NULL_BLOCK_SIZE, 147 .cra_ctxsize = 0, 148 .cra_module = THIS_MODULE, 149 .cra_u = { .compress = { 150 .coa_compress = null_compress, 151 .coa_decompress = null_compress } } 152 } }; 153 154 MODULE_ALIAS_CRYPTO("compress_null"); 155 MODULE_ALIAS_CRYPTO("digest_null"); 156 MODULE_ALIAS_CRYPTO("cipher_null"); 157 158 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void) 159 { 160 struct crypto_sync_skcipher *tfm; 161 162 mutex_lock(&crypto_default_null_skcipher_lock); 163 tfm = crypto_default_null_skcipher; 164 165 if (!tfm) { 166 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0); 167 if (IS_ERR(tfm)) 168 goto unlock; 169 170 crypto_default_null_skcipher = tfm; 171 } 172 173 crypto_default_null_skcipher_refcnt++; 174 175 unlock: 176 mutex_unlock(&crypto_default_null_skcipher_lock); 177 178 return tfm; 179 } 180 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher); 181 182 void crypto_put_default_null_skcipher(void) 183 { 184 mutex_lock(&crypto_default_null_skcipher_lock); 185 if (!--crypto_default_null_skcipher_refcnt) { 186 crypto_free_sync_skcipher(crypto_default_null_skcipher); 187 crypto_default_null_skcipher = NULL; 188 } 189 mutex_unlock(&crypto_default_null_skcipher_lock); 190 } 191 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher); 192 193 static int __init crypto_null_mod_init(void) 194 { 195 int ret = 0; 196 197 ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs)); 198 if (ret < 0) 199 goto out; 200 201 ret = crypto_register_shash(&digest_null); 202 if (ret < 0) 203 goto out_unregister_algs; 204 205 ret = crypto_register_skcipher(&skcipher_null); 206 if (ret < 0) 207 goto out_unregister_shash; 208 209 return 0; 210 211 out_unregister_shash: 212 crypto_unregister_shash(&digest_null); 213 out_unregister_algs: 214 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 215 out: 216 return ret; 217 } 218 219 static void __exit crypto_null_mod_fini(void) 220 { 221 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 222 crypto_unregister_shash(&digest_null); 223 crypto_unregister_skcipher(&skcipher_null); 224 } 225 226 subsys_initcall(crypto_null_mod_init); 227 module_exit(crypto_null_mod_fini); 228 229 MODULE_LICENSE("GPL"); 230 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 231