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_setkey(struct crypto_tfm *tfm, const u8 *key, 69 unsigned int keylen) 70 { return 0; } 71 72 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src) 73 { 74 memcpy(dst, src, NULL_BLOCK_SIZE); 75 } 76 77 static int skcipher_null_crypt(struct blkcipher_desc *desc, 78 struct scatterlist *dst, 79 struct scatterlist *src, unsigned int nbytes) 80 { 81 struct blkcipher_walk walk; 82 int err; 83 84 blkcipher_walk_init(&walk, dst, src, nbytes); 85 err = blkcipher_walk_virt(desc, &walk); 86 87 while (walk.nbytes) { 88 if (walk.src.virt.addr != walk.dst.virt.addr) 89 memcpy(walk.dst.virt.addr, walk.src.virt.addr, 90 walk.nbytes); 91 err = blkcipher_walk_done(desc, &walk, 0); 92 } 93 94 return err; 95 } 96 97 static struct shash_alg digest_null = { 98 .digestsize = NULL_DIGEST_SIZE, 99 .setkey = null_hash_setkey, 100 .init = null_init, 101 .update = null_update, 102 .finup = null_digest, 103 .digest = null_digest, 104 .final = null_final, 105 .base = { 106 .cra_name = "digest_null", 107 .cra_blocksize = NULL_BLOCK_SIZE, 108 .cra_module = THIS_MODULE, 109 } 110 }; 111 112 static struct crypto_alg null_algs[3] = { { 113 .cra_name = "cipher_null", 114 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 115 .cra_blocksize = NULL_BLOCK_SIZE, 116 .cra_ctxsize = 0, 117 .cra_module = THIS_MODULE, 118 .cra_u = { .cipher = { 119 .cia_min_keysize = NULL_KEY_SIZE, 120 .cia_max_keysize = NULL_KEY_SIZE, 121 .cia_setkey = null_setkey, 122 .cia_encrypt = null_crypt, 123 .cia_decrypt = null_crypt } } 124 }, { 125 .cra_name = "ecb(cipher_null)", 126 .cra_driver_name = "ecb-cipher_null", 127 .cra_priority = 100, 128 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, 129 .cra_blocksize = NULL_BLOCK_SIZE, 130 .cra_type = &crypto_blkcipher_type, 131 .cra_ctxsize = 0, 132 .cra_module = THIS_MODULE, 133 .cra_u = { .blkcipher = { 134 .min_keysize = NULL_KEY_SIZE, 135 .max_keysize = NULL_KEY_SIZE, 136 .ivsize = NULL_IV_SIZE, 137 .setkey = null_setkey, 138 .encrypt = skcipher_null_crypt, 139 .decrypt = skcipher_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 return 0; 203 204 out_unregister_algs: 205 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 206 out: 207 return ret; 208 } 209 210 static void __exit crypto_null_mod_fini(void) 211 { 212 crypto_unregister_shash(&digest_null); 213 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 214 } 215 216 module_init(crypto_null_mod_init); 217 module_exit(crypto_null_mod_fini); 218 219 MODULE_LICENSE("GPL"); 220 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 221