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_blkcipher *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_flags = CRYPTO_ALG_TYPE_SHASH, 108 .cra_blocksize = NULL_BLOCK_SIZE, 109 .cra_module = THIS_MODULE, 110 } 111 }; 112 113 static struct crypto_alg null_algs[3] = { { 114 .cra_name = "cipher_null", 115 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 116 .cra_blocksize = NULL_BLOCK_SIZE, 117 .cra_ctxsize = 0, 118 .cra_module = THIS_MODULE, 119 .cra_u = { .cipher = { 120 .cia_min_keysize = NULL_KEY_SIZE, 121 .cia_max_keysize = NULL_KEY_SIZE, 122 .cia_setkey = null_setkey, 123 .cia_encrypt = null_crypt, 124 .cia_decrypt = null_crypt } } 125 }, { 126 .cra_name = "ecb(cipher_null)", 127 .cra_driver_name = "ecb-cipher_null", 128 .cra_priority = 100, 129 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER, 130 .cra_blocksize = NULL_BLOCK_SIZE, 131 .cra_type = &crypto_blkcipher_type, 132 .cra_ctxsize = 0, 133 .cra_module = THIS_MODULE, 134 .cra_u = { .blkcipher = { 135 .min_keysize = NULL_KEY_SIZE, 136 .max_keysize = NULL_KEY_SIZE, 137 .ivsize = NULL_IV_SIZE, 138 .setkey = null_setkey, 139 .encrypt = skcipher_null_crypt, 140 .decrypt = skcipher_null_crypt } } 141 }, { 142 .cra_name = "compress_null", 143 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 144 .cra_blocksize = NULL_BLOCK_SIZE, 145 .cra_ctxsize = 0, 146 .cra_module = THIS_MODULE, 147 .cra_u = { .compress = { 148 .coa_compress = null_compress, 149 .coa_decompress = null_compress } } 150 } }; 151 152 MODULE_ALIAS_CRYPTO("compress_null"); 153 MODULE_ALIAS_CRYPTO("digest_null"); 154 MODULE_ALIAS_CRYPTO("cipher_null"); 155 156 struct crypto_blkcipher *crypto_get_default_null_skcipher(void) 157 { 158 struct crypto_blkcipher *tfm; 159 160 mutex_lock(&crypto_default_null_skcipher_lock); 161 tfm = crypto_default_null_skcipher; 162 163 if (!tfm) { 164 tfm = crypto_alloc_blkcipher("ecb(cipher_null)", 0, 0); 165 if (IS_ERR(tfm)) 166 goto unlock; 167 168 crypto_default_null_skcipher = tfm; 169 } 170 171 crypto_default_null_skcipher_refcnt++; 172 173 unlock: 174 mutex_unlock(&crypto_default_null_skcipher_lock); 175 176 return tfm; 177 } 178 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher); 179 180 void crypto_put_default_null_skcipher(void) 181 { 182 mutex_lock(&crypto_default_null_skcipher_lock); 183 if (!--crypto_default_null_skcipher_refcnt) { 184 crypto_free_blkcipher(crypto_default_null_skcipher); 185 crypto_default_null_skcipher = NULL; 186 } 187 mutex_unlock(&crypto_default_null_skcipher_lock); 188 } 189 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher); 190 191 static int __init crypto_null_mod_init(void) 192 { 193 int ret = 0; 194 195 ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs)); 196 if (ret < 0) 197 goto out; 198 199 ret = crypto_register_shash(&digest_null); 200 if (ret < 0) 201 goto out_unregister_algs; 202 203 return 0; 204 205 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_shash(&digest_null); 214 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs)); 215 } 216 217 module_init(crypto_null_mod_init); 218 module_exit(crypto_null_mod_fini); 219 220 MODULE_LICENSE("GPL"); 221 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 222