1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Cryptographic API. 4 * 5 * Null algorithms, aka Much Ado About Nothing. 6 * 7 * These are needed for IPsec, and may be useful in general for 8 * testing & debugging. 9 * 10 * The null cipher is compliant with RFC2410. 11 * 12 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 13 */ 14 15 #include <crypto/null.h> 16 #include <crypto/internal/hash.h> 17 #include <crypto/internal/skcipher.h> 18 #include <linux/init.h> 19 #include <linux/module.h> 20 #include <linux/mm.h> 21 #include <linux/string.h> 22 23 static DEFINE_MUTEX(crypto_default_null_skcipher_lock); 24 static struct crypto_sync_skcipher *crypto_default_null_skcipher; 25 static int crypto_default_null_skcipher_refcnt; 26 27 static int null_compress(struct crypto_tfm *tfm, const u8 *src, 28 unsigned int slen, u8 *dst, unsigned int *dlen) 29 { 30 if (slen > *dlen) 31 return -EINVAL; 32 memcpy(dst, src, slen); 33 *dlen = slen; 34 return 0; 35 } 36 37 static int null_init(struct shash_desc *desc) 38 { 39 return 0; 40 } 41 42 static int null_update(struct shash_desc *desc, const u8 *data, 43 unsigned int len) 44 { 45 return 0; 46 } 47 48 static int null_final(struct shash_desc *desc, u8 *out) 49 { 50 return 0; 51 } 52 53 static int null_digest(struct shash_desc *desc, const u8 *data, 54 unsigned int len, u8 *out) 55 { 56 return 0; 57 } 58 59 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key, 60 unsigned int keylen) 61 { return 0; } 62 63 static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key, 64 unsigned int keylen) 65 { return 0; } 66 67 static int null_setkey(struct crypto_tfm *tfm, const u8 *key, 68 unsigned int keylen) 69 { return 0; } 70 71 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src) 72 { 73 memcpy(dst, src, NULL_BLOCK_SIZE); 74 } 75 76 static int null_skcipher_crypt(struct skcipher_request *req) 77 { 78 struct skcipher_walk walk; 79 int err; 80 81 err = skcipher_walk_virt(&walk, req, false); 82 83 while (walk.nbytes) { 84 if (walk.src.virt.addr != walk.dst.virt.addr) 85 memcpy(walk.dst.virt.addr, walk.src.virt.addr, 86 walk.nbytes); 87 err = skcipher_walk_done(&walk, 0); 88 } 89 90 return err; 91 } 92 93 static struct shash_alg digest_null = { 94 .digestsize = NULL_DIGEST_SIZE, 95 .setkey = null_hash_setkey, 96 .init = null_init, 97 .update = null_update, 98 .finup = null_digest, 99 .digest = null_digest, 100 .final = null_final, 101 .base = { 102 .cra_name = "digest_null", 103 .cra_blocksize = NULL_BLOCK_SIZE, 104 .cra_module = THIS_MODULE, 105 } 106 }; 107 108 static struct skcipher_alg skcipher_null = { 109 .base.cra_name = "ecb(cipher_null)", 110 .base.cra_driver_name = "ecb-cipher_null", 111 .base.cra_priority = 100, 112 .base.cra_blocksize = NULL_BLOCK_SIZE, 113 .base.cra_ctxsize = 0, 114 .base.cra_module = THIS_MODULE, 115 .min_keysize = NULL_KEY_SIZE, 116 .max_keysize = NULL_KEY_SIZE, 117 .ivsize = NULL_IV_SIZE, 118 .setkey = null_skcipher_setkey, 119 .encrypt = null_skcipher_crypt, 120 .decrypt = null_skcipher_crypt, 121 }; 122 123 static struct crypto_alg null_algs[] = { { 124 .cra_name = "cipher_null", 125 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 126 .cra_blocksize = NULL_BLOCK_SIZE, 127 .cra_ctxsize = 0, 128 .cra_module = THIS_MODULE, 129 .cra_u = { .cipher = { 130 .cia_min_keysize = NULL_KEY_SIZE, 131 .cia_max_keysize = NULL_KEY_SIZE, 132 .cia_setkey = null_setkey, 133 .cia_encrypt = null_crypt, 134 .cia_decrypt = null_crypt } } 135 }, { 136 .cra_name = "compress_null", 137 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 138 .cra_blocksize = NULL_BLOCK_SIZE, 139 .cra_ctxsize = 0, 140 .cra_module = THIS_MODULE, 141 .cra_u = { .compress = { 142 .coa_compress = null_compress, 143 .coa_decompress = null_compress } } 144 } }; 145 146 MODULE_ALIAS_CRYPTO("compress_null"); 147 MODULE_ALIAS_CRYPTO("digest_null"); 148 MODULE_ALIAS_CRYPTO("cipher_null"); 149 150 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void) 151 { 152 struct crypto_sync_skcipher *tfm; 153 154 mutex_lock(&crypto_default_null_skcipher_lock); 155 tfm = crypto_default_null_skcipher; 156 157 if (!tfm) { 158 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0); 159 if (IS_ERR(tfm)) 160 goto unlock; 161 162 crypto_default_null_skcipher = tfm; 163 } 164 165 crypto_default_null_skcipher_refcnt++; 166 167 unlock: 168 mutex_unlock(&crypto_default_null_skcipher_lock); 169 170 return tfm; 171 } 172 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher); 173 174 void crypto_put_default_null_skcipher(void) 175 { 176 mutex_lock(&crypto_default_null_skcipher_lock); 177 if (!--crypto_default_null_skcipher_refcnt) { 178 crypto_free_sync_skcipher(crypto_default_null_skcipher); 179 crypto_default_null_skcipher = NULL; 180 } 181 mutex_unlock(&crypto_default_null_skcipher_lock); 182 } 183 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher); 184 185 static int __init crypto_null_mod_init(void) 186 { 187 int ret = 0; 188 189 ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs)); 190 if (ret < 0) 191 goto out; 192 193 ret = crypto_register_shash(&digest_null); 194 if (ret < 0) 195 goto out_unregister_algs; 196 197 ret = crypto_register_skcipher(&skcipher_null); 198 if (ret < 0) 199 goto out_unregister_shash; 200 201 return 0; 202 203 out_unregister_shash: 204 crypto_unregister_shash(&digest_null); 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_algs(null_algs, ARRAY_SIZE(null_algs)); 214 crypto_unregister_shash(&digest_null); 215 crypto_unregister_skcipher(&skcipher_null); 216 } 217 218 subsys_initcall(crypto_null_mod_init); 219 module_exit(crypto_null_mod_fini); 220 221 MODULE_LICENSE("GPL"); 222 MODULE_DESCRIPTION("Null Cryptographic Algorithms"); 223