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
28static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
29static struct crypto_sync_skcipher *crypto_default_null_skcipher;
30static int crypto_default_null_skcipher_refcnt;
31
32static 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
42static int null_init(struct shash_desc *desc)
43{
44 return 0;
45}
46
47static int null_update(struct shash_desc *desc, const u8 *data,
48 unsigned int len)
49{
50 return 0;
51}
52
53static int null_final(struct shash_desc *desc, u8 *out)
54{
55 return 0;
56}
57
58static int null_digest(struct shash_desc *desc, const u8 *data,
59 unsigned int len, u8 *out)
60{
61 return 0;
62}
63
64static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
65 unsigned int keylen)
66{ return 0; }
67
68static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
69 unsigned int keylen)
70{ return 0; }
71
72static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
73 unsigned int keylen)
74{ return 0; }
75
76static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
77{
78 memcpy(dst, src, NULL_BLOCK_SIZE);
79}
80
81static 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
98static 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
113static 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
128static 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
151MODULE_ALIAS_CRYPTO("compress_null");
152MODULE_ALIAS_CRYPTO("digest_null");
153MODULE_ALIAS_CRYPTO("cipher_null");
154
155struct 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
172unlock:
173 mutex_unlock(&crypto_default_null_skcipher_lock);
174
175 return tfm;
176}
177EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
178
179void 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}
188EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
189
190static 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
208out_unregister_shash:
209 crypto_unregister_shash(&digest_null);
210out_unregister_algs:
211 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
212out:
213 return ret;
214}
215
216static 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
223module_init(crypto_null_mod_init);
224module_exit(crypto_null_mod_fini);
225
226MODULE_LICENSE("GPL");
227MODULE_DESCRIPTION("Null Cryptographic Algorithms");
228