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
23static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
24static struct crypto_sync_skcipher *crypto_default_null_skcipher;
25static int crypto_default_null_skcipher_refcnt;
26
27static 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
37static int null_init(struct shash_desc *desc)
38{
39	return 0;
40}
41
42static int null_update(struct shash_desc *desc, const u8 *data,
43		       unsigned int len)
44{
45	return 0;
46}
47
48static int null_final(struct shash_desc *desc, u8 *out)
49{
50	return 0;
51}
52
53static int null_digest(struct shash_desc *desc, const u8 *data,
54		       unsigned int len, u8 *out)
55{
56	return 0;
57}
58
59static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
60			    unsigned int keylen)
61{ return 0; }
62
63static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
64				unsigned int keylen)
65{ return 0; }
66
67static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
68		       unsigned int keylen)
69{ return 0; }
70
71static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
72{
73	memcpy(dst, src, NULL_BLOCK_SIZE);
74}
75
76static 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
93static 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_driver_name	=	"digest_null-generic",
104		.cra_blocksize		=	NULL_BLOCK_SIZE,
105		.cra_module		=	THIS_MODULE,
106	}
107};
108
109static struct skcipher_alg skcipher_null = {
110	.base.cra_name		=	"ecb(cipher_null)",
111	.base.cra_driver_name	=	"ecb-cipher_null",
112	.base.cra_priority	=	100,
113	.base.cra_blocksize	=	NULL_BLOCK_SIZE,
114	.base.cra_ctxsize	=	0,
115	.base.cra_module	=	THIS_MODULE,
116	.min_keysize		=	NULL_KEY_SIZE,
117	.max_keysize		=	NULL_KEY_SIZE,
118	.ivsize			=	NULL_IV_SIZE,
119	.setkey			=	null_skcipher_setkey,
120	.encrypt		=	null_skcipher_crypt,
121	.decrypt		=	null_skcipher_crypt,
122};
123
124static struct crypto_alg null_algs[] = { {
125	.cra_name		=	"cipher_null",
126	.cra_driver_name	=	"cipher_null-generic",
127	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
128	.cra_blocksize		=	NULL_BLOCK_SIZE,
129	.cra_ctxsize		=	0,
130	.cra_module		=	THIS_MODULE,
131	.cra_u			=	{ .cipher = {
132	.cia_min_keysize	=	NULL_KEY_SIZE,
133	.cia_max_keysize	=	NULL_KEY_SIZE,
134	.cia_setkey		= 	null_setkey,
135	.cia_encrypt		=	null_crypt,
136	.cia_decrypt		=	null_crypt } }
137}, {
138	.cra_name		=	"compress_null",
139	.cra_driver_name	=	"compress_null-generic",
140	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
141	.cra_blocksize		=	NULL_BLOCK_SIZE,
142	.cra_ctxsize		=	0,
143	.cra_module		=	THIS_MODULE,
144	.cra_u			=	{ .compress = {
145	.coa_compress		=	null_compress,
146	.coa_decompress		=	null_compress } }
147} };
148
149MODULE_ALIAS_CRYPTO("compress_null");
150MODULE_ALIAS_CRYPTO("digest_null");
151MODULE_ALIAS_CRYPTO("cipher_null");
152
153struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
154{
155	struct crypto_sync_skcipher *tfm;
156
157	mutex_lock(&crypto_default_null_skcipher_lock);
158	tfm = crypto_default_null_skcipher;
159
160	if (!tfm) {
161		tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
162		if (IS_ERR(tfm))
163			goto unlock;
164
165		crypto_default_null_skcipher = tfm;
166	}
167
168	crypto_default_null_skcipher_refcnt++;
169
170unlock:
171	mutex_unlock(&crypto_default_null_skcipher_lock);
172
173	return tfm;
174}
175EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
176
177void crypto_put_default_null_skcipher(void)
178{
179	mutex_lock(&crypto_default_null_skcipher_lock);
180	if (!--crypto_default_null_skcipher_refcnt) {
181		crypto_free_sync_skcipher(crypto_default_null_skcipher);
182		crypto_default_null_skcipher = NULL;
183	}
184	mutex_unlock(&crypto_default_null_skcipher_lock);
185}
186EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
187
188static int __init crypto_null_mod_init(void)
189{
190	int ret = 0;
191
192	ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
193	if (ret < 0)
194		goto out;
195
196	ret = crypto_register_shash(&digest_null);
197	if (ret < 0)
198		goto out_unregister_algs;
199
200	ret = crypto_register_skcipher(&skcipher_null);
201	if (ret < 0)
202		goto out_unregister_shash;
203
204	return 0;
205
206out_unregister_shash:
207	crypto_unregister_shash(&digest_null);
208out_unregister_algs:
209	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
210out:
211	return ret;
212}
213
214static void __exit crypto_null_mod_fini(void)
215{
216	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
217	crypto_unregister_shash(&digest_null);
218	crypto_unregister_skcipher(&skcipher_null);
219}
220
221subsys_initcall(crypto_null_mod_init);
222module_exit(crypto_null_mod_fini);
223
224MODULE_LICENSE("GPL");
225MODULE_DESCRIPTION("Null Cryptographic Algorithms");
226