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_blkcipher *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_setkey(struct crypto_tfm *tfm, const u8 *key,
69		       unsigned int keylen)
70{ return 0; }
71
72static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
73{
74	memcpy(dst, src, NULL_BLOCK_SIZE);
75}
76
77static 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
97static 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
113static 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
152MODULE_ALIAS_CRYPTO("compress_null");
153MODULE_ALIAS_CRYPTO("digest_null");
154MODULE_ALIAS_CRYPTO("cipher_null");
155
156struct 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
173unlock:
174	mutex_unlock(&crypto_default_null_skcipher_lock);
175
176	return tfm;
177}
178EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
179
180void 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}
189EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
190
191static 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
205out_unregister_algs:
206	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
207out:
208	return ret;
209}
210
211static 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
217module_init(crypto_null_mod_init);
218module_exit(crypto_null_mod_fini);
219
220MODULE_LICENSE("GPL");
221MODULE_DESCRIPTION("Null Cryptographic Algorithms");
222