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/internal/hash.h>
21#include <crypto/internal/skcipher.h>
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/mm.h>
25#include <linux/string.h>
26
27#define NULL_KEY_SIZE		0
28#define NULL_BLOCK_SIZE		1
29#define NULL_DIGEST_SIZE	0
30#define NULL_IV_SIZE		0
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 crypto_alg compress_null = {
98	.cra_name		=	"compress_null",
99	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
100	.cra_blocksize		=	NULL_BLOCK_SIZE,
101	.cra_ctxsize		=	0,
102	.cra_module		=	THIS_MODULE,
103	.cra_list		=       LIST_HEAD_INIT(compress_null.cra_list),
104	.cra_u			=	{ .compress = {
105	.coa_compress 		=	null_compress,
106	.coa_decompress		=	null_compress } }
107};
108
109static struct shash_alg digest_null = {
110	.digestsize		=	NULL_DIGEST_SIZE,
111	.setkey   		=	null_hash_setkey,
112	.init   		=	null_init,
113	.update 		=	null_update,
114	.finup 			=	null_digest,
115	.digest 		=	null_digest,
116	.final  		=	null_final,
117	.base			=	{
118		.cra_name		=	"digest_null",
119		.cra_flags		=	CRYPTO_ALG_TYPE_SHASH,
120		.cra_blocksize		=	NULL_BLOCK_SIZE,
121		.cra_module		=	THIS_MODULE,
122	}
123};
124
125static struct crypto_alg cipher_null = {
126	.cra_name		=	"cipher_null",
127	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
128	.cra_blocksize		=	NULL_BLOCK_SIZE,
129	.cra_ctxsize		=	0,
130	.cra_module		=	THIS_MODULE,
131	.cra_list		=	LIST_HEAD_INIT(cipher_null.cra_list),
132	.cra_u			=	{ .cipher = {
133	.cia_min_keysize	=	NULL_KEY_SIZE,
134	.cia_max_keysize	=	NULL_KEY_SIZE,
135	.cia_setkey		= 	null_setkey,
136	.cia_encrypt		=	null_crypt,
137	.cia_decrypt		=	null_crypt } }
138};
139
140static struct crypto_alg skcipher_null = {
141	.cra_name		=	"ecb(cipher_null)",
142	.cra_driver_name	=	"ecb-cipher_null",
143	.cra_priority		=	100,
144	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
145	.cra_blocksize		=	NULL_BLOCK_SIZE,
146	.cra_type		=	&crypto_blkcipher_type,
147	.cra_ctxsize		=	0,
148	.cra_module		=	THIS_MODULE,
149	.cra_list		=	LIST_HEAD_INIT(skcipher_null.cra_list),
150	.cra_u			=	{ .blkcipher = {
151	.min_keysize		=	NULL_KEY_SIZE,
152	.max_keysize		=	NULL_KEY_SIZE,
153	.ivsize			=	NULL_IV_SIZE,
154	.setkey			= 	null_setkey,
155	.encrypt		=	skcipher_null_crypt,
156	.decrypt		=	skcipher_null_crypt } }
157};
158
159MODULE_ALIAS("compress_null");
160MODULE_ALIAS("digest_null");
161MODULE_ALIAS("cipher_null");
162
163static int __init crypto_null_mod_init(void)
164{
165	int ret = 0;
166
167	ret = crypto_register_alg(&cipher_null);
168	if (ret < 0)
169		goto out;
170
171	ret = crypto_register_alg(&skcipher_null);
172	if (ret < 0)
173		goto out_unregister_cipher;
174
175	ret = crypto_register_shash(&digest_null);
176	if (ret < 0)
177		goto out_unregister_skcipher;
178
179	ret = crypto_register_alg(&compress_null);
180	if (ret < 0)
181		goto out_unregister_digest;
182
183out:
184	return ret;
185
186out_unregister_digest:
187	crypto_unregister_shash(&digest_null);
188out_unregister_skcipher:
189	crypto_unregister_alg(&skcipher_null);
190out_unregister_cipher:
191	crypto_unregister_alg(&cipher_null);
192	goto out;
193}
194
195static void __exit crypto_null_mod_fini(void)
196{
197	crypto_unregister_alg(&compress_null);
198	crypto_unregister_shash(&digest_null);
199	crypto_unregister_alg(&skcipher_null);
200	crypto_unregister_alg(&cipher_null);
201}
202
203module_init(crypto_null_mod_init);
204module_exit(crypto_null_mod_fini);
205
206MODULE_LICENSE("GPL");
207MODULE_DESCRIPTION("Null Cryptographic Algorithms");
208