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 int null_compress(struct crypto_tfm *tfm, const u8 *src,
29			 unsigned int slen, u8 *dst, unsigned int *dlen)
30{
31	if (slen > *dlen)
32		return -EINVAL;
33	memcpy(dst, src, slen);
34	*dlen = slen;
35	return 0;
36}
37
38static int null_init(struct shash_desc *desc)
39{
40	return 0;
41}
42
43static int null_update(struct shash_desc *desc, const u8 *data,
44		       unsigned int len)
45{
46	return 0;
47}
48
49static int null_final(struct shash_desc *desc, u8 *out)
50{
51	return 0;
52}
53
54static int null_digest(struct shash_desc *desc, const u8 *data,
55		       unsigned int len, u8 *out)
56{
57	return 0;
58}
59
60static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
61			    unsigned int keylen)
62{ return 0; }
63
64static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
65		       unsigned int keylen)
66{ return 0; }
67
68static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
69{
70	memcpy(dst, src, NULL_BLOCK_SIZE);
71}
72
73static int skcipher_null_crypt(struct blkcipher_desc *desc,
74			       struct scatterlist *dst,
75			       struct scatterlist *src, unsigned int nbytes)
76{
77	struct blkcipher_walk walk;
78	int err;
79
80	blkcipher_walk_init(&walk, dst, src, nbytes);
81	err = blkcipher_walk_virt(desc, &walk);
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 = blkcipher_walk_done(desc, &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_flags		=	CRYPTO_ALG_TYPE_SHASH,
104		.cra_blocksize		=	NULL_BLOCK_SIZE,
105		.cra_module		=	THIS_MODULE,
106	}
107};
108
109static struct crypto_alg null_algs[3] = { {
110	.cra_name		=	"cipher_null",
111	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
112	.cra_blocksize		=	NULL_BLOCK_SIZE,
113	.cra_ctxsize		=	0,
114	.cra_module		=	THIS_MODULE,
115	.cra_u			=	{ .cipher = {
116	.cia_min_keysize	=	NULL_KEY_SIZE,
117	.cia_max_keysize	=	NULL_KEY_SIZE,
118	.cia_setkey		= 	null_setkey,
119	.cia_encrypt		=	null_crypt,
120	.cia_decrypt		=	null_crypt } }
121}, {
122	.cra_name		=	"ecb(cipher_null)",
123	.cra_driver_name	=	"ecb-cipher_null",
124	.cra_priority		=	100,
125	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
126	.cra_blocksize		=	NULL_BLOCK_SIZE,
127	.cra_type		=	&crypto_blkcipher_type,
128	.cra_ctxsize		=	0,
129	.cra_module		=	THIS_MODULE,
130	.cra_u			=	{ .blkcipher = {
131	.min_keysize		=	NULL_KEY_SIZE,
132	.max_keysize		=	NULL_KEY_SIZE,
133	.ivsize			=	NULL_IV_SIZE,
134	.setkey			= 	null_setkey,
135	.encrypt		=	skcipher_null_crypt,
136	.decrypt		=	skcipher_null_crypt } }
137}, {
138	.cra_name		=	"compress_null",
139	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
140	.cra_blocksize		=	NULL_BLOCK_SIZE,
141	.cra_ctxsize		=	0,
142	.cra_module		=	THIS_MODULE,
143	.cra_u			=	{ .compress = {
144	.coa_compress		=	null_compress,
145	.coa_decompress		=	null_compress } }
146} };
147
148MODULE_ALIAS_CRYPTO("compress_null");
149MODULE_ALIAS_CRYPTO("digest_null");
150MODULE_ALIAS_CRYPTO("cipher_null");
151
152static int __init crypto_null_mod_init(void)
153{
154	int ret = 0;
155
156	ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
157	if (ret < 0)
158		goto out;
159
160	ret = crypto_register_shash(&digest_null);
161	if (ret < 0)
162		goto out_unregister_algs;
163
164	return 0;
165
166out_unregister_algs:
167	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
168out:
169	return ret;
170}
171
172static void __exit crypto_null_mod_fini(void)
173{
174	crypto_unregister_shash(&digest_null);
175	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
176}
177
178module_init(crypto_null_mod_init);
179module_exit(crypto_null_mod_fini);
180
181MODULE_LICENSE("GPL");
182MODULE_DESCRIPTION("Null Cryptographic Algorithms");
183