xref: /openbmc/linux/crypto/crypto_null.c (revision b627b4ed)
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 
32 static 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 
42 static int null_init(struct shash_desc *desc)
43 {
44 	return 0;
45 }
46 
47 static int null_update(struct shash_desc *desc, const u8 *data,
48 		       unsigned int len)
49 {
50 	return 0;
51 }
52 
53 static int null_final(struct shash_desc *desc, u8 *out)
54 {
55 	return 0;
56 }
57 
58 static int null_digest(struct shash_desc *desc, const u8 *data,
59 		       unsigned int len, u8 *out)
60 {
61 	return 0;
62 }
63 
64 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
65 			    unsigned int keylen)
66 { return 0; }
67 
68 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
69 		       unsigned int keylen)
70 { return 0; }
71 
72 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
73 {
74 	memcpy(dst, src, NULL_BLOCK_SIZE);
75 }
76 
77 static 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 
97 static 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 
109 static 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 
125 static 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 
140 static 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 
159 MODULE_ALIAS("compress_null");
160 MODULE_ALIAS("digest_null");
161 MODULE_ALIAS("cipher_null");
162 
163 static 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 
183 out:
184 	return ret;
185 
186 out_unregister_digest:
187 	crypto_unregister_shash(&digest_null);
188 out_unregister_skcipher:
189 	crypto_unregister_alg(&skcipher_null);
190 out_unregister_cipher:
191 	crypto_unregister_alg(&cipher_null);
192 	goto out;
193 }
194 
195 static 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 
203 module_init(crypto_null_mod_init);
204 module_exit(crypto_null_mod_fini);
205 
206 MODULE_LICENSE("GPL");
207 MODULE_DESCRIPTION("Null Cryptographic Algorithms");
208