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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 
null_compress(struct crypto_tfm * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int * dlen)28 static 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 
null_init(struct shash_desc * desc)38 static int null_init(struct shash_desc *desc)
39 {
40 	return 0;
41 }
42 
null_update(struct shash_desc * desc,const u8 * data,unsigned int len)43 static int null_update(struct shash_desc *desc, const u8 *data,
44 		       unsigned int len)
45 {
46 	return 0;
47 }
48 
null_final(struct shash_desc * desc,u8 * out)49 static int null_final(struct shash_desc *desc, u8 *out)
50 {
51 	return 0;
52 }
53 
null_digest(struct shash_desc * desc,const u8 * data,unsigned int len,u8 * out)54 static int null_digest(struct shash_desc *desc, const u8 *data,
55 		       unsigned int len, u8 *out)
56 {
57 	return 0;
58 }
59 
null_hash_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)60 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
61 			    unsigned int keylen)
62 { return 0; }
63 
null_setkey(struct crypto_tfm * tfm,const u8 * key,unsigned int keylen)64 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
65 		       unsigned int keylen)
66 { return 0; }
67 
null_crypt(struct crypto_tfm * tfm,u8 * dst,const u8 * src)68 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
69 {
70 	memcpy(dst, src, NULL_BLOCK_SIZE);
71 }
72 
skcipher_null_crypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)73 static 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 
93 static 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 
109 static 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 
148 MODULE_ALIAS_CRYPTO("compress_null");
149 MODULE_ALIAS_CRYPTO("digest_null");
150 MODULE_ALIAS_CRYPTO("cipher_null");
151 
crypto_null_mod_init(void)152 static 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 
166 out_unregister_algs:
167 	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
168 out:
169 	return ret;
170 }
171 
crypto_null_mod_fini(void)172 static 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 
178 module_init(crypto_null_mod_init);
179 module_exit(crypto_null_mod_fini);
180 
181 MODULE_LICENSE("GPL");
182 MODULE_DESCRIPTION("Null Cryptographic Algorithms");
183