Root/crypto/crypto_null.c

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

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