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 shash_alg digest_null = {
98    .digestsize = NULL_DIGEST_SIZE,
99    .setkey = null_hash_setkey,
100    .init = null_init,
101    .update = null_update,
102    .finup = null_digest,
103    .digest = null_digest,
104    .final = null_final,
105    .base = {
106        .cra_name = "digest_null",
107        .cra_flags = CRYPTO_ALG_TYPE_SHASH,
108        .cra_blocksize = NULL_BLOCK_SIZE,
109        .cra_module = THIS_MODULE,
110    }
111};
112
113static struct crypto_alg null_algs[3] = { {
114    .cra_name = "cipher_null",
115    .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
116    .cra_blocksize = NULL_BLOCK_SIZE,
117    .cra_ctxsize = 0,
118    .cra_module = THIS_MODULE,
119    .cra_u = { .cipher = {
120    .cia_min_keysize = NULL_KEY_SIZE,
121    .cia_max_keysize = NULL_KEY_SIZE,
122    .cia_setkey = null_setkey,
123    .cia_encrypt = null_crypt,
124    .cia_decrypt = null_crypt } }
125}, {
126    .cra_name = "ecb(cipher_null)",
127    .cra_driver_name = "ecb-cipher_null",
128    .cra_priority = 100,
129    .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
130    .cra_blocksize = NULL_BLOCK_SIZE,
131    .cra_type = &crypto_blkcipher_type,
132    .cra_ctxsize = 0,
133    .cra_module = THIS_MODULE,
134    .cra_u = { .blkcipher = {
135    .min_keysize = NULL_KEY_SIZE,
136    .max_keysize = NULL_KEY_SIZE,
137    .ivsize = NULL_IV_SIZE,
138    .setkey = null_setkey,
139    .encrypt = skcipher_null_crypt,
140    .decrypt = skcipher_null_crypt } }
141}, {
142    .cra_name = "compress_null",
143    .cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
144    .cra_blocksize = NULL_BLOCK_SIZE,
145    .cra_ctxsize = 0,
146    .cra_module = THIS_MODULE,
147    .cra_u = { .compress = {
148    .coa_compress = null_compress,
149    .coa_decompress = null_compress } }
150} };
151
152MODULE_ALIAS("compress_null");
153MODULE_ALIAS("digest_null");
154MODULE_ALIAS("cipher_null");
155
156static int __init crypto_null_mod_init(void)
157{
158    int ret = 0;
159
160    ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
161    if (ret < 0)
162        goto out;
163
164    ret = crypto_register_shash(&digest_null);
165    if (ret < 0)
166        goto out_unregister_algs;
167
168    return 0;
169
170out_unregister_algs:
171    crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
172out:
173    return ret;
174}
175
176static void __exit crypto_null_mod_fini(void)
177{
178    crypto_unregister_shash(&digest_null);
179    crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
180}
181
182module_init(crypto_null_mod_init);
183module_exit(crypto_null_mod_fini);
184
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("Null Cryptographic Algorithms");
187

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