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/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("compress_null");
149MODULE_ALIAS("digest_null");
150MODULE_ALIAS("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

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