summaryrefslogtreecommitdiff
path: root/crypto/crc32c.c
blob: a882d9e4e63e741fd90ec2d6183cee337c841c54 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
/* 
 * Cryptographic API.
 *
 * CRC32C chksum
 *
 * This module file is a wrapper to invoke the lib/crc32c routines.
 *
 * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 */

#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crc32c.h>
#include <linux/kernel.h>

#define CHKSUM_BLOCK_SIZE	1
#define CHKSUM_DIGEST_SIZE	4

struct chksum_ctx {
	u32 crc;
	u32 key;
};

/*
 * Steps through buffer one byte at at time, calculates reflected 
 * crc using table.
 */

static void chksum_init(struct crypto_tfm *tfm)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->crc = mctx->key;
}

/*
 * Setting the seed allows arbitrary accumulators and flexible XOR policy
 * If your algorithm starts with ~0, then XOR with ~0 before you set
 * the seed.
 */
static int chksum_setkey(struct crypto_tfm *tfm, const u8 *key,
			 unsigned int keylen)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	if (keylen != sizeof(mctx->crc)) {
		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}
	mctx->key = le32_to_cpu(*(__le32 *)key);
	return 0;
}

static void chksum_update(struct crypto_tfm *tfm, const u8 *data,
			  unsigned int length)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->crc = crc32c(mctx->crc, data, length);
}

static void chksum_final(struct crypto_tfm *tfm, u8 *out)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	
	*(__le32 *)out = ~cpu_to_le32(mctx->crc);
}

static int crc32c_cra_init_old(struct crypto_tfm *tfm)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->key = ~0;
	return 0;
}

static struct crypto_alg old_alg = {
	.cra_name	=	"crc32c",
	.cra_flags	=	CRYPTO_ALG_TYPE_DIGEST,
	.cra_blocksize	=	CHKSUM_BLOCK_SIZE,
	.cra_ctxsize	=	sizeof(struct chksum_ctx),
	.cra_module	=	THIS_MODULE,
	.cra_list	=	LIST_HEAD_INIT(old_alg.cra_list),
	.cra_init	=	crc32c_cra_init_old,
	.cra_u		=	{
		.digest = {
			 .dia_digestsize=	CHKSUM_DIGEST_SIZE,
			 .dia_setkey	=	chksum_setkey,
			 .dia_init   	= 	chksum_init,
			 .dia_update 	=	chksum_update,
			 .dia_final  	=	chksum_final
		 }
	}
};

/*
 * Setting the seed allows arbitrary accumulators and flexible XOR policy
 * If your algorithm starts with ~0, then XOR with ~0 before you set
 * the seed.
 */
static int crc32c_setkey(struct crypto_ahash *hash, const u8 *key,
			 unsigned int keylen)
{
	u32 *mctx = crypto_ahash_ctx(hash);

	if (keylen != sizeof(u32)) {
		crypto_ahash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}
	*mctx = le32_to_cpup((__le32 *)key);
	return 0;
}

static int crc32c_init(struct ahash_request *req)
{
	u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
	u32 *crcp = ahash_request_ctx(req);

	*crcp = *mctx;
	return 0;
}

static int crc32c_update(struct ahash_request *req)
{
	struct crypto_hash_walk walk;
	u32 *crcp = ahash_request_ctx(req);
	u32 crc = *crcp;
	int nbytes;

	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
	     nbytes = crypto_hash_walk_done(&walk, 0))
		crc = crc32c(crc, walk.data, nbytes);

	*crcp = crc;
	return 0;
}

static int crc32c_final(struct ahash_request *req)
{
	u32 *crcp = ahash_request_ctx(req);
	
	*(__le32 *)req->result = ~cpu_to_le32p(crcp);
	return 0;
}

static int crc32c_digest(struct ahash_request *req)
{
	struct crypto_hash_walk walk;
	u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
	u32 crc = *mctx;
	int nbytes;

	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
	     nbytes = crypto_hash_walk_done(&walk, 0))
		crc = crc32c(crc, walk.data, nbytes);

	*(__le32 *)req->result = ~cpu_to_le32(crc);
	return 0;
}

static int crc32c_cra_init(struct crypto_tfm *tfm)
{
	u32 *key = crypto_tfm_ctx(tfm);

	*key = ~0;

	tfm->crt_ahash.reqsize = sizeof(u32);

	return 0;
}

static struct crypto_alg alg = {
	.cra_name		=	"crc32c",
	.cra_driver_name	=	"crc32c-generic",
	.cra_priority		=	100,
	.cra_flags		=	CRYPTO_ALG_TYPE_AHASH,
	.cra_blocksize		=	CHKSUM_BLOCK_SIZE,
	.cra_alignmask		=	3,
	.cra_ctxsize		=	sizeof(u32),
	.cra_module		=	THIS_MODULE,
	.cra_list		=	LIST_HEAD_INIT(alg.cra_list),
	.cra_init		=	crc32c_cra_init,
	.cra_type		=	&crypto_ahash_type,
	.cra_u			=	{
		.ahash = {
			 .digestsize	=	CHKSUM_DIGEST_SIZE,
			 .setkey	=	crc32c_setkey,
			 .init   	= 	crc32c_init,
			 .update 	=	crc32c_update,
			 .final  	=	crc32c_final,
			 .digest  	=	crc32c_digest,
		 }
	}
};

static int __init crc32c_mod_init(void)
{
	int err;

	err = crypto_register_alg(&old_alg);
	if (err)
		return err;

	err = crypto_register_alg(&alg);
	if (err)
		crypto_unregister_alg(&old_alg);

	return err;
}

static void __exit crc32c_mod_fini(void)
{
	crypto_unregister_alg(&alg);
	crypto_unregister_alg(&old_alg);
}

module_init(crc32c_mod_init);
module_exit(crc32c_mod_fini);

MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
MODULE_LICENSE("GPL");