1/* GPL HEADER START
2 *
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 only,
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * General Public License version 2 for more details (a copy is included
13 * in the LICENSE file that accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License
16 * version 2 along with this program; If not, see http://www.gnu.org/licenses
17 *
18 * Please  visit http://www.xyratex.com/contact if you need additional
19 * information or have any questions.
20 *
21 * GPL HEADER END
22 */
23
24/*
25 * Copyright 2012 Xyratex Technology Limited
26 */
27
28/*
29 * This is crypto api shash wrappers to crc32_le.
30 */
31
32#include <linux/crc32.h>
33#include <crypto/internal/hash.h>
34#include <linux/init.h>
35#include <linux/module.h>
36#include <linux/string.h>
37#include <linux/kernel.h>
38
39#define CHKSUM_BLOCK_SIZE	1
40#define CHKSUM_DIGEST_SIZE	4
41
42static u32 __crc32_le(u32 crc, unsigned char const *p, size_t len)
43{
44	return crc32_le(crc, p, len);
45}
46
47/** No default init with ~0 */
48static int crc32_cra_init(struct crypto_tfm *tfm)
49{
50	u32 *key = crypto_tfm_ctx(tfm);
51
52	*key = 0;
53
54	return 0;
55}
56
57
58/*
59 * Setting the seed allows arbitrary accumulators and flexible XOR policy
60 * If your algorithm starts with ~0, then XOR with ~0 before you set
61 * the seed.
62 */
63static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
64			unsigned int keylen)
65{
66	u32 *mctx = crypto_shash_ctx(hash);
67
68	if (keylen != sizeof(u32)) {
69		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
70		return -EINVAL;
71	}
72	*mctx = le32_to_cpup((__le32 *)key);
73	return 0;
74}
75
76static int crc32_init(struct shash_desc *desc)
77{
78	u32 *mctx = crypto_shash_ctx(desc->tfm);
79	u32 *crcp = shash_desc_ctx(desc);
80
81	*crcp = *mctx;
82
83	return 0;
84}
85
86static int crc32_update(struct shash_desc *desc, const u8 *data,
87			unsigned int len)
88{
89	u32 *crcp = shash_desc_ctx(desc);
90
91	*crcp = __crc32_le(*crcp, data, len);
92	return 0;
93}
94
95/* No final XOR 0xFFFFFFFF, like crc32_le */
96static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
97			 u8 *out)
98{
99	*(__le32 *)out = cpu_to_le32(__crc32_le(*crcp, data, len));
100	return 0;
101}
102
103static int crc32_finup(struct shash_desc *desc, const u8 *data,
104		       unsigned int len, u8 *out)
105{
106	return __crc32_finup(shash_desc_ctx(desc), data, len, out);
107}
108
109static int crc32_final(struct shash_desc *desc, u8 *out)
110{
111	u32 *crcp = shash_desc_ctx(desc);
112
113	*(__le32 *)out = cpu_to_le32p(crcp);
114	return 0;
115}
116
117static int crc32_digest(struct shash_desc *desc, const u8 *data,
118			unsigned int len, u8 *out)
119{
120	return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
121			     out);
122}
123static struct shash_alg alg = {
124	.setkey		= crc32_setkey,
125	.init		= crc32_init,
126	.update		= crc32_update,
127	.final		= crc32_final,
128	.finup		= crc32_finup,
129	.digest		= crc32_digest,
130	.descsize	= sizeof(u32),
131	.digestsize	= CHKSUM_DIGEST_SIZE,
132	.base		= {
133		.cra_name		= "crc32",
134		.cra_driver_name	= "crc32-table",
135		.cra_priority		= 100,
136		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
137		.cra_ctxsize		= sizeof(u32),
138		.cra_module		= THIS_MODULE,
139		.cra_init		= crc32_cra_init,
140	}
141};
142
143static int __init crc32_mod_init(void)
144{
145	return crypto_register_shash(&alg);
146}
147
148static void __exit crc32_mod_fini(void)
149{
150	crypto_unregister_shash(&alg);
151}
152
153module_init(crc32_mod_init);
154module_exit(crc32_mod_fini);
155
156MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
157MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
158MODULE_LICENSE("GPL");
159