path: root/crypto/crc32c_generic.c (plain)
blob: 372320399622df00f680dc160425d7ce7b85ff81

1	/*
2	* Cryptographic API.
3	*
4	* CRC32C chksum
5	*
6	*@Article{castagnoli-crc,
7	* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
8	* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
9	* and 32 Parity Bits}},
10	* journal = IEEE Transactions on Communication,
11	* year = {1993},
12	* volume = {41},
13	* number = {6},
14	* pages = {},
15	* month = {June},
16	*}
17	* Used by the iSCSI driver, possibly others, and derived from the
18	* the iscsi-crc.c module of the linux-iscsi driver at
19	* http://linux-iscsi.sourceforge.net.
20	*
21	* Following the example of lib/crc32, this function is intended to be
22	* flexible and useful for all users. Modules that currently have their
23	* own crc32c, but hopefully may be able to use this one are:
24	* net/sctp (please add all your doco to here if you change to
25	* use this one!)
26	* <endoflist>
27	*
28	* Copyright (c) 2004 Cisco Systems, Inc.
29	* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
30	*
31	* This program is free software; you can redistribute it and/or modify it
32	* under the terms of the GNU General Public License as published by the Free
33	* Software Foundation; either version 2 of the License, or (at your option)
34	* any later version.
35	*
36	*/
37
38	#include <crypto/internal/hash.h>
39	#include <linux/init.h>
40	#include <linux/module.h>
41	#include <linux/string.h>
42	#include <linux/kernel.h>
43	#include <linux/crc32.h>
44
45	#define CHKSUM_BLOCK_SIZE 1
46	#define CHKSUM_DIGEST_SIZE 4
47
48	struct chksum_ctx {
49	u32 key;
50	};
51
52	struct chksum_desc_ctx {
53	u32 crc;
54	};
55
56	/*
57	* Steps through buffer one byte at at time, calculates reflected
58	* crc using table.
59	*/
60
61	static int chksum_init(struct shash_desc *desc)
62	{
63	struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
64	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
65
66	ctx->crc = mctx->key;
67
68	return 0;
69	}
70
71	/*
72	* Setting the seed allows arbitrary accumulators and flexible XOR policy
73	* If your algorithm starts with ~0, then XOR with ~0 before you set
74	* the seed.
75	*/
76	static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
77	unsigned int keylen)
78	{
79	struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
80
81	if (keylen != sizeof(mctx->key)) {
82	crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
83	return -EINVAL;
84	}
85	mctx->key = le32_to_cpu(*(__le32 *)key);
86	return 0;
87	}
88
89	static int chksum_update(struct shash_desc *desc, const u8 *data,
90	unsigned int length)
91	{
92	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
93
94	ctx->crc = __crc32c_le(ctx->crc, data, length);
95	return 0;
96	}
97
98	static int chksum_final(struct shash_desc *desc, u8 *out)
99	{
100	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
101
102	*(__le32 *)out = ~cpu_to_le32p(&ctx->crc);
103	return 0;
104	}
105
106	static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
107	{
108	*(__le32 *)out = ~cpu_to_le32(__crc32c_le(*crcp, data, len));
109	return 0;
110	}
111
112	static int chksum_finup(struct shash_desc *desc, const u8 *data,
113	unsigned int len, u8 *out)
114	{
115	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
116
117	return __chksum_finup(&ctx->crc, data, len, out);
118	}
119
120	static int chksum_digest(struct shash_desc *desc, const u8 *data,
121	unsigned int length, u8 *out)
122	{
123	struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
124
125	return __chksum_finup(&mctx->key, data, length, out);
126	}
127
128	static int crc32c_cra_init(struct crypto_tfm *tfm)
129	{
130	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
131
132	mctx->key = ~0;
133	return 0;
134	}
135
136	static struct shash_alg alg = {
137	.digestsize = CHKSUM_DIGEST_SIZE,
138	.setkey = chksum_setkey,
139	.init = chksum_init,
140	.update = chksum_update,
141	.final = chksum_final,
142	.finup = chksum_finup,
143	.digest = chksum_digest,
144	.descsize = sizeof(struct chksum_desc_ctx),
145	.base = {
146	.cra_name = "crc32c",
147	.cra_driver_name = "crc32c-generic",
148	.cra_priority = 100,
149	.cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
150	.cra_blocksize = CHKSUM_BLOCK_SIZE,
151	.cra_alignmask = 3,
152	.cra_ctxsize = sizeof(struct chksum_ctx),
153	.cra_module = THIS_MODULE,
154	.cra_init = crc32c_cra_init,
155	}
156	};
157
158	static int __init crc32c_mod_init(void)
159	{
160	return crypto_register_shash(&alg);
161	}
162
163	static void __exit crc32c_mod_fini(void)
164	{
165	crypto_unregister_shash(&alg);
166	}
167
168	module_init(crc32c_mod_init);
169	module_exit(crc32c_mod_fini);
170
171	MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
172	MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
173	MODULE_LICENSE("GPL");
174	MODULE_ALIAS_CRYPTO("crc32c");
175	MODULE_ALIAS_CRYPTO("crc32c-generic");
176