]>
Commit | Line | Data |
---|---|---|
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"); |