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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_blocksize = CHKSUM_BLOCK_SIZE, |
150 | .cra_alignmask = 3, |
151 | .cra_ctxsize = sizeof(struct chksum_ctx), |
152 | .cra_module = THIS_MODULE, |
153 | .cra_init = crc32c_cra_init, |
154 | } |
155 | }; |
156 | |
157 | static int __init crc32c_mod_init(void) |
158 | { |
159 | return crypto_register_shash(&alg); |
160 | } |
161 | |
162 | static void __exit crc32c_mod_fini(void) |
163 | { |
164 | crypto_unregister_shash(&alg); |
165 | } |
166 | |
167 | module_init(crc32c_mod_init); |
168 | module_exit(crc32c_mod_fini); |
169 | |
170 | MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); |
171 | MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); |
172 | MODULE_LICENSE("GPL"); |
173 | MODULE_ALIAS("crc32c"); |
174 | MODULE_SOFTDEP("pre: crc32c"); |
175 |
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