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1da177e4 LT |
1 | /* |
2 | * Cryptographic API. | |
3 | * | |
4 | * CRC32C chksum | |
5 | * | |
6 | * This module file is a wrapper to invoke the lib/crc32c routines. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License as published by the Free | |
10 | * Software Foundation; either version 2 of the License, or (at your option) | |
11 | * any later version. | |
12 | * | |
13 | */ | |
14 | #include <linux/init.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/string.h> | |
17 | #include <linux/crypto.h> | |
18 | #include <linux/crc32c.h> | |
19 | #include <asm/byteorder.h> | |
20 | ||
21 | #define CHKSUM_BLOCK_SIZE 32 | |
22 | #define CHKSUM_DIGEST_SIZE 4 | |
23 | ||
24 | struct chksum_ctx { | |
25 | u32 crc; | |
26 | }; | |
27 | ||
28 | /* | |
29 | * Steps through buffer one byte at at time, calculates reflected | |
30 | * crc using table. | |
31 | */ | |
32 | ||
33 | static void chksum_init(void *ctx) | |
34 | { | |
35 | struct chksum_ctx *mctx = ctx; | |
36 | ||
37 | mctx->crc = ~(u32)0; /* common usage */ | |
38 | } | |
39 | ||
40 | /* | |
41 | * Setting the seed allows arbitrary accumulators and flexible XOR policy | |
42 | * If your algorithm starts with ~0, then XOR with ~0 before you set | |
43 | * the seed. | |
44 | */ | |
45 | static int chksum_setkey(void *ctx, const u8 *key, unsigned int keylen, | |
46 | u32 *flags) | |
47 | { | |
48 | struct chksum_ctx *mctx = ctx; | |
49 | ||
50 | if (keylen != sizeof(mctx->crc)) { | |
51 | if (flags) | |
52 | *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; | |
53 | return -EINVAL; | |
54 | } | |
55 | mctx->crc = __cpu_to_le32(*(u32 *)key); | |
56 | return 0; | |
57 | } | |
58 | ||
59 | static void chksum_update(void *ctx, const u8 *data, unsigned int length) | |
60 | { | |
61 | struct chksum_ctx *mctx = ctx; | |
62 | u32 mcrc; | |
63 | ||
64 | mcrc = crc32c(mctx->crc, data, (size_t)length); | |
65 | ||
66 | mctx->crc = mcrc; | |
67 | } | |
68 | ||
69 | static void chksum_final(void *ctx, u8 *out) | |
70 | { | |
71 | struct chksum_ctx *mctx = ctx; | |
72 | u32 mcrc = (mctx->crc ^ ~(u32)0); | |
73 | ||
74 | *(u32 *)out = __le32_to_cpu(mcrc); | |
75 | } | |
76 | ||
77 | static struct crypto_alg alg = { | |
78 | .cra_name = "crc32c", | |
79 | .cra_flags = CRYPTO_ALG_TYPE_DIGEST, | |
80 | .cra_blocksize = CHKSUM_BLOCK_SIZE, | |
81 | .cra_ctxsize = sizeof(struct chksum_ctx), | |
82 | .cra_module = THIS_MODULE, | |
83 | .cra_list = LIST_HEAD_INIT(alg.cra_list), | |
84 | .cra_u = { | |
85 | .digest = { | |
86 | .dia_digestsize= CHKSUM_DIGEST_SIZE, | |
87 | .dia_setkey = chksum_setkey, | |
88 | .dia_init = chksum_init, | |
89 | .dia_update = chksum_update, | |
90 | .dia_final = chksum_final | |
91 | } | |
92 | } | |
93 | }; | |
94 | ||
95 | static int __init init(void) | |
96 | { | |
97 | return crypto_register_alg(&alg); | |
98 | } | |
99 | ||
100 | static void __exit fini(void) | |
101 | { | |
102 | crypto_unregister_alg(&alg); | |
103 | } | |
104 | ||
105 | module_init(init); | |
106 | module_exit(fini); | |
107 | ||
108 | MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); | |
109 | MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); | |
110 | MODULE_LICENSE("GPL"); |