tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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
24struct 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
33static 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 */
45static 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
59static 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
69static 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
77static 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
95static int __init init(void)
96{
97 return crypto_register_alg(&alg);
98}
99
100static void __exit fini(void)
101{
102 crypto_unregister_alg(&alg);
103}
104
105module_init(init);
106module_exit(fini);
107
108MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
109MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
110MODULE_LICENSE("GPL");