Merge remote-tracking branch 'mailbox/mailbox-for-next'
[deliverable/linux.git] / crypto / crc32c_generic.c
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db83aabf 1/*
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2 * Cryptographic API.
3 *
4 * CRC32C chksum
5 *
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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.
1da177e4 20 *
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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.
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29 * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
30 *
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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
db83aabf 33 * Software Foundation; either version 2 of the License, or (at your option)
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34 * any later version.
35 *
36 */
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37
38#include <crypto/internal/hash.h>
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39#include <linux/init.h>
40#include <linux/module.h>
41#include <linux/string.h>
25cdbcd9 42#include <linux/kernel.h>
6a0962b2 43#include <linux/crc32.h>
1da177e4 44
5773a3e6 45#define CHKSUM_BLOCK_SIZE 1
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46#define CHKSUM_DIGEST_SIZE 4
47
48struct chksum_ctx {
25cdbcd9 49 u32 key;
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50};
51
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52struct chksum_desc_ctx {
53 u32 crc;
54};
55
1da177e4 56/*
db83aabf 57 * Steps through buffer one byte at at time, calculates reflected
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58 * crc using table.
59 */
60
faccc4bb 61static int chksum_init(struct shash_desc *desc)
1da177e4 62{
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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;
1da177e4 67
faccc4bb 68 return 0;
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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 */
faccc4bb 76static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
560c06ae 77 unsigned int keylen)
1da177e4 78{
faccc4bb 79 struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
1da177e4 80
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81 if (keylen != sizeof(mctx->key)) {
82 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
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83 return -EINVAL;
84 }
25cdbcd9 85 mctx->key = le32_to_cpu(*(__le32 *)key);
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86 return 0;
87}
88
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89static int chksum_update(struct shash_desc *desc, const u8 *data,
90 unsigned int length)
1da177e4 91{
faccc4bb 92 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
1da177e4 93
6a0962b2 94 ctx->crc = __crc32c_le(ctx->crc, data, length);
25cdbcd9 95 return 0;
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96}
97
faccc4bb 98static int chksum_final(struct shash_desc *desc, u8 *out)
5773a3e6 99{
faccc4bb 100 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
5773a3e6 101
faccc4bb 102 *(__le32 *)out = ~cpu_to_le32p(&ctx->crc);
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103 return 0;
104}
105
faccc4bb 106static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
5773a3e6 107{
6a0962b2 108 *(__le32 *)out = ~cpu_to_le32(__crc32c_le(*crcp, data, len));
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109 return 0;
110}
111
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112static int chksum_finup(struct shash_desc *desc, const u8 *data,
113 unsigned int len, u8 *out)
5773a3e6 114{
faccc4bb 115 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
5773a3e6 116
faccc4bb 117 return __chksum_finup(&ctx->crc, data, len, out);
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118}
119
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120static int chksum_digest(struct shash_desc *desc, const u8 *data,
121 unsigned int length, u8 *out)
5773a3e6 122{
faccc4bb 123 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
5773a3e6 124
faccc4bb 125 return __chksum_finup(&mctx->key, data, length, out);
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126}
127
128static int crc32c_cra_init(struct crypto_tfm *tfm)
129{
faccc4bb 130 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
5773a3e6 131
faccc4bb 132 mctx->key = ~0;
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133 return 0;
134}
135
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136static struct shash_alg alg = {
137 .digestsize = CHKSUM_DIGEST_SIZE,
138 .setkey = chksum_setkey,
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139 .init = chksum_init,
140 .update = chksum_update,
141 .final = chksum_final,
142 .finup = chksum_finup,
143 .digest = chksum_digest,
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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,
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154 }
155};
156
3af5b90b 157static int __init crc32c_mod_init(void)
1da177e4 158{
faccc4bb 159 return crypto_register_shash(&alg);
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160}
161
3af5b90b 162static void __exit crc32c_mod_fini(void)
1da177e4 163{
faccc4bb 164 crypto_unregister_shash(&alg);
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165}
166
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167module_init(crc32c_mod_init);
168module_exit(crc32c_mod_fini);
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169
170MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
171MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
172MODULE_LICENSE("GPL");
5d26a105 173MODULE_ALIAS_CRYPTO("crc32c");
3e14dcf7 174MODULE_ALIAS_CRYPTO("crc32c-generic");
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