Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-or-later
2 : /*
3 : * Cryptographic API.
4 : *
5 : * CRC32C chksum
6 : *
7 : *@Article{castagnoli-crc,
8 : * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
9 : * title = {{Optimization of Cyclic Redundancy-Check Codes with 24
10 : * and 32 Parity Bits}},
11 : * journal = IEEE Transactions on Communication,
12 : * year = {1993},
13 : * volume = {41},
14 : * number = {6},
15 : * pages = {},
16 : * month = {June},
17 : *}
18 : * Used by the iSCSI driver, possibly others, and derived from
19 : * the iscsi-crc.c module of the linux-iscsi driver at
20 : * http://linux-iscsi.sourceforge.net.
21 : *
22 : * Following the example of lib/crc32, this function is intended to be
23 : * flexible and useful for all users. Modules that currently have their
24 : * own crc32c, but hopefully may be able to use this one are:
25 : * net/sctp (please add all your doco to here if you change to
26 : * use this one!)
27 : * <endoflist>
28 : *
29 : * Copyright (c) 2004 Cisco Systems, Inc.
30 : * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
31 : */
32 :
33 : #include <asm/unaligned.h>
34 : #include <crypto/internal/hash.h>
35 : #include <linux/init.h>
36 : #include <linux/module.h>
37 : #include <linux/string.h>
38 : #include <linux/kernel.h>
39 : #include <linux/crc32.h>
40 :
41 : #define CHKSUM_BLOCK_SIZE 1
42 : #define CHKSUM_DIGEST_SIZE 4
43 :
44 : struct chksum_ctx {
45 : u32 key;
46 : };
47 :
48 : struct chksum_desc_ctx {
49 : u32 crc;
50 : };
51 :
52 : /*
53 : * Steps through buffer one byte at a time, calculates reflected
54 : * crc using table.
55 : */
56 :
57 0 : static int chksum_init(struct shash_desc *desc)
58 : {
59 0 : struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
60 0 : struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
61 :
62 0 : ctx->crc = mctx->key;
63 :
64 0 : return 0;
65 : }
66 :
67 : /*
68 : * Setting the seed allows arbitrary accumulators and flexible XOR policy
69 : * If your algorithm starts with ~0, then XOR with ~0 before you set
70 : * the seed.
71 : */
72 0 : static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
73 : unsigned int keylen)
74 : {
75 0 : struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
76 :
77 0 : if (keylen != sizeof(mctx->key))
78 : return -EINVAL;
79 0 : mctx->key = get_unaligned_le32(key);
80 0 : return 0;
81 : }
82 :
83 0 : static int chksum_update(struct shash_desc *desc, const u8 *data,
84 : unsigned int length)
85 : {
86 0 : struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
87 :
88 0 : ctx->crc = __crc32c_le(ctx->crc, data, length);
89 0 : return 0;
90 : }
91 :
92 0 : static int chksum_final(struct shash_desc *desc, u8 *out)
93 : {
94 0 : struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
95 :
96 0 : put_unaligned_le32(~ctx->crc, out);
97 0 : return 0;
98 : }
99 :
100 0 : static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
101 : {
102 0 : put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);
103 0 : return 0;
104 : }
105 :
106 0 : static int chksum_finup(struct shash_desc *desc, const u8 *data,
107 : unsigned int len, u8 *out)
108 : {
109 0 : struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
110 :
111 0 : return __chksum_finup(&ctx->crc, data, len, out);
112 : }
113 :
114 0 : static int chksum_digest(struct shash_desc *desc, const u8 *data,
115 : unsigned int length, u8 *out)
116 : {
117 0 : struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
118 :
119 0 : return __chksum_finup(&mctx->key, data, length, out);
120 : }
121 :
122 2 : static int crc32c_cra_init(struct crypto_tfm *tfm)
123 : {
124 2 : struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
125 :
126 2 : mctx->key = ~0;
127 2 : return 0;
128 : }
129 :
130 : static struct shash_alg alg = {
131 : .digestsize = CHKSUM_DIGEST_SIZE,
132 : .setkey = chksum_setkey,
133 : .init = chksum_init,
134 : .update = chksum_update,
135 : .final = chksum_final,
136 : .finup = chksum_finup,
137 : .digest = chksum_digest,
138 : .descsize = sizeof(struct chksum_desc_ctx),
139 : .base = {
140 : .cra_name = "crc32c",
141 : .cra_driver_name = "crc32c-generic",
142 : .cra_priority = 100,
143 : .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
144 : .cra_blocksize = CHKSUM_BLOCK_SIZE,
145 : .cra_ctxsize = sizeof(struct chksum_ctx),
146 : .cra_module = THIS_MODULE,
147 : .cra_init = crc32c_cra_init,
148 : }
149 : };
150 :
151 1 : static int __init crc32c_mod_init(void)
152 : {
153 1 : return crypto_register_shash(&alg);
154 : }
155 :
156 0 : static void __exit crc32c_mod_fini(void)
157 : {
158 0 : crypto_unregister_shash(&alg);
159 0 : }
160 :
161 : subsys_initcall(crc32c_mod_init);
162 : module_exit(crc32c_mod_fini);
163 :
164 : MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
165 : MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
166 : MODULE_LICENSE("GPL");
167 : MODULE_ALIAS_CRYPTO("crc32c");
168 : MODULE_ALIAS_CRYPTO("crc32c-generic");
|
