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 the
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 at time, calculates reflected
54 * crc using table.
55 */
56
chksum_init(struct shash_desc * desc)57 static int chksum_init(struct shash_desc *desc)
58 {
59 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
60 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
61
62 ctx->crc = mctx->key;
63
64 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 */
chksum_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)72 static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
73 unsigned int keylen)
74 {
75 struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
76
77 if (keylen != sizeof(mctx->key)) {
78 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
79 return -EINVAL;
80 }
81 mctx->key = get_unaligned_le32(key);
82 return 0;
83 }
84
chksum_update(struct shash_desc * desc,const u8 * data,unsigned int length)85 static int chksum_update(struct shash_desc *desc, const u8 *data,
86 unsigned int length)
87 {
88 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
89
90 ctx->crc = __crc32c_le(ctx->crc, data, length);
91 return 0;
92 }
93
chksum_final(struct shash_desc * desc,u8 * out)94 static int chksum_final(struct shash_desc *desc, u8 *out)
95 {
96 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
97
98 put_unaligned_le32(~ctx->crc, out);
99 return 0;
100 }
101
__chksum_finup(u32 * crcp,const u8 * data,unsigned int len,u8 * out)102 static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
103 {
104 put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);
105 return 0;
106 }
107
chksum_finup(struct shash_desc * desc,const u8 * data,unsigned int len,u8 * out)108 static int chksum_finup(struct shash_desc *desc, const u8 *data,
109 unsigned int len, u8 *out)
110 {
111 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
112
113 return __chksum_finup(&ctx->crc, data, len, out);
114 }
115
chksum_digest(struct shash_desc * desc,const u8 * data,unsigned int length,u8 * out)116 static int chksum_digest(struct shash_desc *desc, const u8 *data,
117 unsigned int length, u8 *out)
118 {
119 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
120
121 return __chksum_finup(&mctx->key, data, length, out);
122 }
123
crc32c_cra_init(struct crypto_tfm * tfm)124 static int crc32c_cra_init(struct crypto_tfm *tfm)
125 {
126 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
127
128 mctx->key = ~0;
129 return 0;
130 }
131
132 static struct shash_alg alg = {
133 .digestsize = CHKSUM_DIGEST_SIZE,
134 .setkey = chksum_setkey,
135 .init = chksum_init,
136 .update = chksum_update,
137 .final = chksum_final,
138 .finup = chksum_finup,
139 .digest = chksum_digest,
140 .descsize = sizeof(struct chksum_desc_ctx),
141 .base = {
142 .cra_name = "crc32c",
143 .cra_driver_name = "crc32c-generic",
144 .cra_priority = 100,
145 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
146 .cra_blocksize = CHKSUM_BLOCK_SIZE,
147 .cra_ctxsize = sizeof(struct chksum_ctx),
148 .cra_module = THIS_MODULE,
149 .cra_init = crc32c_cra_init,
150 }
151 };
152
crc32c_mod_init(void)153 static int __init crc32c_mod_init(void)
154 {
155 return crypto_register_shash(&alg);
156 }
157
crc32c_mod_fini(void)158 static void __exit crc32c_mod_fini(void)
159 {
160 crypto_unregister_shash(&alg);
161 }
162
163 subsys_initcall(crc32c_mod_init);
164 module_exit(crc32c_mod_fini);
165
166 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
167 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
168 MODULE_LICENSE("GPL");
169 MODULE_ALIAS_CRYPTO("crc32c");
170 MODULE_ALIAS_CRYPTO("crc32c-generic");
171