1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * CRC32C
4  *@Article{castagnoli-crc,
5  * author =       { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
6  * title =        {{Optimization of Cyclic Redundancy-Check Codes with 24
7  *                 and 32 Parity Bits}},
8  * journal =      IEEE Transactions on Communication,
9  * year =         {1993},
10  * volume =       {41},
11  * number =       {6},
12  * pages =        {},
13  * month =        {June},
14  *}
15  * Used by the iSCSI driver, possibly others, and derived from
16  * the iscsi-crc.c module of the linux-iscsi driver at
17  * http://linux-iscsi.sourceforge.net.
18  *
19  * Following the example of lib/crc32, this function is intended to be
20  * flexible and useful for all users.  Modules that currently have their
21  * own crc32c, but hopefully may be able to use this one are:
22  *  net/sctp (please add all your doco to here if you change to
23  *            use this one!)
24  *  <endoflist>
25  *
26  * Copyright (c) 2004 Cisco Systems, Inc.
27  */
28 
29 #include <crypto/hash.h>
30 #include <linux/err.h>
31 #include <linux/init.h>
32 #include <linux/kernel.h>
33 #include <linux/module.h>
34 #include <linux/crc32c.h>
35 
36 static struct crypto_shash *tfm;
37 
crc32c(u32 crc,const void * address,unsigned int length)38 u32 crc32c(u32 crc, const void *address, unsigned int length)
39 {
40 	SHASH_DESC_ON_STACK(shash, tfm);
41 	u32 ret, *ctx = (u32 *)shash_desc_ctx(shash);
42 	int err;
43 
44 	shash->tfm = tfm;
45 	*ctx = crc;
46 
47 	err = crypto_shash_update(shash, address, length);
48 	BUG_ON(err);
49 
50 	ret = *ctx;
51 	barrier_data(ctx);
52 	return ret;
53 }
54 
55 EXPORT_SYMBOL(crc32c);
56 
libcrc32c_mod_init(void)57 static int __init libcrc32c_mod_init(void)
58 {
59 	tfm = crypto_alloc_shash("crc32c", 0, 0);
60 	return PTR_ERR_OR_ZERO(tfm);
61 }
62 
libcrc32c_mod_fini(void)63 static void __exit libcrc32c_mod_fini(void)
64 {
65 	crypto_free_shash(tfm);
66 }
67 
crc32c_impl(void)68 const char *crc32c_impl(void)
69 {
70 	return crypto_shash_driver_name(tfm);
71 }
72 EXPORT_SYMBOL(crc32c_impl);
73 
74 module_init(libcrc32c_mod_init);
75 module_exit(libcrc32c_mod_fini);
76 
77 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
78 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
79 MODULE_LICENSE("GPL");
80 MODULE_SOFTDEP("pre: crc32c");
81