1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* SCTP kernel reference Implementation
3  * Copyright (c) 1999-2001 Motorola, Inc.
4  * Copyright (c) 2001-2003 International Business Machines, Corp.
5  *
6  * This file is part of the SCTP kernel reference Implementation
7  *
8  * SCTP Checksum functions
9  *
10  * Please send any bug reports or fixes you make to the
11  * email address(es):
12  *    lksctp developers <linux-sctp@vger.kernel.org>
13  *
14  * Written or modified by:
15  *    Dinakaran Joseph
16  *    Jon Grimm <jgrimm@us.ibm.com>
17  *    Sridhar Samudrala <sri@us.ibm.com>
18  *
19  * Rewritten to use libcrc32c by:
20  *    Vlad Yasevich <vladislav.yasevich@hp.com>
21  */
22 
23 #ifndef __sctp_checksum_h__
24 #define __sctp_checksum_h__
25 
26 #include <linux/types.h>
27 #include <net/sctp/sctp.h>
28 #include <linux/crc32c.h>
29 #include <linux/crc32.h>
30 
sctp_csum_update(const void * buff,int len,__wsum sum)31 static inline __wsum sctp_csum_update(const void *buff, int len, __wsum sum)
32 {
33 	/* This uses the crypto implementation of crc32c, which is either
34 	 * implemented w/ hardware support or resolves to __crc32c_le().
35 	 */
36 	return (__force __wsum)crc32c((__force __u32)sum, buff, len);
37 }
38 
sctp_csum_combine(__wsum csum,__wsum csum2,int offset,int len)39 static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
40 				       int offset, int len)
41 {
42 	return (__force __wsum)__crc32c_le_combine((__force __u32)csum,
43 						   (__force __u32)csum2, len);
44 }
45 
46 static const struct skb_checksum_ops sctp_csum_ops = {
47 	.update  = sctp_csum_update,
48 	.combine = sctp_csum_combine,
49 };
50 
sctp_compute_cksum(const struct sk_buff * skb,unsigned int offset)51 static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
52 					unsigned int offset)
53 {
54 	struct sctphdr *sh = (struct sctphdr *)(skb->data + offset);
55 	__le32 old = sh->checksum;
56 	__wsum new;
57 
58 	sh->checksum = 0;
59 	new = ~__skb_checksum(skb, offset, skb->len - offset, ~(__wsum)0,
60 			      &sctp_csum_ops);
61 	sh->checksum = old;
62 
63 	return cpu_to_le32((__force __u32)new);
64 }
65 
66 #endif /* __sctp_checksum_h__ */
67