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 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 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 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