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netfilter: nf_nat: use local variable hdrlen
[mirror_ubuntu-bionic-kernel.git] / net / ipv4 / netfilter / nf_nat_proto_sctp.c
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1/*
2 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/types.h>
10#include <linux/init.h>
11#include <linux/ip.h>
12#include <linux/sctp.h>
13#include <net/sctp/checksum.h>
14
15#include <net/netfilter/nf_nat_protocol.h>
16
17static u_int16_t nf_sctp_port_rover;
18
f2ea825f 19static bool
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20sctp_unique_tuple(struct nf_conntrack_tuple *tuple,
21 const struct nf_nat_range *range,
22 enum nf_nat_manip_type maniptype,
23 const struct nf_conn *ct)
24{
25 return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
26 &nf_sctp_port_rover);
27}
28
f2ea825f 29static bool
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30sctp_manip_pkt(struct sk_buff *skb,
31 unsigned int iphdroff,
32 const struct nf_conntrack_tuple *tuple,
33 enum nf_nat_manip_type maniptype)
34{
35 const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
343a9972 36 struct sk_buff *frag;
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37 sctp_sctphdr_t *hdr;
38 unsigned int hdroff = iphdroff + iph->ihl*4;
39 __be32 oldip, newip;
336d3262 40 __be32 crc32;
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41
42 if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
f2ea825f 43 return false;
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44
45 iph = (struct iphdr *)(skb->data + iphdroff);
46 hdr = (struct sctphdr *)(skb->data + hdroff);
47
48 if (maniptype == IP_NAT_MANIP_SRC) {
49 /* Get rid of src ip and src pt */
50 oldip = iph->saddr;
51 newip = tuple->src.u3.ip;
52 hdr->source = tuple->src.u.sctp.port;
53 } else {
54 /* Get rid of dst ip and dst pt */
55 oldip = iph->daddr;
56 newip = tuple->dst.u3.ip;
57 hdr->dest = tuple->dst.u.sctp.port;
58 }
59
60 crc32 = sctp_start_cksum((u8 *)hdr, skb_headlen(skb) - hdroff);
0808dc80 61 skb_walk_frags(skb, frag)
343a9972 62 crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag),
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63 crc32);
64 crc32 = sctp_end_cksum(crc32);
336d3262 65 hdr->checksum = crc32;
9d908a69 66
f2ea825f 67 return true;
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68}
69
70static const struct nf_nat_protocol nf_nat_protocol_sctp = {
71 .protonum = IPPROTO_SCTP,
72 .me = THIS_MODULE,
73 .manip_pkt = sctp_manip_pkt,
74 .in_range = nf_nat_proto_in_range,
75 .unique_tuple = sctp_unique_tuple,
76#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
77 .range_to_nlattr = nf_nat_proto_range_to_nlattr,
78 .nlattr_to_range = nf_nat_proto_nlattr_to_range,
79#endif
80};
81
82static int __init nf_nat_proto_sctp_init(void)
83{
84 return nf_nat_protocol_register(&nf_nat_protocol_sctp);
85}
86
87static void __exit nf_nat_proto_sctp_exit(void)
88{
89 nf_nat_protocol_unregister(&nf_nat_protocol_sctp);
90}
91
92module_init(nf_nat_proto_sctp_init);
93module_exit(nf_nat_proto_sctp_exit);
94
95MODULE_LICENSE("GPL");
96MODULE_DESCRIPTION("SCTP NAT protocol helper");
97MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");