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9#include <linux/types.h>
10#include <linux/init.h>
11#include <linux/sctp.h>
12#include <linux/module.h>
13#include <net/sctp/checksum.h>
14
15#include <net/netfilter/nf_nat_l4proto.h>
16
17static u_int16_t nf_sctp_port_rover;
18
19static void
20sctp_unique_tuple(const struct nf_nat_l3proto *l3proto,
21 struct nf_conntrack_tuple *tuple,
22 const struct nf_nat_range *range,
23 enum nf_nat_manip_type maniptype,
24 const struct nf_conn *ct)
25{
26 nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
27 &nf_sctp_port_rover);
28}
29
30static bool
31sctp_manip_pkt(struct sk_buff *skb,
32 const struct nf_nat_l3proto *l3proto,
33 unsigned int iphdroff, unsigned int hdroff,
34 const struct nf_conntrack_tuple *tuple,
35 enum nf_nat_manip_type maniptype)
36{
37 struct sk_buff *frag;
38 sctp_sctphdr_t *hdr;
39 __u32 crc32;
40
41 if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
42 return false;
43
44 hdr = (struct sctphdr *)(skb->data + hdroff);
45
46 if (maniptype == NF_NAT_MANIP_SRC) {
47
48 hdr->source = tuple->src.u.sctp.port;
49 } else {
50
51 hdr->dest = tuple->dst.u.sctp.port;
52 }
53
54 crc32 = sctp_start_cksum((u8 *)hdr, skb_headlen(skb) - hdroff);
55 skb_walk_frags(skb, frag)
56 crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag),
57 crc32);
58 hdr->checksum = sctp_end_cksum(crc32);
59
60 return true;
61}
62
63static const struct nf_nat_l4proto nf_nat_l4proto_sctp = {
64 .l4proto = IPPROTO_SCTP,
65 .manip_pkt = sctp_manip_pkt,
66 .in_range = nf_nat_l4proto_in_range,
67 .unique_tuple = sctp_unique_tuple,
68#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
69 .nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
70#endif
71};
72
73static int __init nf_nat_proto_sctp_init(void)
74{
75 int err;
76
77 err = nf_nat_l4proto_register(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
78 if (err < 0)
79 goto err1;
80 err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_sctp);
81 if (err < 0)
82 goto err2;
83 return 0;
84
85err2:
86 nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
87err1:
88 return err;
89}
90
91static void __exit nf_nat_proto_sctp_exit(void)
92{
93 nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_sctp);
94 nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
95}
96
97module_init(nf_nat_proto_sctp_init);
98module_exit(nf_nat_proto_sctp_exit);
99
100MODULE_LICENSE("GPL");
101MODULE_DESCRIPTION("SCTP NAT protocol helper");
102MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
103