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 19static void 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 nf_nat_proto_unique_tuple(tuple, range, maniptype, ct, 26 &nf_sctp_port_rover); 27} 28 29static bool 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); 36 struct sk_buff *frag; 37 sctp_sctphdr_t *hdr; 38 unsigned int hdroff = iphdroff + iph->ihl*4; 39 __be32 oldip, newip; 40 __be32 crc32; 41 42 if (!skb_make_writable(skb, hdroff + sizeof(*hdr))) 43 return false; 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); 61 skb_walk_frags(skb, frag) 62 crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag), 63 crc32); 64 crc32 = sctp_end_cksum(crc32); 65 hdr->checksum = crc32; 66 67 return true; 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>"); 98