1/* (C) 1999-2001 Paul `Rusty' Russell 2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 3 * (C) 2008 Patrick McHardy <kaber@trash.net> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10#include <linux/types.h> 11#include <linux/init.h> 12#include <linux/ip.h> 13#include <linux/udp.h> 14 15#include <linux/netfilter.h> 16#include <net/netfilter/nf_nat.h> 17#include <net/netfilter/nf_nat_protocol.h> 18 19static u_int16_t udplite_port_rover; 20 21static void 22udplite_unique_tuple(struct nf_conntrack_tuple *tuple, 23 const struct nf_nat_range *range, 24 enum nf_nat_manip_type maniptype, 25 const struct nf_conn *ct) 26{ 27 nf_nat_proto_unique_tuple(tuple, range, maniptype, ct, 28 &udplite_port_rover); 29} 30 31static bool 32udplite_manip_pkt(struct sk_buff *skb, 33 unsigned int iphdroff, 34 const struct nf_conntrack_tuple *tuple, 35 enum nf_nat_manip_type maniptype) 36{ 37 const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff); 38 struct udphdr *hdr; 39 unsigned int hdroff = iphdroff + iph->ihl*4; 40 __be32 oldip, newip; 41 __be16 *portptr, newport; 42 43 if (!skb_make_writable(skb, hdroff + sizeof(*hdr))) 44 return false; 45 46 iph = (struct iphdr *)(skb->data + iphdroff); 47 hdr = (struct udphdr *)(skb->data + hdroff); 48 49 if (maniptype == IP_NAT_MANIP_SRC) { 50 /* Get rid of src ip and src pt */ 51 oldip = iph->saddr; 52 newip = tuple->src.u3.ip; 53 newport = tuple->src.u.udp.port; 54 portptr = &hdr->source; 55 } else { 56 /* Get rid of dst ip and dst pt */ 57 oldip = iph->daddr; 58 newip = tuple->dst.u3.ip; 59 newport = tuple->dst.u.udp.port; 60 portptr = &hdr->dest; 61 } 62 63 inet_proto_csum_replace4(&hdr->check, skb, oldip, newip, 1); 64 inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport, 0); 65 if (!hdr->check) 66 hdr->check = CSUM_MANGLED_0; 67 68 *portptr = newport; 69 return true; 70} 71 72static const struct nf_nat_protocol nf_nat_protocol_udplite = { 73 .protonum = IPPROTO_UDPLITE, 74 .me = THIS_MODULE, 75 .manip_pkt = udplite_manip_pkt, 76 .in_range = nf_nat_proto_in_range, 77 .unique_tuple = udplite_unique_tuple, 78#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 79 .range_to_nlattr = nf_nat_proto_range_to_nlattr, 80 .nlattr_to_range = nf_nat_proto_nlattr_to_range, 81#endif 82}; 83 84static int __init nf_nat_proto_udplite_init(void) 85{ 86 return nf_nat_protocol_register(&nf_nat_protocol_udplite); 87} 88 89static void __exit nf_nat_proto_udplite_fini(void) 90{ 91 nf_nat_protocol_unregister(&nf_nat_protocol_udplite); 92} 93 94module_init(nf_nat_proto_udplite_init); 95module_exit(nf_nat_proto_udplite_fini); 96 97MODULE_LICENSE("GPL"); 98MODULE_DESCRIPTION("UDP-Lite NAT protocol helper"); 99MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); 100