LXR linux/net/ipv4/netfilter/nf_nat_proto

   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 bool
  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        return 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