net/netfilter/nf_nat_proto_udplite.c

   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/udp.h>
  13
  14 #include <linux/netfilter.h>
  15 #include <linux/module.h>
  16 #include <net/netfilter/nf_nat.h>
  17 #include <net/netfilter/nf_nat_l3proto.h>
  18 #include <net/netfilter/nf_nat_l4proto.h>
  19
  20 static u16 udplite_port_rover;
  21
  22 static void
  23 udplite_unique_tuple(const struct nf_nat_l3proto *l3proto,
  24                      struct nf_conntrack_tuple *tuple,
  25                      const struct nf_nat_range *range,
  26                      enum nf_nat_manip_type maniptype,
  27                      const struct nf_conn *ct)
  28 {
  29         nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
  30                                     &udplite_port_rover);
  31 }
  32
  33 static bool
  34 udplite_manip_pkt(struct sk_buff *skb,
  35                   const struct nf_nat_l3proto *l3proto,
  36                   unsigned int iphdroff, unsigned int hdroff,
  37                   const struct nf_conntrack_tuple *tuple,
  38                   enum nf_nat_manip_type maniptype)
  39 {
  40         struct udphdr *hdr;
  41         __be16 *portptr, newport;
  42
  43         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  44                 return false;
  45
  46         hdr = (struct udphdr *)(skb->data + hdroff);
  47
  48         if (maniptype == NF_NAT_MANIP_SRC) {
  49                 /* Get rid of source port */
  50                 newport = tuple->src.u.udp.port;
  51                 portptr = &hdr->source;
  52         } else {
  53                 /* Get rid of dst port */
  54                 newport = tuple->dst.u.udp.port;
  55                 portptr = &hdr->dest;
  56         }
  57
  58         l3proto->csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
  59         inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport, 0);
  60         if (!hdr->check)
  61                 hdr->check = CSUM_MANGLED_0;
  62
  63         *portptr = newport;
  64         return true;
  65 }
  66
  67 static const struct nf_nat_l4proto nf_nat_l4proto_udplite = {
  68         .l4proto                = IPPROTO_UDPLITE,
  69         .manip_pkt              = udplite_manip_pkt,
  70         .in_range               = nf_nat_l4proto_in_range,
  71         .unique_tuple           = udplite_unique_tuple,
  72 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
  73         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
  74 #endif
  75 };
  76
  77 static int __init nf_nat_proto_udplite_init(void)
  78 {
  79         int err;
  80
  81         err = nf_nat_l4proto_register(NFPROTO_IPV4, &nf_nat_l4proto_udplite);
  82         if (err < 0)
  83                 goto err1;
  84         err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_udplite);
  85         if (err < 0)
  86                 goto err2;
  87         return 0;
  88
  89 err2:
  90         nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_udplite);
  91 err1:
  92         return err;
  93 }
  94
  95 static void __exit nf_nat_proto_udplite_fini(void)
  96 {
  97         nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_udplite);
  98         nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_udplite);
  99 }
 100
 101 module_init(nf_nat_proto_udplite_init);
 102 module_exit(nf_nat_proto_udplite_fini);
 103
 104 MODULE_LICENSE("GPL");
 105 MODULE_DESCRIPTION("UDP-Lite NAT protocol helper");
 106 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");