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/udp.h>
  12
  13 #include <linux/netfilter.h>
  14 #include <net/netfilter/nf_nat.h>
  15 #include <net/netfilter/nf_nat_l3proto.h>
  16 #include <net/netfilter/nf_nat_l4proto.h>
  17
  18 static u16 udplite_port_rover;
  19
  20 static void
  21 udplite_unique_tuple(const struct nf_nat_l3proto *l3proto,
  22                      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_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
  28                                     &udplite_port_rover);
  29 }
  30
  31 static bool
  32 udplite_manip_pkt(struct sk_buff *skb,
  33                   const struct nf_nat_l3proto *l3proto,
  34                   unsigned int iphdroff, unsigned int hdroff,
  35                   const struct nf_conntrack_tuple *tuple,
  36                   enum nf_nat_manip_type maniptype)
  37 {
  38         struct udphdr *hdr;
  39         __be16 *portptr, newport;
  40
  41         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  42                 return false;
  43
  44         hdr = (struct udphdr *)(skb->data + hdroff);
  45
  46         if (maniptype == NF_NAT_MANIP_SRC) {
  47                 /* Get rid of source port */
  48                 newport = tuple->src.u.udp.port;
  49                 portptr = &hdr->source;
  50         } else {
  51                 /* Get rid of dst port */
  52                 newport = tuple->dst.u.udp.port;
  53                 portptr = &hdr->dest;
  54         }
  55
  56         l3proto->csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
  57         inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport, false);
  58         if (!hdr->check)
  59                 hdr->check = CSUM_MANGLED_0;
  60
  61         *portptr = newport;
  62         return true;
  63 }
  64
  65 const struct nf_nat_l4proto nf_nat_l4proto_udplite = {
  66         .l4proto                = IPPROTO_UDPLITE,
  67         .manip_pkt              = udplite_manip_pkt,
  68         .in_range               = nf_nat_l4proto_in_range,
  69         .unique_tuple           = udplite_unique_tuple,
  70 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  71         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
  72 #endif
  73 };