net/netfilter/nf_nat_proto_sctp.c

   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/sctp.h>
  11 #include <net/sctp/checksum.h>
  12
  13 #include <net/netfilter/nf_nat_l4proto.h>
  14
  15 static u_int16_t nf_sctp_port_rover;
  16
  17 static void
  18 sctp_unique_tuple(const struct nf_nat_l3proto *l3proto,
  19                   struct nf_conntrack_tuple *tuple,
  20                   const struct nf_nat_range *range,
  21                   enum nf_nat_manip_type maniptype,
  22                   const struct nf_conn *ct)
  23 {
  24         nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
  25                                     &nf_sctp_port_rover);
  26 }
  27
  28 static bool
  29 sctp_manip_pkt(struct sk_buff *skb,
  30                const struct nf_nat_l3proto *l3proto,
  31                unsigned int iphdroff, unsigned int hdroff,
  32                const struct nf_conntrack_tuple *tuple,
  33                enum nf_nat_manip_type maniptype)
  34 {
  35         sctp_sctphdr_t *hdr;
  36
  37         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  38                 return false;
  39
  40         hdr = (struct sctphdr *)(skb->data + hdroff);
  41
  42         if (maniptype == NF_NAT_MANIP_SRC) {
  43                 /* Get rid of src port */
  44                 hdr->source = tuple->src.u.sctp.port;
  45         } else {
  46                 /* Get rid of dst port */
  47                 hdr->dest = tuple->dst.u.sctp.port;
  48         }
  49
  50         hdr->checksum = sctp_compute_cksum(skb, hdroff);
  51
  52         return true;
  53 }
  54
  55 const struct nf_nat_l4proto nf_nat_l4proto_sctp = {
  56         .l4proto                = IPPROTO_SCTP,
  57         .manip_pkt              = sctp_manip_pkt,
  58         .in_range               = nf_nat_l4proto_in_range,
  59         .unique_tuple           = sctp_unique_tuple,
  60 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  61         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
  62 #endif
  63 };