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/init.h>
  11 #include <linux/sctp.h>
  12 #include <linux/module.h>
  13 #include <net/sctp/checksum.h>
  14
  15 #include <net/netfilter/nf_nat_l4proto.h>
  16
  17 static u_int16_t nf_sctp_port_rover;
  18
  19 static void
  20 sctp_unique_tuple(const struct nf_nat_l3proto *l3proto,
  21                   struct nf_conntrack_tuple *tuple,
  22                   const struct nf_nat_range *range,
  23                   enum nf_nat_manip_type maniptype,
  24                   const struct nf_conn *ct)
  25 {
  26         nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
  27                                     &nf_sctp_port_rover);
  28 }
  29
  30 static bool
  31 sctp_manip_pkt(struct sk_buff *skb,
  32                const struct nf_nat_l3proto *l3proto,
  33                unsigned int iphdroff, unsigned int hdroff,
  34                const struct nf_conntrack_tuple *tuple,
  35                enum nf_nat_manip_type maniptype)
  36 {
  37         sctp_sctphdr_t *hdr;
  38
  39         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  40                 return false;
  41
  42         hdr = (struct sctphdr *)(skb->data + hdroff);
  43
  44         if (maniptype == NF_NAT_MANIP_SRC) {
  45                 /* Get rid of src port */
  46                 hdr->source = tuple->src.u.sctp.port;
  47         } else {
  48                 /* Get rid of dst port */
  49                 hdr->dest = tuple->dst.u.sctp.port;
  50         }
  51
  52         hdr->checksum = sctp_compute_cksum(skb, hdroff);
  53
  54         return true;
  55 }
  56
  57 static const struct nf_nat_l4proto nf_nat_l4proto_sctp = {
  58         .l4proto                = IPPROTO_SCTP,
  59         .manip_pkt              = sctp_manip_pkt,
  60         .in_range               = nf_nat_l4proto_in_range,
  61         .unique_tuple           = sctp_unique_tuple,
  62 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  63         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
  64 #endif
  65 };
  66
  67 static int __init nf_nat_proto_sctp_init(void)
  68 {
  69         int err;
  70
  71         err = nf_nat_l4proto_register(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
  72         if (err < 0)
  73                 goto err1;
  74         err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_sctp);
  75         if (err < 0)
  76                 goto err2;
  77         return 0;
  78
  79 err2:
  80         nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
  81 err1:
  82         return err;
  83 }
  84
  85 static void __exit nf_nat_proto_sctp_exit(void)
  86 {
  87         nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_sctp);
  88         nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_sctp);
  89 }
  90
  91 module_init(nf_nat_proto_sctp_init);
  92 module_exit(nf_nat_proto_sctp_exit);
  93
  94 MODULE_LICENSE("GPL");
  95 MODULE_DESCRIPTION("SCTP NAT protocol helper");
  96 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");