LXR linux/net/netfilter/nf_conntrack_netbios

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      NetBIOS name service broadcast connection tracking helper
   4 *
   5 *      (c) 2005 Patrick McHardy <kaber@trash.net>
   6 */
   7/*
   8 *      This helper tracks locally originating NetBIOS name service
   9 *      requests by issuing permanent expectations (valid until
  10 *      timing out) matching all reply connections from the
  11 *      destination network. The only NetBIOS specific thing is
  12 *      actually the port number.
  13 */
  14#include <linux/kernel.h>
  15#include <linux/module.h>
  16#include <linux/init.h>
  17#include <linux/in.h>
  18
  19#include <net/netfilter/nf_conntrack.h>
  20#include <net/netfilter/nf_conntrack_helper.h>
  21#include <net/netfilter/nf_conntrack_expect.h>
  22
  23#define NMBD_PORT       137
  24
  25MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  26MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
  27MODULE_LICENSE("GPL");
  28MODULE_ALIAS("ip_conntrack_netbios_ns");
  29MODULE_ALIAS_NFCT_HELPER("netbios_ns");
  30
  31static unsigned int timeout __read_mostly = 3;
  32module_param(timeout, uint, 0400);
  33MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
  34
  35static struct nf_conntrack_expect_policy exp_policy = {
  36        .max_expected   = 1,
  37};
  38
  39static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff,
  40                           struct nf_conn *ct,
  41                           enum ip_conntrack_info ctinfo)
  42{
  43        return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout);
  44}
  45
  46static struct nf_conntrack_helper helper __read_mostly = {
  47        .name                   = "netbios-ns",
  48        .tuple.src.l3num        = NFPROTO_IPV4,
  49        .tuple.src.u.udp.port   = cpu_to_be16(NMBD_PORT),
  50        .tuple.dst.protonum     = IPPROTO_UDP,
  51        .me                     = THIS_MODULE,
  52        .help                   = netbios_ns_help,
  53        .expect_policy          = &exp_policy,
  54};
  55
  56static int __init nf_conntrack_netbios_ns_init(void)
  57{
  58        NF_CT_HELPER_BUILD_BUG_ON(0);
  59
  60        exp_policy.timeout = timeout;
  61        return nf_conntrack_helper_register(&helper);
  62}
  63
  64static void __exit nf_conntrack_netbios_ns_fini(void)
  65{
  66        nf_conntrack_helper_unregister(&helper);
  67}
  68
  69module_init(nf_conntrack_netbios_ns_init);
  70module_exit(nf_conntrack_netbios_ns_fini);
  71