2 * NetBIOS name service broadcast connection tracking helper
4 * (c) 2005 Patrick McHardy <kaber@trash.net>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 * This helper tracks locally originating NetBIOS name service
13 * requests by issuing permanent expectations (valid until
14 * timing out) matching all reply connections from the
15 * destination network. The only NetBIOS specific thing is
16 * actually the port number.
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/init.h>
21 #include <linux/skbuff.h>
22 #include <linux/netdevice.h>
23 #include <linux/inetdevice.h>
26 #include <net/route.h>
28 #include <linux/netfilter.h>
29 #include <linux/netfilter_ipv4.h>
30 #include <linux/netfilter_ipv4/ip_conntrack.h>
31 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
35 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
36 MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
37 MODULE_LICENSE("GPL");
39 static unsigned int timeout = 3;
40 module_param(timeout, uint, 0400);
41 MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
43 static int help(struct sk_buff **pskb,
44 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
46 struct ip_conntrack_expect *exp;
47 struct iphdr *iph = (*pskb)->nh.iph;
48 struct rtable *rt = (struct rtable *)(*pskb)->dst;
49 struct in_device *in_dev;
52 /* we're only interested in locally generated packets */
53 if ((*pskb)->sk == NULL)
55 if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST))
57 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
61 in_dev = __in_dev_get_rcu(rt->u.dst.dev);
63 for_primary_ifa(in_dev) {
64 if (ifa->ifa_broadcast == iph->daddr) {
75 exp = ip_conntrack_expect_alloc(ct);
79 exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
80 exp->tuple.src.u.udp.port = ntohs(NMBD_PORT);
82 exp->mask.src.ip = mask;
83 exp->mask.src.u.udp.port = 0xFFFF;
84 exp->mask.dst.ip = 0xFFFFFFFF;
85 exp->mask.dst.u.udp.port = 0xFFFF;
86 exp->mask.dst.protonum = 0xFF;
89 exp->flags = IP_CT_EXPECT_PERMANENT;
91 ip_conntrack_expect_related(exp);
92 ip_conntrack_expect_put(exp);
94 ip_ct_refresh(ct, *pskb, timeout * HZ);
99 static struct ip_conntrack_helper helper = {
100 .name = "netbios-ns",
105 .port = __constant_htons(NMBD_PORT),
110 .protonum = IPPROTO_UDP,
130 static int __init ip_conntrack_netbios_ns_init(void)
132 helper.timeout = timeout;
133 return ip_conntrack_helper_register(&helper);
136 static void __exit ip_conntrack_netbios_ns_fini(void)
138 ip_conntrack_helper_unregister(&helper);
141 module_init(ip_conntrack_netbios_ns_init);
142 module_exit(ip_conntrack_netbios_ns_fini);