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>
24 #include <linux/if_addr.h>
27 #include <linux/netfilter.h>
28 #include <net/route.h>
30 #include <net/netfilter/nf_conntrack.h>
31 #include <net/netfilter/nf_conntrack_helper.h>
32 #include <net/netfilter/nf_conntrack_expect.h>
36 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
37 MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
38 MODULE_LICENSE("GPL");
39 MODULE_ALIAS("ip_conntrack_netbios_ns");
41 static unsigned int timeout __read_mostly = 3;
42 module_param(timeout, uint, 0400);
43 MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
45 static int help(struct sk_buff *skb, unsigned int protoff,
46 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
48 struct nf_conntrack_expect *exp;
49 struct iphdr *iph = ip_hdr(skb);
50 struct rtable *rt = skb->rtable;
51 struct in_device *in_dev;
54 /* we're only interested in locally generated packets */
57 if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST))
59 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
63 in_dev = __in_dev_get_rcu(rt->u.dst.dev);
65 for_primary_ifa(in_dev) {
66 if (ifa->ifa_broadcast == iph->daddr) {
77 exp = nf_ct_expect_alloc(ct);
81 exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
82 exp->tuple.src.u.udp.port = htons(NMBD_PORT);
84 exp->mask.src.u3.ip = mask;
85 exp->mask.src.u.udp.port = htons(0xFFFF);
88 exp->flags = NF_CT_EXPECT_PERMANENT;
91 nf_ct_expect_related(exp);
92 nf_ct_expect_put(exp);
94 nf_ct_refresh(ct, skb, timeout * HZ);
99 static struct nf_conntrack_helper helper __read_mostly = {
100 .name = "netbios-ns",
101 .tuple.src.l3num = AF_INET,
102 .tuple.src.u.udp.port = __constant_htons(NMBD_PORT),
103 .tuple.dst.protonum = IPPROTO_UDP,
109 static int __init nf_conntrack_netbios_ns_init(void)
111 helper.timeout = timeout;
112 return nf_conntrack_helper_register(&helper);
115 static void __exit nf_conntrack_netbios_ns_fini(void)
117 nf_conntrack_helper_unregister(&helper);
120 module_init(nf_conntrack_netbios_ns_init);
121 module_exit(nf_conntrack_netbios_ns_fini);