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
, int, 0600);
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
init(void)
132 helper
.timeout
= timeout
;
133 return ip_conntrack_helper_register(&helper
);
136 static void __exit
fini(void)
138 ip_conntrack_helper_unregister(&helper
);