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
**pskb
, 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(*pskb
);
50 struct rtable
*rt
= (struct rtable
*)(*pskb
)->dst
;
51 struct in_device
*in_dev
;
54 /* we're only interested in locally generated packets */
55 if ((*pskb
)->sk
== NULL
)
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
, *pskb
, 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
);