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 HELPER_NAME "netbios-ns" |
24 | #define NMBD_PORT 137 |
25 | |
26 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>" ); |
27 | MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper" ); |
28 | MODULE_LICENSE("GPL" ); |
29 | MODULE_ALIAS("ip_conntrack_netbios_ns" ); |
30 | MODULE_ALIAS_NFCT_HELPER(HELPER_NAME); |
31 | |
32 | static unsigned int timeout __read_mostly = 3; |
33 | module_param(timeout, uint, 0400); |
34 | MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds" ); |
35 | |
36 | static struct nf_conntrack_expect_policy exp_policy = { |
37 | .max_expected = 1, |
38 | }; |
39 | |
40 | static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff, |
41 | struct nf_conn *ct, |
42 | enum ip_conntrack_info ctinfo) |
43 | { |
44 | return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout); |
45 | } |
46 | |
47 | static struct nf_conntrack_helper helper __read_mostly = { |
48 | .name = HELPER_NAME, |
49 | .tuple.src.l3num = NFPROTO_IPV4, |
50 | .tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT), |
51 | .tuple.dst.protonum = IPPROTO_UDP, |
52 | .me = THIS_MODULE, |
53 | .help = netbios_ns_help, |
54 | .expect_policy = &exp_policy, |
55 | }; |
56 | |
57 | static int __init nf_conntrack_netbios_ns_init(void) |
58 | { |
59 | NF_CT_HELPER_BUILD_BUG_ON(0); |
60 | |
61 | exp_policy.timeout = timeout; |
62 | return nf_conntrack_helper_register(&helper); |
63 | } |
64 | |
65 | static void __exit nf_conntrack_netbios_ns_fini(void) |
66 | { |
67 | nf_conntrack_helper_unregister(&helper); |
68 | } |
69 | |
70 | module_init(nf_conntrack_netbios_ns_init); |
71 | module_exit(nf_conntrack_netbios_ns_fini); |
72 | |