1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * SNMP service broadcast connection tracking helper |
4 | * |
5 | * (c) 2011 Jiri Olsa <jolsa@redhat.com> |
6 | */ |
7 | #include <linux/kernel.h> |
8 | #include <linux/module.h> |
9 | #include <linux/init.h> |
10 | #include <linux/in.h> |
11 | |
12 | #include <net/netfilter/nf_conntrack.h> |
13 | #include <net/netfilter/nf_conntrack_helper.h> |
14 | #include <net/netfilter/nf_conntrack_expect.h> |
15 | #include <linux/netfilter/nf_conntrack_snmp.h> |
16 | |
17 | #define SNMP_PORT 161 |
18 | |
19 | MODULE_AUTHOR("Jiri Olsa <jolsa@redhat.com>" ); |
20 | MODULE_DESCRIPTION("SNMP service broadcast connection tracking helper" ); |
21 | MODULE_LICENSE("GPL" ); |
22 | MODULE_ALIAS_NFCT_HELPER("snmp" ); |
23 | |
24 | static unsigned int timeout __read_mostly = 30; |
25 | module_param(timeout, uint, 0400); |
26 | MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds" ); |
27 | |
28 | int (*nf_nat_snmp_hook)(struct sk_buff *skb, |
29 | unsigned int protoff, |
30 | struct nf_conn *ct, |
31 | enum ip_conntrack_info ctinfo); |
32 | EXPORT_SYMBOL_GPL(nf_nat_snmp_hook); |
33 | |
34 | static int snmp_conntrack_help(struct sk_buff *skb, unsigned int protoff, |
35 | struct nf_conn *ct, |
36 | enum ip_conntrack_info ctinfo) |
37 | { |
38 | typeof(nf_nat_snmp_hook) nf_nat_snmp; |
39 | |
40 | nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout); |
41 | |
42 | nf_nat_snmp = rcu_dereference(nf_nat_snmp_hook); |
43 | if (nf_nat_snmp && ct->status & IPS_NAT_MASK) |
44 | return nf_nat_snmp(skb, protoff, ct, ctinfo); |
45 | |
46 | return NF_ACCEPT; |
47 | } |
48 | |
49 | static struct nf_conntrack_expect_policy exp_policy = { |
50 | .max_expected = 1, |
51 | }; |
52 | |
53 | static struct nf_conntrack_helper helper __read_mostly = { |
54 | .name = "snmp" , |
55 | .tuple.src.l3num = NFPROTO_IPV4, |
56 | .tuple.src.u.udp.port = cpu_to_be16(SNMP_PORT), |
57 | .tuple.dst.protonum = IPPROTO_UDP, |
58 | .me = THIS_MODULE, |
59 | .help = snmp_conntrack_help, |
60 | .expect_policy = &exp_policy, |
61 | }; |
62 | |
63 | static int __init nf_conntrack_snmp_init(void) |
64 | { |
65 | exp_policy.timeout = timeout; |
66 | return nf_conntrack_helper_register(&helper); |
67 | } |
68 | |
69 | static void __exit nf_conntrack_snmp_fini(void) |
70 | { |
71 | nf_conntrack_helper_unregister(&helper); |
72 | } |
73 | |
74 | module_init(nf_conntrack_snmp_init); |
75 | module_exit(nf_conntrack_snmp_fini); |
76 | |