| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * SNMP service broadcast connection tracking helper |
| * |
| * (c) 2011 Jiri Olsa <jolsa@redhat.com> |
| */ |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/in.h> |
| |
| #include <net/netfilter/nf_conntrack.h> |
| #include <net/netfilter/nf_conntrack_helper.h> |
| #include <net/netfilter/nf_conntrack_expect.h> |
| #include <linux/netfilter/nf_conntrack_snmp.h> |
| |
| #define SNMP_PORT 161 |
| |
| MODULE_AUTHOR("Jiri Olsa <jolsa@redhat.com>"); |
| MODULE_DESCRIPTION("SNMP service broadcast connection tracking helper"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS_NFCT_HELPER("snmp"); |
| |
| static unsigned int timeout __read_mostly = 30; |
| module_param(timeout, uint, 0400); |
| MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); |
| |
| int (*nf_nat_snmp_hook)(struct sk_buff *skb, |
| unsigned int protoff, |
| struct nf_conn *ct, |
| enum ip_conntrack_info ctinfo); |
| EXPORT_SYMBOL_GPL(nf_nat_snmp_hook); |
| |
| static int snmp_conntrack_help(struct sk_buff *skb, unsigned int protoff, |
| struct nf_conn *ct, |
| enum ip_conntrack_info ctinfo) |
| { |
| typeof(nf_nat_snmp_hook) nf_nat_snmp; |
| |
| nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout); |
| |
| nf_nat_snmp = rcu_dereference(nf_nat_snmp_hook); |
| if (nf_nat_snmp && ct->status & IPS_NAT_MASK) |
| return nf_nat_snmp(skb, protoff, ct, ctinfo); |
| |
| return NF_ACCEPT; |
| } |
| |
| static struct nf_conntrack_expect_policy exp_policy = { |
| .max_expected = 1, |
| }; |
| |
| static struct nf_conntrack_helper helper __read_mostly = { |
| .name = "snmp", |
| .tuple.src.l3num = NFPROTO_IPV4, |
| .tuple.src.u.udp.port = cpu_to_be16(SNMP_PORT), |
| .tuple.dst.protonum = IPPROTO_UDP, |
| .me = THIS_MODULE, |
| .help = snmp_conntrack_help, |
| .expect_policy = &exp_policy, |
| }; |
| |
| static int __init nf_conntrack_snmp_init(void) |
| { |
| exp_policy.timeout = timeout; |
| return nf_conntrack_helper_register(&helper); |
| } |
| |
| static void __exit nf_conntrack_snmp_fini(void) |
| { |
| nf_conntrack_helper_unregister(&helper); |
| } |
| |
| module_init(nf_conntrack_snmp_init); |
| module_exit(nf_conntrack_snmp_fini); |