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