// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* NetBIOS name service broadcast connection tracking helper
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*
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* (c) 2005 Patrick McHardy <kaber@trash.net>
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*/
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/*
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* This helper tracks locally originating NetBIOS name service
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* requests by issuing permanent expectations (valid until
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* timing out) matching all reply connections from the
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* destination network. The only NetBIOS specific thing is
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* actually the port number.
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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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#define NMBD_PORT 137
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ip_conntrack_netbios_ns");
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MODULE_ALIAS_NFCT_HELPER("netbios_ns");
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static unsigned int timeout __read_mostly = 3;
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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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static struct nf_conntrack_expect_policy exp_policy = {
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.max_expected = 1,
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};
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static int netbios_ns_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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return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout);
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}
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static struct nf_conntrack_helper helper __read_mostly = {
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.name = "netbios-ns",
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.tuple.src.l3num = NFPROTO_IPV4,
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.tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT),
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.tuple.dst.protonum = IPPROTO_UDP,
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.me = THIS_MODULE,
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.help = netbios_ns_help,
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.expect_policy = &exp_policy,
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};
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static int __init nf_conntrack_netbios_ns_init(void)
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{
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NF_CT_HELPER_BUILD_BUG_ON(0);
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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_netbios_ns_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_netbios_ns_init);
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module_exit(nf_conntrack_netbios_ns_fini);
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