93557f53e1
Adding support for SNMP broadcast connection tracking. The SNMP broadcast requests are now paired with the SNMP responses. Thus allowing using SNMP broadcasts with firewall enabled. Please refer to the following conversation: http://marc.info/?l=netfilter-devel&m=125992205006600&w=2 Patrick McHardy wrote: > > The best solution would be to add generic broadcast tracking, the > > use of expectations for this is a bit of abuse. > > The second best choice I guess would be to move the help() function > > to a shared module and generalize it so it can be used for both. This patch implements the "second best choice". Since the netbios-ns conntrack module uses the same helper functionality as the snmp, only one helper function is added for both snmp and netbios-ns modules into the new object - nf_conntrack_broadcast. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Patrick McHardy <kaber@trash.net>
72 lines
2.2 KiB
C
72 lines
2.2 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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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, S_IRUSR);
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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, enum ip_conntrack_info ctinfo)
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{
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return nf_conntrack_broadcast_help(skb, protoff, 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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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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