337fbc4166
The NAT helpr hooks are protected by RCU, but all of the conntrack helpers test and use the global pointers instead of copying them first using rcu_dereference() Also replace synchronize_net() by synchronize_rcu() for clarity since sychronizing only with packet receive processing is insufficient to prevent races. Signed-off-by: Patrick McHardy <kaber@trash.net>
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Version: 0.0.7
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*
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* Thu 21 Mar 2002 Harald Welte <laforge@gnumonks.org>
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* - Port to newnat API
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*
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* This module currently supports DNAT:
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* iptables -t nat -A PREROUTING -d x.x.x.x -j DNAT --to-dest x.x.x.y
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*
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* and SNAT:
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* iptables -t nat -A POSTROUTING { -j MASQUERADE , -j SNAT --to-source x.x.x.x }
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*
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* It has not been tested with
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* -j SNAT --to-source x.x.x.x-x.x.x.y since I only have one external ip
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* If you do test this please let me know if it works or not.
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*
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*/
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#include <linux/module.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/ip.h>
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#include <linux/udp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#include <linux/netfilter_ipv4/ip_conntrack_tftp.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/moduleparam.h>
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MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
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MODULE_DESCRIPTION("tftp NAT helper");
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MODULE_LICENSE("GPL");
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static unsigned int help(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct ip_conntrack_expect *exp)
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{
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struct ip_conntrack *ct = exp->master;
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exp->saved_proto.udp.port
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= ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
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exp->dir = IP_CT_DIR_REPLY;
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exp->expectfn = ip_nat_follow_master;
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if (ip_conntrack_expect_related(exp) != 0)
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return NF_DROP;
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return NF_ACCEPT;
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}
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static void __exit ip_nat_tftp_fini(void)
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{
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rcu_assign_pointer(ip_nat_tftp_hook, NULL);
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synchronize_rcu();
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}
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static int __init ip_nat_tftp_init(void)
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{
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BUG_ON(rcu_dereference(ip_nat_tftp_hook));
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rcu_assign_pointer(ip_nat_tftp_hook, help);
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return 0;
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}
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module_init(ip_nat_tftp_init);
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module_exit(ip_nat_tftp_fini);
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