netfilter: ip6tables: add REDIRECT target
Signed-off-by: Patrick McHardy <kaber@trash.net>
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@ -156,6 +156,17 @@ config IP6_NF_TARGET_MASQUERADE
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To compile it as a module, choose M here. If unsure, say N.
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config IP6_NF_TARGET_REDIRECT
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tristate "REDIRECT target support"
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depends on NF_NAT_IPV6
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help
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REDIRECT is a special case of NAT: all incoming connections are
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mapped onto the incoming interface's address, causing the packets to
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come to the local machine instead of passing through. This is
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useful for transparent proxies.
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To compile it as a module, choose M here. If unsure, say N.
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config IP6_NF_FILTER
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tristate "Packet filtering"
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default m if NETFILTER_ADVANCED=n
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@ -35,4 +35,5 @@ obj-$(CONFIG_IP6_NF_MATCH_RT) += ip6t_rt.o
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# targets
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obj-$(CONFIG_IP6_NF_TARGET_MASQUERADE) += ip6t_MASQUERADE.o
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obj-$(CONFIG_IP6_NF_TARGET_REDIRECT) += ip6t_REDIRECT.o
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obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o
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98
net/ipv6/netfilter/ip6t_REDIRECT.c
Normal file
98
net/ipv6/netfilter/ip6t_REDIRECT.c
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@ -0,0 +1,98 @@
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/*
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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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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* Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
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* NAT funded by Astaro.
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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/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/addrconf.h>
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#include <net/netfilter/nf_nat.h>
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static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
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static unsigned int
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redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct nf_nat_range *range = par->targinfo;
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struct nf_nat_range newrange;
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struct in6_addr newdst;
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct;
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ct = nf_ct_get(skb, &ctinfo);
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if (par->hooknum == NF_INET_LOCAL_OUT)
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newdst = loopback_addr;
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else {
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struct inet6_dev *idev;
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struct inet6_ifaddr *ifa;
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bool addr = false;
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rcu_read_lock();
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idev = __in6_dev_get(skb->dev);
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if (idev != NULL) {
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list_for_each_entry(ifa, &idev->addr_list, if_list) {
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newdst = ifa->addr;
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addr = true;
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break;
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}
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}
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rcu_read_unlock();
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if (!addr)
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return NF_DROP;
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}
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newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
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newrange.min_addr.in6 = newdst;
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newrange.max_addr.in6 = newdst;
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newrange.min_proto = range->min_proto;
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newrange.max_proto = range->max_proto;
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return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
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}
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static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_range *range = par->targinfo;
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if (range->flags & NF_NAT_RANGE_MAP_IPS)
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return -EINVAL;
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return 0;
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}
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static struct xt_target redirect_tg6_reg __read_mostly = {
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.name = "REDIRECT",
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.family = NFPROTO_IPV6,
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.checkentry = redirect_tg6_checkentry,
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.target = redirect_tg6,
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.targetsize = sizeof(struct nf_nat_range),
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.table = "nat",
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.hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
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.me = THIS_MODULE,
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};
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static int __init redirect_tg6_init(void)
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{
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return xt_register_target(&redirect_tg6_reg);
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}
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static void __exit redirect_tg6_exit(void)
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{
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xt_unregister_target(&redirect_tg6_reg);
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}
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module_init(redirect_tg6_init);
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module_exit(redirect_tg6_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
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