247 lines
6.2 KiB
C
247 lines
6.2 KiB
C
/*
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* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
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*
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* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
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* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
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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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#include <linux/module.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/route.h>
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#include <linux/ip.h>
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#include <net/ip.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("iptables mangle table");
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#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
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(1 << NF_INET_LOCAL_IN) | \
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(1 << NF_INET_FORWARD) | \
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(1 << NF_INET_LOCAL_OUT) | \
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(1 << NF_INET_POST_ROUTING))
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/* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
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static struct
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{
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struct ipt_replace repl;
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struct ipt_standard entries[5];
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struct ipt_error term;
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} initial_table __net_initdata = {
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.repl = {
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.name = "mangle",
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.valid_hooks = MANGLE_VALID_HOOKS,
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.num_entries = 6,
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.size = sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
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.hook_entry = {
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[NF_INET_PRE_ROUTING] = 0,
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[NF_INET_LOCAL_IN] = sizeof(struct ipt_standard),
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[NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2,
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[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
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[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4,
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},
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.underflow = {
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[NF_INET_PRE_ROUTING] = 0,
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[NF_INET_LOCAL_IN] = sizeof(struct ipt_standard),
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[NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2,
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[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
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[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4,
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},
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},
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.entries = {
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IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
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IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */
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IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */
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IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
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IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
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},
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.term = IPT_ERROR_INIT, /* ERROR */
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};
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static struct xt_table packet_mangler = {
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.name = "mangle",
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.valid_hooks = MANGLE_VALID_HOOKS,
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.me = THIS_MODULE,
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.af = AF_INET,
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};
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/* The work comes in here from netfilter.c. */
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static unsigned int
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ipt_pre_routing_hook(unsigned int hook,
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struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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return ipt_do_table(skb, hook, in, out,
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dev_net(in)->ipv4.iptable_mangle);
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}
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static unsigned int
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ipt_post_routing_hook(unsigned int hook,
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struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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return ipt_do_table(skb, hook, in, out,
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dev_net(out)->ipv4.iptable_mangle);
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}
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static unsigned int
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ipt_local_in_hook(unsigned int hook,
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struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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return ipt_do_table(skb, hook, in, out,
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dev_net(in)->ipv4.iptable_mangle);
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}
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static unsigned int
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ipt_forward_hook(unsigned int hook,
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struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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return ipt_do_table(skb, hook, in, out,
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dev_net(in)->ipv4.iptable_mangle);
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}
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static unsigned int
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ipt_local_hook(unsigned int hook,
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struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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unsigned int ret;
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const struct iphdr *iph;
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u_int8_t tos;
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__be32 saddr, daddr;
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u_int32_t mark;
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/* root is playing with raw sockets. */
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if (skb->len < sizeof(struct iphdr)
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|| ip_hdrlen(skb) < sizeof(struct iphdr))
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return NF_ACCEPT;
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/* Save things which could affect route */
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mark = skb->mark;
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iph = ip_hdr(skb);
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saddr = iph->saddr;
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daddr = iph->daddr;
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tos = iph->tos;
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ret = ipt_do_table(skb, hook, in, out,
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dev_net(out)->ipv4.iptable_mangle);
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/* Reroute for ANY change. */
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if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE) {
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iph = ip_hdr(skb);
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if (iph->saddr != saddr ||
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iph->daddr != daddr ||
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skb->mark != mark ||
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iph->tos != tos)
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if (ip_route_me_harder(skb, RTN_UNSPEC))
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ret = NF_DROP;
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}
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return ret;
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}
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static struct nf_hook_ops ipt_ops[] __read_mostly = {
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{
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.hook = ipt_pre_routing_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_INET_PRE_ROUTING,
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.priority = NF_IP_PRI_MANGLE,
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},
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{
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.hook = ipt_local_in_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_INET_LOCAL_IN,
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.priority = NF_IP_PRI_MANGLE,
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},
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{
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.hook = ipt_forward_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_INET_FORWARD,
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.priority = NF_IP_PRI_MANGLE,
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},
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{
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.hook = ipt_local_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_INET_LOCAL_OUT,
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.priority = NF_IP_PRI_MANGLE,
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},
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{
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.hook = ipt_post_routing_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_INET_POST_ROUTING,
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.priority = NF_IP_PRI_MANGLE,
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},
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};
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static int __net_init iptable_mangle_net_init(struct net *net)
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{
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/* Register table */
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net->ipv4.iptable_mangle =
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ipt_register_table(net, &packet_mangler, &initial_table.repl);
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if (IS_ERR(net->ipv4.iptable_mangle))
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return PTR_ERR(net->ipv4.iptable_mangle);
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return 0;
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}
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static void __net_exit iptable_mangle_net_exit(struct net *net)
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{
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ipt_unregister_table(net->ipv4.iptable_mangle);
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}
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static struct pernet_operations iptable_mangle_net_ops = {
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.init = iptable_mangle_net_init,
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.exit = iptable_mangle_net_exit,
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};
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static int __init iptable_mangle_init(void)
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{
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int ret;
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ret = register_pernet_subsys(&iptable_mangle_net_ops);
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if (ret < 0)
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return ret;
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/* Register hooks */
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ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
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if (ret < 0)
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goto cleanup_table;
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return ret;
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cleanup_table:
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unregister_pernet_subsys(&iptable_mangle_net_ops);
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return ret;
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}
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static void __exit iptable_mangle_fini(void)
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{
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nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
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unregister_pernet_subsys(&iptable_mangle_net_ops);
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}
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module_init(iptable_mangle_init);
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module_exit(iptable_mangle_fini);
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