262 lines
6.8 KiB
C
262 lines
6.8 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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* Extended to all five netfilter hooks by Brad Chapman & Harald Welte
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*/
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#include <linux/config.h>
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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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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_IP_PRE_ROUTING) | \
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(1 << NF_IP_LOCAL_IN) | \
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(1 << NF_IP_FORWARD) | \
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(1 << NF_IP_LOCAL_OUT) | \
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(1 << NF_IP_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 __initdata
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= { { "mangle", MANGLE_VALID_HOOKS, 6,
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sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
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{ [NF_IP_PRE_ROUTING] = 0,
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[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
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[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
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[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
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[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
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{ [NF_IP_PRE_ROUTING] = 0,
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[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
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[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
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[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
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[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
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0, NULL, { } },
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{
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/* PRE_ROUTING */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_standard),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
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-NF_ACCEPT - 1 } },
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/* LOCAL_IN */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_standard),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
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-NF_ACCEPT - 1 } },
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/* FORWARD */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_standard),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
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-NF_ACCEPT - 1 } },
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/* LOCAL_OUT */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_standard),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
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-NF_ACCEPT - 1 } },
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/* POST_ROUTING */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_standard),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
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-NF_ACCEPT - 1 } },
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},
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/* ERROR */
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{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
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0,
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sizeof(struct ipt_entry),
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sizeof(struct ipt_error),
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0, { 0, 0 }, { } },
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{ { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
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{ } },
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"ERROR"
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}
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}
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};
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static struct ipt_table packet_mangler = {
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.name = "mangle",
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.valid_hooks = MANGLE_VALID_HOOKS,
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.lock = RW_LOCK_UNLOCKED,
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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_route_hook(unsigned int hook,
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struct sk_buff **pskb,
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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(pskb, hook, in, out, &packet_mangler, NULL);
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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 **pskb,
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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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u_int8_t tos;
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u_int32_t saddr, daddr;
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unsigned long nfmark;
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/* root is playing with raw sockets. */
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if ((*pskb)->len < sizeof(struct iphdr)
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|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
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if (net_ratelimit())
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printk("ipt_hook: happy cracking.\n");
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return NF_ACCEPT;
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}
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/* Save things which could affect route */
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nfmark = (*pskb)->nfmark;
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saddr = (*pskb)->nh.iph->saddr;
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daddr = (*pskb)->nh.iph->daddr;
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tos = (*pskb)->nh.iph->tos;
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ret = ipt_do_table(pskb, hook, in, out, &packet_mangler, NULL);
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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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&& ((*pskb)->nh.iph->saddr != saddr
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|| (*pskb)->nh.iph->daddr != daddr
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#ifdef CONFIG_IP_ROUTE_FWMARK
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|| (*pskb)->nfmark != nfmark
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#endif
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|| (*pskb)->nh.iph->tos != tos))
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return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
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return ret;
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}
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static struct nf_hook_ops ipt_ops[] = {
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{
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.hook = ipt_route_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_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_route_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_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_route_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_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_IP_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_route_hook,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_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 __init init(void)
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{
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int ret;
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/* Register table */
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ret = ipt_register_table(&packet_mangler, &initial_table.repl);
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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_hook(&ipt_ops[0]);
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if (ret < 0)
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goto cleanup_table;
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ret = nf_register_hook(&ipt_ops[1]);
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if (ret < 0)
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goto cleanup_hook0;
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ret = nf_register_hook(&ipt_ops[2]);
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if (ret < 0)
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goto cleanup_hook1;
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ret = nf_register_hook(&ipt_ops[3]);
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if (ret < 0)
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goto cleanup_hook2;
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ret = nf_register_hook(&ipt_ops[4]);
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if (ret < 0)
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goto cleanup_hook3;
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return ret;
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cleanup_hook3:
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nf_unregister_hook(&ipt_ops[3]);
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cleanup_hook2:
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nf_unregister_hook(&ipt_ops[2]);
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cleanup_hook1:
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nf_unregister_hook(&ipt_ops[1]);
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cleanup_hook0:
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nf_unregister_hook(&ipt_ops[0]);
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cleanup_table:
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ipt_unregister_table(&packet_mangler);
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return ret;
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}
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static void __exit fini(void)
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{
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unsigned int i;
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for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++)
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nf_unregister_hook(&ipt_ops[i]);
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ipt_unregister_table(&packet_mangler);
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}
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module_init(init);
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module_exit(fini);
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