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/*
* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
*
* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/route.h>
#include <linux/ip.h>
#include <net/ip.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables mangle table");
#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
(1 << NF_INET_LOCAL_IN) | \
(1 << NF_INET_FORWARD) | \
(1 << NF_INET_LOCAL_OUT) | \
(1 << NF_INET_POST_ROUTING))
static int __net_init iptable_mangle_table_init(struct net *net);
static const struct xt_table packet_mangler = {
.name = "mangle",
.valid_hooks = MANGLE_VALID_HOOKS,
.me = THIS_MODULE,
.af = NFPROTO_IPV4,
.priority = NF_IP_PRI_MANGLE,
.table_init = iptable_mangle_table_init,
};
static unsigned int
ipt_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
{
unsigned int ret;
const struct iphdr *iph;
u_int8_t tos;
__be32 saddr, daddr;
u_int32_t mark;
int err;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct iphdr) ||
ip_hdrlen(skb) < sizeof(struct iphdr))
return NF_ACCEPT;
/* Save things which could affect route */
mark = skb->mark;
iph = ip_hdr(skb);
saddr = iph->saddr;
daddr = iph->daddr;
tos = iph->tos;
ret = ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
/* Reroute for ANY change. */
if (ret != NF_DROP && ret != NF_STOLEN) {
iph = ip_hdr(skb);
if (iph->saddr != saddr ||
iph->daddr != daddr ||
skb->mark != mark ||
iph->tos != tos) {
err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
if (err < 0)
ret = NF_DROP_ERR(err);
}
}
return ret;
}
/* The work comes in here from netfilter.c. */
static unsigned int
iptable_mangle_hook(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
if (state->hook == NF_INET_LOCAL_OUT)
return ipt_mangle_out(skb, state);
if (state->hook == NF_INET_POST_ROUTING)
return ipt_do_table(skb, state,
state->net->ipv4.iptable_mangle);
/* PREROUTING/INPUT/FORWARD: */
return ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
}
static struct nf_hook_ops *mangle_ops __read_mostly;
static int __net_init iptable_mangle_table_init(struct net *net)
{
struct ipt_replace *repl;
int ret;
if (net->ipv4.iptable_mangle)
return 0;
repl = ipt_alloc_initial_table(&packet_mangler);
if (repl == NULL)
return -ENOMEM;
ret = ipt_register_table(net, &packet_mangler, repl, mangle_ops,
&net->ipv4.iptable_mangle);
kfree(repl);
return ret;
}
static void __net_exit iptable_mangle_net_exit(struct net *net)
{
if (!net->ipv4.iptable_mangle)
return;
ipt_unregister_table(net, net->ipv4.iptable_mangle, mangle_ops);
net->ipv4.iptable_mangle = NULL;
}
static struct pernet_operations iptable_mangle_net_ops = {
.exit = iptable_mangle_net_exit,
};
static int __init iptable_mangle_init(void)
{
int ret;
mangle_ops = xt_hook_ops_alloc(&packet_mangler, iptable_mangle_hook);
if (IS_ERR(mangle_ops)) {
ret = PTR_ERR(mangle_ops);
return ret;
}
ret = register_pernet_subsys(&iptable_mangle_net_ops);
if (ret < 0) {
kfree(mangle_ops);
return ret;
}
ret = iptable_mangle_table_init(&init_net);
if (ret) {
unregister_pernet_subsys(&iptable_mangle_net_ops);
kfree(mangle_ops);
}
return ret;
}
static void __exit iptable_mangle_fini(void)
{
unregister_pernet_subsys(&iptable_mangle_net_ops);
kfree(mangle_ops);
}
module_init(iptable_mangle_init);
module_exit(iptable_mangle_fini);
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