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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 <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))
/* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
static struct
{
struct ipt_replace repl;
struct ipt_standard entries[5];
struct ipt_error term;
} initial_table __net_initdata = {
.repl = {
.name = "mangle",
.valid_hooks = MANGLE_VALID_HOOKS,
.num_entries = 6,
.size = sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
.hook_entry = {
[NF_INET_PRE_ROUTING] = 0,
[NF_INET_LOCAL_IN] = sizeof(struct ipt_standard),
[NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2,
[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4,
},
.underflow = {
[NF_INET_PRE_ROUTING] = 0,
[NF_INET_LOCAL_IN] = sizeof(struct ipt_standard),
[NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2,
[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4,
},
},
.entries = {
IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */
IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */
IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
},
.term = IPT_ERROR_INIT, /* ERROR */
};
static struct xt_table packet_mangler = {
.name = "mangle",
.valid_hooks = MANGLE_VALID_HOOKS,
.me = THIS_MODULE,
.af = AF_INET,
};
/* The work comes in here from netfilter.c. */
static unsigned int
ipt_pre_routing_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(in)->ipv4.iptable_mangle);
}
static unsigned int
ipt_post_routing_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(out)->ipv4.iptable_mangle);
}
static unsigned int
ipt_local_in_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(in)->ipv4.iptable_mangle);
}
static unsigned int
ipt_forward_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(in)->ipv4.iptable_mangle);
}
static unsigned int
ipt_local_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
unsigned int ret;
const struct iphdr *iph;
u_int8_t tos;
__be32 saddr, daddr;
u_int32_t mark;
/* 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, hook, in, out,
dev_net(out)->ipv4.iptable_mangle);
/* Reroute for ANY change. */
if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE) {
iph = ip_hdr(skb);
if (iph->saddr != saddr ||
iph->daddr != daddr ||
skb->mark != mark ||
iph->tos != tos)
if (ip_route_me_harder(skb, RTN_UNSPEC))
ret = NF_DROP;
}
return ret;
}
static struct nf_hook_ops ipt_ops[] __read_mostly = {
{
.hook = ipt_pre_routing_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_PRE_ROUTING,
.priority = NF_IP_PRI_MANGLE,
},
{
.hook = ipt_local_in_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP_PRI_MANGLE,
},
{
.hook = ipt_forward_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_FORWARD,
.priority = NF_IP_PRI_MANGLE,
},
{
.hook = ipt_local_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP_PRI_MANGLE,
},
{
.hook = ipt_post_routing_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_MANGLE,
},
};
static int __net_init iptable_mangle_net_init(struct net *net)
{
/* Register table */
net->ipv4.iptable_mangle =
ipt_register_table(net, &packet_mangler, &initial_table.repl);
if (IS_ERR(net->ipv4.iptable_mangle))
return PTR_ERR(net->ipv4.iptable_mangle);
return 0;
}
static void __net_exit iptable_mangle_net_exit(struct net *net)
{
ipt_unregister_table(net->ipv4.iptable_mangle);
}
static struct pernet_operations iptable_mangle_net_ops = {
.init = iptable_mangle_net_init,
.exit = iptable_mangle_net_exit,
};
static int __init iptable_mangle_init(void)
{
int ret;
ret = register_pernet_subsys(&iptable_mangle_net_ops);
if (ret < 0)
return ret;
/* Register hooks */
ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
if (ret < 0)
goto cleanup_table;
return ret;
cleanup_table:
unregister_pernet_subsys(&iptable_mangle_net_ops);
return ret;
}
static void __exit iptable_mangle_fini(void)
{
nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
unregister_pernet_subsys(&iptable_mangle_net_ops);
}
module_init(iptable_mangle_init);
module_exit(iptable_mangle_fini);
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