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/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 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.
*/
/* Everything about the rules for NAT. */
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <net/checksum.h>
#include <net/route.h>
#include <linux/bitops.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_rule.h>
#define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
(1 << NF_INET_POST_ROUTING) | \
(1 << NF_INET_LOCAL_OUT))
static const struct xt_table nat_table = {
.name = "nat",
.valid_hooks = NAT_VALID_HOOKS,
.me = THIS_MODULE,
.af = NFPROTO_IPV4,
};
/* Source NAT */
static unsigned int
ipt_snat_target(struct sk_buff *skb, const struct xt_target_param *par)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
const struct nf_nat_multi_range_compat *mr = par->targinfo;
NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
ct = nf_ct_get(skb, &ctinfo);
/* Connection must be valid and new. */
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
NF_CT_ASSERT(par->out != NULL);
return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC);
}
static unsigned int
ipt_dnat_target(struct sk_buff *skb, const struct xt_target_param *par)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
const struct nf_nat_multi_range_compat *mr = par->targinfo;
NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
par->hooknum == NF_INET_LOCAL_OUT);
ct = nf_ct_get(skb, &ctinfo);
/* Connection must be valid and new. */
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
}
static bool ipt_snat_checkentry(const struct xt_tgchk_param *par)
{
const struct nf_nat_multi_range_compat *mr = par->targinfo;
/* Must be a valid range */
if (mr->rangesize != 1) {
printk("SNAT: multiple ranges no longer supported\n");
return false;
}
return true;
}
static bool ipt_dnat_checkentry(const struct xt_tgchk_param *par)
{
const struct nf_nat_multi_range_compat *mr = par->targinfo;
/* Must be a valid range */
if (mr->rangesize != 1) {
printk("DNAT: multiple ranges no longer supported\n");
return false;
}
return true;
}
unsigned int
alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
{
/* Force range to this IP; let proto decide mapping for
per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
Use reply in case it's already been mangled (eg local packet).
*/
__be32 ip
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
struct nf_nat_range range
= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, &ip);
return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
}
int nf_nat_rule_find(struct sk_buff *skb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
struct nf_conn *ct)
{
struct net *net = nf_ct_net(ct);
int ret;
ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
if (ret == NF_ACCEPT) {
if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
/* NUL mapping */
ret = alloc_null_binding(ct, hooknum);
}
return ret;
}
static struct xt_target ipt_snat_reg __read_mostly = {
.name = "SNAT",
.target = ipt_snat_target,
.targetsize = sizeof(struct nf_nat_multi_range_compat),
.table = "nat",
.hooks = 1 << NF_INET_POST_ROUTING,
.checkentry = ipt_snat_checkentry,
.family = AF_INET,
};
static struct xt_target ipt_dnat_reg __read_mostly = {
.name = "DNAT",
.target = ipt_dnat_target,
.targetsize = sizeof(struct nf_nat_multi_range_compat),
.table = "nat",
.hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
.checkentry = ipt_dnat_checkentry,
.family = AF_INET,
};
static int __net_init nf_nat_rule_net_init(struct net *net)
{
struct ipt_replace *repl;
repl = ipt_alloc_initial_table(&nat_table);
if (repl == NULL)
return -ENOMEM;
net->ipv4.nat_table = ipt_register_table(net, &nat_table, repl);
kfree(repl);
if (IS_ERR(net->ipv4.nat_table))
return PTR_ERR(net->ipv4.nat_table);
return 0;
}
static void __net_exit nf_nat_rule_net_exit(struct net *net)
{
ipt_unregister_table(net, net->ipv4.nat_table);
}
static struct pernet_operations nf_nat_rule_net_ops = {
.init = nf_nat_rule_net_init,
.exit = nf_nat_rule_net_exit,
};
int __init nf_nat_rule_init(void)
{
int ret;
ret = register_pernet_subsys(&nf_nat_rule_net_ops);
if (ret != 0)
goto out;
ret = xt_register_target(&ipt_snat_reg);
if (ret != 0)
goto unregister_table;
ret = xt_register_target(&ipt_dnat_reg);
if (ret != 0)
goto unregister_snat;
return ret;
unregister_snat:
xt_unregister_target(&ipt_snat_reg);
unregister_table:
unregister_pernet_subsys(&nf_nat_rule_net_ops);
out:
return ret;
}
void nf_nat_rule_cleanup(void)
{
xt_unregister_target(&ipt_dnat_reg);
xt_unregister_target(&ipt_snat_reg);
unregister_pernet_subsys(&nf_nat_rule_net_ops);
}
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