/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 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.
*/
/* 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>
#define ASSERT_READ_LOCK(x)
#define ASSERT_WRITE_LOCK(x)
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/listhelp.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
#define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT))
static struct
{
struct ipt_replace repl;
struct ipt_standard entries[3];
struct ipt_error term;
} nat_initial_table __initdata
= { { "nat", NAT_VALID_HOOKS, 4,
sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
{ [NF_IP_PRE_ROUTING] = 0,
[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
{ [NF_IP_PRE_ROUTING] = 0,
[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
0, NULL, { } },
{
/* PRE_ROUTING */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } },
/* POST_ROUTING */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } },
/* LOCAL_OUT */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } }
},
/* ERROR */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_error),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
{ } },
"ERROR"
}
}
};
static struct ipt_table nat_table = {
.name = "nat",
.valid_hooks = NAT_VALID_HOOKS,
.lock = RW_LOCK_UNLOCKED,
.me = THIS_MODULE,
.af = AF_INET,
};
/* Source NAT */
static unsigned int ipt_snat_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
const struct ip_nat_multi_range_compat *mr = targinfo;
IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
ct = ip_conntrack_get(*pskb, &ctinfo);
/* Connection must be valid and new. */
IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
|| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
IP_NF_ASSERT(out);
return ip_nat_setup_info(ct, &mr->range[0], hooknum);
}
/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
static void warn_if_extra_mangle(u32 dstip, u32 srcip)
{
static int warned = 0;
struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
struct rtable *rt;
if (ip_route_output_key(&rt, &fl) != 0)
return;
if (rt->rt_src != srcip && !warned) {
printk("NAT: no longer support implicit source local NAT\n");
printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
NIPQUAD(srcip), NIPQUAD(dstip));
warned = 1;
}
ip_rt_put(rt);
}
static unsigned int ipt_dnat_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
const struct ip_nat_multi_range_compat *mr = targinfo;
IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
|| hooknum == NF_IP_LOCAL_OUT);
ct = ip_conntrack_get(*pskb, &ctinfo);
/* Connection must be valid and new. */
IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
if (hooknum == NF_IP_LOCAL_OUT
&& mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
warn_if_extra_mangle((*pskb)->nh.iph->daddr,
mr->range[0].min_ip);
return ip_nat_setup_info(ct, &mr->range[0], hooknum);
}
static int ipt_snat_checkentry(const char *tablename,
const void *entry,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
struct ip_nat_multi_range_compat *mr = targinfo;
/* Must be a valid range */
if (mr->rangesize != 1) {
printk("SNAT: multiple ranges no longer supported\n");
return 0;
}
return 1;
}
static int ipt_dnat_checkentry(const char *tablename,
const void *entry,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
struct ip_nat_multi_range_compat *mr = targinfo;
/* Must be a valid range */
if (mr->rangesize != 1) {
printk("DNAT: multiple ranges no longer supported\n");
return 0;
}
return 1;
}
inline unsigned int
alloc_null_binding(struct ip_conntrack *conntrack,
struct ip_nat_info *info,
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).
*/
u_int32_t ip
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
: conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
struct ip_nat_range range
= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", conntrack,
NIPQUAD(ip));
return ip_nat_setup_info(conntrack, &range, hooknum);
}
unsigned int
alloc_null_binding_confirmed(struct ip_conntrack *conntrack,
struct ip_nat_info *info,
unsigned int hooknum)
{
u_int32_t ip
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
: conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
u_int16_t all
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
: conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
struct ip_nat_range range
= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
conntrack, NIPQUAD(ip));
return ip_nat_setup_info(conntrack, &range, hooknum);
}
int ip_nat_rule_find(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
struct ip_conntrack *ct,
struct ip_nat_info *info)
{
int ret;
ret = ipt_do_table(pskb, hooknum, in, out, &nat_table, NULL);
if (ret == NF_ACCEPT) {
if (!ip_nat_initialized(ct, HOOK2MANIP(hooknum)))
/* NUL mapping */
ret = alloc_null_binding(ct, info, hooknum);
}
return ret;
}
static struct ipt_target ipt_snat_reg = {
.name = "SNAT",
.target = ipt_snat_target,
.targetsize = sizeof(struct ip_nat_multi_range_compat),
.table = "nat",
.hooks = 1 << NF_IP_POST_ROUTING,
.checkentry = ipt_snat_checkentry,
};
static struct ipt_target ipt_dnat_reg = {
.name = "DNAT",
.target = ipt_dnat_target,
.targetsize = sizeof(struct ip_nat_multi_range_compat),
.table = "nat",
.hooks = 1 << NF_IP_PRE_ROUTING,
.checkentry = ipt_dnat_checkentry,
};
int __init ip_nat_rule_init(void)
{
int ret;
ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
if (ret != 0)
return ret;
ret = ipt_register_target(&ipt_snat_reg);
if (ret != 0)
goto unregister_table;
ret = ipt_register_target(&ipt_dnat_reg);
if (ret != 0)
goto unregister_snat;
return ret;
unregister_snat:
ipt_unregister_target(&ipt_snat_reg);
unregister_table:
ipt_unregister_table(&nat_table);
return ret;
}
void ip_nat_rule_cleanup(void)
{
ipt_unregister_target(&ipt_dnat_reg);
ipt_unregister_target(&ipt_snat_reg);
ipt_unregister_table(&nat_table);
}
