276 lines
7.3 KiB
C
276 lines
7.3 KiB
C
/* (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_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 = {
|
|
.repl = {
|
|
.name = "nat",
|
|
.valid_hooks = NAT_VALID_HOOKS,
|
|
.num_entries = 4,
|
|
.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
|
|
.hook_entry = {
|
|
[NF_IP_PRE_ROUTING] = 0,
|
|
[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
|
|
[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
|
|
},
|
|
.underflow = {
|
|
[NF_IP_PRE_ROUTING] = 0,
|
|
[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
|
|
[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
|
|
},
|
|
},
|
|
.entries = {
|
|
IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
|
|
IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
|
|
IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
|
|
},
|
|
.term = IPT_ERROR_INIT, /* ERROR */
|
|
};
|
|
|
|
static struct xt_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 *skb,
|
|
const struct net_device *in,
|
|
const struct net_device *out,
|
|
unsigned int hooknum,
|
|
const struct xt_target *target,
|
|
const void *targinfo)
|
|
{
|
|
struct nf_conn *ct;
|
|
enum ip_conntrack_info ctinfo;
|
|
const struct nf_nat_multi_range_compat *mr = targinfo;
|
|
|
|
NF_CT_ASSERT(hooknum == NF_IP_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(out);
|
|
|
|
return nf_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(__be32 dstip, __be32 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 *skb,
|
|
const struct net_device *in,
|
|
const struct net_device *out,
|
|
unsigned int hooknum,
|
|
const struct xt_target *target,
|
|
const void *targinfo)
|
|
{
|
|
struct nf_conn *ct;
|
|
enum ip_conntrack_info ctinfo;
|
|
const struct nf_nat_multi_range_compat *mr = targinfo;
|
|
|
|
NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
|
|
hooknum == NF_IP_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));
|
|
|
|
if (hooknum == NF_IP_LOCAL_OUT &&
|
|
mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
|
|
warn_if_extra_mangle(ip_hdr(skb)->daddr,
|
|
mr->range[0].min_ip);
|
|
|
|
return nf_nat_setup_info(ct, &mr->range[0], hooknum);
|
|
}
|
|
|
|
static bool ipt_snat_checkentry(const char *tablename,
|
|
const void *entry,
|
|
const struct xt_target *target,
|
|
void *targinfo,
|
|
unsigned int hook_mask)
|
|
{
|
|
struct nf_nat_multi_range_compat *mr = 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 char *tablename,
|
|
const void *entry,
|
|
const struct xt_target *target,
|
|
void *targinfo,
|
|
unsigned int hook_mask)
|
|
{
|
|
struct nf_nat_multi_range_compat *mr = 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 (%u.%u.%u.%u)\n",
|
|
ct, NIPQUAD(ip));
|
|
return nf_nat_setup_info(ct, &range, hooknum);
|
|
}
|
|
|
|
unsigned int
|
|
alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
|
|
{
|
|
__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);
|
|
__be16 all
|
|
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
|
|
? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
|
|
: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
|
|
struct nf_nat_range range
|
|
= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
|
|
|
|
pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
|
|
ct, NIPQUAD(ip));
|
|
return nf_nat_setup_info(ct, &range, 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)
|
|
{
|
|
int ret;
|
|
|
|
ret = ipt_do_table(skb, hooknum, in, out, &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_IP_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_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT),
|
|
.checkentry = ipt_dnat_checkentry,
|
|
.family = AF_INET,
|
|
};
|
|
|
|
int __init nf_nat_rule_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
|
|
if (ret != 0)
|
|
return ret;
|
|
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:
|
|
ipt_unregister_table(&nat_table);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void nf_nat_rule_cleanup(void)
|
|
{
|
|
xt_unregister_target(&ipt_dnat_reg);
|
|
xt_unregister_target(&ipt_snat_reg);
|
|
ipt_unregister_table(&nat_table);
|
|
}
|