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/* This file contains all the functions required for the standalone
ip_nat module.
These are not required by the compatibility layer.
*/
/* (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.
*/
/*
* 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
* - new API and handling of conntrack/nat helpers
* - now capable of multiple expectations for one master
* */
#include <linux/types.h>
#include <linux/icmp.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <linux/spinlock.h>
#define ASSERT_READ_LOCK(x)
#define ASSERT_WRITE_LOCK(x)
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/listhelp.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
#define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
: ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
: ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
: ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
: "*ERROR*")))
#ifdef CONFIG_XFRM
static void nat_decode_session(struct sk_buff *skb, struct flowi *fl)
{
struct ip_conntrack *ct;
struct ip_conntrack_tuple *t;
enum ip_conntrack_info ctinfo;
enum ip_conntrack_dir dir;
unsigned long statusbit;
ct = ip_conntrack_get(skb, &ctinfo);
if (ct == NULL)
return;
dir = CTINFO2DIR(ctinfo);
t = &ct->tuplehash[dir].tuple;
if (dir == IP_CT_DIR_ORIGINAL)
statusbit = IPS_DST_NAT;
else
statusbit = IPS_SRC_NAT;
if (ct->status & statusbit) {
fl->fl4_dst = t->dst.ip;
if (t->dst.protonum == IPPROTO_TCP ||
t->dst.protonum == IPPROTO_UDP)
fl->fl_ip_dport = t->dst.u.tcp.port;
}
statusbit ^= IPS_NAT_MASK;
if (ct->status & statusbit) {
fl->fl4_src = t->src.ip;
if (t->dst.protonum == IPPROTO_TCP ||
t->dst.protonum == IPPROTO_UDP)
fl->fl_ip_sport = t->src.u.tcp.port;
}
}
#endif
static unsigned int
ip_nat_fn(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
struct ip_nat_info *info;
/* maniptype == SRC for postrouting. */
enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
/* We never see fragments: conntrack defrags on pre-routing
and local-out, and ip_nat_out protects post-routing. */
IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
& htons(IP_MF|IP_OFFSET)));
/* If we had a hardware checksum before, it's now invalid */
if ((*pskb)->ip_summed == CHECKSUM_PARTIAL ||
(*pskb)->ip_summed == CHECKSUM_COMPLETE)
if (skb_checksum_help(*pskb))
return NF_DROP;
ct = ip_conntrack_get(*pskb, &ctinfo);
/* Can't track? It's not due to stress, or conntrack would
have dropped it. Hence it's the user's responsibilty to
packet filter it out, or implement conntrack/NAT for that
protocol. 8) --RR */
if (!ct) {
/* Exception: ICMP redirect to new connection (not in
hash table yet). We must not let this through, in
case we're doing NAT to the same network. */
if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
struct icmphdr _hdr, *hp;
hp = skb_header_pointer(*pskb,
(*pskb)->nh.iph->ihl*4,
sizeof(_hdr), &_hdr);
if (hp != NULL &&
hp->type == ICMP_REDIRECT)
return NF_DROP;
}
return NF_ACCEPT;
}
/* Don't try to NAT if this packet is not conntracked */
if (ct == &ip_conntrack_untracked)
return NF_ACCEPT;
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED+IP_CT_IS_REPLY:
if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
if (!ip_nat_icmp_reply_translation(pskb, ct, maniptype,
CTINFO2DIR(ctinfo)))
return NF_DROP;
else
return NF_ACCEPT;
}
/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
case IP_CT_NEW:
info = &ct->nat.info;
/* Seen it before? This can happen for loopback, retrans,
or local packets.. */
if (!ip_nat_initialized(ct, maniptype)) {
unsigned int ret;
if (unlikely(is_confirmed(ct)))
/* NAT module was loaded late */
ret = alloc_null_binding_confirmed(ct, info,
hooknum);
else if (hooknum == NF_IP_LOCAL_IN)
/* LOCAL_IN hook doesn't have a chain! */
ret = alloc_null_binding(ct, info, hooknum);
else
ret = ip_nat_rule_find(pskb, hooknum,
in, out, ct,
info);
if (ret != NF_ACCEPT) {
return ret;
}
} else
DEBUGP("Already setup manip %s for ct %p\n",
maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
ct);
break;
default:
/* ESTABLISHED */
IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
|| ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
info = &ct->nat.info;
}
IP_NF_ASSERT(info);
return ip_nat_packet(ct, ctinfo, hooknum, pskb);
}
static unsigned int
ip_nat_in(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
unsigned int ret;
u_int32_t daddr = (*pskb)->nh.iph->daddr;
ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN
&& daddr != (*pskb)->nh.iph->daddr) {
dst_release((*pskb)->dst);
(*pskb)->dst = NULL;
}
return ret;
}
static unsigned int
ip_nat_out(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#ifdef CONFIG_XFRM
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
#endif
unsigned int ret;
/* root is playing with raw sockets. */
if ((*pskb)->len < sizeof(struct iphdr)
|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
return NF_ACCEPT;
ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
#ifdef CONFIG_XFRM
if (ret != NF_DROP && ret != NF_STOLEN
&& (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (ct->tuplehash[dir].tuple.src.ip !=
ct->tuplehash[!dir].tuple.dst.ip
|| ct->tuplehash[dir].tuple.src.u.all !=
ct->tuplehash[!dir].tuple.dst.u.all
)
return ip_xfrm_me_harder(pskb) == 0 ? ret : NF_DROP;
}
#endif
return ret;
}
static unsigned int
ip_nat_local_fn(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
unsigned int ret;
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