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080774a243
Add ctnetlink subsystem for userspace-access to ip_conntrack table. This allows reading and updating of existing entries, as well as creating new ones (and new expect's) via nfnetlink. Please note the 'strange' byte order: nfattr (tag+length) are in host byte order, while the payload is always guaranteed to be in network byte order. This allows a simple userspace process to encapsulate netlink messages into arch-independent udp packets by just processing/swapping the headers and not knowing anything about the actual payload. Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
404 lines
11 KiB
C
404 lines
11 KiB
C
/* This file contains all the functions required for the standalone
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ip_nat module.
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These are not required by the compatibility layer.
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*/
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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/*
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* 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
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* - new API and handling of conntrack/nat helpers
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* - now capable of multiple expectations for one master
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* */
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#include <linux/config.h>
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#include <linux/types.h>
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#include <linux/icmp.h>
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#include <linux/ip.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/proc_fs.h>
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#include <net/ip.h>
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#include <net/checksum.h>
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#include <linux/spinlock.h>
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#define ASSERT_READ_LOCK(x)
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#define ASSERT_WRITE_LOCK(x)
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/netfilter_ipv4/ip_nat_protocol.h>
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#include <linux/netfilter_ipv4/ip_nat_core.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ip_conntrack_core.h>
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#include <linux/netfilter_ipv4/listhelp.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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#define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
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: ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
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: ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
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: ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
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: "*ERROR*")))
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static unsigned int
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ip_nat_fn(unsigned int hooknum,
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struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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struct ip_conntrack *ct;
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enum ip_conntrack_info ctinfo;
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struct ip_nat_info *info;
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/* maniptype == SRC for postrouting. */
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enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
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/* We never see fragments: conntrack defrags on pre-routing
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and local-out, and ip_nat_out protects post-routing. */
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IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
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& htons(IP_MF|IP_OFFSET)));
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/* If we had a hardware checksum before, it's now invalid */
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if ((*pskb)->ip_summed == CHECKSUM_HW)
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if (skb_checksum_help(*pskb, (out == NULL)))
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return NF_DROP;
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ct = ip_conntrack_get(*pskb, &ctinfo);
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/* Can't track? It's not due to stress, or conntrack would
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have dropped it. Hence it's the user's responsibilty to
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packet filter it out, or implement conntrack/NAT for that
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protocol. 8) --RR */
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if (!ct) {
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/* Exception: ICMP redirect to new connection (not in
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hash table yet). We must not let this through, in
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case we're doing NAT to the same network. */
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if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
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struct icmphdr _hdr, *hp;
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hp = skb_header_pointer(*pskb,
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(*pskb)->nh.iph->ihl*4,
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sizeof(_hdr), &_hdr);
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if (hp != NULL &&
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hp->type == ICMP_REDIRECT)
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return NF_DROP;
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}
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return NF_ACCEPT;
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}
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/* Don't try to NAT if this packet is not conntracked */
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if (ct == &ip_conntrack_untracked)
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return NF_ACCEPT;
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switch (ctinfo) {
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case IP_CT_RELATED:
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case IP_CT_RELATED+IP_CT_IS_REPLY:
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if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
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if (!icmp_reply_translation(pskb, ct, maniptype,
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CTINFO2DIR(ctinfo)))
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return NF_DROP;
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else
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return NF_ACCEPT;
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}
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/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
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case IP_CT_NEW:
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info = &ct->nat.info;
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/* Seen it before? This can happen for loopback, retrans,
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or local packets.. */
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if (!ip_nat_initialized(ct, maniptype)) {
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unsigned int ret;
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/* LOCAL_IN hook doesn't have a chain! */
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if (hooknum == NF_IP_LOCAL_IN)
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ret = alloc_null_binding(ct, info, hooknum);
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else
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ret = ip_nat_rule_find(pskb, hooknum,
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in, out, ct,
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info);
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if (ret != NF_ACCEPT) {
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return ret;
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}
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} else
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DEBUGP("Already setup manip %s for ct %p\n",
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maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
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ct);
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break;
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default:
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/* ESTABLISHED */
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IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
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|| ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
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info = &ct->nat.info;
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}
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IP_NF_ASSERT(info);
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return nat_packet(ct, ctinfo, hooknum, pskb);
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}
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static unsigned int
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ip_nat_in(unsigned int hooknum,
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struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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u_int32_t saddr, daddr;
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unsigned int ret;
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saddr = (*pskb)->nh.iph->saddr;
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daddr = (*pskb)->nh.iph->daddr;
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ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
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if (ret != NF_DROP && ret != NF_STOLEN
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&& ((*pskb)->nh.iph->saddr != saddr
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|| (*pskb)->nh.iph->daddr != daddr)) {
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dst_release((*pskb)->dst);
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(*pskb)->dst = NULL;
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}
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return ret;
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}
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static unsigned int
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ip_nat_out(unsigned int hooknum,
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struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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/* root is playing with raw sockets. */
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if ((*pskb)->len < sizeof(struct iphdr)
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|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
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return NF_ACCEPT;
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/* We can hit fragment here; forwarded packets get
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defragmented by connection tracking coming in, then
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fragmented (grr) by the forward code.
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In future: If we have nfct != NULL, AND we have NAT
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initialized, AND there is no helper, then we can do full
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NAPT on the head, and IP-address-only NAT on the rest.
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I'm starting to have nightmares about fragments. */
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if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
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*pskb = ip_ct_gather_frags(*pskb, IP_DEFRAG_NAT_OUT);
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if (!*pskb)
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return NF_STOLEN;
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}
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return ip_nat_fn(hooknum, pskb, in, out, okfn);
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}
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static unsigned int
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ip_nat_local_fn(unsigned int hooknum,
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struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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u_int32_t saddr, daddr;
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unsigned int ret;
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/* root is playing with raw sockets. */
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if ((*pskb)->len < sizeof(struct iphdr)
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|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
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return NF_ACCEPT;
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saddr = (*pskb)->nh.iph->saddr;
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daddr = (*pskb)->nh.iph->daddr;
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ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
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if (ret != NF_DROP && ret != NF_STOLEN
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&& ((*pskb)->nh.iph->saddr != saddr
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|| (*pskb)->nh.iph->daddr != daddr))
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return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
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return ret;
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}
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static unsigned int
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ip_nat_adjust(unsigned int hooknum,
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struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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int (*okfn)(struct sk_buff *))
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{
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struct ip_conntrack *ct;
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enum ip_conntrack_info ctinfo;
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ct = ip_conntrack_get(*pskb, &ctinfo);
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if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
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DEBUGP("ip_nat_standalone: adjusting sequence number\n");
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if (!ip_nat_seq_adjust(pskb, ct, ctinfo))
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return NF_DROP;
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}
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return NF_ACCEPT;
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}
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/* We must be after connection tracking and before packet filtering. */
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/* Before packet filtering, change destination */
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static struct nf_hook_ops ip_nat_in_ops = {
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.hook = ip_nat_in,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_PRE_ROUTING,
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.priority = NF_IP_PRI_NAT_DST,
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};
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/* After packet filtering, change source */
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static struct nf_hook_ops ip_nat_out_ops = {
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.hook = ip_nat_out,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_POST_ROUTING,
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.priority = NF_IP_PRI_NAT_SRC,
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};
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/* After conntrack, adjust sequence number */
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static struct nf_hook_ops ip_nat_adjust_out_ops = {
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.hook = ip_nat_adjust,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_POST_ROUTING,
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.priority = NF_IP_PRI_NAT_SEQ_ADJUST,
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};
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/* Before packet filtering, change destination */
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static struct nf_hook_ops ip_nat_local_out_ops = {
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.hook = ip_nat_local_fn,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_LOCAL_OUT,
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.priority = NF_IP_PRI_NAT_DST,
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};
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/* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
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static struct nf_hook_ops ip_nat_local_in_ops = {
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.hook = ip_nat_fn,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_LOCAL_IN,
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.priority = NF_IP_PRI_NAT_SRC,
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};
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/* After conntrack, adjust sequence number */
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static struct nf_hook_ops ip_nat_adjust_in_ops = {
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.hook = ip_nat_adjust,
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.owner = THIS_MODULE,
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.pf = PF_INET,
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.hooknum = NF_IP_LOCAL_IN,
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.priority = NF_IP_PRI_NAT_SEQ_ADJUST,
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};
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static int init_or_cleanup(int init)
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{
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int ret = 0;
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need_ip_conntrack();
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if (!init) goto cleanup;
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ret = ip_nat_rule_init();
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if (ret < 0) {
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printk("ip_nat_init: can't setup rules.\n");
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goto cleanup_nothing;
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}
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ret = ip_nat_init();
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if (ret < 0) {
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printk("ip_nat_init: can't setup rules.\n");
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goto cleanup_rule_init;
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}
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ret = nf_register_hook(&ip_nat_in_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register in hook.\n");
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goto cleanup_nat;
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}
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ret = nf_register_hook(&ip_nat_out_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register out hook.\n");
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goto cleanup_inops;
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}
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ret = nf_register_hook(&ip_nat_adjust_in_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register adjust in hook.\n");
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goto cleanup_outops;
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}
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ret = nf_register_hook(&ip_nat_adjust_out_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register adjust out hook.\n");
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goto cleanup_adjustin_ops;
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}
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ret = nf_register_hook(&ip_nat_local_out_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register local out hook.\n");
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goto cleanup_adjustout_ops;;
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}
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ret = nf_register_hook(&ip_nat_local_in_ops);
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if (ret < 0) {
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printk("ip_nat_init: can't register local in hook.\n");
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goto cleanup_localoutops;
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}
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return ret;
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cleanup:
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nf_unregister_hook(&ip_nat_local_in_ops);
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cleanup_localoutops:
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nf_unregister_hook(&ip_nat_local_out_ops);
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cleanup_adjustout_ops:
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nf_unregister_hook(&ip_nat_adjust_out_ops);
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cleanup_adjustin_ops:
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nf_unregister_hook(&ip_nat_adjust_in_ops);
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cleanup_outops:
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nf_unregister_hook(&ip_nat_out_ops);
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cleanup_inops:
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nf_unregister_hook(&ip_nat_in_ops);
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cleanup_nat:
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ip_nat_cleanup();
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cleanup_rule_init:
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ip_nat_rule_cleanup();
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cleanup_nothing:
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return ret;
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}
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static int __init init(void)
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{
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return init_or_cleanup(1);
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}
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static void __exit fini(void)
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{
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init_or_cleanup(0);
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}
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module_init(init);
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module_exit(fini);
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EXPORT_SYMBOL(ip_nat_setup_info);
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EXPORT_SYMBOL(ip_nat_protocol_register);
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EXPORT_SYMBOL(ip_nat_protocol_unregister);
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EXPORT_SYMBOL_GPL(ip_nat_proto_find_get);
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EXPORT_SYMBOL_GPL(ip_nat_proto_put);
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EXPORT_SYMBOL(ip_nat_cheat_check);
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EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
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EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
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EXPORT_SYMBOL(ip_nat_used_tuple);
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EXPORT_SYMBOL(ip_nat_follow_master);
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MODULE_LICENSE("GPL");
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