/* This file contains all the functions required for the standalone
ip_nat module.
These are not required by the compatibility layer.
*/
/* (c) 1999 Paul `Rusty' Russell. Licenced under the GNU General
* Public Licence.
*
* 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/config.h>
#include <linux/types.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/checksum.h>
#include <linux/spinlock.h>
#include <linux/version.h>
#include <linux/brlock.h>
#define ASSERT_READ_LOCK(x) MUST_BE_READ_LOCKED(&ip_nat_lock)
#define ASSERT_WRITE_LOCK(x) MUST_BE_WRITE_LOCKED(&ip_nat_lock)
#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*")))
static inline int call_expect(struct ip_conntrack *master,
struct sk_buff **pskb,
unsigned int hooknum,
struct ip_conntrack *ct,
struct ip_nat_info *info)
{
return master->nat.info.helper->expect(pskb, hooknum, ct, info);
}
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)));
(*pskb)->nfcache |= NFC_UNKNOWN;
/* If we had a hardware checksum before, it's now invalid */
if ((*pskb)->ip_summed == CHECKSUM_HW)
(*pskb)->ip_summed = CHECKSUM_NONE;
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. */
struct iphdr *iph = (*pskb)->nh.iph;
struct icmphdr *hdr = (struct icmphdr *)
((u_int32_t *)iph + iph->ihl);
if (iph->protocol == IPPROTO_ICMP
&& hdr->type == ICMP_REDIRECT)
return NF_DROP;
return NF_ACCEPT;
}
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED+IP_CT_IS_REPLY:
if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
return icmp_reply_translation(*pskb, ct, hooknum,
CTINFO2DIR(ctinfo));
}
/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
case IP_CT_NEW:
info = &ct->nat.info;
WRITE_LOCK(&ip_nat_lock);
/* Seen it before? This can happen for loopback, retrans,
or local packets.. */
if (!(info->initialized & (1 << maniptype))) {
unsigned int ret;
if (ct->master
&& master_ct(ct)->nat.info.helper
&& master_ct(ct)->nat.info.helper->expect) {
ret = call_expect(master_ct(ct), pskb,
hooknum, ct, info);
} else {
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) {
WRITE_UNLOCK(&ip_nat_lock);
return ret;
}
} else
DEBUGP("Already setup manip %s for ct %p\n",
maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
ct);
WRITE_UNLOCK(&ip_nat_lock);
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 do_bindings(ct, ctinfo, info, 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 *))
{
u_int32_t saddr, daddr;
unsigned int ret;
saddr = (*pskb)->nh.iph->saddr;
daddr = (*pskb)->nh.iph->daddr;
ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN
&& ((*pskb)->nh.iph->saddr != saddr
|| (*pskb)->nh.iph->daddr != 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 *))
{
/* root is playing with raw sockets. */
if ((*pskb)->len < sizeof(struct iphdr)
|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
return NF_ACCEPT;
/* We can hit fragment here; forwarded packets get
defragmented by connection tracking coming in, then
fragmented (grr) by the forward code.
In future: If we have nfct != NULL, AND we have NAT
initialized, AND there is no helper, then we can do full
NAPT on the head, and IP-address-only NAT on the rest.
I'm starting to have nightmares about fragments. */
if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
*pskb = ip_ct_gather_frags(*pskb, IP_DEFRAG_NAT_OUT);
if (!*pskb)
return NF_STOLEN;
}
return ip_nat_fn(hooknum, pskb, in, out, okfn);
}
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 *))
{
u_int32_t saddr, daddr;
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;
saddr = (*pskb)->nh.iph->saddr;
daddr = (*pskb)->nh.iph->daddr;
ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN
&& ((*pskb)->nh.iph->saddr != saddr
|| (*pskb)->nh.iph->daddr != daddr))
return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
return ret;
}
/* We must be after connection tracking and before packet filtering. */
/* Before packet filtering, change destination */
static struct nf_hook_ops ip_nat_in_ops
= { { NULL, NULL }, ip_nat_in, PF_INET, NF_IP_PRE_ROUTING, NF_IP_PRI_NAT_DST };
/* After packet filtering, change source */
static struct nf_hook_ops ip_nat_out_ops
= { { NULL, NULL }, ip_nat_out, PF_INET, NF_IP_POST_ROUTING, NF_IP_PRI_NAT_SRC};
/* Before packet filtering, change destination */
static struct nf_hook_ops ip_nat_local_out_ops
= { { NULL, NULL }, ip_nat_local_fn, PF_INET, NF_IP_LOCAL_OUT, NF_IP_PRI_NAT_DST };
/* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
static struct nf_hook_ops ip_nat_local_in_ops
= { { NULL, NULL }, ip_nat_fn, PF_INET, NF_IP_LOCAL_IN, NF_IP_PRI_NAT_SRC };
/* Protocol registration. */
int ip_nat_protocol_register(struct ip_nat_protocol *proto)
{
int ret = 0;
struct list_head *i;
WRITE_LOCK(&ip_nat_lock);
for (i = protos.next; i != &protos; i = i->next) {
if (((struct ip_nat_protocol *)i)->protonum
== proto->protonum) {
ret = -EBUSY;
goto out;
}
}
list_prepend(&protos, proto);
MOD_INC_USE_COUNT;
out:
WRITE_UNLOCK(&ip_nat_lock);
return ret;
}
/* Noone stores the protocol anywhere; simply delete it. */
void ip_nat_protocol_unregister(struct ip_nat_protocol *proto)
{
WRITE_LOCK(&ip_nat_lock);
LIST_DELETE(&protos, proto);
WRITE_UNLOCK(&ip_nat_lock);
/* Someone could be still looking at the proto in a bh. */
br_write_lock_bh(BR_NETPROTO_LOCK);
br_write_unlock_bh(BR_NETPROTO_LOCK);
MOD_DEC_USE_COUNT;
}
static int init_or_cleanup(int init)
{
int ret = 0;
if (!init) goto cleanup;
ret = ip_nat_rule_init();
if (ret < 0) {
printk("ip_nat_init: can't setup rules.\n");
goto cleanup_nothing;
}
ret = ip_nat_init();
if (ret < 0) {
printk("ip_nat_init: can't setup rules.\n");
goto cleanup_rule_init;
}
ret = nf_register_hook(&ip_nat_in_ops);
if (ret < 0) {
printk("ip_nat_init: can't register in hook.\n");
goto cleanup_nat;
}
ret = nf_register_hook(&ip_nat_out_ops);
if (ret < 0) {
printk("ip_nat_init: can't register out hook.\n");
goto cleanup_inops;
}
ret = nf_register_hook(&ip_nat_local_out_ops);
if (ret < 0) {
printk("ip_nat_init: can't register local out hook.\n");
goto cleanup_outops;
}
ret = nf_register_hook(&ip_nat_local_in_ops);
if (ret < 0) {
printk("ip_nat_init: can't register local in hook.\n");
goto cleanup_localoutops;
}
return ret;
cleanup:
nf_unregister_hook(&ip_nat_local_in_ops);
cleanup_localoutops:
nf_unregister_hook(&ip_nat_local_out_ops);
cleanup_outops:
nf_unregister_hook(&ip_nat_out_ops);
cleanup_inops:
nf_unregister_hook(&ip_nat_in_ops);
cleanup_nat:
ip_nat_cleanup();
cleanup_rule_init:
ip_nat_rule_cleanup();
cleanup_nothing:
MUST_BE_READ_WRITE_UNLOCKED(&ip_nat_lock);
return ret;
}
static int __init init(void)
{
return init_or_cleanup(1);
}
static void __exit fini(void)
{
init_or_cleanup(0);
}
module_init(init);
module_exit(fini);
EXPORT_SYMBOL(ip_nat_setup_info);
EXPORT_SYMBOL(ip_nat_protocol_register);
EXPORT_SYMBOL(ip_nat_protocol_unregister);
EXPORT_SYMBOL(ip_nat_helper_register);
EXPORT_SYMBOL(ip_nat_helper_unregister);
EXPORT_SYMBOL(ip_nat_cheat_check);
EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
EXPORT_SYMBOL(ip_nat_used_tuple);
MODULE_LICENSE("GPL");
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