1 /* This file contains all the functions required for the standalone
4 These are not required by the compatibility layer.
7 /* (C) 1999-2001 Paul `Rusty' Russell
8 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 * 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
17 * - new API and handling of conntrack/nat helpers
18 * - now capable of multiple expectations for one master
21 #include <linux/config.h>
22 #include <linux/types.h>
23 #include <linux/icmp.h>
25 #include <linux/netfilter.h>
26 #include <linux/netfilter_ipv4.h>
27 #include <linux/module.h>
28 #include <linux/skbuff.h>
29 #include <linux/proc_fs.h>
30 #include <net/checksum.h>
31 #include <linux/spinlock.h>
33 #define ASSERT_READ_LOCK(x) MUST_BE_READ_LOCKED(&ip_nat_lock)
34 #define ASSERT_WRITE_LOCK(x) MUST_BE_WRITE_LOCKED(&ip_nat_lock)
36 #include <linux/netfilter_ipv4/ip_nat.h>
37 #include <linux/netfilter_ipv4/ip_nat_rule.h>
38 #include <linux/netfilter_ipv4/ip_nat_protocol.h>
39 #include <linux/netfilter_ipv4/ip_nat_core.h>
40 #include <linux/netfilter_ipv4/ip_nat_helper.h>
41 #include <linux/netfilter_ipv4/ip_tables.h>
42 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
43 #include <linux/netfilter_ipv4/listhelp.h>
48 #define DEBUGP(format, args...)
51 #define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
52 : ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
53 : ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
54 : ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
57 static inline int call_expect(struct ip_conntrack *master,
58 struct sk_buff **pskb,
60 struct ip_conntrack *ct,
61 struct ip_nat_info *info)
63 return master->nat.info.helper->expect(pskb, hooknum, ct, info);
67 ip_nat_fn(unsigned int hooknum,
68 struct sk_buff **pskb,
69 const struct net_device *in,
70 const struct net_device *out,
71 int (*okfn)(struct sk_buff *))
73 struct ip_conntrack *ct;
74 enum ip_conntrack_info ctinfo;
75 struct ip_nat_info *info;
76 /* maniptype == SRC for postrouting. */
77 enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
79 /* We never see fragments: conntrack defrags on pre-routing
80 and local-out, and ip_nat_out protects post-routing. */
81 IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
82 & htons(IP_MF|IP_OFFSET)));
84 (*pskb)->nfcache |= NFC_UNKNOWN;
86 /* If we had a hardware checksum before, it's now invalid */
87 if ((*pskb)->ip_summed == CHECKSUM_HW)
88 if (skb_checksum_help(pskb, (out == NULL)))
91 ct = ip_conntrack_get(*pskb, &ctinfo);
92 /* Can't track? It's not due to stress, or conntrack would
93 have dropped it. Hence it's the user's responsibilty to
94 packet filter it out, or implement conntrack/NAT for that
97 /* Exception: ICMP redirect to new connection (not in
98 hash table yet). We must not let this through, in
99 case we're doing NAT to the same network. */
100 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
103 if (skb_copy_bits(*pskb, (*pskb)->nh.iph->ihl*4,
104 &hdr, sizeof(hdr)) == 0
105 && hdr.type == ICMP_REDIRECT)
113 case IP_CT_RELATED+IP_CT_IS_REPLY:
114 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
115 if (!icmp_reply_translation(pskb, ct, hooknum,
121 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
123 info = &ct->nat.info;
125 WRITE_LOCK(&ip_nat_lock);
126 /* Seen it before? This can happen for loopback, retrans,
127 or local packets.. */
128 if (!(info->initialized & (1 << maniptype))
129 #ifndef CONFIG_IP_NF_NAT_LOCAL
130 /* If this session has already been confirmed we must not
131 * touch it again even if there is no mapping set up.
132 * Can only happen on local->local traffic with
133 * CONFIG_IP_NF_NAT_LOCAL disabled.
135 && !(ct->status & IPS_CONFIRMED)
141 && master_ct(ct)->nat.info.helper
142 && master_ct(ct)->nat.info.helper->expect) {
143 ret = call_expect(master_ct(ct), pskb,
146 #ifdef CONFIG_IP_NF_NAT_LOCAL
147 /* LOCAL_IN hook doesn't have a chain! */
148 if (hooknum == NF_IP_LOCAL_IN)
149 ret = alloc_null_binding(ct, info,
153 ret = ip_nat_rule_find(pskb, hooknum, in, out,
157 if (ret != NF_ACCEPT) {
158 WRITE_UNLOCK(&ip_nat_lock);
162 DEBUGP("Already setup manip %s for ct %p\n",
163 maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
165 WRITE_UNLOCK(&ip_nat_lock);
170 IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
171 || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
172 info = &ct->nat.info;
176 return do_bindings(ct, ctinfo, info, hooknum, pskb);
180 ip_nat_out(unsigned int hooknum,
181 struct sk_buff **pskb,
182 const struct net_device *in,
183 const struct net_device *out,
184 int (*okfn)(struct sk_buff *))
186 /* root is playing with raw sockets. */
187 if ((*pskb)->len < sizeof(struct iphdr)
188 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
191 /* We can hit fragment here; forwarded packets get
192 defragmented by connection tracking coming in, then
193 fragmented (grr) by the forward code.
195 In future: If we have nfct != NULL, AND we have NAT
196 initialized, AND there is no helper, then we can do full
197 NAPT on the head, and IP-address-only NAT on the rest.
199 I'm starting to have nightmares about fragments. */
201 if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
202 *pskb = ip_ct_gather_frags(*pskb);
208 return ip_nat_fn(hooknum, pskb, in, out, okfn);
211 #ifdef CONFIG_IP_NF_NAT_LOCAL
213 ip_nat_local_fn(unsigned int hooknum,
214 struct sk_buff **pskb,
215 const struct net_device *in,
216 const struct net_device *out,
217 int (*okfn)(struct sk_buff *))
219 u_int32_t saddr, daddr;
222 /* root is playing with raw sockets. */
223 if ((*pskb)->len < sizeof(struct iphdr)
224 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
227 saddr = (*pskb)->nh.iph->saddr;
228 daddr = (*pskb)->nh.iph->daddr;
230 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
231 if (ret != NF_DROP && ret != NF_STOLEN
232 && ((*pskb)->nh.iph->saddr != saddr
233 || (*pskb)->nh.iph->daddr != daddr))
234 return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
239 /* We must be after connection tracking and before packet filtering. */
241 /* Before packet filtering, change destination */
242 static struct nf_hook_ops ip_nat_in_ops = {
244 .owner = THIS_MODULE,
246 .hooknum = NF_IP_PRE_ROUTING,
247 .priority = NF_IP_PRI_NAT_DST,
250 /* After packet filtering, change source */
251 static struct nf_hook_ops ip_nat_out_ops = {
253 .owner = THIS_MODULE,
255 .hooknum = NF_IP_POST_ROUTING,
256 .priority = NF_IP_PRI_NAT_SRC,
259 #ifdef CONFIG_IP_NF_NAT_LOCAL
260 /* Before packet filtering, change destination */
261 static struct nf_hook_ops ip_nat_local_out_ops = {
262 .hook = ip_nat_local_fn,
263 .owner = THIS_MODULE,
265 .hooknum = NF_IP_LOCAL_OUT,
266 .priority = NF_IP_PRI_NAT_DST,
269 /* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
270 static struct nf_hook_ops ip_nat_local_in_ops = {
272 .owner = THIS_MODULE,
274 .hooknum = NF_IP_LOCAL_IN,
275 .priority = NF_IP_PRI_NAT_SRC,
279 /* Protocol registration. */
280 int ip_nat_protocol_register(struct ip_nat_protocol *proto)
285 WRITE_LOCK(&ip_nat_lock);
286 list_for_each(i, &protos) {
287 if (((struct ip_nat_protocol *)i)->protonum
288 == proto->protonum) {
294 list_prepend(&protos, proto);
296 WRITE_UNLOCK(&ip_nat_lock);
300 /* Noone stores the protocol anywhere; simply delete it. */
301 void ip_nat_protocol_unregister(struct ip_nat_protocol *proto)
303 WRITE_LOCK(&ip_nat_lock);
304 LIST_DELETE(&protos, proto);
305 WRITE_UNLOCK(&ip_nat_lock);
307 /* Someone could be still looking at the proto in a bh. */
311 static int init_or_cleanup(int init)
317 if (!init) goto cleanup;
319 ret = ip_nat_rule_init();
321 printk("ip_nat_init: can't setup rules.\n");
322 goto cleanup_nothing;
326 printk("ip_nat_init: can't setup rules.\n");
327 goto cleanup_rule_init;
329 ret = nf_register_hook(&ip_nat_in_ops);
331 printk("ip_nat_init: can't register in hook.\n");
334 ret = nf_register_hook(&ip_nat_out_ops);
336 printk("ip_nat_init: can't register out hook.\n");
339 #ifdef CONFIG_IP_NF_NAT_LOCAL
340 ret = nf_register_hook(&ip_nat_local_out_ops);
342 printk("ip_nat_init: can't register local out hook.\n");
345 ret = nf_register_hook(&ip_nat_local_in_ops);
347 printk("ip_nat_init: can't register local in hook.\n");
348 goto cleanup_localoutops;
354 #ifdef CONFIG_IP_NF_NAT_LOCAL
355 nf_unregister_hook(&ip_nat_local_in_ops);
357 nf_unregister_hook(&ip_nat_local_out_ops);
360 nf_unregister_hook(&ip_nat_out_ops);
362 nf_unregister_hook(&ip_nat_in_ops);
366 ip_nat_rule_cleanup();
368 MUST_BE_READ_WRITE_UNLOCKED(&ip_nat_lock);
372 static int __init init(void)
374 return init_or_cleanup(1);
377 static void __exit fini(void)
385 EXPORT_SYMBOL(ip_nat_setup_info);
386 EXPORT_SYMBOL(ip_nat_protocol_register);
387 EXPORT_SYMBOL(ip_nat_protocol_unregister);
388 EXPORT_SYMBOL(ip_nat_helper_register);
389 EXPORT_SYMBOL(ip_nat_helper_unregister);
390 EXPORT_SYMBOL(ip_nat_cheat_check);
391 EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
392 EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
393 EXPORT_SYMBOL(ip_nat_used_tuple);
394 MODULE_LICENSE("GPL");