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>
31 #include <net/checksum.h>
32 #include <linux/spinlock.h>
34 #define ASSERT_READ_LOCK(x) MUST_BE_READ_LOCKED(&ip_nat_lock)
35 #define ASSERT_WRITE_LOCK(x) MUST_BE_WRITE_LOCKED(&ip_nat_lock)
37 #include <linux/netfilter_ipv4/ip_nat.h>
38 #include <linux/netfilter_ipv4/ip_nat_rule.h>
39 #include <linux/netfilter_ipv4/ip_nat_protocol.h>
40 #include <linux/netfilter_ipv4/ip_nat_core.h>
41 #include <linux/netfilter_ipv4/ip_nat_helper.h>
42 #include <linux/netfilter_ipv4/ip_tables.h>
43 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
44 #include <linux/netfilter_ipv4/listhelp.h>
49 #define DEBUGP(format, args...)
52 #define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
53 : ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
54 : ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
55 : ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
58 static inline int call_expect(struct ip_conntrack *master,
59 struct sk_buff **pskb,
61 struct ip_conntrack *ct,
62 struct ip_nat_info *info)
64 return master->nat.info.helper->expect(pskb, hooknum, ct, info);
68 ip_nat_fn(unsigned int hooknum,
69 struct sk_buff **pskb,
70 const struct net_device *in,
71 const struct net_device *out,
72 int (*okfn)(struct sk_buff *))
74 struct ip_conntrack *ct;
75 enum ip_conntrack_info ctinfo;
76 struct ip_nat_info *info;
77 /* maniptype == SRC for postrouting. */
78 enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
80 /* We never see fragments: conntrack defrags on pre-routing
81 and local-out, and ip_nat_out protects post-routing. */
82 IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
83 & htons(IP_MF|IP_OFFSET)));
85 (*pskb)->nfcache |= NFC_UNKNOWN;
87 /* If we had a hardware checksum before, it's now invalid */
88 if ((*pskb)->ip_summed == CHECKSUM_HW)
89 if (skb_checksum_help(pskb, (out == NULL)))
92 ct = ip_conntrack_get(*pskb, &ctinfo);
93 /* Can't track? It's not due to stress, or conntrack would
94 have dropped it. Hence it's the user's responsibilty to
95 packet filter it out, or implement conntrack/NAT for that
98 /* Exception: ICMP redirect to new connection (not in
99 hash table yet). We must not let this through, in
100 case we're doing NAT to the same network. */
101 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
102 struct icmphdr _hdr, *hp;
104 hp = skb_header_pointer(*pskb,
105 (*pskb)->nh.iph->ihl*4,
106 sizeof(_hdr), &_hdr);
108 hp->type == ICMP_REDIRECT)
116 case IP_CT_RELATED+IP_CT_IS_REPLY:
117 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
118 if (!icmp_reply_translation(pskb, ct, hooknum,
124 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
126 info = &ct->nat.info;
128 WRITE_LOCK(&ip_nat_lock);
129 /* Seen it before? This can happen for loopback, retrans,
130 or local packets.. */
131 if (!(info->initialized & (1 << maniptype))
132 #ifndef CONFIG_IP_NF_NAT_LOCAL
133 /* If this session has already been confirmed we must not
134 * touch it again even if there is no mapping set up.
135 * Can only happen on local->local traffic with
136 * CONFIG_IP_NF_NAT_LOCAL disabled.
138 && !(ct->status & IPS_CONFIRMED)
144 && master_ct(ct)->nat.info.helper
145 && master_ct(ct)->nat.info.helper->expect) {
146 ret = call_expect(master_ct(ct), pskb,
149 #ifdef CONFIG_IP_NF_NAT_LOCAL
150 /* LOCAL_IN hook doesn't have a chain! */
151 if (hooknum == NF_IP_LOCAL_IN)
152 ret = alloc_null_binding(ct, info,
156 ret = ip_nat_rule_find(pskb, hooknum, in, out,
160 if (ret != NF_ACCEPT) {
161 WRITE_UNLOCK(&ip_nat_lock);
165 DEBUGP("Already setup manip %s for ct %p\n",
166 maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
168 WRITE_UNLOCK(&ip_nat_lock);
173 IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
174 || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
175 info = &ct->nat.info;
179 return do_bindings(ct, ctinfo, info, hooknum, pskb);
183 ip_nat_out(unsigned int hooknum,
184 struct sk_buff **pskb,
185 const struct net_device *in,
186 const struct net_device *out,
187 int (*okfn)(struct sk_buff *))
189 /* root is playing with raw sockets. */
190 if ((*pskb)->len < sizeof(struct iphdr)
191 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
194 /* We can hit fragment here; forwarded packets get
195 defragmented by connection tracking coming in, then
196 fragmented (grr) by the forward code.
198 In future: If we have nfct != NULL, AND we have NAT
199 initialized, AND there is no helper, then we can do full
200 NAPT on the head, and IP-address-only NAT on the rest.
202 I'm starting to have nightmares about fragments. */
204 if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
205 *pskb = ip_ct_gather_frags(*pskb);
211 return ip_nat_fn(hooknum, pskb, in, out, okfn);
214 #ifdef CONFIG_IP_NF_NAT_LOCAL
216 ip_nat_local_fn(unsigned int hooknum,
217 struct sk_buff **pskb,
218 const struct net_device *in,
219 const struct net_device *out,
220 int (*okfn)(struct sk_buff *))
222 u_int32_t saddr, daddr;
225 /* root is playing with raw sockets. */
226 if ((*pskb)->len < sizeof(struct iphdr)
227 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
230 saddr = (*pskb)->nh.iph->saddr;
231 daddr = (*pskb)->nh.iph->daddr;
233 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
234 if (ret != NF_DROP && ret != NF_STOLEN
235 && ((*pskb)->nh.iph->saddr != saddr
236 || (*pskb)->nh.iph->daddr != daddr))
237 return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
242 /* We must be after connection tracking and before packet filtering. */
244 /* Before packet filtering, change destination */
245 static struct nf_hook_ops ip_nat_in_ops = {
247 .owner = THIS_MODULE,
249 .hooknum = NF_IP_PRE_ROUTING,
250 .priority = NF_IP_PRI_NAT_DST,
253 /* After packet filtering, change source */
254 static struct nf_hook_ops ip_nat_out_ops = {
256 .owner = THIS_MODULE,
258 .hooknum = NF_IP_POST_ROUTING,
259 .priority = NF_IP_PRI_NAT_SRC,
262 #ifdef CONFIG_IP_NF_NAT_LOCAL
263 /* Before packet filtering, change destination */
264 static struct nf_hook_ops ip_nat_local_out_ops = {
265 .hook = ip_nat_local_fn,
266 .owner = THIS_MODULE,
268 .hooknum = NF_IP_LOCAL_OUT,
269 .priority = NF_IP_PRI_NAT_DST,
272 /* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
273 static struct nf_hook_ops ip_nat_local_in_ops = {
275 .owner = THIS_MODULE,
277 .hooknum = NF_IP_LOCAL_IN,
278 .priority = NF_IP_PRI_NAT_SRC,
282 /* Protocol registration. */
283 int ip_nat_protocol_register(struct ip_nat_protocol *proto)
287 WRITE_LOCK(&ip_nat_lock);
288 if (ip_nat_protos[proto->protonum] != &ip_nat_unknown_protocol) {
292 ip_nat_protos[proto->protonum] = proto;
294 WRITE_UNLOCK(&ip_nat_lock);
298 /* Noone stores the protocol anywhere; simply delete it. */
299 void ip_nat_protocol_unregister(struct ip_nat_protocol *proto)
301 WRITE_LOCK(&ip_nat_lock);
302 ip_nat_protos[proto->protonum] = &ip_nat_unknown_protocol;
303 WRITE_UNLOCK(&ip_nat_lock);
305 /* Someone could be still looking at the proto in a bh. */
309 static int init_or_cleanup(int init)
315 if (!init) goto cleanup;
317 ret = ip_nat_rule_init();
319 printk("ip_nat_init: can't setup rules.\n");
320 goto cleanup_nothing;
324 printk("ip_nat_init: can't setup rules.\n");
325 goto cleanup_rule_init;
327 ret = nf_register_hook(&ip_nat_in_ops);
329 printk("ip_nat_init: can't register in hook.\n");
332 ret = nf_register_hook(&ip_nat_out_ops);
334 printk("ip_nat_init: can't register out hook.\n");
337 #ifdef CONFIG_IP_NF_NAT_LOCAL
338 ret = nf_register_hook(&ip_nat_local_out_ops);
340 printk("ip_nat_init: can't register local out hook.\n");
343 ret = nf_register_hook(&ip_nat_local_in_ops);
345 printk("ip_nat_init: can't register local in hook.\n");
346 goto cleanup_localoutops;
352 #ifdef CONFIG_IP_NF_NAT_LOCAL
353 nf_unregister_hook(&ip_nat_local_in_ops);
355 nf_unregister_hook(&ip_nat_local_out_ops);
358 nf_unregister_hook(&ip_nat_out_ops);
360 nf_unregister_hook(&ip_nat_in_ops);
364 ip_nat_rule_cleanup();
366 MUST_BE_READ_WRITE_UNLOCKED(&ip_nat_lock);
370 static int __init init(void)
372 return init_or_cleanup(1);
375 static void __exit fini(void)
383 EXPORT_SYMBOL(ip_nat_setup_info);
384 EXPORT_SYMBOL(ip_nat_protocol_register);
385 EXPORT_SYMBOL(ip_nat_protocol_unregister);
386 EXPORT_SYMBOL(ip_nat_helper_register);
387 EXPORT_SYMBOL(ip_nat_helper_unregister);
388 EXPORT_SYMBOL(ip_nat_cheat_check);
389 EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
390 EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
391 EXPORT_SYMBOL(ip_nat_used_tuple);
392 EXPORT_SYMBOL(ip_nat_find_helper);
393 EXPORT_SYMBOL(__ip_nat_find_helper);
394 MODULE_LICENSE("GPL");