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)
35 #define ASSERT_WRITE_LOCK(x)
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" \
59 ip_nat_fn(unsigned int hooknum,
60 struct sk_buff **pskb,
61 const struct net_device *in,
62 const struct net_device *out,
63 int (*okfn)(struct sk_buff *))
65 struct ip_conntrack *ct;
66 enum ip_conntrack_info ctinfo;
67 struct ip_nat_info *info;
68 /* maniptype == SRC for postrouting. */
69 enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
71 /* We never see fragments: conntrack defrags on pre-routing
72 and local-out, and ip_nat_out protects post-routing. */
73 IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
74 & htons(IP_MF|IP_OFFSET)));
76 /* If we had a hardware checksum before, it's now invalid */
77 if ((*pskb)->ip_summed == CHECKSUM_HW)
78 if (skb_checksum_help(*pskb, (out == NULL)))
81 ct = ip_conntrack_get(*pskb, &ctinfo);
82 /* Can't track? It's not due to stress, or conntrack would
83 have dropped it. Hence it's the user's responsibilty to
84 packet filter it out, or implement conntrack/NAT for that
87 /* Exception: ICMP redirect to new connection (not in
88 hash table yet). We must not let this through, in
89 case we're doing NAT to the same network. */
90 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
91 struct icmphdr _hdr, *hp;
93 hp = skb_header_pointer(*pskb,
94 (*pskb)->nh.iph->ihl*4,
97 hp->type == ICMP_REDIRECT)
103 /* Don't try to NAT if this packet is not conntracked */
104 if (ct == &ip_conntrack_untracked)
109 case IP_CT_RELATED+IP_CT_IS_REPLY:
110 if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
111 if (!icmp_reply_translation(pskb, ct, maniptype,
117 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
119 info = &ct->nat.info;
121 /* Seen it before? This can happen for loopback, retrans,
122 or local packets.. */
123 if (!ip_nat_initialized(ct, maniptype)) {
126 /* LOCAL_IN hook doesn't have a chain! */
127 if (hooknum == NF_IP_LOCAL_IN)
128 ret = alloc_null_binding(ct, info, hooknum);
130 ret = ip_nat_rule_find(pskb, hooknum,
134 if (ret != NF_ACCEPT) {
138 DEBUGP("Already setup manip %s for ct %p\n",
139 maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
145 IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
146 || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
147 info = &ct->nat.info;
151 return nat_packet(ct, ctinfo, hooknum, pskb);
155 ip_nat_in(unsigned int hooknum,
156 struct sk_buff **pskb,
157 const struct net_device *in,
158 const struct net_device *out,
159 int (*okfn)(struct sk_buff *))
161 u_int32_t saddr, daddr;
164 saddr = (*pskb)->nh.iph->saddr;
165 daddr = (*pskb)->nh.iph->daddr;
167 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
168 if (ret != NF_DROP && ret != NF_STOLEN
169 && ((*pskb)->nh.iph->saddr != saddr
170 || (*pskb)->nh.iph->daddr != daddr)) {
171 dst_release((*pskb)->dst);
178 ip_nat_out(unsigned int hooknum,
179 struct sk_buff **pskb,
180 const struct net_device *in,
181 const struct net_device *out,
182 int (*okfn)(struct sk_buff *))
184 /* root is playing with raw sockets. */
185 if ((*pskb)->len < sizeof(struct iphdr)
186 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
189 /* We can hit fragment here; forwarded packets get
190 defragmented by connection tracking coming in, then
191 fragmented (grr) by the forward code.
193 In future: If we have nfct != NULL, AND we have NAT
194 initialized, AND there is no helper, then we can do full
195 NAPT on the head, and IP-address-only NAT on the rest.
197 I'm starting to have nightmares about fragments. */
199 if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
200 *pskb = ip_ct_gather_frags(*pskb, IP_DEFRAG_NAT_OUT);
206 return ip_nat_fn(hooknum, pskb, in, out, okfn);
210 ip_nat_local_fn(unsigned int hooknum,
211 struct sk_buff **pskb,
212 const struct net_device *in,
213 const struct net_device *out,
214 int (*okfn)(struct sk_buff *))
216 u_int32_t saddr, daddr;
219 /* root is playing with raw sockets. */
220 if ((*pskb)->len < sizeof(struct iphdr)
221 || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
224 saddr = (*pskb)->nh.iph->saddr;
225 daddr = (*pskb)->nh.iph->daddr;
227 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
228 if (ret != NF_DROP && ret != NF_STOLEN
229 && ((*pskb)->nh.iph->saddr != saddr
230 || (*pskb)->nh.iph->daddr != daddr))
231 return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
236 ip_nat_adjust(unsigned int hooknum,
237 struct sk_buff **pskb,
238 const struct net_device *in,
239 const struct net_device *out,
240 int (*okfn)(struct sk_buff *))
242 struct ip_conntrack *ct;
243 enum ip_conntrack_info ctinfo;
245 ct = ip_conntrack_get(*pskb, &ctinfo);
246 if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
247 DEBUGP("ip_nat_standalone: adjusting sequence number\n");
248 if (!ip_nat_seq_adjust(pskb, ct, ctinfo))
254 /* We must be after connection tracking and before packet filtering. */
256 /* Before packet filtering, change destination */
257 static struct nf_hook_ops ip_nat_in_ops = {
259 .owner = THIS_MODULE,
261 .hooknum = NF_IP_PRE_ROUTING,
262 .priority = NF_IP_PRI_NAT_DST,
265 /* After packet filtering, change source */
266 static struct nf_hook_ops ip_nat_out_ops = {
268 .owner = THIS_MODULE,
270 .hooknum = NF_IP_POST_ROUTING,
271 .priority = NF_IP_PRI_NAT_SRC,
274 /* After conntrack, adjust sequence number */
275 static struct nf_hook_ops ip_nat_adjust_out_ops = {
276 .hook = ip_nat_adjust,
277 .owner = THIS_MODULE,
279 .hooknum = NF_IP_POST_ROUTING,
280 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
283 /* Before packet filtering, change destination */
284 static struct nf_hook_ops ip_nat_local_out_ops = {
285 .hook = ip_nat_local_fn,
286 .owner = THIS_MODULE,
288 .hooknum = NF_IP_LOCAL_OUT,
289 .priority = NF_IP_PRI_NAT_DST,
292 /* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
293 static struct nf_hook_ops ip_nat_local_in_ops = {
295 .owner = THIS_MODULE,
297 .hooknum = NF_IP_LOCAL_IN,
298 .priority = NF_IP_PRI_NAT_SRC,
301 /* After conntrack, adjust sequence number */
302 static struct nf_hook_ops ip_nat_adjust_in_ops = {
303 .hook = ip_nat_adjust,
304 .owner = THIS_MODULE,
306 .hooknum = NF_IP_LOCAL_IN,
307 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
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 ret = nf_register_hook(&ip_nat_adjust_in_ops);
341 printk("ip_nat_init: can't register adjust in hook.\n");
344 ret = nf_register_hook(&ip_nat_adjust_out_ops);
346 printk("ip_nat_init: can't register adjust out hook.\n");
347 goto cleanup_adjustin_ops;
349 ret = nf_register_hook(&ip_nat_local_out_ops);
351 printk("ip_nat_init: can't register local out hook.\n");
352 goto cleanup_adjustout_ops;;
354 ret = nf_register_hook(&ip_nat_local_in_ops);
356 printk("ip_nat_init: can't register local in hook.\n");
357 goto cleanup_localoutops;
362 nf_unregister_hook(&ip_nat_local_in_ops);
364 nf_unregister_hook(&ip_nat_local_out_ops);
365 cleanup_adjustout_ops:
366 nf_unregister_hook(&ip_nat_adjust_out_ops);
367 cleanup_adjustin_ops:
368 nf_unregister_hook(&ip_nat_adjust_in_ops);
370 nf_unregister_hook(&ip_nat_out_ops);
372 nf_unregister_hook(&ip_nat_in_ops);
376 ip_nat_rule_cleanup();
381 static int __init init(void)
383 return init_or_cleanup(1);
386 static void __exit fini(void)
394 EXPORT_SYMBOL(ip_nat_setup_info);
395 EXPORT_SYMBOL(ip_nat_protocol_register);
396 EXPORT_SYMBOL(ip_nat_protocol_unregister);
397 EXPORT_SYMBOL_GPL(ip_nat_proto_find_get);
398 EXPORT_SYMBOL_GPL(ip_nat_proto_put);
399 EXPORT_SYMBOL(ip_nat_cheat_check);
400 EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
401 EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
402 EXPORT_SYMBOL(ip_nat_used_tuple);
403 EXPORT_SYMBOL(ip_nat_follow_master);
404 MODULE_LICENSE("GPL");