1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
3 * (C) 2011 Patrick McHardy <kaber@trash.net>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/module.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter_ipv4.h>
13 #include <linux/netfilter_ipv4/ip_tables.h>
17 #include <net/netfilter/nf_nat.h>
18 #include <net/netfilter/nf_nat_core.h>
19 #include <net/netfilter/nf_nat_l3proto.h>
21 static const struct xt_table nf_nat_ipv4_table = {
23 .valid_hooks = (1 << NF_INET_PRE_ROUTING) |
24 (1 << NF_INET_POST_ROUTING) |
25 (1 << NF_INET_LOCAL_OUT) |
26 (1 << NF_INET_LOCAL_IN),
31 static unsigned int alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
33 /* Force range to this IP; let proto decide mapping for
34 * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
36 struct nf_nat_range range;
39 pr_debug("Allocating NULL binding for %p (%pI4)\n", ct,
40 HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ?
41 &ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip :
42 &ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
44 return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
47 static unsigned int nf_nat_rule_find(struct sk_buff *skb, unsigned int hooknum,
48 const struct net_device *in,
49 const struct net_device *out,
52 struct net *net = nf_ct_net(ct);
55 ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
56 if (ret == NF_ACCEPT) {
57 if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
58 ret = alloc_null_binding(ct, hooknum);
64 nf_nat_ipv4_fn(unsigned int hooknum,
66 const struct net_device *in,
67 const struct net_device *out,
68 int (*okfn)(struct sk_buff *))
71 enum ip_conntrack_info ctinfo;
72 struct nf_conn_nat *nat;
73 /* maniptype == SRC for postrouting. */
74 enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);
76 /* We never see fragments: conntrack defrags on pre-routing
77 * and local-out, and nf_nat_out protects post-routing.
79 NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb)));
81 ct = nf_ct_get(skb, &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
90 /* Don't try to NAT if this packet is not conntracked */
91 if (nf_ct_is_untracked(ct))
96 /* NAT module was loaded late. */
97 if (nf_ct_is_confirmed(ct))
99 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
101 pr_debug("failed to add NAT extension\n");
108 case IP_CT_RELATED_REPLY:
109 if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
110 if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
116 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
118 /* Seen it before? This can happen for loopback, retrans,
121 if (!nf_nat_initialized(ct, maniptype)) {
124 ret = nf_nat_rule_find(skb, hooknum, in, out, ct);
125 if (ret != NF_ACCEPT)
128 pr_debug("Already setup manip %s for ct %p\n",
129 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
135 NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
136 ctinfo == IP_CT_ESTABLISHED_REPLY);
137 if (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) {
138 nf_ct_kill_acct(ct, ctinfo, skb);
143 return nf_nat_packet(ct, ctinfo, hooknum, skb);
147 nf_nat_ipv4_in(unsigned int hooknum,
149 const struct net_device *in,
150 const struct net_device *out,
151 int (*okfn)(struct sk_buff *))
154 __be32 daddr = ip_hdr(skb)->daddr;
156 ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
157 if (ret != NF_DROP && ret != NF_STOLEN &&
158 daddr != ip_hdr(skb)->daddr)
165 nf_nat_ipv4_out(unsigned int hooknum,
167 const struct net_device *in,
168 const struct net_device *out,
169 int (*okfn)(struct sk_buff *))
172 const struct nf_conn *ct;
173 enum ip_conntrack_info ctinfo;
177 /* root is playing with raw sockets. */
178 if (skb->len < sizeof(struct iphdr) ||
179 ip_hdrlen(skb) < sizeof(struct iphdr))
182 ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
184 if (ret != NF_DROP && ret != NF_STOLEN &&
185 !(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
186 (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
187 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
189 if ((ct->tuplehash[dir].tuple.src.u3.ip !=
190 ct->tuplehash[!dir].tuple.dst.u3.ip) ||
191 (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
192 ct->tuplehash[dir].tuple.src.u.all !=
193 ct->tuplehash[!dir].tuple.dst.u.all))
194 if (nf_xfrm_me_harder(skb, AF_INET) < 0)
202 nf_nat_ipv4_local_fn(unsigned int hooknum,
204 const struct net_device *in,
205 const struct net_device *out,
206 int (*okfn)(struct sk_buff *))
208 const struct nf_conn *ct;
209 enum ip_conntrack_info ctinfo;
212 /* root is playing with raw sockets. */
213 if (skb->len < sizeof(struct iphdr) ||
214 ip_hdrlen(skb) < sizeof(struct iphdr))
217 ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
218 if (ret != NF_DROP && ret != NF_STOLEN &&
219 (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
220 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
222 if (ct->tuplehash[dir].tuple.dst.u3.ip !=
223 ct->tuplehash[!dir].tuple.src.u3.ip) {
224 if (ip_route_me_harder(skb, RTN_UNSPEC))
228 else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
229 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
230 ct->tuplehash[dir].tuple.dst.u.all !=
231 ct->tuplehash[!dir].tuple.src.u.all)
232 if (nf_xfrm_me_harder(skb, AF_INET) < 0)
239 static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = {
240 /* Before packet filtering, change destination */
242 .hook = nf_nat_ipv4_in,
243 .owner = THIS_MODULE,
245 .hooknum = NF_INET_PRE_ROUTING,
246 .priority = NF_IP_PRI_NAT_DST,
248 /* After packet filtering, change source */
250 .hook = nf_nat_ipv4_out,
251 .owner = THIS_MODULE,
253 .hooknum = NF_INET_POST_ROUTING,
254 .priority = NF_IP_PRI_NAT_SRC,
256 /* Before packet filtering, change destination */
258 .hook = nf_nat_ipv4_local_fn,
259 .owner = THIS_MODULE,
261 .hooknum = NF_INET_LOCAL_OUT,
262 .priority = NF_IP_PRI_NAT_DST,
264 /* After packet filtering, change source */
266 .hook = nf_nat_ipv4_fn,
267 .owner = THIS_MODULE,
269 .hooknum = NF_INET_LOCAL_IN,
270 .priority = NF_IP_PRI_NAT_SRC,
274 static int __net_init iptable_nat_net_init(struct net *net)
276 struct ipt_replace *repl;
278 repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
281 net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl);
283 return PTR_RET(net->ipv4.nat_table);
286 static void __net_exit iptable_nat_net_exit(struct net *net)
288 ipt_unregister_table(net, net->ipv4.nat_table);
291 static struct pernet_operations iptable_nat_net_ops = {
292 .init = iptable_nat_net_init,
293 .exit = iptable_nat_net_exit,
296 static int __init iptable_nat_init(void)
300 err = register_pernet_subsys(&iptable_nat_net_ops);
304 err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
310 unregister_pernet_subsys(&iptable_nat_net_ops);
315 static void __exit iptable_nat_exit(void)
317 nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
318 unregister_pernet_subsys(&iptable_nat_net_ops);
321 module_init(iptable_nat_init);
322 module_exit(iptable_nat_exit);
324 MODULE_LICENSE("GPL");