1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 /* Everything about the rules for NAT. */
10 #include <linux/types.h>
12 #include <linux/netfilter.h>
13 #include <linux/netfilter_ipv4.h>
14 #include <linux/module.h>
15 #include <linux/kmod.h>
16 #include <linux/skbuff.h>
17 #include <linux/proc_fs.h>
18 #include <net/checksum.h>
19 #include <net/route.h>
20 #include <linux/bitops.h>
22 #include <linux/netfilter_ipv4/ip_tables.h>
23 #include <net/netfilter/nf_nat.h>
24 #include <net/netfilter/nf_nat_core.h>
25 #include <net/netfilter/nf_nat_rule.h>
27 #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
28 (1 << NF_INET_POST_ROUTING) | \
29 (1 << NF_INET_LOCAL_OUT))
33 struct ipt_replace repl;
34 struct ipt_standard entries[3];
35 struct ipt_error term;
36 } nat_initial_table __net_initdata = {
39 .valid_hooks = NAT_VALID_HOOKS,
41 .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
43 [NF_INET_PRE_ROUTING] = 0,
44 [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
45 [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
48 [NF_INET_PRE_ROUTING] = 0,
49 [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
50 [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
54 IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
55 IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
56 IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
58 .term = IPT_ERROR_INIT, /* ERROR */
61 static struct xt_table nat_table = {
63 .valid_hooks = NAT_VALID_HOOKS,
64 .lock = __RW_LOCK_UNLOCKED(__nat_table.lock),
71 ipt_snat_target(struct sk_buff *skb, const struct xt_target_param *par)
74 enum ip_conntrack_info ctinfo;
75 const struct nf_nat_multi_range_compat *mr = par->targinfo;
77 NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
79 ct = nf_ct_get(skb, &ctinfo);
81 /* Connection must be valid and new. */
82 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
83 ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
84 NF_CT_ASSERT(par->out != NULL);
86 return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC);
90 ipt_dnat_target(struct sk_buff *skb, const struct xt_target_param *par)
93 enum ip_conntrack_info ctinfo;
94 const struct nf_nat_multi_range_compat *mr = par->targinfo;
96 NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
97 par->hooknum == NF_INET_LOCAL_OUT);
99 ct = nf_ct_get(skb, &ctinfo);
101 /* Connection must be valid and new. */
102 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
104 return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
107 static bool ipt_snat_checkentry(const struct xt_tgchk_param *par)
109 const struct nf_nat_multi_range_compat *mr = par->targinfo;
111 /* Must be a valid range */
112 if (mr->rangesize != 1) {
113 printk("SNAT: multiple ranges no longer supported\n");
119 static bool ipt_dnat_checkentry(const struct xt_tgchk_param *par)
121 const struct nf_nat_multi_range_compat *mr = par->targinfo;
123 /* Must be a valid range */
124 if (mr->rangesize != 1) {
125 printk("DNAT: multiple ranges no longer supported\n");
132 alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
134 /* Force range to this IP; let proto decide mapping for
135 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
136 Use reply in case it's already been mangled (eg local packet).
139 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
140 ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
141 : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
142 struct nf_nat_range range
143 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
145 pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, &ip);
146 return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
149 int nf_nat_rule_find(struct sk_buff *skb,
150 unsigned int hooknum,
151 const struct net_device *in,
152 const struct net_device *out,
155 struct net *net = nf_ct_net(ct);
158 ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
160 if (ret == NF_ACCEPT) {
161 if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
163 ret = alloc_null_binding(ct, hooknum);
168 static struct xt_target ipt_snat_reg __read_mostly = {
170 .target = ipt_snat_target,
171 .targetsize = sizeof(struct nf_nat_multi_range_compat),
173 .hooks = 1 << NF_INET_POST_ROUTING,
174 .checkentry = ipt_snat_checkentry,
178 static struct xt_target ipt_dnat_reg __read_mostly = {
180 .target = ipt_dnat_target,
181 .targetsize = sizeof(struct nf_nat_multi_range_compat),
183 .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
184 .checkentry = ipt_dnat_checkentry,
188 static int __net_init nf_nat_rule_net_init(struct net *net)
190 net->ipv4.nat_table = ipt_register_table(net, &nat_table,
191 &nat_initial_table.repl);
192 if (IS_ERR(net->ipv4.nat_table))
193 return PTR_ERR(net->ipv4.nat_table);
197 static void __net_exit nf_nat_rule_net_exit(struct net *net)
199 ipt_unregister_table(net->ipv4.nat_table);
202 static struct pernet_operations nf_nat_rule_net_ops = {
203 .init = nf_nat_rule_net_init,
204 .exit = nf_nat_rule_net_exit,
207 int __init nf_nat_rule_init(void)
211 ret = register_pernet_subsys(&nf_nat_rule_net_ops);
214 ret = xt_register_target(&ipt_snat_reg);
216 goto unregister_table;
218 ret = xt_register_target(&ipt_dnat_reg);
220 goto unregister_snat;
225 xt_unregister_target(&ipt_snat_reg);
227 unregister_pernet_subsys(&nf_nat_rule_net_ops);
232 void nf_nat_rule_cleanup(void)
234 xt_unregister_target(&ipt_dnat_reg);
235 xt_unregister_target(&ipt_snat_reg);
236 unregister_pernet_subsys(&nf_nat_rule_net_ops);