1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 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 #define ASSERT_READ_LOCK(x)
23 #define ASSERT_WRITE_LOCK(x)
25 #include <linux/netfilter_ipv4/ip_tables.h>
26 #include <linux/netfilter_ipv4/ip_nat.h>
27 #include <linux/netfilter_ipv4/ip_nat_core.h>
28 #include <linux/netfilter_ipv4/ip_nat_rule.h>
29 #include <linux/netfilter_ipv4/listhelp.h>
34 #define DEBUGP(format, args...)
37 #define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT))
41 struct ipt_replace repl;
42 struct ipt_standard entries[3];
43 struct ipt_error term;
44 } nat_initial_table __initdata
45 = { { "nat", NAT_VALID_HOOKS, 4,
46 sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
47 { [NF_IP_PRE_ROUTING] = 0,
48 [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
49 [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
50 { [NF_IP_PRE_ROUTING] = 0,
51 [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
52 [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
56 { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
58 sizeof(struct ipt_entry),
59 sizeof(struct ipt_standard),
61 { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
64 { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
66 sizeof(struct ipt_entry),
67 sizeof(struct ipt_standard),
69 { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
72 { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
74 sizeof(struct ipt_entry),
75 sizeof(struct ipt_standard),
77 { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
81 { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
83 sizeof(struct ipt_entry),
84 sizeof(struct ipt_error),
86 { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
93 static struct ipt_table nat_table = {
95 .valid_hooks = NAT_VALID_HOOKS,
96 .lock = RW_LOCK_UNLOCKED,
102 static unsigned int ipt_snat_target(struct sk_buff **pskb,
103 const struct net_device *in,
104 const struct net_device *out,
105 unsigned int hooknum,
106 const struct ipt_target *target,
107 const void *targinfo,
110 struct ip_conntrack *ct;
111 enum ip_conntrack_info ctinfo;
112 const struct ip_nat_multi_range_compat *mr = targinfo;
114 IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
116 ct = ip_conntrack_get(*pskb, &ctinfo);
118 /* Connection must be valid and new. */
119 IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
120 || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
123 return ip_nat_setup_info(ct, &mr->range[0], hooknum);
126 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
127 static void warn_if_extra_mangle(u32 dstip, u32 srcip)
129 static int warned = 0;
130 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
133 if (ip_route_output_key(&rt, &fl) != 0)
136 if (rt->rt_src != srcip && !warned) {
137 printk("NAT: no longer support implicit source local NAT\n");
138 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
139 NIPQUAD(srcip), NIPQUAD(dstip));
145 static unsigned int ipt_dnat_target(struct sk_buff **pskb,
146 const struct net_device *in,
147 const struct net_device *out,
148 unsigned int hooknum,
149 const struct ipt_target *target,
150 const void *targinfo,
153 struct ip_conntrack *ct;
154 enum ip_conntrack_info ctinfo;
155 const struct ip_nat_multi_range_compat *mr = targinfo;
157 IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
158 || hooknum == NF_IP_LOCAL_OUT);
160 ct = ip_conntrack_get(*pskb, &ctinfo);
162 /* Connection must be valid and new. */
163 IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
165 if (hooknum == NF_IP_LOCAL_OUT
166 && mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
167 warn_if_extra_mangle((*pskb)->nh.iph->daddr,
168 mr->range[0].min_ip);
170 return ip_nat_setup_info(ct, &mr->range[0], hooknum);
173 static int ipt_snat_checkentry(const char *tablename,
175 const struct ipt_target *target,
177 unsigned int targinfosize,
178 unsigned int hook_mask)
180 struct ip_nat_multi_range_compat *mr = targinfo;
182 /* Must be a valid range */
183 if (mr->rangesize != 1) {
184 printk("SNAT: multiple ranges no longer supported\n");
190 static int ipt_dnat_checkentry(const char *tablename,
192 const struct ipt_target *target,
194 unsigned int targinfosize,
195 unsigned int hook_mask)
197 struct ip_nat_multi_range_compat *mr = targinfo;
199 /* Must be a valid range */
200 if (mr->rangesize != 1) {
201 printk("DNAT: multiple ranges no longer supported\n");
208 alloc_null_binding(struct ip_conntrack *conntrack,
209 struct ip_nat_info *info,
210 unsigned int hooknum)
212 /* Force range to this IP; let proto decide mapping for
213 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
214 Use reply in case it's already been mangled (eg local packet).
217 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
218 ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
219 : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
220 struct ip_nat_range range
221 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
223 DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", conntrack,
225 return ip_nat_setup_info(conntrack, &range, hooknum);
229 alloc_null_binding_confirmed(struct ip_conntrack *conntrack,
230 struct ip_nat_info *info,
231 unsigned int hooknum)
234 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
235 ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
236 : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
238 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
239 ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
240 : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
241 struct ip_nat_range range
242 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
244 DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
245 conntrack, NIPQUAD(ip));
246 return ip_nat_setup_info(conntrack, &range, hooknum);
249 int ip_nat_rule_find(struct sk_buff **pskb,
250 unsigned int hooknum,
251 const struct net_device *in,
252 const struct net_device *out,
253 struct ip_conntrack *ct,
254 struct ip_nat_info *info)
258 ret = ipt_do_table(pskb, hooknum, in, out, &nat_table, NULL);
260 if (ret == NF_ACCEPT) {
261 if (!ip_nat_initialized(ct, HOOK2MANIP(hooknum)))
263 ret = alloc_null_binding(ct, info, hooknum);
268 static struct ipt_target ipt_snat_reg = {
270 .target = ipt_snat_target,
271 .targetsize = sizeof(struct ip_nat_multi_range_compat),
273 .hooks = 1 << NF_IP_POST_ROUTING,
274 .checkentry = ipt_snat_checkentry,
277 static struct ipt_target ipt_dnat_reg = {
279 .target = ipt_dnat_target,
280 .targetsize = sizeof(struct ip_nat_multi_range_compat),
282 .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT),
283 .checkentry = ipt_dnat_checkentry,
286 int __init ip_nat_rule_init(void)
290 ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
293 ret = ipt_register_target(&ipt_snat_reg);
295 goto unregister_table;
297 ret = ipt_register_target(&ipt_dnat_reg);
299 goto unregister_snat;
304 ipt_unregister_target(&ipt_snat_reg);
306 ipt_unregister_table(&nat_table);
311 void ip_nat_rule_cleanup(void)
313 ipt_unregister_target(&ipt_dnat_reg);
314 ipt_unregister_target(&ipt_snat_reg);
315 ipt_unregister_table(&nat_table);