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>
30 #define DEBUGP(format, args...)
33 #define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT))
37 struct ipt_replace repl;
38 struct ipt_standard entries[3];
39 struct ipt_error term;
40 } nat_initial_table __initdata = {
43 .valid_hooks = NAT_VALID_HOOKS,
45 .size = 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 },
51 [NF_IP_PRE_ROUTING] = 0,
52 [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
53 [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
59 .target_offset = sizeof(struct ipt_entry),
60 .next_offset = sizeof(struct ipt_standard),
65 .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
68 .verdict = -NF_ACCEPT - 1,
74 .target_offset = sizeof(struct ipt_entry),
75 .next_offset = sizeof(struct ipt_standard),
80 .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
83 .verdict = -NF_ACCEPT - 1,
89 .target_offset = sizeof(struct ipt_entry),
90 .next_offset = sizeof(struct ipt_standard),
95 .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
98 .verdict = -NF_ACCEPT - 1,
105 .target_offset = sizeof(struct ipt_entry),
106 .next_offset = sizeof(struct ipt_error),
112 .target_size = IPT_ALIGN(sizeof(struct ipt_error_target)),
113 .name = IPT_ERROR_TARGET,
117 .errorname = "ERROR",
122 static struct xt_table nat_table = {
124 .valid_hooks = NAT_VALID_HOOKS,
125 .lock = RW_LOCK_UNLOCKED,
131 static unsigned int ipt_snat_target(struct sk_buff **pskb,
132 const struct net_device *in,
133 const struct net_device *out,
134 unsigned int hooknum,
135 const struct xt_target *target,
136 const void *targinfo)
139 enum ip_conntrack_info ctinfo;
140 const struct nf_nat_multi_range_compat *mr = targinfo;
142 NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING);
144 ct = nf_ct_get(*pskb, &ctinfo);
146 /* Connection must be valid and new. */
147 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
148 ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
151 return nf_nat_setup_info(ct, &mr->range[0], hooknum);
154 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
155 static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
157 static int warned = 0;
158 struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
161 if (ip_route_output_key(&rt, &fl) != 0)
164 if (rt->rt_src != srcip && !warned) {
165 printk("NAT: no longer support implicit source local NAT\n");
166 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
167 NIPQUAD(srcip), NIPQUAD(dstip));
173 static unsigned int ipt_dnat_target(struct sk_buff **pskb,
174 const struct net_device *in,
175 const struct net_device *out,
176 unsigned int hooknum,
177 const struct xt_target *target,
178 const void *targinfo)
181 enum ip_conntrack_info ctinfo;
182 const struct nf_nat_multi_range_compat *mr = targinfo;
184 NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
185 hooknum == NF_IP_LOCAL_OUT);
187 ct = nf_ct_get(*pskb, &ctinfo);
189 /* Connection must be valid and new. */
190 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
192 if (hooknum == NF_IP_LOCAL_OUT &&
193 mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
194 warn_if_extra_mangle(ip_hdr(*pskb)->daddr,
195 mr->range[0].min_ip);
197 return nf_nat_setup_info(ct, &mr->range[0], hooknum);
200 static int ipt_snat_checkentry(const char *tablename,
202 const struct xt_target *target,
204 unsigned int hook_mask)
206 struct nf_nat_multi_range_compat *mr = targinfo;
208 /* Must be a valid range */
209 if (mr->rangesize != 1) {
210 printk("SNAT: multiple ranges no longer supported\n");
216 static int ipt_dnat_checkentry(const char *tablename,
218 const struct xt_target *target,
220 unsigned int hook_mask)
222 struct nf_nat_multi_range_compat *mr = targinfo;
224 /* Must be a valid range */
225 if (mr->rangesize != 1) {
226 printk("DNAT: multiple ranges no longer supported\n");
229 if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) {
230 printk("DNAT: port randomization not supported\n");
237 alloc_null_binding(struct nf_conn *ct,
238 struct nf_nat_info *info,
239 unsigned int hooknum)
241 /* Force range to this IP; let proto decide mapping for
242 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
243 Use reply in case it's already been mangled (eg local packet).
246 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
247 ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
248 : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
249 struct nf_nat_range range
250 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
252 DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
254 return nf_nat_setup_info(ct, &range, hooknum);
258 alloc_null_binding_confirmed(struct nf_conn *ct,
259 struct nf_nat_info *info,
260 unsigned int hooknum)
263 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
264 ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
265 : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
267 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
268 ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
269 : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
270 struct nf_nat_range range
271 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
273 DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
275 return nf_nat_setup_info(ct, &range, hooknum);
278 int nf_nat_rule_find(struct sk_buff **pskb,
279 unsigned int hooknum,
280 const struct net_device *in,
281 const struct net_device *out,
283 struct nf_nat_info *info)
287 ret = ipt_do_table(pskb, hooknum, in, out, &nat_table);
289 if (ret == NF_ACCEPT) {
290 if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
292 ret = alloc_null_binding(ct, info, hooknum);
297 static struct xt_target ipt_snat_reg = {
299 .target = ipt_snat_target,
300 .targetsize = sizeof(struct nf_nat_multi_range_compat),
302 .hooks = 1 << NF_IP_POST_ROUTING,
303 .checkentry = ipt_snat_checkentry,
307 static struct xt_target ipt_dnat_reg = {
309 .target = ipt_dnat_target,
310 .targetsize = sizeof(struct nf_nat_multi_range_compat),
312 .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT),
313 .checkentry = ipt_dnat_checkentry,
317 int __init nf_nat_rule_init(void)
321 ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
324 ret = xt_register_target(&ipt_snat_reg);
326 goto unregister_table;
328 ret = xt_register_target(&ipt_dnat_reg);
330 goto unregister_snat;
335 xt_unregister_target(&ipt_snat_reg);
337 ipt_unregister_table(&nat_table);
342 void nf_nat_rule_cleanup(void)
344 xt_unregister_target(&ipt_dnat_reg);
345 xt_unregister_target(&ipt_snat_reg);
346 ipt_unregister_table(&nat_table);