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_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT))
31 struct ipt_replace repl
;
32 struct ipt_standard entries
[3];
33 struct ipt_error term
;
34 } nat_initial_table __initdata
= {
37 .valid_hooks
= NAT_VALID_HOOKS
,
39 .size
= sizeof(struct ipt_standard
) * 3 + sizeof(struct ipt_error
),
41 [NF_IP_PRE_ROUTING
] = 0,
42 [NF_IP_POST_ROUTING
] = sizeof(struct ipt_standard
),
43 [NF_IP_LOCAL_OUT
] = sizeof(struct ipt_standard
) * 2
46 [NF_IP_PRE_ROUTING
] = 0,
47 [NF_IP_POST_ROUTING
] = sizeof(struct ipt_standard
),
48 [NF_IP_LOCAL_OUT
] = sizeof(struct ipt_standard
) * 2
52 IPT_STANDARD_INIT(NF_ACCEPT
), /* PRE_ROUTING */
53 IPT_STANDARD_INIT(NF_ACCEPT
), /* POST_ROUTING */
54 IPT_STANDARD_INIT(NF_ACCEPT
), /* LOCAL_OUT */
56 .term
= IPT_ERROR_INIT
, /* ERROR */
59 static struct xt_table nat_table
= {
61 .valid_hooks
= NAT_VALID_HOOKS
,
62 .lock
= RW_LOCK_UNLOCKED
,
68 static unsigned int ipt_snat_target(struct sk_buff
**pskb
,
69 const struct net_device
*in
,
70 const struct net_device
*out
,
72 const struct xt_target
*target
,
76 enum ip_conntrack_info ctinfo
;
77 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
79 NF_CT_ASSERT(hooknum
== NF_IP_POST_ROUTING
);
81 ct
= nf_ct_get(*pskb
, &ctinfo
);
83 /* Connection must be valid and new. */
84 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
||
85 ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
88 return nf_nat_setup_info(ct
, &mr
->range
[0], hooknum
);
91 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
92 static void warn_if_extra_mangle(__be32 dstip
, __be32 srcip
)
94 static int warned
= 0;
95 struct flowi fl
= { .nl_u
= { .ip4_u
= { .daddr
= dstip
} } };
98 if (ip_route_output_key(&rt
, &fl
) != 0)
101 if (rt
->rt_src
!= srcip
&& !warned
) {
102 printk("NAT: no longer support implicit source local NAT\n");
103 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
104 NIPQUAD(srcip
), NIPQUAD(dstip
));
110 static unsigned int ipt_dnat_target(struct sk_buff
**pskb
,
111 const struct net_device
*in
,
112 const struct net_device
*out
,
113 unsigned int hooknum
,
114 const struct xt_target
*target
,
115 const void *targinfo
)
118 enum ip_conntrack_info ctinfo
;
119 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
121 NF_CT_ASSERT(hooknum
== NF_IP_PRE_ROUTING
||
122 hooknum
== NF_IP_LOCAL_OUT
);
124 ct
= nf_ct_get(*pskb
, &ctinfo
);
126 /* Connection must be valid and new. */
127 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
));
129 if (hooknum
== NF_IP_LOCAL_OUT
&&
130 mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)
131 warn_if_extra_mangle(ip_hdr(*pskb
)->daddr
,
132 mr
->range
[0].min_ip
);
134 return nf_nat_setup_info(ct
, &mr
->range
[0], hooknum
);
137 static bool ipt_snat_checkentry(const char *tablename
,
139 const struct xt_target
*target
,
141 unsigned int hook_mask
)
143 struct nf_nat_multi_range_compat
*mr
= targinfo
;
145 /* Must be a valid range */
146 if (mr
->rangesize
!= 1) {
147 printk("SNAT: multiple ranges no longer supported\n");
153 static bool ipt_dnat_checkentry(const char *tablename
,
155 const struct xt_target
*target
,
157 unsigned int hook_mask
)
159 struct nf_nat_multi_range_compat
*mr
= targinfo
;
161 /* Must be a valid range */
162 if (mr
->rangesize
!= 1) {
163 printk("DNAT: multiple ranges no longer supported\n");
170 alloc_null_binding(struct nf_conn
*ct
, unsigned int hooknum
)
172 /* Force range to this IP; let proto decide mapping for
173 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
174 Use reply in case it's already been mangled (eg local packet).
177 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
178 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
179 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
180 struct nf_nat_range range
181 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { 0 }, { 0 } };
183 pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
185 return nf_nat_setup_info(ct
, &range
, hooknum
);
189 alloc_null_binding_confirmed(struct nf_conn
*ct
, unsigned int hooknum
)
192 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
193 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
194 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
196 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
197 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u
.all
198 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u
.all
);
199 struct nf_nat_range range
200 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { all
}, { all
} };
202 pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
204 return nf_nat_setup_info(ct
, &range
, hooknum
);
207 int nf_nat_rule_find(struct sk_buff
**pskb
,
208 unsigned int hooknum
,
209 const struct net_device
*in
,
210 const struct net_device
*out
,
215 ret
= ipt_do_table(pskb
, hooknum
, in
, out
, &nat_table
);
217 if (ret
== NF_ACCEPT
) {
218 if (!nf_nat_initialized(ct
, HOOK2MANIP(hooknum
)))
220 ret
= alloc_null_binding(ct
, hooknum
);
225 static struct xt_target ipt_snat_reg __read_mostly
= {
227 .target
= ipt_snat_target
,
228 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
230 .hooks
= 1 << NF_IP_POST_ROUTING
,
231 .checkentry
= ipt_snat_checkentry
,
235 static struct xt_target ipt_dnat_reg __read_mostly
= {
237 .target
= ipt_dnat_target
,
238 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
240 .hooks
= (1 << NF_IP_PRE_ROUTING
) | (1 << NF_IP_LOCAL_OUT
),
241 .checkentry
= ipt_dnat_checkentry
,
245 int __init
nf_nat_rule_init(void)
249 ret
= ipt_register_table(&nat_table
, &nat_initial_table
.repl
);
252 ret
= xt_register_target(&ipt_snat_reg
);
254 goto unregister_table
;
256 ret
= xt_register_target(&ipt_dnat_reg
);
258 goto unregister_snat
;
263 xt_unregister_target(&ipt_snat_reg
);
265 ipt_unregister_table(&nat_table
);
270 void nf_nat_rule_cleanup(void)
272 xt_unregister_target(&ipt_dnat_reg
);
273 xt_unregister_target(&ipt_snat_reg
);
274 ipt_unregister_table(&nat_table
);