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 __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
,
68 static struct xt_table
*nat_table
;
71 static unsigned int ipt_snat_target(struct sk_buff
*skb
,
72 const struct net_device
*in
,
73 const struct net_device
*out
,
75 const struct xt_target
*target
,
79 enum ip_conntrack_info ctinfo
;
80 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
82 NF_CT_ASSERT(hooknum
== NF_INET_POST_ROUTING
);
84 ct
= nf_ct_get(skb
, &ctinfo
);
86 /* Connection must be valid and new. */
87 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
||
88 ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
91 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_SRC
);
94 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
95 static void warn_if_extra_mangle(__be32 dstip
, __be32 srcip
)
97 static int warned
= 0;
98 struct flowi fl
= { .nl_u
= { .ip4_u
= { .daddr
= dstip
} } };
101 if (ip_route_output_key(&init_net
, &rt
, &fl
) != 0)
104 if (rt
->rt_src
!= srcip
&& !warned
) {
105 printk("NAT: no longer support implicit source local NAT\n");
106 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
107 NIPQUAD(srcip
), NIPQUAD(dstip
));
113 static unsigned int ipt_dnat_target(struct sk_buff
*skb
,
114 const struct net_device
*in
,
115 const struct net_device
*out
,
116 unsigned int hooknum
,
117 const struct xt_target
*target
,
118 const void *targinfo
)
121 enum ip_conntrack_info ctinfo
;
122 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
124 NF_CT_ASSERT(hooknum
== NF_INET_PRE_ROUTING
||
125 hooknum
== NF_INET_LOCAL_OUT
);
127 ct
= nf_ct_get(skb
, &ctinfo
);
129 /* Connection must be valid and new. */
130 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
));
132 if (hooknum
== NF_INET_LOCAL_OUT
&&
133 mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)
134 warn_if_extra_mangle(ip_hdr(skb
)->daddr
,
135 mr
->range
[0].min_ip
);
137 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_DST
);
140 static bool ipt_snat_checkentry(const char *tablename
,
142 const struct xt_target
*target
,
144 unsigned int hook_mask
)
146 struct nf_nat_multi_range_compat
*mr
= targinfo
;
148 /* Must be a valid range */
149 if (mr
->rangesize
!= 1) {
150 printk("SNAT: multiple ranges no longer supported\n");
156 static bool ipt_dnat_checkentry(const char *tablename
,
158 const struct xt_target
*target
,
160 unsigned int hook_mask
)
162 struct nf_nat_multi_range_compat
*mr
= targinfo
;
164 /* Must be a valid range */
165 if (mr
->rangesize
!= 1) {
166 printk("DNAT: multiple ranges no longer supported\n");
173 alloc_null_binding(struct nf_conn
*ct
, unsigned int hooknum
)
175 /* Force range to this IP; let proto decide mapping for
176 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
177 Use reply in case it's already been mangled (eg local packet).
180 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
181 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
182 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
183 struct nf_nat_range range
184 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { 0 }, { 0 } };
186 pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
188 return nf_nat_setup_info(ct
, &range
, HOOK2MANIP(hooknum
));
192 alloc_null_binding_confirmed(struct nf_conn
*ct
, unsigned int hooknum
)
195 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
196 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
197 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
199 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
200 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u
.all
201 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u
.all
);
202 struct nf_nat_range range
203 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { all
}, { all
} };
205 pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
207 return nf_nat_setup_info(ct
, &range
, HOOK2MANIP(hooknum
));
210 int nf_nat_rule_find(struct sk_buff
*skb
,
211 unsigned int hooknum
,
212 const struct net_device
*in
,
213 const struct net_device
*out
,
218 ret
= ipt_do_table(skb
, hooknum
, in
, out
, nat_table
);
220 if (ret
== NF_ACCEPT
) {
221 if (!nf_nat_initialized(ct
, HOOK2MANIP(hooknum
)))
223 ret
= alloc_null_binding(ct
, hooknum
);
228 static struct xt_target ipt_snat_reg __read_mostly
= {
230 .target
= ipt_snat_target
,
231 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
233 .hooks
= 1 << NF_INET_POST_ROUTING
,
234 .checkentry
= ipt_snat_checkentry
,
238 static struct xt_target ipt_dnat_reg __read_mostly
= {
240 .target
= ipt_dnat_target
,
241 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
243 .hooks
= (1 << NF_INET_PRE_ROUTING
) | (1 << NF_INET_LOCAL_OUT
),
244 .checkentry
= ipt_dnat_checkentry
,
248 int __init
nf_nat_rule_init(void)
252 nat_table
= ipt_register_table(&init_net
, &__nat_table
,
253 &nat_initial_table
.repl
);
254 if (IS_ERR(nat_table
))
255 return PTR_ERR(nat_table
);
256 ret
= xt_register_target(&ipt_snat_reg
);
258 goto unregister_table
;
260 ret
= xt_register_target(&ipt_dnat_reg
);
262 goto unregister_snat
;
267 xt_unregister_target(&ipt_snat_reg
);
269 ipt_unregister_table(nat_table
);
274 void nf_nat_rule_cleanup(void)
276 xt_unregister_target(&ipt_dnat_reg
);
277 xt_unregister_target(&ipt_snat_reg
);
278 ipt_unregister_table(nat_table
);