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))
31 static const struct xt_table nat_table
= {
33 .valid_hooks
= NAT_VALID_HOOKS
,
40 ipt_snat_target(struct sk_buff
*skb
, const struct xt_target_param
*par
)
43 enum ip_conntrack_info ctinfo
;
44 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
46 NF_CT_ASSERT(par
->hooknum
== NF_INET_POST_ROUTING
);
48 ct
= nf_ct_get(skb
, &ctinfo
);
50 /* Connection must be valid and new. */
51 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
||
52 ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
53 NF_CT_ASSERT(par
->out
!= NULL
);
55 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_SRC
);
59 ipt_dnat_target(struct sk_buff
*skb
, const struct xt_target_param
*par
)
62 enum ip_conntrack_info ctinfo
;
63 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
65 NF_CT_ASSERT(par
->hooknum
== NF_INET_PRE_ROUTING
||
66 par
->hooknum
== NF_INET_LOCAL_OUT
);
68 ct
= nf_ct_get(skb
, &ctinfo
);
70 /* Connection must be valid and new. */
71 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
));
73 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_DST
);
76 static bool ipt_snat_checkentry(const struct xt_tgchk_param
*par
)
78 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
80 /* Must be a valid range */
81 if (mr
->rangesize
!= 1) {
82 printk("SNAT: multiple ranges no longer supported\n");
88 static bool ipt_dnat_checkentry(const struct xt_tgchk_param
*par
)
90 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
92 /* Must be a valid range */
93 if (mr
->rangesize
!= 1) {
94 printk("DNAT: multiple ranges no longer supported\n");
101 alloc_null_binding(struct nf_conn
*ct
, unsigned int hooknum
)
103 /* Force range to this IP; let proto decide mapping for
104 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
105 Use reply in case it's already been mangled (eg local packet).
108 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
109 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
110 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
111 struct nf_nat_range range
112 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { 0 }, { 0 } };
114 pr_debug("Allocating NULL binding for %p (%pI4)\n", ct
, &ip
);
115 return nf_nat_setup_info(ct
, &range
, HOOK2MANIP(hooknum
));
118 int nf_nat_rule_find(struct sk_buff
*skb
,
119 unsigned int hooknum
,
120 const struct net_device
*in
,
121 const struct net_device
*out
,
124 struct net
*net
= nf_ct_net(ct
);
127 ret
= ipt_do_table(skb
, hooknum
, in
, out
, net
->ipv4
.nat_table
);
129 if (ret
== NF_ACCEPT
) {
130 if (!nf_nat_initialized(ct
, HOOK2MANIP(hooknum
)))
132 ret
= alloc_null_binding(ct
, hooknum
);
137 static struct xt_target ipt_snat_reg __read_mostly
= {
139 .target
= ipt_snat_target
,
140 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
142 .hooks
= 1 << NF_INET_POST_ROUTING
,
143 .checkentry
= ipt_snat_checkentry
,
147 static struct xt_target ipt_dnat_reg __read_mostly
= {
149 .target
= ipt_dnat_target
,
150 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
152 .hooks
= (1 << NF_INET_PRE_ROUTING
) | (1 << NF_INET_LOCAL_OUT
),
153 .checkentry
= ipt_dnat_checkentry
,
157 static int __net_init
nf_nat_rule_net_init(struct net
*net
)
159 struct ipt_replace
*repl
;
161 repl
= ipt_alloc_initial_table(&nat_table
);
164 net
->ipv4
.nat_table
= ipt_register_table(net
, &nat_table
, repl
);
166 if (IS_ERR(net
->ipv4
.nat_table
))
167 return PTR_ERR(net
->ipv4
.nat_table
);
171 static void __net_exit
nf_nat_rule_net_exit(struct net
*net
)
173 ipt_unregister_table(net
, net
->ipv4
.nat_table
);
176 static struct pernet_operations nf_nat_rule_net_ops
= {
177 .init
= nf_nat_rule_net_init
,
178 .exit
= nf_nat_rule_net_exit
,
181 int __init
nf_nat_rule_init(void)
185 ret
= register_pernet_subsys(&nf_nat_rule_net_ops
);
188 ret
= xt_register_target(&ipt_snat_reg
);
190 goto unregister_table
;
192 ret
= xt_register_target(&ipt_dnat_reg
);
194 goto unregister_snat
;
199 xt_unregister_target(&ipt_snat_reg
);
201 unregister_pernet_subsys(&nf_nat_rule_net_ops
);
206 void nf_nat_rule_cleanup(void)
208 xt_unregister_target(&ipt_dnat_reg
);
209 xt_unregister_target(&ipt_snat_reg
);
210 unregister_pernet_subsys(&nf_nat_rule_net_ops
);