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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/netfilter_ipv4.h>
15 #include <linux/module.h>
16 #include <linux/kmod.h>
17 #include <linux/skbuff.h>
18 #include <linux/proc_fs.h>
19 #include <linux/slab.h>
20 #include <net/checksum.h>
21 #include <net/route.h>
22 #include <linux/bitops.h>
24 #include <linux/netfilter_ipv4/ip_tables.h>
25 #include <net/netfilter/nf_nat.h>
26 #include <net/netfilter/nf_nat_core.h>
27 #include <net/netfilter/nf_nat_rule.h>
29 #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
30 (1 << NF_INET_POST_ROUTING) | \
31 (1 << NF_INET_LOCAL_OUT))
33 static const struct xt_table nat_table
= {
35 .valid_hooks
= NAT_VALID_HOOKS
,
42 ipt_snat_target(struct sk_buff
*skb
, const struct xt_action_param
*par
)
45 enum ip_conntrack_info ctinfo
;
46 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
48 NF_CT_ASSERT(par
->hooknum
== NF_INET_POST_ROUTING
);
50 ct
= nf_ct_get(skb
, &ctinfo
);
52 /* Connection must be valid and new. */
53 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
||
54 ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
55 NF_CT_ASSERT(par
->out
!= NULL
);
57 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_SRC
);
61 ipt_dnat_target(struct sk_buff
*skb
, const struct xt_action_param
*par
)
64 enum ip_conntrack_info ctinfo
;
65 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
67 NF_CT_ASSERT(par
->hooknum
== NF_INET_PRE_ROUTING
||
68 par
->hooknum
== NF_INET_LOCAL_OUT
);
70 ct
= nf_ct_get(skb
, &ctinfo
);
72 /* Connection must be valid and new. */
73 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
));
75 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_DST
);
78 static int ipt_snat_checkentry(const struct xt_tgchk_param
*par
)
80 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
82 /* Must be a valid range */
83 if (mr
->rangesize
!= 1) {
84 pr_info("SNAT: multiple ranges no longer supported\n");
90 static int ipt_dnat_checkentry(const struct xt_tgchk_param
*par
)
92 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
94 /* Must be a valid range */
95 if (mr
->rangesize
!= 1) {
96 pr_info("DNAT: multiple ranges no longer supported\n");
103 alloc_null_binding(struct nf_conn
*ct
, unsigned int hooknum
)
105 /* Force range to this IP; let proto decide mapping for
106 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
107 Use reply in case it's already been mangled (eg local packet).
110 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
111 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
112 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
113 struct nf_nat_range range
114 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { 0 }, { 0 } };
116 pr_debug("Allocating NULL binding for %p (%pI4)\n", ct
, &ip
);
117 return nf_nat_setup_info(ct
, &range
, HOOK2MANIP(hooknum
));
120 int nf_nat_rule_find(struct sk_buff
*skb
,
121 unsigned int hooknum
,
122 const struct net_device
*in
,
123 const struct net_device
*out
,
126 struct net
*net
= nf_ct_net(ct
);
129 ret
= ipt_do_table(skb
, hooknum
, in
, out
, net
->ipv4
.nat_table
);
131 if (ret
== NF_ACCEPT
) {
132 if (!nf_nat_initialized(ct
, HOOK2MANIP(hooknum
)))
134 ret
= alloc_null_binding(ct
, hooknum
);
139 static struct xt_target ipt_snat_reg __read_mostly
= {
141 .target
= ipt_snat_target
,
142 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
144 .hooks
= 1 << NF_INET_POST_ROUTING
,
145 .checkentry
= ipt_snat_checkentry
,
149 static struct xt_target ipt_dnat_reg __read_mostly
= {
151 .target
= ipt_dnat_target
,
152 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
154 .hooks
= (1 << NF_INET_PRE_ROUTING
) | (1 << NF_INET_LOCAL_OUT
),
155 .checkentry
= ipt_dnat_checkentry
,
159 static int __net_init
nf_nat_rule_net_init(struct net
*net
)
161 struct ipt_replace
*repl
;
163 repl
= ipt_alloc_initial_table(&nat_table
);
166 net
->ipv4
.nat_table
= ipt_register_table(net
, &nat_table
, repl
);
168 if (IS_ERR(net
->ipv4
.nat_table
))
169 return PTR_ERR(net
->ipv4
.nat_table
);
173 static void __net_exit
nf_nat_rule_net_exit(struct net
*net
)
175 ipt_unregister_table(net
, net
->ipv4
.nat_table
);
178 static struct pernet_operations nf_nat_rule_net_ops
= {
179 .init
= nf_nat_rule_net_init
,
180 .exit
= nf_nat_rule_net_exit
,
183 int __init
nf_nat_rule_init(void)
187 ret
= register_pernet_subsys(&nf_nat_rule_net_ops
);
190 ret
= xt_register_target(&ipt_snat_reg
);
192 goto unregister_table
;
194 ret
= xt_register_target(&ipt_dnat_reg
);
196 goto unregister_snat
;
201 xt_unregister_target(&ipt_snat_reg
);
203 unregister_pernet_subsys(&nf_nat_rule_net_ops
);
208 void nf_nat_rule_cleanup(void)
210 xt_unregister_target(&ipt_dnat_reg
);
211 xt_unregister_target(&ipt_snat_reg
);
212 unregister_pernet_subsys(&nf_nat_rule_net_ops
);