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 __net_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(nat_table
.lock
),
71 ipt_snat_target(struct sk_buff
*skb
, const struct xt_target_param
*par
)
74 enum ip_conntrack_info ctinfo
;
75 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
77 NF_CT_ASSERT(par
->hooknum
== NF_INET_POST_ROUTING
);
79 ct
= nf_ct_get(skb
, &ctinfo
);
81 /* Connection must be valid and new. */
82 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
||
83 ctinfo
== IP_CT_RELATED
+ IP_CT_IS_REPLY
));
84 NF_CT_ASSERT(par
->out
!= NULL
);
86 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_SRC
);
89 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
90 static void warn_if_extra_mangle(struct net
*net
, __be32 dstip
, __be32 srcip
)
92 static int warned
= 0;
93 struct flowi fl
= { .nl_u
= { .ip4_u
= { .daddr
= dstip
} } };
96 if (ip_route_output_key(net
, &rt
, &fl
) != 0)
99 if (rt
->rt_src
!= srcip
&& !warned
) {
100 printk("NAT: no longer support implicit source local NAT\n");
101 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
102 NIPQUAD(srcip
), NIPQUAD(dstip
));
109 ipt_dnat_target(struct sk_buff
*skb
, const struct xt_target_param
*par
)
112 enum ip_conntrack_info ctinfo
;
113 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
115 NF_CT_ASSERT(par
->hooknum
== NF_INET_PRE_ROUTING
||
116 par
->hooknum
== NF_INET_LOCAL_OUT
);
118 ct
= nf_ct_get(skb
, &ctinfo
);
120 /* Connection must be valid and new. */
121 NF_CT_ASSERT(ct
&& (ctinfo
== IP_CT_NEW
|| ctinfo
== IP_CT_RELATED
));
123 if (par
->hooknum
== NF_INET_LOCAL_OUT
&&
124 mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)
125 warn_if_extra_mangle(dev_net(par
->out
), ip_hdr(skb
)->daddr
,
126 mr
->range
[0].min_ip
);
128 return nf_nat_setup_info(ct
, &mr
->range
[0], IP_NAT_MANIP_DST
);
131 static bool ipt_snat_checkentry(const struct xt_tgchk_param
*par
)
133 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
135 /* Must be a valid range */
136 if (mr
->rangesize
!= 1) {
137 printk("SNAT: multiple ranges no longer supported\n");
143 static bool ipt_dnat_checkentry(const struct xt_tgchk_param
*par
)
145 const struct nf_nat_multi_range_compat
*mr
= par
->targinfo
;
147 /* Must be a valid range */
148 if (mr
->rangesize
!= 1) {
149 printk("DNAT: multiple ranges no longer supported\n");
156 alloc_null_binding(struct nf_conn
*ct
, unsigned int hooknum
)
158 /* Force range to this IP; let proto decide mapping for
159 per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
160 Use reply in case it's already been mangled (eg local packet).
163 = (HOOK2MANIP(hooknum
) == IP_NAT_MANIP_SRC
164 ? ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.dst
.u3
.ip
165 : ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
.src
.u3
.ip
);
166 struct nf_nat_range range
167 = { IP_NAT_RANGE_MAP_IPS
, ip
, ip
, { 0 }, { 0 } };
169 pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
171 return nf_nat_setup_info(ct
, &range
, HOOK2MANIP(hooknum
));
174 int nf_nat_rule_find(struct sk_buff
*skb
,
175 unsigned int hooknum
,
176 const struct net_device
*in
,
177 const struct net_device
*out
,
180 struct net
*net
= nf_ct_net(ct
);
183 ret
= ipt_do_table(skb
, hooknum
, in
, out
, net
->ipv4
.nat_table
);
185 if (ret
== NF_ACCEPT
) {
186 if (!nf_nat_initialized(ct
, HOOK2MANIP(hooknum
)))
188 ret
= alloc_null_binding(ct
, hooknum
);
193 static struct xt_target ipt_snat_reg __read_mostly
= {
195 .target
= ipt_snat_target
,
196 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
198 .hooks
= 1 << NF_INET_POST_ROUTING
,
199 .checkentry
= ipt_snat_checkentry
,
203 static struct xt_target ipt_dnat_reg __read_mostly
= {
205 .target
= ipt_dnat_target
,
206 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
208 .hooks
= (1 << NF_INET_PRE_ROUTING
) | (1 << NF_INET_LOCAL_OUT
),
209 .checkentry
= ipt_dnat_checkentry
,
213 static int __net_init
nf_nat_rule_net_init(struct net
*net
)
215 net
->ipv4
.nat_table
= ipt_register_table(net
, &nat_table
,
216 &nat_initial_table
.repl
);
217 if (IS_ERR(net
->ipv4
.nat_table
))
218 return PTR_ERR(net
->ipv4
.nat_table
);
222 static void __net_exit
nf_nat_rule_net_exit(struct net
*net
)
224 ipt_unregister_table(net
->ipv4
.nat_table
);
227 static struct pernet_operations nf_nat_rule_net_ops
= {
228 .init
= nf_nat_rule_net_init
,
229 .exit
= nf_nat_rule_net_exit
,
232 int __init
nf_nat_rule_init(void)
236 ret
= register_pernet_subsys(&nf_nat_rule_net_ops
);
239 ret
= xt_register_target(&ipt_snat_reg
);
241 goto unregister_table
;
243 ret
= xt_register_target(&ipt_dnat_reg
);
245 goto unregister_snat
;
250 xt_unregister_target(&ipt_snat_reg
);
252 unregister_pernet_subsys(&nf_nat_rule_net_ops
);
257 void nf_nat_rule_cleanup(void)
259 xt_unregister_target(&ipt_dnat_reg
);
260 xt_unregister_target(&ipt_snat_reg
);
261 unregister_pernet_subsys(&nf_nat_rule_net_ops
);