2 * (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2011 Patrick McHardy <kaber@trash.net>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/types.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
15 #include <linux/icmp.h>
16 #include <linux/netfilter.h>
17 #include <linux/netfilter_ipv4.h>
18 #include <net/secure_seq.h>
19 #include <net/checksum.h>
20 #include <net/route.h>
23 #include <net/netfilter/nf_conntrack_core.h>
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_nat_core.h>
26 #include <net/netfilter/nf_nat_l3proto.h>
27 #include <net/netfilter/nf_nat_l4proto.h>
29 static const struct nf_nat_l3proto nf_nat_l3proto_ipv4
;
32 static void nf_nat_ipv4_decode_session(struct sk_buff
*skb
,
33 const struct nf_conn
*ct
,
34 enum ip_conntrack_dir dir
,
35 unsigned long statusbit
,
38 const struct nf_conntrack_tuple
*t
= &ct
->tuplehash
[dir
].tuple
;
39 struct flowi4
*fl4
= &fl
->u
.ip4
;
41 if (ct
->status
& statusbit
) {
42 fl4
->daddr
= t
->dst
.u3
.ip
;
43 if (t
->dst
.protonum
== IPPROTO_TCP
||
44 t
->dst
.protonum
== IPPROTO_UDP
||
45 t
->dst
.protonum
== IPPROTO_UDPLITE
||
46 t
->dst
.protonum
== IPPROTO_DCCP
||
47 t
->dst
.protonum
== IPPROTO_SCTP
)
48 fl4
->fl4_dport
= t
->dst
.u
.all
;
51 statusbit
^= IPS_NAT_MASK
;
53 if (ct
->status
& statusbit
) {
54 fl4
->saddr
= t
->src
.u3
.ip
;
55 if (t
->dst
.protonum
== IPPROTO_TCP
||
56 t
->dst
.protonum
== IPPROTO_UDP
||
57 t
->dst
.protonum
== IPPROTO_UDPLITE
||
58 t
->dst
.protonum
== IPPROTO_DCCP
||
59 t
->dst
.protonum
== IPPROTO_SCTP
)
60 fl4
->fl4_sport
= t
->src
.u
.all
;
63 #endif /* CONFIG_XFRM */
65 static bool nf_nat_ipv4_in_range(const struct nf_conntrack_tuple
*t
,
66 const struct nf_nat_range
*range
)
68 return ntohl(t
->src
.u3
.ip
) >= ntohl(range
->min_addr
.ip
) &&
69 ntohl(t
->src
.u3
.ip
) <= ntohl(range
->max_addr
.ip
);
72 static u32
nf_nat_ipv4_secure_port(const struct nf_conntrack_tuple
*t
,
75 return secure_ipv4_port_ephemeral(t
->src
.u3
.ip
, t
->dst
.u3
.ip
, dport
);
78 static bool nf_nat_ipv4_manip_pkt(struct sk_buff
*skb
,
79 unsigned int iphdroff
,
80 const struct nf_nat_l4proto
*l4proto
,
81 const struct nf_conntrack_tuple
*target
,
82 enum nf_nat_manip_type maniptype
)
87 if (!skb_make_writable(skb
, iphdroff
+ sizeof(*iph
)))
90 iph
= (void *)skb
->data
+ iphdroff
;
91 hdroff
= iphdroff
+ iph
->ihl
* 4;
93 if (!l4proto
->manip_pkt(skb
, &nf_nat_l3proto_ipv4
, iphdroff
, hdroff
,
96 iph
= (void *)skb
->data
+ iphdroff
;
98 if (maniptype
== NF_NAT_MANIP_SRC
) {
99 csum_replace4(&iph
->check
, iph
->saddr
, target
->src
.u3
.ip
);
100 iph
->saddr
= target
->src
.u3
.ip
;
102 csum_replace4(&iph
->check
, iph
->daddr
, target
->dst
.u3
.ip
);
103 iph
->daddr
= target
->dst
.u3
.ip
;
108 static void nf_nat_ipv4_csum_update(struct sk_buff
*skb
,
109 unsigned int iphdroff
, __sum16
*check
,
110 const struct nf_conntrack_tuple
*t
,
111 enum nf_nat_manip_type maniptype
)
113 struct iphdr
*iph
= (struct iphdr
*)(skb
->data
+ iphdroff
);
116 if (maniptype
== NF_NAT_MANIP_SRC
) {
118 newip
= t
->src
.u3
.ip
;
121 newip
= t
->dst
.u3
.ip
;
123 inet_proto_csum_replace4(check
, skb
, oldip
, newip
, 1);
126 static void nf_nat_ipv4_csum_recalc(struct sk_buff
*skb
,
127 u8 proto
, void *data
, __sum16
*check
,
128 int datalen
, int oldlen
)
130 const struct iphdr
*iph
= ip_hdr(skb
);
131 struct rtable
*rt
= skb_rtable(skb
);
133 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
) {
134 if (!(rt
->rt_flags
& RTCF_LOCAL
) &&
135 (!skb
->dev
|| skb
->dev
->features
& NETIF_F_V4_CSUM
)) {
136 skb
->ip_summed
= CHECKSUM_PARTIAL
;
137 skb
->csum_start
= skb_headroom(skb
) +
138 skb_network_offset(skb
) +
140 skb
->csum_offset
= (void *)check
- data
;
141 *check
= ~csum_tcpudp_magic(iph
->saddr
, iph
->daddr
,
145 *check
= csum_tcpudp_magic(iph
->saddr
, iph
->daddr
,
147 csum_partial(data
, datalen
,
149 if (proto
== IPPROTO_UDP
&& !*check
)
150 *check
= CSUM_MANGLED_0
;
153 inet_proto_csum_replace2(check
, skb
,
154 htons(oldlen
), htons(datalen
), 1);
157 static int nf_nat_ipv4_nlattr_to_range(struct nlattr
*tb
[],
158 struct nf_nat_range
*range
)
160 if (tb
[CTA_NAT_V4_MINIP
]) {
161 range
->min_addr
.ip
= nla_get_be32(tb
[CTA_NAT_V4_MINIP
]);
162 range
->flags
|= NF_NAT_RANGE_MAP_IPS
;
165 if (tb
[CTA_NAT_V4_MAXIP
])
166 range
->max_addr
.ip
= nla_get_be32(tb
[CTA_NAT_V4_MAXIP
]);
168 range
->max_addr
.ip
= range
->min_addr
.ip
;
173 static const struct nf_nat_l3proto nf_nat_l3proto_ipv4
= {
174 .l3proto
= NFPROTO_IPV4
,
175 .in_range
= nf_nat_ipv4_in_range
,
176 .secure_port
= nf_nat_ipv4_secure_port
,
177 .manip_pkt
= nf_nat_ipv4_manip_pkt
,
178 .csum_update
= nf_nat_ipv4_csum_update
,
179 .csum_recalc
= nf_nat_ipv4_csum_recalc
,
180 .nlattr_to_range
= nf_nat_ipv4_nlattr_to_range
,
182 .decode_session
= nf_nat_ipv4_decode_session
,
186 int nf_nat_icmp_reply_translation(struct sk_buff
*skb
,
188 enum ip_conntrack_info ctinfo
,
189 unsigned int hooknum
)
195 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
196 enum nf_nat_manip_type manip
= HOOK2MANIP(hooknum
);
197 unsigned int hdrlen
= ip_hdrlen(skb
);
198 const struct nf_nat_l4proto
*l4proto
;
199 struct nf_conntrack_tuple target
;
200 unsigned long statusbit
;
202 NF_CT_ASSERT(ctinfo
== IP_CT_RELATED
|| ctinfo
== IP_CT_RELATED_REPLY
);
204 if (!skb_make_writable(skb
, hdrlen
+ sizeof(*inside
)))
206 if (nf_ip_checksum(skb
, hooknum
, hdrlen
, 0))
209 inside
= (void *)skb
->data
+ hdrlen
;
210 if (inside
->icmp
.type
== ICMP_REDIRECT
) {
211 if ((ct
->status
& IPS_NAT_DONE_MASK
) != IPS_NAT_DONE_MASK
)
213 if (ct
->status
& IPS_NAT_MASK
)
217 if (manip
== NF_NAT_MANIP_SRC
)
218 statusbit
= IPS_SRC_NAT
;
220 statusbit
= IPS_DST_NAT
;
222 /* Invert if this is reply direction */
223 if (dir
== IP_CT_DIR_REPLY
)
224 statusbit
^= IPS_NAT_MASK
;
226 if (!(ct
->status
& statusbit
))
229 l4proto
= __nf_nat_l4proto_find(NFPROTO_IPV4
, inside
->ip
.protocol
);
230 if (!nf_nat_ipv4_manip_pkt(skb
, hdrlen
+ sizeof(inside
->icmp
),
231 l4proto
, &ct
->tuplehash
[!dir
].tuple
, !manip
))
234 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
) {
235 /* Reloading "inside" here since manip_pkt may reallocate */
236 inside
= (void *)skb
->data
+ hdrlen
;
237 inside
->icmp
.checksum
= 0;
238 inside
->icmp
.checksum
=
239 csum_fold(skb_checksum(skb
, hdrlen
,
240 skb
->len
- hdrlen
, 0));
243 /* Change outer to look like the reply to an incoming packet */
244 nf_ct_invert_tuplepr(&target
, &ct
->tuplehash
[!dir
].tuple
);
245 l4proto
= __nf_nat_l4proto_find(NFPROTO_IPV4
, 0);
246 if (!nf_nat_ipv4_manip_pkt(skb
, 0, l4proto
, &target
, manip
))
251 EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation
);
253 static int __init
nf_nat_l3proto_ipv4_init(void)
257 err
= nf_nat_l4proto_register(NFPROTO_IPV4
, &nf_nat_l4proto_icmp
);
260 err
= nf_nat_l3proto_register(&nf_nat_l3proto_ipv4
);
266 nf_nat_l4proto_unregister(NFPROTO_IPV4
, &nf_nat_l4proto_icmp
);
271 static void __exit
nf_nat_l3proto_ipv4_exit(void)
273 nf_nat_l3proto_unregister(&nf_nat_l3proto_ipv4
);
274 nf_nat_l4proto_unregister(NFPROTO_IPV4
, &nf_nat_l4proto_icmp
);
277 MODULE_LICENSE("GPL");
278 MODULE_ALIAS("nf-nat-" __stringify(AF_INET
));
280 module_init(nf_nat_l3proto_ipv4_init
);
281 module_exit(nf_nat_l3proto_ipv4_exit
);