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 #include <linux/types.h>
10 #include <linux/init.h>
11 #include <linux/random.h>
13 #include <linux/udp.h>
15 #include <linux/netfilter.h>
16 #include <net/netfilter/nf_nat.h>
17 #include <net/netfilter/nf_nat_core.h>
18 #include <net/netfilter/nf_nat_rule.h>
19 #include <net/netfilter/nf_nat_protocol.h>
22 udp_in_range(const struct nf_conntrack_tuple
*tuple
,
23 enum nf_nat_manip_type maniptype
,
24 const union nf_conntrack_man_proto
*min
,
25 const union nf_conntrack_man_proto
*max
)
29 if (maniptype
== IP_NAT_MANIP_SRC
)
30 port
= tuple
->src
.u
.udp
.port
;
32 port
= tuple
->dst
.u
.udp
.port
;
34 return ntohs(port
) >= ntohs(min
->udp
.port
) &&
35 ntohs(port
) <= ntohs(max
->udp
.port
);
39 udp_unique_tuple(struct nf_conntrack_tuple
*tuple
,
40 const struct nf_nat_range
*range
,
41 enum nf_nat_manip_type maniptype
,
42 const struct nf_conn
*ct
)
44 static u_int16_t port
;
46 unsigned int range_size
, min
, i
;
48 if (maniptype
== IP_NAT_MANIP_SRC
)
49 portptr
= &tuple
->src
.u
.udp
.port
;
51 portptr
= &tuple
->dst
.u
.udp
.port
;
53 /* If no range specified... */
54 if (!(range
->flags
& IP_NAT_RANGE_PROTO_SPECIFIED
)) {
55 /* If it's dst rewrite, can't change port */
56 if (maniptype
== IP_NAT_MANIP_DST
)
59 if (ntohs(*portptr
) < 1024) {
60 /* Loose convention: >> 512 is credential passing */
61 if (ntohs(*portptr
)<512) {
63 range_size
= 511 - min
+ 1;
66 range_size
= 1023 - min
+ 1;
70 range_size
= 65535 - 1024 + 1;
73 min
= ntohs(range
->min
.udp
.port
);
74 range_size
= ntohs(range
->max
.udp
.port
) - min
+ 1;
77 if (range
->flags
& IP_NAT_RANGE_PROTO_RANDOM
)
80 for (i
= 0; i
< range_size
; i
++, port
++) {
81 *portptr
= htons(min
+ port
% range_size
);
82 if (!nf_nat_used_tuple(tuple
, ct
))
89 udp_manip_pkt(struct sk_buff
*skb
,
90 unsigned int iphdroff
,
91 const struct nf_conntrack_tuple
*tuple
,
92 enum nf_nat_manip_type maniptype
)
94 struct iphdr
*iph
= (struct iphdr
*)(skb
->data
+ iphdroff
);
96 unsigned int hdroff
= iphdroff
+ iph
->ihl
*4;
98 __be16
*portptr
, newport
;
100 if (!skb_make_writable(skb
, hdroff
+ sizeof(*hdr
)))
103 iph
= (struct iphdr
*)(skb
->data
+ iphdroff
);
104 hdr
= (struct udphdr
*)(skb
->data
+ hdroff
);
106 if (maniptype
== IP_NAT_MANIP_SRC
) {
107 /* Get rid of src ip and src pt */
109 newip
= tuple
->src
.u3
.ip
;
110 newport
= tuple
->src
.u
.udp
.port
;
111 portptr
= &hdr
->source
;
113 /* Get rid of dst ip and dst pt */
115 newip
= tuple
->dst
.u3
.ip
;
116 newport
= tuple
->dst
.u
.udp
.port
;
117 portptr
= &hdr
->dest
;
119 if (hdr
->check
|| skb
->ip_summed
== CHECKSUM_PARTIAL
) {
120 inet_proto_csum_replace4(&hdr
->check
, skb
, oldip
, newip
, 1);
121 inet_proto_csum_replace2(&hdr
->check
, skb
, *portptr
, newport
,
124 hdr
->check
= CSUM_MANGLED_0
;
130 struct nf_nat_protocol nf_nat_protocol_udp
= {
132 .protonum
= IPPROTO_UDP
,
134 .manip_pkt
= udp_manip_pkt
,
135 .in_range
= udp_in_range
,
136 .unique_tuple
= udp_unique_tuple
,
137 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
138 .range_to_nlattr
= nf_nat_port_range_to_nlattr
,
139 .nlattr_to_range
= nf_nat_port_nlattr_to_range
,