1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
3 *
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.
7 */
8
9 #include <linux/types.h>
10 #include <linux/export.h>
11 #include <linux/init.h>
12 #include <linux/udp.h>
13
14 #include <linux/netfilter.h>
15 #include <net/netfilter/nf_nat.h>
16 #include <net/netfilter/nf_nat_core.h>
17 #include <net/netfilter/nf_nat_l3proto.h>
18 #include <net/netfilter/nf_nat_l4proto.h>
19
20 static u16 udp_port_rover;
21
22 static void
udp_unique_tuple(const struct nf_nat_l3proto * l3proto,struct nf_conntrack_tuple * tuple,const struct nf_nat_range * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct)23 udp_unique_tuple(const struct nf_nat_l3proto *l3proto,
24 struct nf_conntrack_tuple *tuple,
25 const struct nf_nat_range *range,
26 enum nf_nat_manip_type maniptype,
27 const struct nf_conn *ct)
28 {
29 nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
30 &udp_port_rover);
31 }
32
33 static void
__udp_manip_pkt(struct sk_buff * skb,const struct nf_nat_l3proto * l3proto,unsigned int iphdroff,struct udphdr * hdr,const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype,bool do_csum)34 __udp_manip_pkt(struct sk_buff *skb,
35 const struct nf_nat_l3proto *l3proto,
36 unsigned int iphdroff, struct udphdr *hdr,
37 const struct nf_conntrack_tuple *tuple,
38 enum nf_nat_manip_type maniptype, bool do_csum)
39 {
40 __be16 *portptr, newport;
41
42 if (maniptype == NF_NAT_MANIP_SRC) {
43 /* Get rid of src port */
44 newport = tuple->src.u.udp.port;
45 portptr = &hdr->source;
46 } else {
47 /* Get rid of dst port */
48 newport = tuple->dst.u.udp.port;
49 portptr = &hdr->dest;
50 }
51 if (do_csum) {
52 l3proto->csum_update(skb, iphdroff, &hdr->check,
53 tuple, maniptype);
54 inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
55 false);
56 if (!hdr->check)
57 hdr->check = CSUM_MANGLED_0;
58 }
59 *portptr = newport;
60 }
61
udp_manip_pkt(struct sk_buff * skb,const struct nf_nat_l3proto * l3proto,unsigned int iphdroff,unsigned int hdroff,const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype)62 static bool udp_manip_pkt(struct sk_buff *skb,
63 const struct nf_nat_l3proto *l3proto,
64 unsigned int iphdroff, unsigned int hdroff,
65 const struct nf_conntrack_tuple *tuple,
66 enum nf_nat_manip_type maniptype)
67 {
68 struct udphdr *hdr;
69 bool do_csum;
70
71 if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
72 return false;
73
74 hdr = (struct udphdr *)(skb->data + hdroff);
75 do_csum = hdr->check || skb->ip_summed == CHECKSUM_PARTIAL;
76
77 __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, do_csum);
78 return true;
79 }
80
81 #ifdef CONFIG_NF_NAT_PROTO_UDPLITE
82 static u16 udplite_port_rover;
83
udplite_manip_pkt(struct sk_buff * skb,const struct nf_nat_l3proto * l3proto,unsigned int iphdroff,unsigned int hdroff,const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype)84 static bool udplite_manip_pkt(struct sk_buff *skb,
85 const struct nf_nat_l3proto *l3proto,
86 unsigned int iphdroff, unsigned int hdroff,
87 const struct nf_conntrack_tuple *tuple,
88 enum nf_nat_manip_type maniptype)
89 {
90 struct udphdr *hdr;
91
92 if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
93 return false;
94
95 hdr = (struct udphdr *)(skb->data + hdroff);
96 __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, true);
97 return true;
98 }
99
100 static void
udplite_unique_tuple(const struct nf_nat_l3proto * l3proto,struct nf_conntrack_tuple * tuple,const struct nf_nat_range * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct)101 udplite_unique_tuple(const struct nf_nat_l3proto *l3proto,
102 struct nf_conntrack_tuple *tuple,
103 const struct nf_nat_range *range,
104 enum nf_nat_manip_type maniptype,
105 const struct nf_conn *ct)
106 {
107 nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
108 &udplite_port_rover);
109 }
110
111 const struct nf_nat_l4proto nf_nat_l4proto_udplite = {
112 .l4proto = IPPROTO_UDPLITE,
113 .manip_pkt = udplite_manip_pkt,
114 .in_range = nf_nat_l4proto_in_range,
115 .unique_tuple = udplite_unique_tuple,
116 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
117 .nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
118 #endif
119 };
120 #endif /* CONFIG_NF_NAT_PROTO_UDPLITE */
121
122 const struct nf_nat_l4proto nf_nat_l4proto_udp = {
123 .l4proto = IPPROTO_UDP,
124 .manip_pkt = udp_manip_pkt,
125 .in_range = nf_nat_l4proto_in_range,
126 .unique_tuple = udp_unique_tuple,
127 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
128 .nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
129 #endif
130 };
131