]>
Commit | Line | Data |
---|---|---|
5b1158e9 JK |
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/init.h> | |
41f4689a | 11 | #include <linux/random.h> |
5b1158e9 JK |
12 | #include <linux/ip.h> |
13 | #include <linux/udp.h> | |
14 | ||
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> | |
20 | ||
21 | static int | |
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) | |
26 | { | |
27 | __be16 port; | |
28 | ||
29 | if (maniptype == IP_NAT_MANIP_SRC) | |
30 | port = tuple->src.u.udp.port; | |
31 | else | |
32 | port = tuple->dst.u.udp.port; | |
33 | ||
34 | return ntohs(port) >= ntohs(min->udp.port) && | |
35 | ntohs(port) <= ntohs(max->udp.port); | |
36 | } | |
37 | ||
38 | static int | |
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) | |
43 | { | |
44 | static u_int16_t port; | |
45 | __be16 *portptr; | |
46 | unsigned int range_size, min, i; | |
47 | ||
48 | if (maniptype == IP_NAT_MANIP_SRC) | |
49 | portptr = &tuple->src.u.udp.port; | |
50 | else | |
51 | portptr = &tuple->dst.u.udp.port; | |
52 | ||
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) | |
57 | return 0; | |
58 | ||
59 | if (ntohs(*portptr) < 1024) { | |
60 | /* Loose convention: >> 512 is credential passing */ | |
61 | if (ntohs(*portptr)<512) { | |
62 | min = 1; | |
63 | range_size = 511 - min + 1; | |
64 | } else { | |
65 | min = 600; | |
66 | range_size = 1023 - min + 1; | |
67 | } | |
68 | } else { | |
69 | min = 1024; | |
70 | range_size = 65535 - 1024 + 1; | |
71 | } | |
72 | } else { | |
73 | min = ntohs(range->min.udp.port); | |
74 | range_size = ntohs(range->max.udp.port) - min + 1; | |
75 | } | |
76 | ||
41f4689a EL |
77 | if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) |
78 | port = net_random(); | |
79 | ||
5b1158e9 JK |
80 | for (i = 0; i < range_size; i++, port++) { |
81 | *portptr = htons(min + port % range_size); | |
82 | if (!nf_nat_used_tuple(tuple, ct)) | |
83 | return 1; | |
84 | } | |
85 | return 0; | |
86 | } | |
87 | ||
88 | static int | |
89 | udp_manip_pkt(struct sk_buff **pskb, | |
90 | unsigned int iphdroff, | |
91 | const struct nf_conntrack_tuple *tuple, | |
92 | enum nf_nat_manip_type maniptype) | |
93 | { | |
94 | struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); | |
95 | struct udphdr *hdr; | |
96 | unsigned int hdroff = iphdroff + iph->ihl*4; | |
97 | __be32 oldip, newip; | |
98 | __be16 *portptr, newport; | |
99 | ||
100 | if (!skb_make_writable(pskb, hdroff + sizeof(*hdr))) | |
101 | return 0; | |
102 | ||
103 | iph = (struct iphdr *)((*pskb)->data + iphdroff); | |
104 | hdr = (struct udphdr *)((*pskb)->data + hdroff); | |
105 | ||
106 | if (maniptype == IP_NAT_MANIP_SRC) { | |
107 | /* Get rid of src ip and src pt */ | |
108 | oldip = iph->saddr; | |
109 | newip = tuple->src.u3.ip; | |
110 | newport = tuple->src.u.udp.port; | |
111 | portptr = &hdr->source; | |
112 | } else { | |
113 | /* Get rid of dst ip and dst pt */ | |
114 | oldip = iph->daddr; | |
115 | newip = tuple->dst.u3.ip; | |
116 | newport = tuple->dst.u.udp.port; | |
117 | portptr = &hdr->dest; | |
118 | } | |
119 | if (hdr->check || (*pskb)->ip_summed == CHECKSUM_PARTIAL) { | |
120 | nf_proto_csum_replace4(&hdr->check, *pskb, oldip, newip, 1); | |
121 | nf_proto_csum_replace2(&hdr->check, *pskb, *portptr, newport, | |
122 | 0); | |
123 | if (!hdr->check) | |
124 | hdr->check = CSUM_MANGLED_0; | |
125 | } | |
126 | *portptr = newport; | |
127 | return 1; | |
128 | } | |
129 | ||
130 | struct nf_nat_protocol nf_nat_protocol_udp = { | |
131 | .name = "UDP", | |
132 | .protonum = IPPROTO_UDP, | |
133 | .me = THIS_MODULE, | |
134 | .manip_pkt = udp_manip_pkt, | |
135 | .in_range = udp_in_range, | |
136 | .unique_tuple = udp_unique_tuple, | |
137 | #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ | |
138 | defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) | |
139 | .range_to_nfattr = nf_nat_port_range_to_nfattr, | |
140 | .nfattr_to_range = nf_nat_port_nfattr_to_range, | |
141 | #endif | |
142 | }; |