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1da177e4 LT |
1 | /* (C) 1999-2001 Paul `Rusty' Russell |
2 | * (C) 2002-2004 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> | |
11 | #include <linux/netfilter.h> | |
12 | #include <linux/ip.h> | |
13 | #include <linux/udp.h> | |
14 | #include <linux/if.h> | |
15 | ||
16 | #include <linux/netfilter_ipv4/ip_nat.h> | |
17 | #include <linux/netfilter_ipv4/ip_nat_core.h> | |
18 | #include <linux/netfilter_ipv4/ip_nat_rule.h> | |
19 | #include <linux/netfilter_ipv4/ip_nat_protocol.h> | |
20 | ||
21 | static int | |
22 | udp_in_range(const struct ip_conntrack_tuple *tuple, | |
23 | enum ip_nat_manip_type maniptype, | |
24 | const union ip_conntrack_manip_proto *min, | |
25 | const union ip_conntrack_manip_proto *max) | |
26 | { | |
27 | u_int16_t 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 ip_conntrack_tuple *tuple, | |
40 | const struct ip_nat_range *range, | |
41 | enum ip_nat_manip_type maniptype, | |
42 | const struct ip_conntrack *conntrack) | |
43 | { | |
d04b4f8c PM |
44 | static u_int16_t port; |
45 | u_int16_t *portptr; | |
1da177e4 LT |
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 | ||
77 | for (i = 0; i < range_size; i++, port++) { | |
78 | *portptr = htons(min + port % range_size); | |
79 | if (!ip_nat_used_tuple(tuple, conntrack)) | |
80 | return 1; | |
81 | } | |
82 | return 0; | |
83 | } | |
84 | ||
85 | static int | |
86 | udp_manip_pkt(struct sk_buff **pskb, | |
87 | unsigned int iphdroff, | |
88 | const struct ip_conntrack_tuple *tuple, | |
89 | enum ip_nat_manip_type maniptype) | |
90 | { | |
91 | struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); | |
92 | struct udphdr *hdr; | |
93 | unsigned int hdroff = iphdroff + iph->ihl*4; | |
94 | u32 oldip, newip; | |
95 | u16 *portptr, newport; | |
96 | ||
97 | if (!skb_ip_make_writable(pskb, hdroff + sizeof(*hdr))) | |
98 | return 0; | |
99 | ||
100 | iph = (struct iphdr *)((*pskb)->data + iphdroff); | |
101 | hdr = (struct udphdr *)((*pskb)->data + hdroff); | |
102 | ||
103 | if (maniptype == IP_NAT_MANIP_SRC) { | |
104 | /* Get rid of src ip and src pt */ | |
105 | oldip = iph->saddr; | |
106 | newip = tuple->src.ip; | |
107 | newport = tuple->src.u.udp.port; | |
108 | portptr = &hdr->source; | |
109 | } else { | |
110 | /* Get rid of dst ip and dst pt */ | |
111 | oldip = iph->daddr; | |
112 | newip = tuple->dst.ip; | |
113 | newport = tuple->dst.u.udp.port; | |
114 | portptr = &hdr->dest; | |
115 | } | |
116 | if (hdr->check) /* 0 is a special case meaning no checksum */ | |
117 | hdr->check = ip_nat_cheat_check(~oldip, newip, | |
118 | ip_nat_cheat_check(*portptr ^ 0xFFFF, | |
119 | newport, | |
120 | hdr->check)); | |
121 | *portptr = newport; | |
122 | return 1; | |
123 | } | |
124 | ||
125 | static unsigned int | |
126 | udp_print(char *buffer, | |
127 | const struct ip_conntrack_tuple *match, | |
128 | const struct ip_conntrack_tuple *mask) | |
129 | { | |
130 | unsigned int len = 0; | |
131 | ||
132 | if (mask->src.u.udp.port) | |
133 | len += sprintf(buffer + len, "srcpt=%u ", | |
134 | ntohs(match->src.u.udp.port)); | |
135 | ||
136 | ||
137 | if (mask->dst.u.udp.port) | |
138 | len += sprintf(buffer + len, "dstpt=%u ", | |
139 | ntohs(match->dst.u.udp.port)); | |
140 | ||
141 | return len; | |
142 | } | |
143 | ||
144 | static unsigned int | |
145 | udp_print_range(char *buffer, const struct ip_nat_range *range) | |
146 | { | |
147 | if (range->min.udp.port != 0 || range->max.udp.port != 0xFFFF) { | |
148 | if (range->min.udp.port == range->max.udp.port) | |
149 | return sprintf(buffer, "port %u ", | |
150 | ntohs(range->min.udp.port)); | |
151 | else | |
152 | return sprintf(buffer, "ports %u-%u ", | |
153 | ntohs(range->min.udp.port), | |
154 | ntohs(range->max.udp.port)); | |
155 | } | |
156 | else return 0; | |
157 | } | |
158 | ||
159 | struct ip_nat_protocol ip_nat_protocol_udp | |
080774a2 | 160 | = { "UDP", IPPROTO_UDP, THIS_MODULE, |
1da177e4 LT |
161 | udp_manip_pkt, |
162 | udp_in_range, | |
163 | udp_unique_tuple, | |
164 | udp_print, | |
080774a2 HW |
165 | udp_print_range, |
166 | #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ | |
167 | defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) | |
168 | ip_nat_port_range_to_nfattr, | |
169 | ip_nat_port_nfattr_to_range, | |
170 | #endif | |
1da177e4 | 171 | }; |