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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/sched.h> | |
11 | #include <linux/timer.h> | |
12 | #include <linux/netfilter.h> | |
13 | #include <linux/in.h> | |
14 | #include <linux/udp.h> | |
15 | #include <linux/seq_file.h> | |
16 | #include <net/checksum.h> | |
17 | #include <linux/netfilter.h> | |
18 | #include <linux/netfilter_ipv4.h> | |
19 | #include <linux/netfilter_ipv4/ip_conntrack_protocol.h> | |
20 | ||
21 | unsigned long ip_ct_udp_timeout = 30*HZ; | |
22 | unsigned long ip_ct_udp_timeout_stream = 180*HZ; | |
23 | ||
24 | static int udp_pkt_to_tuple(const struct sk_buff *skb, | |
25 | unsigned int dataoff, | |
26 | struct ip_conntrack_tuple *tuple) | |
27 | { | |
28 | struct udphdr _hdr, *hp; | |
29 | ||
30 | /* Actually only need first 8 bytes. */ | |
31 | hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); | |
32 | if (hp == NULL) | |
33 | return 0; | |
34 | ||
35 | tuple->src.u.udp.port = hp->source; | |
36 | tuple->dst.u.udp.port = hp->dest; | |
37 | ||
38 | return 1; | |
39 | } | |
40 | ||
41 | static int udp_invert_tuple(struct ip_conntrack_tuple *tuple, | |
42 | const struct ip_conntrack_tuple *orig) | |
43 | { | |
44 | tuple->src.u.udp.port = orig->dst.u.udp.port; | |
45 | tuple->dst.u.udp.port = orig->src.u.udp.port; | |
46 | return 1; | |
47 | } | |
48 | ||
49 | /* Print out the per-protocol part of the tuple. */ | |
50 | static int udp_print_tuple(struct seq_file *s, | |
51 | const struct ip_conntrack_tuple *tuple) | |
52 | { | |
53 | return seq_printf(s, "sport=%hu dport=%hu ", | |
54 | ntohs(tuple->src.u.udp.port), | |
55 | ntohs(tuple->dst.u.udp.port)); | |
56 | } | |
57 | ||
58 | /* Print out the private part of the conntrack. */ | |
59 | static int udp_print_conntrack(struct seq_file *s, | |
60 | const struct ip_conntrack *conntrack) | |
61 | { | |
62 | return 0; | |
63 | } | |
64 | ||
65 | /* Returns verdict for packet, and may modify conntracktype */ | |
66 | static int udp_packet(struct ip_conntrack *conntrack, | |
67 | const struct sk_buff *skb, | |
68 | enum ip_conntrack_info ctinfo) | |
69 | { | |
70 | /* If we've seen traffic both ways, this is some kind of UDP | |
71 | stream. Extend timeout. */ | |
72 | if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) { | |
73 | ip_ct_refresh_acct(conntrack, ctinfo, skb, | |
74 | ip_ct_udp_timeout_stream); | |
75 | /* Also, more likely to be important, and not a probe */ | |
ac3247ba HW |
76 | if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status)) |
77 | ip_conntrack_event_cache(IPCT_STATUS, skb); | |
1da177e4 LT |
78 | } else |
79 | ip_ct_refresh_acct(conntrack, ctinfo, skb, ip_ct_udp_timeout); | |
80 | ||
81 | return NF_ACCEPT; | |
82 | } | |
83 | ||
84 | /* Called when a new connection for this protocol found. */ | |
85 | static int udp_new(struct ip_conntrack *conntrack, const struct sk_buff *skb) | |
86 | { | |
87 | return 1; | |
88 | } | |
89 | ||
90 | static int udp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo, | |
91 | unsigned int hooknum) | |
92 | { | |
93 | struct iphdr *iph = skb->nh.iph; | |
94 | unsigned int udplen = skb->len - iph->ihl * 4; | |
95 | struct udphdr _hdr, *hdr; | |
96 | ||
97 | /* Header is too small? */ | |
98 | hdr = skb_header_pointer(skb, iph->ihl*4, sizeof(_hdr), &_hdr); | |
99 | if (hdr == NULL) { | |
100 | if (LOG_INVALID(IPPROTO_UDP)) | |
101 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, | |
102 | "ip_ct_udp: short packet "); | |
103 | return -NF_ACCEPT; | |
104 | } | |
105 | ||
106 | /* Truncated/malformed packets */ | |
107 | if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) { | |
108 | if (LOG_INVALID(IPPROTO_UDP)) | |
109 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, | |
110 | "ip_ct_udp: truncated/malformed packet "); | |
111 | return -NF_ACCEPT; | |
112 | } | |
113 | ||
114 | /* Packet with no checksum */ | |
115 | if (!hdr->check) | |
116 | return NF_ACCEPT; | |
117 | ||
118 | /* Checksum invalid? Ignore. | |
119 | * We skip checking packets on the outgoing path | |
120 | * because the semantic of CHECKSUM_HW is different there | |
121 | * and moreover root might send raw packets. | |
122 | * FIXME: Source route IP option packets --RR */ | |
123 | if (hooknum == NF_IP_PRE_ROUTING | |
e3be8ba7 | 124 | && skb->ip_summed != CHECKSUM_UNNECESSARY |
1da177e4 LT |
125 | && csum_tcpudp_magic(iph->saddr, iph->daddr, udplen, IPPROTO_UDP, |
126 | skb->ip_summed == CHECKSUM_HW ? skb->csum | |
127 | : skb_checksum(skb, iph->ihl*4, udplen, 0))) { | |
128 | if (LOG_INVALID(IPPROTO_UDP)) | |
129 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, | |
130 | "ip_ct_udp: bad UDP checksum "); | |
131 | return -NF_ACCEPT; | |
132 | } | |
133 | ||
134 | return NF_ACCEPT; | |
135 | } | |
136 | ||
137 | struct ip_conntrack_protocol ip_conntrack_protocol_udp = | |
138 | { | |
139 | .proto = IPPROTO_UDP, | |
140 | .name = "udp", | |
141 | .pkt_to_tuple = udp_pkt_to_tuple, | |
142 | .invert_tuple = udp_invert_tuple, | |
143 | .print_tuple = udp_print_tuple, | |
144 | .print_conntrack = udp_print_conntrack, | |
145 | .packet = udp_packet, | |
146 | .new = udp_new, | |
147 | .error = udp_error, | |
148 | }; |