[NETFILTER]: conntrack: add sysctl to disable checksumming
[linux-2.6.git] / net / ipv4 / netfilter / ip_conntrack_proto_udp.c
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/ip.h>
15 #include <linux/udp.h>
16 #include <linux/seq_file.h>
17 #include <net/checksum.h>
18 #include <linux/netfilter_ipv4.h>
19 #include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
20
21 unsigned int ip_ct_udp_timeout = 30*HZ;
22 unsigned int 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 */
76                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
77                         ip_conntrack_event_cache(IPCT_STATUS, skb);
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, 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, 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 (ip_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
124             nf_ip_checksum(skb, hooknum, iph->ihl * 4, IPPROTO_UDP)) {
125                 if (LOG_INVALID(IPPROTO_UDP))
126                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
127                                   "ip_ct_udp: bad UDP checksum ");
128                 return -NF_ACCEPT;
129         }
130         
131         return NF_ACCEPT;
132 }
133
134 struct ip_conntrack_protocol ip_conntrack_protocol_udp =
135 {
136         .proto                  = IPPROTO_UDP,
137         .name                   = "udp",
138         .pkt_to_tuple           = udp_pkt_to_tuple,
139         .invert_tuple           = udp_invert_tuple,
140         .print_tuple            = udp_print_tuple,
141         .print_conntrack        = udp_print_conntrack,
142         .packet                 = udp_packet,
143         .new                    = udp_new,
144         .error                  = udp_error,
145 #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
146     defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
147         .tuple_to_nfattr        = ip_ct_port_tuple_to_nfattr,
148         .nfattr_to_tuple        = ip_ct_port_nfattr_to_tuple,
149 #endif
150 };