[NETFILTER]: conntrack: add sysctl to disable checksumming
[linux-2.6.git] / net / netfilter / nf_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  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
9  *      - enable working with Layer 3 protocol independent connection tracking.
10  *
11  * Derived from net/ipv4/netfilter/ip_conntrack_proto_udp.c
12  */
13
14 #include <linux/types.h>
15 #include <linux/sched.h>
16 #include <linux/timer.h>
17 #include <linux/module.h>
18 #include <linux/netfilter.h>
19 #include <linux/udp.h>
20 #include <linux/seq_file.h>
21 #include <linux/skbuff.h>
22 #include <linux/ipv6.h>
23 #include <net/ip6_checksum.h>
24 #include <net/checksum.h>
25 #include <linux/netfilter.h>
26 #include <linux/netfilter_ipv4.h>
27 #include <linux/netfilter_ipv6.h>
28 #include <net/netfilter/nf_conntrack_protocol.h>
29
30 unsigned int nf_ct_udp_timeout = 30*HZ;
31 unsigned int nf_ct_udp_timeout_stream = 180*HZ;
32
33 static int udp_pkt_to_tuple(const struct sk_buff *skb,
34                              unsigned int dataoff,
35                              struct nf_conntrack_tuple *tuple)
36 {
37         struct udphdr _hdr, *hp;
38
39         /* Actually only need first 8 bytes. */
40         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
41         if (hp == NULL)
42                 return 0;
43
44         tuple->src.u.udp.port = hp->source;
45         tuple->dst.u.udp.port = hp->dest;
46
47         return 1;
48 }
49
50 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
51                             const struct nf_conntrack_tuple *orig)
52 {
53         tuple->src.u.udp.port = orig->dst.u.udp.port;
54         tuple->dst.u.udp.port = orig->src.u.udp.port;
55         return 1;
56 }
57
58 /* Print out the per-protocol part of the tuple. */
59 static int udp_print_tuple(struct seq_file *s,
60                            const struct nf_conntrack_tuple *tuple)
61 {
62         return seq_printf(s, "sport=%hu dport=%hu ",
63                           ntohs(tuple->src.u.udp.port),
64                           ntohs(tuple->dst.u.udp.port));
65 }
66
67 /* Print out the private part of the conntrack. */
68 static int udp_print_conntrack(struct seq_file *s,
69                                const struct nf_conn *conntrack)
70 {
71         return 0;
72 }
73
74 /* Returns verdict for packet, and may modify conntracktype */
75 static int udp_packet(struct nf_conn *conntrack,
76                       const struct sk_buff *skb,
77                       unsigned int dataoff,
78                       enum ip_conntrack_info ctinfo,
79                       int pf,
80                       unsigned int hooknum)
81 {
82         /* If we've seen traffic both ways, this is some kind of UDP
83            stream.  Extend timeout. */
84         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
85                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
86                                    nf_ct_udp_timeout_stream);
87                 /* Also, more likely to be important, and not a probe */
88                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
89                         nf_conntrack_event_cache(IPCT_STATUS, skb);
90         } else
91                 nf_ct_refresh_acct(conntrack, ctinfo, skb, nf_ct_udp_timeout);
92
93         return NF_ACCEPT;
94 }
95
96 /* Called when a new connection for this protocol found. */
97 static int udp_new(struct nf_conn *conntrack, const struct sk_buff *skb,
98                    unsigned int dataoff)
99 {
100         return 1;
101 }
102
103 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
104                      enum ip_conntrack_info *ctinfo,
105                      int pf,
106                      unsigned int hooknum)
107 {
108         unsigned int udplen = skb->len - dataoff;
109         struct udphdr _hdr, *hdr;
110
111         /* Header is too small? */
112         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
113         if (hdr == NULL) {
114                 if (LOG_INVALID(IPPROTO_UDP))
115                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
116                                       "nf_ct_udp: short packet ");
117                 return -NF_ACCEPT;
118         }
119
120         /* Truncated/malformed packets */
121         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
122                 if (LOG_INVALID(IPPROTO_UDP))
123                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
124                                 "nf_ct_udp: truncated/malformed packet ");
125                 return -NF_ACCEPT;
126         }
127
128         /* Packet with no checksum */
129         if (!hdr->check)
130                 return NF_ACCEPT;
131
132         /* Checksum invalid? Ignore.
133          * We skip checking packets on the outgoing path
134          * because the semantic of CHECKSUM_HW is different there
135          * and moreover root might send raw packets.
136          * FIXME: Source route IP option packets --RR */
137         if (nf_conntrack_checksum &&
138             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
139              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
140             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
141                 if (LOG_INVALID(IPPROTO_UDP))
142                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
143                                 "nf_ct_udp: bad UDP checksum ");
144                 return -NF_ACCEPT;
145         }
146
147         return NF_ACCEPT;
148 }
149
150 struct nf_conntrack_protocol nf_conntrack_protocol_udp4 =
151 {
152         .l3proto                = PF_INET,
153         .proto                  = IPPROTO_UDP,
154         .name                   = "udp",
155         .pkt_to_tuple           = udp_pkt_to_tuple,
156         .invert_tuple           = udp_invert_tuple,
157         .print_tuple            = udp_print_tuple,
158         .print_conntrack        = udp_print_conntrack,
159         .packet                 = udp_packet,
160         .new                    = udp_new,
161         .error                  = udp_error,
162 #if defined(CONFIG_NF_CT_NETLINK) || \
163     defined(CONFIG_NF_CT_NETLINK_MODULE)
164         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
165         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
166 #endif
167 };
168
169 struct nf_conntrack_protocol nf_conntrack_protocol_udp6 =
170 {
171         .l3proto                = PF_INET6,
172         .proto                  = IPPROTO_UDP,
173         .name                   = "udp",
174         .pkt_to_tuple           = udp_pkt_to_tuple,
175         .invert_tuple           = udp_invert_tuple,
176         .print_tuple            = udp_print_tuple,
177         .print_conntrack        = udp_print_conntrack,
178         .packet                 = udp_packet,
179         .new                    = udp_new,
180         .error                  = udp_error,
181 #if defined(CONFIG_NF_CT_NETLINK) || \
182     defined(CONFIG_NF_CT_NETLINK_MODULE)
183         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
184         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
185 #endif
186 };
187
188 EXPORT_SYMBOL(nf_conntrack_protocol_udp4);
189 EXPORT_SYMBOL(nf_conntrack_protocol_udp6);