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/timer.h>
11 #include <linux/module.h>
12 #include <linux/udp.h>
13 #include <linux/seq_file.h>
14 #include <linux/skbuff.h>
15 #include <linux/ipv6.h>
16 #include <net/ip6_checksum.h>
17 #include <net/checksum.h>
18
19 #include <linux/netfilter.h>
20 #include <linux/netfilter_ipv4.h>
21 #include <linux/netfilter_ipv6.h>
22 #include <net/netfilter/nf_conntrack_l4proto.h>
23 #include <net/netfilter/nf_conntrack_ecache.h>
24 #include <net/netfilter/nf_log.h>
25
26 static unsigned int nf_ct_udp_timeout __read_mostly = 30*HZ;
27 static unsigned int nf_ct_udp_timeout_stream __read_mostly = 180*HZ;
28
29 static int udp_pkt_to_tuple(const struct sk_buff *skb,
30 unsigned int dataoff,
31 struct nf_conntrack_tuple *tuple)
32 {
33 const struct udphdr *hp;
34 struct udphdr _hdr;
35
36 /* Actually only need first 8 bytes. */
37 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
38 if (hp == NULL)
39 return 0;
40
41 tuple->src.u.udp.port = hp->source;
42 tuple->dst.u.udp.port = hp->dest;
43
44 return 1;
45 }
46
47 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
48 const struct nf_conntrack_tuple *orig)
49 {
50 tuple->src.u.udp.port = orig->dst.u.udp.port;
51 tuple->dst.u.udp.port = orig->src.u.udp.port;
52 return 1;
53 }
54
55 /* Print out the per-protocol part of the tuple. */
56 static int udp_print_tuple(struct seq_file *s,
57 const struct nf_conntrack_tuple *tuple)
58 {
59 return seq_printf(s, "sport=%hu dport=%hu ",
60 ntohs(tuple->src.u.udp.port),
61 ntohs(tuple->dst.u.udp.port));
62 }
63
64 /* Returns verdict for packet, and may modify conntracktype */
65 static int udp_packet(struct nf_conn *ct,
66 const struct sk_buff *skb,
67 unsigned int dataoff,
68 enum ip_conntrack_info ctinfo,
69 int pf,
70 unsigned int hooknum)
71 {
72 /* If we've seen traffic both ways, this is some kind of UDP
73 stream. Extend timeout. */
74 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
75 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout_stream);
76 /* Also, more likely to be important, and not a probe */
77 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
78 nf_conntrack_event_cache(IPCT_STATUS, skb);
79 } else
80 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout);
81
82 return NF_ACCEPT;
83 }
84
85 /* Called when a new connection for this protocol found. */
86 static int udp_new(struct nf_conn *ct, const struct sk_buff *skb,
87 unsigned int dataoff)
88 {
89 return 1;
90 }
91
92 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
93 enum ip_conntrack_info *ctinfo,
94 int pf,
95 unsigned int hooknum)
96 {
97 unsigned int udplen = skb->len - dataoff;
98 const struct udphdr *hdr;
99 struct udphdr _hdr;
100
101 /* Header is too small? */
102 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
103 if (hdr == NULL) {
104 if (LOG_INVALID(IPPROTO_UDP))
105 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
106 "nf_ct_udp: short packet ");
107 return -NF_ACCEPT;
108 }
109
110 /* Truncated/malformed packets */
111 if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
112 if (LOG_INVALID(IPPROTO_UDP))
113 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
114 "nf_ct_udp: truncated/malformed packet ");
115 return -NF_ACCEPT;
116 }
117
118 /* Packet with no checksum */
119 if (!hdr->check)
120 return NF_ACCEPT;
121
122 /* Checksum invalid? Ignore.
123 * We skip checking packets on the outgoing path
124 * because the checksum is assumed to be correct.
125 * FIXME: Source route IP option packets --RR */
126 if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
127 nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
128 if (LOG_INVALID(IPPROTO_UDP))
129 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
130 "nf_ct_udp: bad UDP checksum ");
131 return -NF_ACCEPT;
132 }
133
134 return NF_ACCEPT;
135 }
136
137 #ifdef CONFIG_SYSCTL
138 static unsigned int udp_sysctl_table_users;
139 static struct ctl_table_header *udp_sysctl_header;
140 static struct ctl_table udp_sysctl_table[] = {
141 {
142 .procname = "nf_conntrack_udp_timeout",
143 .data = &nf_ct_udp_timeout,
144 .maxlen = sizeof(unsigned int),
145 .mode = 0644,
146 .proc_handler = &proc_dointvec_jiffies,
147 },
148 {
149 .procname = "nf_conntrack_udp_timeout_stream",
150 .data = &nf_ct_udp_timeout_stream,
151 .maxlen = sizeof(unsigned int),
152 .mode = 0644,
153 .proc_handler = &proc_dointvec_jiffies,
154 },
155 {
156 .ctl_name = 0
157 }
158 };
159 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
160 static struct ctl_table udp_compat_sysctl_table[] = {
161 {
162 .procname = "ip_conntrack_udp_timeout",
163 .data = &nf_ct_udp_timeout,
164 .maxlen = sizeof(unsigned int),
165 .mode = 0644,
166 .proc_handler = &proc_dointvec_jiffies,
167 },
168 {
169 .procname = "ip_conntrack_udp_timeout_stream",
170 .data = &nf_ct_udp_timeout_stream,
171 .maxlen = sizeof(unsigned int),
172 .mode = 0644,
173 .proc_handler = &proc_dointvec_jiffies,
174 },
175 {
176 .ctl_name = 0
177 }
178 };
179 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
180 #endif /* CONFIG_SYSCTL */
181
182 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
183 {
184 .l3proto = PF_INET,
185 .l4proto = IPPROTO_UDP,
186 .name = "udp",
187 .pkt_to_tuple = udp_pkt_to_tuple,
188 .invert_tuple = udp_invert_tuple,
189 .print_tuple = udp_print_tuple,
190 .packet = udp_packet,
191 .new = udp_new,
192 .error = udp_error,
193 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
194 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
195 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
196 .nla_policy = nf_ct_port_nla_policy,
197 #endif
198 #ifdef CONFIG_SYSCTL
199 .ctl_table_users = &udp_sysctl_table_users,
200 .ctl_table_header = &udp_sysctl_header,
201 .ctl_table = udp_sysctl_table,
202 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
203 .ctl_compat_table = udp_compat_sysctl_table,
204 #endif
205 #endif
206 };
207 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
208
209 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
210 {
211 .l3proto = PF_INET6,
212 .l4proto = IPPROTO_UDP,
213 .name = "udp",
214 .pkt_to_tuple = udp_pkt_to_tuple,
215 .invert_tuple = udp_invert_tuple,
216 .print_tuple = udp_print_tuple,
217 .packet = udp_packet,
218 .new = udp_new,
219 .error = udp_error,
220 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
221 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
222 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
223 .nla_policy = nf_ct_port_nla_policy,
224 #endif
225 #ifdef CONFIG_SYSCTL
226 .ctl_table_users = &udp_sysctl_table_users,
227 .ctl_table_header = &udp_sysctl_header,
228 .ctl_table = udp_sysctl_table,
229 #endif
230 };
231 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
232
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