1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3 * (C) 2007 Patrick McHardy <kaber@trash.net>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10 #include <linux/types.h>
11 #include <linux/timer.h>
12 #include <linux/module.h>
13 #include <linux/udp.h>
14 #include <linux/seq_file.h>
15 #include <linux/skbuff.h>
16 #include <linux/ipv6.h>
17 #include <net/ip6_checksum.h>
18 #include <net/checksum.h>
19
20 #include <linux/netfilter.h>
21 #include <linux/netfilter_ipv4.h>
22 #include <linux/netfilter_ipv6.h>
23 #include <net/netfilter/nf_conntrack_l4proto.h>
24 #include <net/netfilter/nf_conntrack_ecache.h>
25 #include <net/netfilter/nf_log.h>
26
27 static unsigned int nf_ct_udplite_timeout __read_mostly = 30*HZ;
28 static unsigned int nf_ct_udplite_timeout_stream __read_mostly = 180*HZ;
29
30 static bool udplite_pkt_to_tuple(const struct sk_buff *skb,
31 unsigned int dataoff,
32 struct nf_conntrack_tuple *tuple)
33 {
34 const struct udphdr *hp;
35 struct udphdr _hdr;
36
37 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
38 if (hp == NULL)
39 return false;
40
41 tuple->src.u.udp.port = hp->source;
42 tuple->dst.u.udp.port = hp->dest;
43 return true;
44 }
45
46 static bool udplite_invert_tuple(struct nf_conntrack_tuple *tuple,
47 const struct nf_conntrack_tuple *orig)
48 {
49 tuple->src.u.udp.port = orig->dst.u.udp.port;
50 tuple->dst.u.udp.port = orig->src.u.udp.port;
51 return true;
52 }
53
54 /* Print out the per-protocol part of the tuple. */
55 static int udplite_print_tuple(struct seq_file *s,
56 const struct nf_conntrack_tuple *tuple)
57 {
58 return seq_printf(s, "sport=%hu dport=%hu ",
59 ntohs(tuple->src.u.udp.port),
60 ntohs(tuple->dst.u.udp.port));
61 }
62
63 /* Returns verdict for packet, and may modify conntracktype */
64 static int udplite_packet(struct nf_conn *ct,
65 const struct sk_buff *skb,
66 unsigned int dataoff,
67 enum ip_conntrack_info ctinfo,
68 u_int8_t pf,
69 unsigned int hooknum)
70 {
71 /* If we've seen traffic both ways, this is some kind of UDP
72 stream. Extend timeout. */
73 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
74 nf_ct_refresh_acct(ct, ctinfo, skb,
75 nf_ct_udplite_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, ct);
79 } else
80 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udplite_timeout);
81
82 return NF_ACCEPT;
83 }
84
85 /* Called when a new connection for this protocol found. */
86 static bool udplite_new(struct nf_conn *ct, const struct sk_buff *skb,
87 unsigned int dataoff)
88 {
89 return true;
90 }
91
92 static int udplite_error(struct net *net,
93 struct sk_buff *skb,
94 unsigned int dataoff,
95 enum ip_conntrack_info *ctinfo,
96 u_int8_t pf,
97 unsigned int hooknum)
98 {
99 unsigned int udplen = skb->len - dataoff;
100 const struct udphdr *hdr;
101 struct udphdr _hdr;
102 unsigned int cscov;
103
104 /* Header is too small? */
105 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
106 if (hdr == NULL) {
107 if (LOG_INVALID(net, IPPROTO_UDPLITE))
108 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
109 "nf_ct_udplite: short packet ");
110 return -NF_ACCEPT;
111 }
112
113 cscov = ntohs(hdr->len);
114 if (cscov == 0)
115 cscov = udplen;
116 else if (cscov < sizeof(*hdr) || cscov > udplen) {
117 if (LOG_INVALID(net, IPPROTO_UDPLITE))
118 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
119 "nf_ct_udplite: invalid checksum coverage ");
120 return -NF_ACCEPT;
121 }
122
123 /* UDPLITE mandates checksums */
124 if (!hdr->check) {
125 if (LOG_INVALID(net, IPPROTO_UDPLITE))
126 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
127 "nf_ct_udplite: checksum missing ");
128 return -NF_ACCEPT;
129 }
130
131 /* Checksum invalid? Ignore. */
132 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
133 nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
134 pf)) {
135 if (LOG_INVALID(net, IPPROTO_UDPLITE))
136 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
137 "nf_ct_udplite: bad UDPLite checksum ");
138 return -NF_ACCEPT;
139 }
140
141 return NF_ACCEPT;
142 }
143
144 #ifdef CONFIG_SYSCTL
145 static unsigned int udplite_sysctl_table_users;
146 static struct ctl_table_header *udplite_sysctl_header;
147 static struct ctl_table udplite_sysctl_table[] = {
148 {
149 .ctl_name = CTL_UNNUMBERED,
150 .procname = "nf_conntrack_udplite_timeout",
151 .data = &nf_ct_udplite_timeout,
152 .maxlen = sizeof(unsigned int),
153 .mode = 0644,
154 .proc_handler = proc_dointvec_jiffies,
155 },
156 {
157 .ctl_name = CTL_UNNUMBERED,
158 .procname = "nf_conntrack_udplite_timeout_stream",
159 .data = &nf_ct_udplite_timeout_stream,
160 .maxlen = sizeof(unsigned int),
161 .mode = 0644,
162 .proc_handler = proc_dointvec_jiffies,
163 },
164 {
165 .ctl_name = 0
166 }
167 };
168 #endif /* CONFIG_SYSCTL */
169
170 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
171 {
172 .l3proto = PF_INET,
173 .l4proto = IPPROTO_UDPLITE,
174 .name = "udplite",
175 .pkt_to_tuple = udplite_pkt_to_tuple,
176 .invert_tuple = udplite_invert_tuple,
177 .print_tuple = udplite_print_tuple,
178 .packet = udplite_packet,
179 .new = udplite_new,
180 .error = udplite_error,
181 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
182 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
183 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
184 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
185 .nla_policy = nf_ct_port_nla_policy,
186 #endif
187 #ifdef CONFIG_SYSCTL
188 .ctl_table_users = &udplite_sysctl_table_users,
189 .ctl_table_header = &udplite_sysctl_header,
190 .ctl_table = udplite_sysctl_table,
191 #endif
192 };
193
194 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
195 {
196 .l3proto = PF_INET6,
197 .l4proto = IPPROTO_UDPLITE,
198 .name = "udplite",
199 .pkt_to_tuple = udplite_pkt_to_tuple,
200 .invert_tuple = udplite_invert_tuple,
201 .print_tuple = udplite_print_tuple,
202 .packet = udplite_packet,
203 .new = udplite_new,
204 .error = udplite_error,
205 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
206 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
207 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
208 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
209 .nla_policy = nf_ct_port_nla_policy,
210 #endif
211 #ifdef CONFIG_SYSCTL
212 .ctl_table_users = &udplite_sysctl_table_users,
213 .ctl_table_header = &udplite_sysctl_header,
214 .ctl_table = udplite_sysctl_table,
215 #endif
216 };
217
218 static int __init nf_conntrack_proto_udplite_init(void)
219 {
220 int err;
221
222 err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
223 if (err < 0)
224 goto err1;
225 err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
226 if (err < 0)
227 goto err2;
228 return 0;
229 err2:
230 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
231 err1:
232 return err;
233 }
234
235 static void __exit nf_conntrack_proto_udplite_exit(void)
236 {
237 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
238 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
239 }
240
241 module_init(nf_conntrack_proto_udplite_init);
242 module_exit(nf_conntrack_proto_udplite_exit);
243
244 MODULE_LICENSE("GPL");
245
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