1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3 * (C) 2006-2012 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 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
27 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
28
29 static unsigned int udp_timeouts[UDP_CT_MAX] = {
30 [UDP_CT_UNREPLIED] = 30*HZ,
31 [UDP_CT_REPLIED] = 180*HZ,
32 };
33
udp_pernet(struct net * net)34 static inline struct nf_udp_net *udp_pernet(struct net *net)
35 {
36 return &net->ct.nf_ct_proto.udp;
37 }
38
udp_pkt_to_tuple(const struct sk_buff * skb,unsigned int dataoff,struct net * net,struct nf_conntrack_tuple * tuple)39 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
40 unsigned int dataoff,
41 struct net *net,
42 struct nf_conntrack_tuple *tuple)
43 {
44 const struct udphdr *hp;
45 struct udphdr _hdr;
46
47 /* Actually only need first 4 bytes to get ports. */
48 hp = skb_header_pointer(skb, dataoff, 4, &_hdr);
49 if (hp == NULL)
50 return false;
51
52 tuple->src.u.udp.port = hp->source;
53 tuple->dst.u.udp.port = hp->dest;
54
55 return true;
56 }
57
udp_invert_tuple(struct nf_conntrack_tuple * tuple,const struct nf_conntrack_tuple * orig)58 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
59 const struct nf_conntrack_tuple *orig)
60 {
61 tuple->src.u.udp.port = orig->dst.u.udp.port;
62 tuple->dst.u.udp.port = orig->src.u.udp.port;
63 return true;
64 }
65
66 /* Print out the per-protocol part of the tuple. */
udp_print_tuple(struct seq_file * s,const struct nf_conntrack_tuple * tuple)67 static void udp_print_tuple(struct seq_file *s,
68 const struct nf_conntrack_tuple *tuple)
69 {
70 seq_printf(s, "sport=%hu dport=%hu ",
71 ntohs(tuple->src.u.udp.port),
72 ntohs(tuple->dst.u.udp.port));
73 }
74
udp_get_timeouts(struct net * net)75 static unsigned int *udp_get_timeouts(struct net *net)
76 {
77 return udp_pernet(net)->timeouts;
78 }
79
80 /* Returns verdict for packet, and may modify conntracktype */
udp_packet(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,u_int8_t pf,unsigned int hooknum,unsigned int * timeouts)81 static int udp_packet(struct nf_conn *ct,
82 const struct sk_buff *skb,
83 unsigned int dataoff,
84 enum ip_conntrack_info ctinfo,
85 u_int8_t pf,
86 unsigned int hooknum,
87 unsigned int *timeouts)
88 {
89 /* If we've seen traffic both ways, this is some kind of UDP
90 stream. Extend timeout. */
91 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
92 nf_ct_refresh_acct(ct, ctinfo, skb,
93 timeouts[UDP_CT_REPLIED]);
94 /* Also, more likely to be important, and not a probe */
95 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
96 nf_conntrack_event_cache(IPCT_ASSURED, ct);
97 } else {
98 nf_ct_refresh_acct(ct, ctinfo, skb,
99 timeouts[UDP_CT_UNREPLIED]);
100 }
101 return NF_ACCEPT;
102 }
103
104 /* Called when a new connection for this protocol found. */
udp_new(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,unsigned int * timeouts)105 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
106 unsigned int dataoff, unsigned int *timeouts)
107 {
108 return true;
109 }
110
udp_error(struct net * net,struct nf_conn * tmpl,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info * ctinfo,u_int8_t pf,unsigned int hooknum)111 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
112 unsigned int dataoff, enum ip_conntrack_info *ctinfo,
113 u_int8_t pf,
114 unsigned int hooknum)
115 {
116 unsigned int udplen = skb->len - dataoff;
117 const struct udphdr *hdr;
118 struct udphdr _hdr;
119
120 /* Header is too small? */
121 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
122 if (hdr == NULL) {
123 if (LOG_INVALID(net, IPPROTO_UDP))
124 nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
125 "nf_ct_udp: short packet ");
126 return -NF_ACCEPT;
127 }
128
129 /* Truncated/malformed packets */
130 if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
131 if (LOG_INVALID(net, IPPROTO_UDP))
132 nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
133 "nf_ct_udp: truncated/malformed packet ");
134 return -NF_ACCEPT;
135 }
136
137 /* Packet with no checksum */
138 if (!hdr->check)
139 return NF_ACCEPT;
140
141 /* Checksum invalid? Ignore.
142 * We skip checking packets on the outgoing path
143 * because the checksum is assumed to be correct.
144 * FIXME: Source route IP option packets --RR */
145 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
146 nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
147 if (LOG_INVALID(net, IPPROTO_UDP))
148 nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
149 "nf_ct_udp: bad UDP checksum ");
150 return -NF_ACCEPT;
151 }
152
153 return NF_ACCEPT;
154 }
155
156 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
157
158 #include <linux/netfilter/nfnetlink.h>
159 #include <linux/netfilter/nfnetlink_cttimeout.h>
160
udp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)161 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
162 struct net *net, void *data)
163 {
164 unsigned int *timeouts = data;
165 struct nf_udp_net *un = udp_pernet(net);
166
167 /* set default timeouts for UDP. */
168 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
169 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
170
171 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
172 timeouts[UDP_CT_UNREPLIED] =
173 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
174 }
175 if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
176 timeouts[UDP_CT_REPLIED] =
177 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
178 }
179 return 0;
180 }
181
182 static int
udp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)183 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
184 {
185 const unsigned int *timeouts = data;
186
187 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
188 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
189 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
190 htonl(timeouts[UDP_CT_REPLIED] / HZ)))
191 goto nla_put_failure;
192 return 0;
193
194 nla_put_failure:
195 return -ENOSPC;
196 }
197
198 static const struct nla_policy
199 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
200 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
201 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
202 };
203 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
204
205 #ifdef CONFIG_SYSCTL
206 static struct ctl_table udp_sysctl_table[] = {
207 {
208 .procname = "nf_conntrack_udp_timeout",
209 .maxlen = sizeof(unsigned int),
210 .mode = 0644,
211 .proc_handler = proc_dointvec_jiffies,
212 },
213 {
214 .procname = "nf_conntrack_udp_timeout_stream",
215 .maxlen = sizeof(unsigned int),
216 .mode = 0644,
217 .proc_handler = proc_dointvec_jiffies,
218 },
219 { }
220 };
221 #endif /* CONFIG_SYSCTL */
222
udp_kmemdup_sysctl_table(struct nf_proto_net * pn,struct nf_udp_net * un)223 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
224 struct nf_udp_net *un)
225 {
226 #ifdef CONFIG_SYSCTL
227 if (pn->ctl_table)
228 return 0;
229 pn->ctl_table = kmemdup(udp_sysctl_table,
230 sizeof(udp_sysctl_table),
231 GFP_KERNEL);
232 if (!pn->ctl_table)
233 return -ENOMEM;
234 pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
235 pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
236 #endif
237 return 0;
238 }
239
udp_init_net(struct net * net,u_int16_t proto)240 static int udp_init_net(struct net *net, u_int16_t proto)
241 {
242 struct nf_udp_net *un = udp_pernet(net);
243 struct nf_proto_net *pn = &un->pn;
244
245 if (!pn->users) {
246 int i;
247
248 for (i = 0; i < UDP_CT_MAX; i++)
249 un->timeouts[i] = udp_timeouts[i];
250 }
251
252 return udp_kmemdup_sysctl_table(pn, un);
253 }
254
udp_get_net_proto(struct net * net)255 static struct nf_proto_net *udp_get_net_proto(struct net *net)
256 {
257 return &net->ct.nf_ct_proto.udp.pn;
258 }
259
260 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
261 {
262 .l3proto = PF_INET,
263 .l4proto = IPPROTO_UDP,
264 .name = "udp",
265 .allow_clash = true,
266 .pkt_to_tuple = udp_pkt_to_tuple,
267 .invert_tuple = udp_invert_tuple,
268 .print_tuple = udp_print_tuple,
269 .packet = udp_packet,
270 .get_timeouts = udp_get_timeouts,
271 .new = udp_new,
272 .error = udp_error,
273 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
274 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
275 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
276 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
277 .nla_policy = nf_ct_port_nla_policy,
278 #endif
279 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
280 .ctnl_timeout = {
281 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
282 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
283 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
284 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
285 .nla_policy = udp_timeout_nla_policy,
286 },
287 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
288 .init_net = udp_init_net,
289 .get_net_proto = udp_get_net_proto,
290 };
291 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
292
293 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
294 {
295 .l3proto = PF_INET6,
296 .l4proto = IPPROTO_UDP,
297 .name = "udp",
298 .allow_clash = true,
299 .pkt_to_tuple = udp_pkt_to_tuple,
300 .invert_tuple = udp_invert_tuple,
301 .print_tuple = udp_print_tuple,
302 .packet = udp_packet,
303 .get_timeouts = udp_get_timeouts,
304 .new = udp_new,
305 .error = udp_error,
306 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
307 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
308 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
309 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
310 .nla_policy = nf_ct_port_nla_policy,
311 #endif
312 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
313 .ctnl_timeout = {
314 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
315 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
316 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
317 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
318 .nla_policy = udp_timeout_nla_policy,
319 },
320 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
321 .init_net = udp_init_net,
322 .get_net_proto = udp_get_net_proto,
323 };
324 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
325