1// SPDX-License-Identifier: GPL-2.0-only
2/* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
5 */
6
7#include <linux/types.h>
8#include <linux/timer.h>
9#include <linux/module.h>
10#include <linux/udp.h>
11#include <linux/seq_file.h>
12#include <linux/skbuff.h>
13#include <linux/ipv6.h>
14#include <net/ip6_checksum.h>
15#include <net/checksum.h>
16
17#include <linux/netfilter.h>
18#include <linux/netfilter_ipv4.h>
19#include <linux/netfilter_ipv6.h>
20#include <net/netfilter/nf_conntrack_l4proto.h>
21#include <net/netfilter/nf_conntrack_ecache.h>
22#include <net/netfilter/nf_conntrack_timeout.h>
23#include <net/netfilter/nf_log.h>
24#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
25#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
26
27static const unsigned int udp_timeouts[UDP_CT_MAX] = {
28 [UDP_CT_UNREPLIED] = 30*HZ,
29 [UDP_CT_REPLIED] = 120*HZ,
30};
31
32static unsigned int *udp_get_timeouts(struct net *net)
33{
34 return nf_udp_pernet(net)->timeouts;
35}
36
37static void udp_error_log(const struct sk_buff *skb,
38 const struct nf_hook_state *state,
39 const char *msg)
40{
41 nf_l4proto_log_invalid(skb, state, IPPROTO_UDP, fmt: "%s", msg);
42}
43
44static bool udp_error(struct sk_buff *skb,
45 unsigned int dataoff,
46 const struct nf_hook_state *state)
47{
48 unsigned int udplen = skb->len - dataoff;
49 const struct udphdr *hdr;
50 struct udphdr _hdr;
51
52 /* Header is too small? */
53 hdr = skb_header_pointer(skb, offset: dataoff, len: sizeof(_hdr), buffer: &_hdr);
54 if (!hdr) {
55 udp_error_log(skb, state, msg: "short packet");
56 return true;
57 }
58
59 /* Truncated/malformed packets */
60 if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
61 udp_error_log(skb, state, msg: "truncated/malformed packet");
62 return true;
63 }
64
65 /* Packet with no checksum */
66 if (!hdr->check)
67 return false;
68
69 /* Checksum invalid? Ignore.
70 * We skip checking packets on the outgoing path
71 * because the checksum is assumed to be correct.
72 * FIXME: Source route IP option packets --RR */
73 if (state->hook == NF_INET_PRE_ROUTING &&
74 state->net->ct.sysctl_checksum &&
75 nf_checksum(skb, hook: state->hook, dataoff, IPPROTO_UDP, family: state->pf)) {
76 udp_error_log(skb, state, msg: "bad checksum");
77 return true;
78 }
79
80 return false;
81}
82
83/* Returns verdict for packet, and may modify conntracktype */
84int nf_conntrack_udp_packet(struct nf_conn *ct,
85 struct sk_buff *skb,
86 unsigned int dataoff,
87 enum ip_conntrack_info ctinfo,
88 const struct nf_hook_state *state)
89{
90 unsigned int *timeouts;
91 unsigned long status;
92
93 if (udp_error(skb, dataoff, state))
94 return -NF_ACCEPT;
95
96 timeouts = nf_ct_timeout_lookup(ct);
97 if (!timeouts)
98 timeouts = udp_get_timeouts(net: nf_ct_net(ct));
99
100 status = READ_ONCE(ct->status);
101 if ((status & IPS_CONFIRMED) == 0)
102 ct->proto.udp.stream_ts = 2 * HZ + jiffies;
103
104 /* If we've seen traffic both ways, this is some kind of UDP
105 * stream. Set Assured.
106 */
107 if (status & IPS_SEEN_REPLY) {
108 unsigned long extra = timeouts[UDP_CT_UNREPLIED];
109 bool stream = false;
110
111 /* Still active after two seconds? Extend timeout. */
112 if (time_after(jiffies, ct->proto.udp.stream_ts)) {
113 extra = timeouts[UDP_CT_REPLIED];
114 stream = (status & IPS_ASSURED) == 0;
115 }
116
117 nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies: extra);
118
119 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */
120 if (unlikely((status & IPS_NAT_CLASH)))
121 return NF_ACCEPT;
122
123 /* Also, more likely to be important, and not a probe */
124 if (stream && !test_and_set_bit(nr: IPS_ASSURED_BIT, addr: &ct->status))
125 nf_conntrack_event_cache(event: IPCT_ASSURED, ct);
126 } else {
127 nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies: timeouts[UDP_CT_UNREPLIED]);
128 }
129 return NF_ACCEPT;
130}
131
132#ifdef CONFIG_NF_CT_PROTO_UDPLITE
133static void udplite_error_log(const struct sk_buff *skb,
134 const struct nf_hook_state *state,
135 const char *msg)
136{
137 nf_l4proto_log_invalid(skb, state, IPPROTO_UDPLITE, "%s", msg);
138}
139
140static bool udplite_error(struct sk_buff *skb,
141 unsigned int dataoff,
142 const struct nf_hook_state *state)
143{
144 unsigned int udplen = skb->len - dataoff;
145 const struct udphdr *hdr;
146 struct udphdr _hdr;
147 unsigned int cscov;
148
149 /* Header is too small? */
150 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
151 if (!hdr) {
152 udplite_error_log(skb, state, "short packet");
153 return true;
154 }
155
156 cscov = ntohs(hdr->len);
157 if (cscov == 0) {
158 cscov = udplen;
159 } else if (cscov < sizeof(*hdr) || cscov > udplen) {
160 udplite_error_log(skb, state, "invalid checksum coverage");
161 return true;
162 }
163
164 /* UDPLITE mandates checksums */
165 if (!hdr->check) {
166 udplite_error_log(skb, state, "checksum missing");
167 return true;
168 }
169
170 /* Checksum invalid? Ignore. */
171 if (state->hook == NF_INET_PRE_ROUTING &&
172 state->net->ct.sysctl_checksum &&
173 nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
174 state->pf)) {
175 udplite_error_log(skb, state, "bad checksum");
176 return true;
177 }
178
179 return false;
180}
181
182/* Returns verdict for packet, and may modify conntracktype */
183int nf_conntrack_udplite_packet(struct nf_conn *ct,
184 struct sk_buff *skb,
185 unsigned int dataoff,
186 enum ip_conntrack_info ctinfo,
187 const struct nf_hook_state *state)
188{
189 unsigned int *timeouts;
190
191 if (udplite_error(skb, dataoff, state))
192 return -NF_ACCEPT;
193
194 timeouts = nf_ct_timeout_lookup(ct);
195 if (!timeouts)
196 timeouts = udp_get_timeouts(nf_ct_net(ct));
197
198 /* If we've seen traffic both ways, this is some kind of UDP
199 stream. Extend timeout. */
200 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
201 nf_ct_refresh_acct(ct, ctinfo, skb,
202 timeouts[UDP_CT_REPLIED]);
203
204 if (unlikely((ct->status & IPS_NAT_CLASH)))
205 return NF_ACCEPT;
206
207 /* Also, more likely to be important, and not a probe */
208 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
209 nf_conntrack_event_cache(IPCT_ASSURED, ct);
210 } else {
211 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
212 }
213 return NF_ACCEPT;
214}
215#endif
216
217#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
218
219#include <linux/netfilter/nfnetlink.h>
220#include <linux/netfilter/nfnetlink_cttimeout.h>
221
222static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
223 struct net *net, void *data)
224{
225 unsigned int *timeouts = data;
226 struct nf_udp_net *un = nf_udp_pernet(net);
227
228 if (!timeouts)
229 timeouts = un->timeouts;
230
231 /* set default timeouts for UDP. */
232 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
233 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
234
235 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
236 timeouts[UDP_CT_UNREPLIED] =
237 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
238 }
239 if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
240 timeouts[UDP_CT_REPLIED] =
241 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
242 }
243 return 0;
244}
245
246static int
247udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
248{
249 const unsigned int *timeouts = data;
250
251 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
252 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
253 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
254 htonl(timeouts[UDP_CT_REPLIED] / HZ)))
255 goto nla_put_failure;
256 return 0;
257
258nla_put_failure:
259 return -ENOSPC;
260}
261
262static const struct nla_policy
263udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
264 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
265 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
266};
267#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
268
269void nf_conntrack_udp_init_net(struct net *net)
270{
271 struct nf_udp_net *un = nf_udp_pernet(net);
272 int i;
273
274 for (i = 0; i < UDP_CT_MAX; i++)
275 un->timeouts[i] = udp_timeouts[i];
276
277#if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
278 un->offload_timeout = 30 * HZ;
279#endif
280}
281
282const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
283{
284 .l4proto = IPPROTO_UDP,
285 .allow_clash = true,
286#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
287 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
288 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
289 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
290 .nla_policy = nf_ct_port_nla_policy,
291#endif
292#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
293 .ctnl_timeout = {
294 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
295 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
296 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
297 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
298 .nla_policy = udp_timeout_nla_policy,
299 },
300#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
301};
302
303#ifdef CONFIG_NF_CT_PROTO_UDPLITE
304const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
305{
306 .l4proto = IPPROTO_UDPLITE,
307 .allow_clash = true,
308#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
309 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
310 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
311 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
312 .nla_policy = nf_ct_port_nla_policy,
313#endif
314#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
315 .ctnl_timeout = {
316 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
317 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
318 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
319 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
320 .nla_policy = udp_timeout_nla_policy,
321 },
322#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
323};
324#endif
325