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
27 static const unsigned int udp_timeouts[UDP_CT_MAX] = {
28 [UDP_CT_UNREPLIED] = 30*HZ,
29 [UDP_CT_REPLIED] = 120*HZ,
30 };
31
udp_get_timeouts(struct net * net)32 static unsigned int *udp_get_timeouts(struct net *net)
33 {
34 return nf_udp_pernet(net)->timeouts;
35 }
36
udp_error_log(const struct sk_buff * skb,const struct nf_hook_state * state,const char * msg)37 static 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->net, state->pf,
42 IPPROTO_UDP, "%s", msg);
43 }
44
udp_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)45 static bool udp_error(struct sk_buff *skb,
46 unsigned int dataoff,
47 const struct nf_hook_state *state)
48 {
49 unsigned int udplen = skb->len - dataoff;
50 const struct udphdr *hdr;
51 struct udphdr _hdr;
52
53 /* Header is too small? */
54 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
55 if (!hdr) {
56 udp_error_log(skb, state, "short packet");
57 return true;
58 }
59
60 /* Truncated/malformed packets */
61 if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
62 udp_error_log(skb, state, "truncated/malformed packet");
63 return true;
64 }
65
66 /* Packet with no checksum */
67 if (!hdr->check)
68 return false;
69
70 /* Checksum invalid? Ignore.
71 * We skip checking packets on the outgoing path
72 * because the checksum is assumed to be correct.
73 * FIXME: Source route IP option packets --RR */
74 if (state->hook == NF_INET_PRE_ROUTING &&
75 state->net->ct.sysctl_checksum &&
76 nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
77 udp_error_log(skb, state, "bad checksum");
78 return true;
79 }
80
81 return false;
82 }
83
84 /* Returns verdict for packet, and may modify conntracktype */
nf_conntrack_udp_packet(struct nf_conn * ct,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,const struct nf_hook_state * state)85 int nf_conntrack_udp_packet(struct nf_conn *ct,
86 struct sk_buff *skb,
87 unsigned int dataoff,
88 enum ip_conntrack_info ctinfo,
89 const struct nf_hook_state *state)
90 {
91 unsigned int *timeouts;
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(nf_ct_net(ct));
99
100 if (!nf_ct_is_confirmed(ct))
101 ct->proto.udp.stream_ts = 2 * HZ + jiffies;
102
103 /* If we've seen traffic both ways, this is some kind of UDP
104 * stream. Set Assured.
105 */
106 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
107 unsigned long extra = timeouts[UDP_CT_UNREPLIED];
108 bool stream = false;
109
110 /* Still active after two seconds? Extend timeout. */
111 if (time_after(jiffies, ct->proto.udp.stream_ts)) {
112 extra = timeouts[UDP_CT_REPLIED];
113 stream = true;
114 }
115
116 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
117
118 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */
119 if (unlikely((ct->status & IPS_NAT_CLASH)))
120 return NF_ACCEPT;
121
122 /* Also, more likely to be important, and not a probe */
123 if (stream && !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
124 nf_conntrack_event_cache(IPCT_ASSURED, ct);
125 } else {
126 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
127 }
128 return NF_ACCEPT;
129 }
130
131 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
udplite_error_log(const struct sk_buff * skb,const struct nf_hook_state * state,const char * msg)132 static void udplite_error_log(const struct sk_buff *skb,
133 const struct nf_hook_state *state,
134 const char *msg)
135 {
136 nf_l4proto_log_invalid(skb, state->net, state->pf,
137 IPPROTO_UDPLITE, "%s", msg);
138 }
139
udplite_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)140 static 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 */
nf_conntrack_udplite_packet(struct nf_conn * ct,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,const struct nf_hook_state * state)183 int 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
udp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)222 static 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
246 static int
udp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)247 udp_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
258 nla_put_failure:
259 return -ENOSPC;
260 }
261
262 static const struct nla_policy
263 udp_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
nf_conntrack_udp_init_net(struct net * net)269 void 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
278 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
279 {
280 .l4proto = IPPROTO_UDP,
281 .allow_clash = true,
282 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
283 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
284 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
285 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
286 .nla_policy = nf_ct_port_nla_policy,
287 #endif
288 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
289 .ctnl_timeout = {
290 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
291 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
292 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
293 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
294 .nla_policy = udp_timeout_nla_policy,
295 },
296 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
297 };
298
299 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
300 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
301 {
302 .l4proto = IPPROTO_UDPLITE,
303 .allow_clash = true,
304 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
305 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
306 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
307 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
308 .nla_policy = nf_ct_port_nla_policy,
309 #endif
310 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
311 .ctnl_timeout = {
312 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
313 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
314 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
315 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
316 .nla_policy = udp_timeout_nla_policy,
317 },
318 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
319 };
320 #endif
321