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, IPPROTO_UDP, "%s", msg);
42 }
43
udp_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)44 static 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, dataoff, sizeof(_hdr), &_hdr);
54 if (!hdr) {
55 udp_error_log(skb, state, "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, "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, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
76 udp_error_log(skb, state, "bad checksum");
77 return true;
78 }
79
80 return false;
81 }
82
83 /* 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)84 int 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
92 if (udp_error(skb, dataoff, state))
93 return -NF_ACCEPT;
94
95 timeouts = nf_ct_timeout_lookup(ct);
96 if (!timeouts)
97 timeouts = udp_get_timeouts(nf_ct_net(ct));
98
99 if (!nf_ct_is_confirmed(ct))
100 ct->proto.udp.stream_ts = 2 * HZ + jiffies;
101
102 /* If we've seen traffic both ways, this is some kind of UDP
103 * stream. Set Assured.
104 */
105 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
106 unsigned long extra = timeouts[UDP_CT_UNREPLIED];
107 bool stream = false;
108
109 /* Still active after two seconds? Extend timeout. */
110 if (time_after(jiffies, ct->proto.udp.stream_ts)) {
111 extra = timeouts[UDP_CT_REPLIED];
112 stream = true;
113 }
114
115 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
116
117 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */
118 if (unlikely((ct->status & IPS_NAT_CLASH)))
119 return NF_ACCEPT;
120
121 /* Also, more likely to be important, and not a probe */
122 if (stream && !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
123 nf_conntrack_event_cache(IPCT_ASSURED, ct);
124 } else {
125 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
126 }
127 return NF_ACCEPT;
128 }
129
130 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
udplite_error_log(const struct sk_buff * skb,const struct nf_hook_state * state,const char * msg)131 static void udplite_error_log(const struct sk_buff *skb,
132 const struct nf_hook_state *state,
133 const char *msg)
134 {
135 nf_l4proto_log_invalid(skb, state, IPPROTO_UDPLITE, "%s", msg);
136 }
137
udplite_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)138 static bool udplite_error(struct sk_buff *skb,
139 unsigned int dataoff,
140 const struct nf_hook_state *state)
141 {
142 unsigned int udplen = skb->len - dataoff;
143 const struct udphdr *hdr;
144 struct udphdr _hdr;
145 unsigned int cscov;
146
147 /* Header is too small? */
148 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
149 if (!hdr) {
150 udplite_error_log(skb, state, "short packet");
151 return true;
152 }
153
154 cscov = ntohs(hdr->len);
155 if (cscov == 0) {
156 cscov = udplen;
157 } else if (cscov < sizeof(*hdr) || cscov > udplen) {
158 udplite_error_log(skb, state, "invalid checksum coverage");
159 return true;
160 }
161
162 /* UDPLITE mandates checksums */
163 if (!hdr->check) {
164 udplite_error_log(skb, state, "checksum missing");
165 return true;
166 }
167
168 /* Checksum invalid? Ignore. */
169 if (state->hook == NF_INET_PRE_ROUTING &&
170 state->net->ct.sysctl_checksum &&
171 nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
172 state->pf)) {
173 udplite_error_log(skb, state, "bad checksum");
174 return true;
175 }
176
177 return false;
178 }
179
180 /* 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)181 int nf_conntrack_udplite_packet(struct nf_conn *ct,
182 struct sk_buff *skb,
183 unsigned int dataoff,
184 enum ip_conntrack_info ctinfo,
185 const struct nf_hook_state *state)
186 {
187 unsigned int *timeouts;
188
189 if (udplite_error(skb, dataoff, state))
190 return -NF_ACCEPT;
191
192 timeouts = nf_ct_timeout_lookup(ct);
193 if (!timeouts)
194 timeouts = udp_get_timeouts(nf_ct_net(ct));
195
196 /* If we've seen traffic both ways, this is some kind of UDP
197 stream. Extend timeout. */
198 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
199 nf_ct_refresh_acct(ct, ctinfo, skb,
200 timeouts[UDP_CT_REPLIED]);
201
202 if (unlikely((ct->status & IPS_NAT_CLASH)))
203 return NF_ACCEPT;
204
205 /* Also, more likely to be important, and not a probe */
206 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
207 nf_conntrack_event_cache(IPCT_ASSURED, ct);
208 } else {
209 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
210 }
211 return NF_ACCEPT;
212 }
213 #endif
214
215 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
216
217 #include <linux/netfilter/nfnetlink.h>
218 #include <linux/netfilter/nfnetlink_cttimeout.h>
219
udp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)220 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
221 struct net *net, void *data)
222 {
223 unsigned int *timeouts = data;
224 struct nf_udp_net *un = nf_udp_pernet(net);
225
226 if (!timeouts)
227 timeouts = un->timeouts;
228
229 /* set default timeouts for UDP. */
230 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
231 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
232
233 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
234 timeouts[UDP_CT_UNREPLIED] =
235 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
236 }
237 if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
238 timeouts[UDP_CT_REPLIED] =
239 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
240 }
241 return 0;
242 }
243
244 static int
udp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)245 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
246 {
247 const unsigned int *timeouts = data;
248
249 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
250 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
251 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
252 htonl(timeouts[UDP_CT_REPLIED] / HZ)))
253 goto nla_put_failure;
254 return 0;
255
256 nla_put_failure:
257 return -ENOSPC;
258 }
259
260 static const struct nla_policy
261 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
262 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
263 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
264 };
265 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
266
nf_conntrack_udp_init_net(struct net * net)267 void nf_conntrack_udp_init_net(struct net *net)
268 {
269 struct nf_udp_net *un = nf_udp_pernet(net);
270 int i;
271
272 for (i = 0; i < UDP_CT_MAX; i++)
273 un->timeouts[i] = udp_timeouts[i];
274
275 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
276 un->offload_timeout = 30 * HZ;
277 #endif
278 }
279
280 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
281 {
282 .l4proto = IPPROTO_UDP,
283 .allow_clash = true,
284 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
285 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
286 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
287 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
288 .nla_policy = nf_ct_port_nla_policy,
289 #endif
290 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
291 .ctnl_timeout = {
292 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
293 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
294 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
295 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
296 .nla_policy = udp_timeout_nla_policy,
297 },
298 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
299 };
300
301 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
302 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
303 {
304 .l4proto = IPPROTO_UDPLITE,
305 .allow_clash = true,
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 #ifdef CONFIG_NF_CONNTRACK_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_CONNTRACK_TIMEOUT */
321 };
322 #endif
323