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
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
113 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
114
115 /* Also, more likely to be important, and not a probe */
116 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
117 nf_conntrack_event_cache(IPCT_ASSURED, ct);
118 } else {
119 nf_ct_refresh_acct(ct, ctinfo, skb,
120 timeouts[UDP_CT_UNREPLIED]);
121 }
122 return NF_ACCEPT;
123 }
124
125 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
udplite_error_log(const struct sk_buff * skb,const struct nf_hook_state * state,const char * msg)126 static void udplite_error_log(const struct sk_buff *skb,
127 const struct nf_hook_state *state,
128 const char *msg)
129 {
130 nf_l4proto_log_invalid(skb, state->net, state->pf,
131 IPPROTO_UDPLITE, "%s", msg);
132 }
133
udplite_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)134 static bool udplite_error(struct sk_buff *skb,
135 unsigned int dataoff,
136 const struct nf_hook_state *state)
137 {
138 unsigned int udplen = skb->len - dataoff;
139 const struct udphdr *hdr;
140 struct udphdr _hdr;
141 unsigned int cscov;
142
143 /* Header is too small? */
144 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
145 if (!hdr) {
146 udplite_error_log(skb, state, "short packet");
147 return true;
148 }
149
150 cscov = ntohs(hdr->len);
151 if (cscov == 0) {
152 cscov = udplen;
153 } else if (cscov < sizeof(*hdr) || cscov > udplen) {
154 udplite_error_log(skb, state, "invalid checksum coverage");
155 return true;
156 }
157
158 /* UDPLITE mandates checksums */
159 if (!hdr->check) {
160 udplite_error_log(skb, state, "checksum missing");
161 return true;
162 }
163
164 /* Checksum invalid? Ignore. */
165 if (state->hook == NF_INET_PRE_ROUTING &&
166 state->net->ct.sysctl_checksum &&
167 nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
168 state->pf)) {
169 udplite_error_log(skb, state, "bad checksum");
170 return true;
171 }
172
173 return false;
174 }
175
176 /* 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)177 int nf_conntrack_udplite_packet(struct nf_conn *ct,
178 struct sk_buff *skb,
179 unsigned int dataoff,
180 enum ip_conntrack_info ctinfo,
181 const struct nf_hook_state *state)
182 {
183 unsigned int *timeouts;
184
185 if (udplite_error(skb, dataoff, state))
186 return -NF_ACCEPT;
187
188 timeouts = nf_ct_timeout_lookup(ct);
189 if (!timeouts)
190 timeouts = udp_get_timeouts(nf_ct_net(ct));
191
192 /* If we've seen traffic both ways, this is some kind of UDP
193 stream. Extend timeout. */
194 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
195 nf_ct_refresh_acct(ct, ctinfo, skb,
196 timeouts[UDP_CT_REPLIED]);
197 /* Also, more likely to be important, and not a probe */
198 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
199 nf_conntrack_event_cache(IPCT_ASSURED, ct);
200 } else {
201 nf_ct_refresh_acct(ct, ctinfo, skb,
202 timeouts[UDP_CT_UNREPLIED]);
203 }
204 return NF_ACCEPT;
205 }
206 #endif
207
208 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
209
210 #include <linux/netfilter/nfnetlink.h>
211 #include <linux/netfilter/nfnetlink_cttimeout.h>
212
udp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)213 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
214 struct net *net, void *data)
215 {
216 unsigned int *timeouts = data;
217 struct nf_udp_net *un = nf_udp_pernet(net);
218
219 if (!timeouts)
220 timeouts = un->timeouts;
221
222 /* set default timeouts for UDP. */
223 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
224 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
225
226 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
227 timeouts[UDP_CT_UNREPLIED] =
228 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
229 }
230 if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
231 timeouts[UDP_CT_REPLIED] =
232 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
233 }
234 return 0;
235 }
236
237 static int
udp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)238 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
239 {
240 const unsigned int *timeouts = data;
241
242 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
243 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
244 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
245 htonl(timeouts[UDP_CT_REPLIED] / HZ)))
246 goto nla_put_failure;
247 return 0;
248
249 nla_put_failure:
250 return -ENOSPC;
251 }
252
253 static const struct nla_policy
254 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
255 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
256 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
257 };
258 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
259
nf_conntrack_udp_init_net(struct net * net)260 void nf_conntrack_udp_init_net(struct net *net)
261 {
262 struct nf_udp_net *un = nf_udp_pernet(net);
263 int i;
264
265 for (i = 0; i < UDP_CT_MAX; i++)
266 un->timeouts[i] = udp_timeouts[i];
267 }
268
269 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
270 {
271 .l4proto = IPPROTO_UDP,
272 .allow_clash = true,
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 #ifdef CONFIG_NF_CONNTRACK_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_CONNTRACK_TIMEOUT */
288 };
289
290 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
291 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
292 {
293 .l4proto = IPPROTO_UDPLITE,
294 .allow_clash = true,
295 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
296 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
297 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
298 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
299 .nla_policy = nf_ct_port_nla_policy,
300 #endif
301 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
302 .ctnl_timeout = {
303 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
304 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
305 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
306 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
307 .nla_policy = udp_timeout_nla_policy,
308 },
309 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
310 };
311 #endif
312