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
108 /* Still active after two seconds? Extend timeout. */
109 if (time_after(jiffies, ct->proto.udp.stream_ts))
110 extra = timeouts[UDP_CT_REPLIED];
111
112 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
113
114 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */
115 if (unlikely((ct->status & IPS_NAT_CLASH)))
116 return NF_ACCEPT;
117
118 /* Also, more likely to be important, and not a probe */
119 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
120 nf_conntrack_event_cache(IPCT_ASSURED, ct);
121 } else {
122 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
123 }
124 return NF_ACCEPT;
125 }
126
127 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
udplite_error_log(const struct sk_buff * skb,const struct nf_hook_state * state,const char * msg)128 static void udplite_error_log(const struct sk_buff *skb,
129 const struct nf_hook_state *state,
130 const char *msg)
131 {
132 nf_l4proto_log_invalid(skb, state, IPPROTO_UDPLITE, "%s", msg);
133 }
134
udplite_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)135 static bool udplite_error(struct sk_buff *skb,
136 unsigned int dataoff,
137 const struct nf_hook_state *state)
138 {
139 unsigned int udplen = skb->len - dataoff;
140 const struct udphdr *hdr;
141 struct udphdr _hdr;
142 unsigned int cscov;
143
144 /* Header is too small? */
145 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
146 if (!hdr) {
147 udplite_error_log(skb, state, "short packet");
148 return true;
149 }
150
151 cscov = ntohs(hdr->len);
152 if (cscov == 0) {
153 cscov = udplen;
154 } else if (cscov < sizeof(*hdr) || cscov > udplen) {
155 udplite_error_log(skb, state, "invalid checksum coverage");
156 return true;
157 }
158
159 /* UDPLITE mandates checksums */
160 if (!hdr->check) {
161 udplite_error_log(skb, state, "checksum missing");
162 return true;
163 }
164
165 /* Checksum invalid? Ignore. */
166 if (state->hook == NF_INET_PRE_ROUTING &&
167 state->net->ct.sysctl_checksum &&
168 nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
169 state->pf)) {
170 udplite_error_log(skb, state, "bad checksum");
171 return true;
172 }
173
174 return false;
175 }
176
177 /* 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)178 int nf_conntrack_udplite_packet(struct nf_conn *ct,
179 struct sk_buff *skb,
180 unsigned int dataoff,
181 enum ip_conntrack_info ctinfo,
182 const struct nf_hook_state *state)
183 {
184 unsigned int *timeouts;
185
186 if (udplite_error(skb, dataoff, state))
187 return -NF_ACCEPT;
188
189 timeouts = nf_ct_timeout_lookup(ct);
190 if (!timeouts)
191 timeouts = udp_get_timeouts(nf_ct_net(ct));
192
193 /* If we've seen traffic both ways, this is some kind of UDP
194 stream. Extend timeout. */
195 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
196 nf_ct_refresh_acct(ct, ctinfo, skb,
197 timeouts[UDP_CT_REPLIED]);
198
199 if (unlikely((ct->status & IPS_NAT_CLASH)))
200 return NF_ACCEPT;
201
202 /* Also, more likely to be important, and not a probe */
203 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
204 nf_conntrack_event_cache(IPCT_ASSURED, ct);
205 } else {
206 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
207 }
208 return NF_ACCEPT;
209 }
210 #endif
211
212 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
213
214 #include <linux/netfilter/nfnetlink.h>
215 #include <linux/netfilter/nfnetlink_cttimeout.h>
216
udp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)217 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
218 struct net *net, void *data)
219 {
220 unsigned int *timeouts = data;
221 struct nf_udp_net *un = nf_udp_pernet(net);
222
223 if (!timeouts)
224 timeouts = un->timeouts;
225
226 /* set default timeouts for UDP. */
227 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
228 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
229
230 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
231 timeouts[UDP_CT_UNREPLIED] =
232 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
233 }
234 if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
235 timeouts[UDP_CT_REPLIED] =
236 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
237 }
238 return 0;
239 }
240
241 static int
udp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)242 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
243 {
244 const unsigned int *timeouts = data;
245
246 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
247 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
248 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
249 htonl(timeouts[UDP_CT_REPLIED] / HZ)))
250 goto nla_put_failure;
251 return 0;
252
253 nla_put_failure:
254 return -ENOSPC;
255 }
256
257 static const struct nla_policy
258 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
259 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
260 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
261 };
262 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
263
nf_conntrack_udp_init_net(struct net * net)264 void nf_conntrack_udp_init_net(struct net *net)
265 {
266 struct nf_udp_net *un = nf_udp_pernet(net);
267 int i;
268
269 for (i = 0; i < UDP_CT_MAX; i++)
270 un->timeouts[i] = udp_timeouts[i];
271
272 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
273 un->offload_timeout = 30 * HZ;
274 #endif
275 }
276
277 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
278 {
279 .l4proto = IPPROTO_UDP,
280 .allow_clash = true,
281 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
282 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
283 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
284 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
285 .nla_policy = nf_ct_port_nla_policy,
286 #endif
287 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
288 .ctnl_timeout = {
289 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
290 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
291 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
292 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
293 .nla_policy = udp_timeout_nla_policy,
294 },
295 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
296 };
297
298 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
299 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
300 {
301 .l4proto = IPPROTO_UDPLITE,
302 .allow_clash = true,
303 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
304 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
305 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
306 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
307 .nla_policy = nf_ct_port_nla_policy,
308 #endif
309 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
310 .ctnl_timeout = {
311 .nlattr_to_obj = udp_timeout_nlattr_to_obj,
312 .obj_to_nlattr = udp_timeout_obj_to_nlattr,
313 .nlattr_max = CTA_TIMEOUT_UDP_MAX,
314 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
315 .nla_policy = udp_timeout_nla_policy,
316 },
317 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
318 };
319 #endif
320
