dpd.c revision 1.17 
1/*	$OpenBSD: dpd.c,v 1.17 2014/01/22 03:09:31 deraadt Exp $	*/
2
3/*
4 * Copyright (c) 2004 H�kan Olsson.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/types.h>
28#include <stdlib.h>
29#include <string.h>
30
31#include "conf.h"
32#include "dpd.h"
33#include "exchange.h"
34#include "hash.h"
35#include "ipsec.h"
36#include "isakmp_fld.h"
37#include "log.h"
38#include "message.h"
39#include "pf_key_v2.h"
40#include "sa.h"
41#include "timer.h"
42#include "transport.h"
43#include "util.h"
44
45/* From RFC 3706.  */
46#define DPD_MAJOR		0x01
47#define DPD_MINOR		0x00
48#define DPD_SEQNO_SZ		4
49
50static const u_int8_t dpd_vendor_id[] = {
51	0xAF, 0xCA, 0xD7, 0x13, 0x68, 0xA1, 0xF1,	/* RFC 3706 */
52	0xC9, 0x6B, 0x86, 0x96, 0xFC, 0x77, 0x57,
53	DPD_MAJOR,
54	DPD_MINOR
55};
56
57#define DPD_RETRANS_MAX		5	/* max number of retries.  */
58#define DPD_RETRANS_WAIT	5	/* seconds between retries.  */
59
60/* DPD Timer State */
61enum dpd_tstate { DPD_TIMER_NORMAL, DPD_TIMER_CHECK };
62
63static void	 dpd_check_event(void *);
64static void	 dpd_event(void *);
65static u_int32_t dpd_timer_interval(u_int32_t);
66static void	 dpd_timer_reset(struct sa *, u_int32_t, enum dpd_tstate);
67
68/* Add the DPD VENDOR ID payload.  */
69int
70dpd_add_vendor_payload(struct message *msg)
71{
72	u_int8_t *buf;
73	size_t buflen = sizeof dpd_vendor_id + ISAKMP_GEN_SZ;
74
75	buf = malloc(buflen);
76	if (!buf) {
77		log_error("dpd_add_vendor_payload: malloc(%lu) failed",
78		    (unsigned long)buflen);
79		return -1;
80	}
81
82	SET_ISAKMP_GEN_LENGTH(buf, buflen);
83	memcpy(buf + ISAKMP_VENDOR_ID_OFF, dpd_vendor_id,
84	    sizeof dpd_vendor_id);
85	if (message_add_payload(msg, ISAKMP_PAYLOAD_VENDOR, buf, buflen, 1)) {
86		free(buf);
87		return -1;
88	}
89
90	return 0;
91}
92
93/*
94 * Check an incoming message for DPD capability markers.
95 */
96void
97dpd_check_vendor_payload(struct message *msg, struct payload *p)
98{
99	u_int8_t *pbuf = p->p;
100	size_t vlen;
101
102	/* Already checked? */
103	if (msg->exchange->flags & EXCHANGE_FLAG_DPD_CAP_PEER) {
104		/* Just mark it as handled and return.  */
105		p->flags |= PL_MARK;
106		return;
107	}
108
109	vlen = GET_ISAKMP_GEN_LENGTH(pbuf) - ISAKMP_GEN_SZ;
110	if (vlen != sizeof dpd_vendor_id) {
111		LOG_DBG((LOG_EXCHANGE, 90,
112		    "dpd_check_vendor_payload: bad size %lu != %lu",
113		    (unsigned long)vlen, (unsigned long)sizeof dpd_vendor_id));
114		return;
115	}
116
117	if (memcmp(dpd_vendor_id, pbuf + ISAKMP_GEN_SZ, vlen) == 0) {
118		/* This peer is DPD capable.  */
119		if (msg->isakmp_sa) {
120			msg->exchange->flags |= EXCHANGE_FLAG_DPD_CAP_PEER;
121			LOG_DBG((LOG_EXCHANGE, 10, "dpd_check_vendor_payload: "
122			    "DPD capable peer detected"));
123		}
124		p->flags |= PL_MARK;
125	}
126}
127
128/*
129 * Arm the DPD timer
130 */
131void
132dpd_start(struct sa *isakmp_sa)
133{
134	if (dpd_timer_interval(0) != 0) {
135		LOG_DBG((LOG_EXCHANGE, 10, "dpd_enable: enabling"));
136		isakmp_sa->flags |= SA_FLAG_DPD;
137		dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_NORMAL);
138	}
139}
140
141/*
142 * All incoming DPD Notify messages enter here. Message has been validated.
143 */
144void
145dpd_handle_notify(struct message *msg, struct payload *p)
146{
147	struct sa	*isakmp_sa = msg->isakmp_sa;
148	u_int16_t	 notify = GET_ISAKMP_NOTIFY_MSG_TYPE(p->p);
149	u_int32_t	 p_seq;
150
151	/* Extract the sequence number.  */
152	memcpy(&p_seq, p->p + ISAKMP_NOTIFY_SPI_OFF + ISAKMP_HDR_COOKIES_LEN,
153	    sizeof p_seq);
154	p_seq = ntohl(p_seq);
155
156	LOG_DBG((LOG_MESSAGE, 40, "dpd_handle_notify: got %s seq %u",
157	    constant_name(isakmp_notify_cst, notify), p_seq));
158
159	switch (notify) {
160	case ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE:
161		/* The other peer wants to know we're alive.  */
162		if (p_seq < isakmp_sa->dpd_rseq ||
163		    (p_seq == isakmp_sa->dpd_rseq &&
164		    ++isakmp_sa->dpd_rdupcount >= DPD_RETRANS_MAX)) {
165			log_print("dpd_handle_notify: bad R_U_THERE seqno "
166			    "%u <= %u", p_seq, isakmp_sa->dpd_rseq);
167			return;
168		}
169		if (isakmp_sa->dpd_rseq != p_seq) {
170			isakmp_sa->dpd_rdupcount = 0;
171			isakmp_sa->dpd_rseq = p_seq;
172		}
173		message_send_dpd_notify(isakmp_sa,
174		    ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE_ACK, p_seq);
175		break;
176
177	case ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE_ACK:
178		/* This should be a response to a R_U_THERE we've sent.  */
179		if (isakmp_sa->dpd_seq != p_seq) {
180			log_print("dpd_handle_notify: got bad ACK seqno %u, "
181			    "expected %u", p_seq, isakmp_sa->dpd_seq);
182			/* XXX Give up? Retry? */
183			return;
184		}
185		break;
186	default:
187		break;
188	}
189
190	/* Mark handled.  */
191	p->flags |= PL_MARK;
192
193	/* The other peer is alive, so we can safely wait a while longer.  */
194	if (isakmp_sa->flags & SA_FLAG_DPD)
195		dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_NORMAL);
196}
197
198/* Calculate the time until next DPD exchange.  */
199static u_int32_t
200dpd_timer_interval(u_int32_t offset)
201{
202	int32_t v = 0;
203
204#ifdef notyet
205	v = ...; /* XXX Per-peer specified DPD intervals?  */
206#endif
207	if (!v)
208		v = conf_get_num("General", "DPD-check-interval", 0);
209	if (v < 1)
210		return 0;	/* DPD-Check-Interval < 1 means disable DPD */
211
212	v -= offset;
213	return v < 1 ? 1 : v;
214}
215
216static void
217dpd_timer_reset(struct sa *sa, u_int32_t time_passed, enum dpd_tstate mode)
218{
219	struct timeval	tv;
220
221	if (sa->dpd_event)
222		timer_remove_event(sa->dpd_event);
223
224	gettimeofday(&tv, 0);
225	switch (mode) {
226	case DPD_TIMER_NORMAL:
227		sa->dpd_failcount = 0;
228		tv.tv_sec += dpd_timer_interval(time_passed);
229		sa->dpd_event = timer_add_event("dpd_event", dpd_event, sa,
230		    &tv);
231		break;
232	case DPD_TIMER_CHECK:
233		tv.tv_sec += DPD_RETRANS_WAIT;
234		sa->dpd_event = timer_add_event("dpd_check_event",
235		    dpd_check_event, sa, &tv);
236		break;
237	default:
238		break;
239	}
240	if (!sa->dpd_event)
241		log_print("dpd_timer_reset: timer_add_event failed");
242}
243
244/* Helper function for dpd_exchange_finalization().  */
245static int
246dpd_find_sa(struct sa *sa, void *v_sa)
247{
248	struct sa	*isakmp_sa = v_sa;
249
250	if (!isakmp_sa->id_i || !isakmp_sa->id_r)
251		return 0;
252	return (sa->phase == 2 && (sa->flags & SA_FLAG_READY) &&
253	    memcmp(sa->id_i, isakmp_sa->id_i, sa->id_i_len) == 0 &&
254	    memcmp(sa->id_r, isakmp_sa->id_r, sa->id_r_len) == 0);
255}
256
257struct dpd_args {
258	struct sa	*isakmp_sa;
259	u_int32_t	 interval;
260};
261
262/* Helper function for dpd_event().  */
263static int
264dpd_check_time(struct sa *sa, void *v_arg)
265{
266	struct dpd_args *args = v_arg;
267	struct sockaddr *dst;
268	struct proto *proto;
269	struct sa_kinfo *ksa;
270	struct timeval tv;
271
272	if (sa->phase == 1 || (args->isakmp_sa->flags & SA_FLAG_DPD) == 0 ||
273	    dpd_find_sa(sa, args->isakmp_sa) == 0)
274		return 0;
275
276	proto = TAILQ_FIRST(&sa->protos);
277	if (!proto || !proto->data)
278		return 0;
279	sa->transport->vtbl->get_src(sa->transport, &dst);
280
281	gettimeofday(&tv, 0);
282	ksa = pf_key_v2_get_kernel_sa(proto->spi[1], proto->spi_sz[1],
283	    proto->proto, dst);
284
285	if (!ksa || !ksa->last_used)
286		return 0;
287
288	LOG_DBG((LOG_MESSAGE, 80, "dpd_check_time: "
289	    "SA %p last use %u second(s) ago", sa,
290	    (u_int32_t)(tv.tv_sec - ksa->last_used)));
291
292	if ((u_int32_t)(tv.tv_sec - ksa->last_used) < args->interval) {
293		args->interval = (u_int32_t)(tv.tv_sec - ksa->last_used);
294		return 1;
295	}
296	return 0;
297}
298
299/* Called by the timer.  */
300static void
301dpd_event(void *v_sa)
302{
303	struct sa	*isakmp_sa = v_sa;
304	struct dpd_args args;
305	struct sockaddr *dst;
306	char *addr;
307
308	isakmp_sa->dpd_event = 0;
309
310	/* Check if there's been any incoming SA activity since last time.  */
311	args.isakmp_sa = isakmp_sa;
312	args.interval = dpd_timer_interval(0);
313	if (sa_find(dpd_check_time, &args)) {
314		if (args.interval > dpd_timer_interval(0))
315			args.interval = 0;
316		dpd_timer_reset(isakmp_sa, args.interval, DPD_TIMER_NORMAL);
317		return;
318	}
319
320	/* No activity seen, do a DPD exchange.  */
321	if (isakmp_sa->dpd_seq == 0) {
322		/*
323		 * RFC 3706: first seq# should be random, with MSB zero,
324		 * otherwise we just increment it.
325		 */
326		getrandom((u_int8_t *)&isakmp_sa->dpd_seq,
327		    sizeof isakmp_sa->dpd_seq);
328		isakmp_sa->dpd_seq &= 0x7FFF;
329	} else
330		isakmp_sa->dpd_seq++;
331
332	isakmp_sa->transport->vtbl->get_dst(isakmp_sa->transport, &dst);
333	if (sockaddr2text(dst, &addr, 0) == -1)
334		addr = 0;
335	LOG_DBG((LOG_MESSAGE, 30, "dpd_event: sending R_U_THERE to %s seq %u",
336	    addr ? addr : "<unknown>", isakmp_sa->dpd_seq));
337	if (addr)
338		free(addr);
339	message_send_dpd_notify(isakmp_sa, ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE,
340	    isakmp_sa->dpd_seq);
341
342	/* And set the short timer.  */
343	dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_CHECK);
344}
345
346/*
347 * Called by the timer. If this function is called, it means we did not
348 * received any R_U_THERE_ACK confirmation from the other peer.
349 */
350static void
351dpd_check_event(void *v_sa)
352{
353	struct sa	*isakmp_sa = v_sa;
354	struct sa	*sa;
355
356	isakmp_sa->dpd_event = 0;
357
358	if (++isakmp_sa->dpd_failcount < DPD_RETRANS_MAX) {
359		LOG_DBG((LOG_MESSAGE, 10, "dpd_check_event: "
360		    "peer not responding, retry %u of %u",
361		    isakmp_sa->dpd_failcount, DPD_RETRANS_MAX));
362		message_send_dpd_notify(isakmp_sa,
363		    ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE, isakmp_sa->dpd_seq);
364		dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_CHECK);
365		return;
366	}
367
368	/*
369	 * Peer is considered dead. Delete all SAs created under isakmp_sa.
370	 */
371	LOG_DBG((LOG_MESSAGE, 10, "dpd_check_event: peer is dead, "
372	    "deleting all SAs connected to SA %p", isakmp_sa));
373	while ((sa = sa_find(dpd_find_sa, isakmp_sa)) != 0) {
374		LOG_DBG((LOG_MESSAGE, 30, "dpd_check_event: deleting SA %p",
375		    sa));
376		sa_delete(sa, 0);
377	}
378	LOG_DBG((LOG_MESSAGE, 30, "dpd_check_event: deleting ISAKMP SA %p",
379	    isakmp_sa));
380	sa_delete(isakmp_sa, 0);
381}
382