OpenBSD-4.6/sbin/isakmpd/dpd.c
/* $OpenBSD: dpd.c,v 1.16 2006/07/24 11:45:44 ho Exp $ */
/*
* Copyright (c) 2004 Håkan Olsson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include "sysdep.h"
#include "conf.h"
#include "dpd.h"
#include "exchange.h"
#include "hash.h"
#include "ipsec.h"
#include "isakmp_fld.h"
#include "log.h"
#include "message.h"
#include "pf_key_v2.h"
#include "sa.h"
#include "timer.h"
#include "transport.h"
#include "util.h"
/* From RFC 3706. */
#define DPD_MAJOR 0x01
#define DPD_MINOR 0x00
#define DPD_SEQNO_SZ 4
static const u_int8_t dpd_vendor_id[] = {
0xAF, 0xCA, 0xD7, 0x13, 0x68, 0xA1, 0xF1, /* RFC 3706 */
0xC9, 0x6B, 0x86, 0x96, 0xFC, 0x77, 0x57,
DPD_MAJOR,
DPD_MINOR
};
#define DPD_RETRANS_MAX 5 /* max number of retries. */
#define DPD_RETRANS_WAIT 5 /* seconds between retries. */
/* DPD Timer State */
enum dpd_tstate { DPD_TIMER_NORMAL, DPD_TIMER_CHECK };
static void dpd_check_event(void *);
static void dpd_event(void *);
static u_int32_t dpd_timer_interval(u_int32_t);
static void dpd_timer_reset(struct sa *, u_int32_t, enum dpd_tstate);
/* Add the DPD VENDOR ID payload. */
int
dpd_add_vendor_payload(struct message *msg)
{
u_int8_t *buf;
size_t buflen = sizeof dpd_vendor_id + ISAKMP_GEN_SZ;
buf = malloc(buflen);
if (!buf) {
log_error("dpd_add_vendor_payload: malloc(%lu) failed",
(unsigned long)buflen);
return -1;
}
SET_ISAKMP_GEN_LENGTH(buf, buflen);
memcpy(buf + ISAKMP_VENDOR_ID_OFF, dpd_vendor_id,
sizeof dpd_vendor_id);
if (message_add_payload(msg, ISAKMP_PAYLOAD_VENDOR, buf, buflen, 1)) {
free(buf);
return -1;
}
return 0;
}
/*
* Check an incoming message for DPD capability markers.
*/
void
dpd_check_vendor_payload(struct message *msg, struct payload *p)
{
u_int8_t *pbuf = p->p;
size_t vlen;
/* Already checked? */
if (msg->exchange->flags & EXCHANGE_FLAG_DPD_CAP_PEER) {
/* Just mark it as handled and return. */
p->flags |= PL_MARK;
return;
}
vlen = GET_ISAKMP_GEN_LENGTH(pbuf) - ISAKMP_GEN_SZ;
if (vlen != sizeof dpd_vendor_id) {
LOG_DBG((LOG_EXCHANGE, 90,
"dpd_check_vendor_payload: bad size %lu != %lu",
(unsigned long)vlen, (unsigned long)sizeof dpd_vendor_id));
return;
}
if (memcmp(dpd_vendor_id, pbuf + ISAKMP_GEN_SZ, vlen) == 0) {
/* This peer is DPD capable. */
if (msg->isakmp_sa) {
msg->exchange->flags |= EXCHANGE_FLAG_DPD_CAP_PEER;
LOG_DBG((LOG_EXCHANGE, 10, "dpd_check_vendor_payload: "
"DPD capable peer detected"));
}
p->flags |= PL_MARK;
}
}
/*
* Arm the DPD timer
*/
void
dpd_start(struct sa *isakmp_sa)
{
if (dpd_timer_interval(0) != 0) {
LOG_DBG((LOG_EXCHANGE, 10, "dpd_enable: enabling"));
isakmp_sa->flags |= SA_FLAG_DPD;
dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_NORMAL);
}
}
/*
* All incoming DPD Notify messages enter here. Message has been validated.
*/
void
dpd_handle_notify(struct message *msg, struct payload *p)
{
struct sa *isakmp_sa = msg->isakmp_sa;
u_int16_t notify = GET_ISAKMP_NOTIFY_MSG_TYPE(p->p);
u_int32_t p_seq;
/* Extract the sequence number. */
memcpy(&p_seq, p->p + ISAKMP_NOTIFY_SPI_OFF + ISAKMP_HDR_COOKIES_LEN,
sizeof p_seq);
p_seq = ntohl(p_seq);
LOG_DBG((LOG_MESSAGE, 40, "dpd_handle_notify: got %s seq %u",
constant_name(isakmp_notify_cst, notify), p_seq));
switch (notify) {
case ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE:
/* The other peer wants to know we're alive. */
if (p_seq < isakmp_sa->dpd_rseq ||
(p_seq == isakmp_sa->dpd_rseq &&
++isakmp_sa->dpd_rdupcount >= DPD_RETRANS_MAX)) {
log_print("dpd_handle_notify: bad R_U_THERE seqno "
"%u <= %u", p_seq, isakmp_sa->dpd_rseq);
return;
}
if (isakmp_sa->dpd_rseq != p_seq) {
isakmp_sa->dpd_rdupcount = 0;
isakmp_sa->dpd_rseq = p_seq;
}
message_send_dpd_notify(isakmp_sa,
ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE_ACK, p_seq);
break;
case ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE_ACK:
/* This should be a response to a R_U_THERE we've sent. */
if (isakmp_sa->dpd_seq != p_seq) {
log_print("dpd_handle_notify: got bad ACK seqno %u, "
"expected %u", p_seq, isakmp_sa->dpd_seq);
/* XXX Give up? Retry? */
return;
}
break;
default:
break;
}
/* Mark handled. */
p->flags |= PL_MARK;
/* The other peer is alive, so we can safely wait a while longer. */
if (isakmp_sa->flags & SA_FLAG_DPD)
dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_NORMAL);
}
/* Calculate the time until next DPD exchange. */
static u_int32_t
dpd_timer_interval(u_int32_t offset)
{
int32_t v = 0;
#ifdef notyet
v = ...; /* XXX Per-peer specified DPD intervals? */
#endif
if (!v)
v = conf_get_num("General", "DPD-check-interval", 0);
if (v < 1)
return 0; /* DPD-Check-Interval < 1 means disable DPD */
v -= offset;
return v < 1 ? 1 : v;
}
static void
dpd_timer_reset(struct sa *sa, u_int32_t time_passed, enum dpd_tstate mode)
{
struct timeval tv;
if (sa->dpd_event)
timer_remove_event(sa->dpd_event);
gettimeofday(&tv, 0);
switch (mode) {
case DPD_TIMER_NORMAL:
sa->dpd_failcount = 0;
tv.tv_sec += dpd_timer_interval(time_passed);
sa->dpd_event = timer_add_event("dpd_event", dpd_event, sa,
&tv);
break;
case DPD_TIMER_CHECK:
tv.tv_sec += DPD_RETRANS_WAIT;
sa->dpd_event = timer_add_event("dpd_check_event",
dpd_check_event, sa, &tv);
break;
default:
break;
}
if (!sa->dpd_event)
log_print("dpd_timer_reset: timer_add_event failed");
}
/* Helper function for dpd_exchange_finalization(). */
static int
dpd_find_sa(struct sa *sa, void *v_sa)
{
struct sa *isakmp_sa = v_sa;
if (!isakmp_sa->id_i || !isakmp_sa->id_r)
return 0;
return (sa->phase == 2 && (sa->flags & SA_FLAG_READY) &&
memcmp(sa->id_i, isakmp_sa->id_i, sa->id_i_len) == 0 &&
memcmp(sa->id_r, isakmp_sa->id_r, sa->id_r_len) == 0);
}
struct dpd_args {
struct sa *isakmp_sa;
u_int32_t interval;
};
/* Helper function for dpd_event(). */
static int
dpd_check_time(struct sa *sa, void *v_arg)
{
struct dpd_args *args = v_arg;
struct sockaddr *dst;
struct proto *proto;
struct sa_kinfo *ksa;
struct timeval tv;
if (sa->phase == 1 || (args->isakmp_sa->flags & SA_FLAG_DPD) == 0 ||
dpd_find_sa(sa, args->isakmp_sa) == 0)
return 0;
proto = TAILQ_FIRST(&sa->protos);
if (!proto || !proto->data)
return 0;
sa->transport->vtbl->get_src(sa->transport, &dst);
gettimeofday(&tv, 0);
ksa = pf_key_v2_get_kernel_sa(proto->spi[1], proto->spi_sz[1],
proto->proto, dst);
if (!ksa || !ksa->last_used)
return 0;
LOG_DBG((LOG_MESSAGE, 80, "dpd_check_time: "
"SA %p last use %u second(s) ago", sa,
(u_int32_t)(tv.tv_sec - ksa->last_used)));
if ((u_int32_t)(tv.tv_sec - ksa->last_used) < args->interval) {
args->interval = (u_int32_t)(tv.tv_sec - ksa->last_used);
return 1;
}
return 0;
}
/* Called by the timer. */
static void
dpd_event(void *v_sa)
{
struct sa *isakmp_sa = v_sa;
struct dpd_args args;
struct sockaddr *dst;
char *addr;
isakmp_sa->dpd_event = 0;
/* Check if there's been any incoming SA activity since last time. */
args.isakmp_sa = isakmp_sa;
args.interval = dpd_timer_interval(0);
if (sa_find(dpd_check_time, &args)) {
if (args.interval > dpd_timer_interval(0))
args.interval = 0;
dpd_timer_reset(isakmp_sa, args.interval, DPD_TIMER_NORMAL);
return;
}
/* No activity seen, do a DPD exchange. */
if (isakmp_sa->dpd_seq == 0) {
/*
* RFC 3706: first seq# should be random, with MSB zero,
* otherwise we just increment it.
*/
getrandom((u_int8_t *)&isakmp_sa->dpd_seq,
sizeof isakmp_sa->dpd_seq);
isakmp_sa->dpd_seq &= 0x7FFF;
} else
isakmp_sa->dpd_seq++;
isakmp_sa->transport->vtbl->get_dst(isakmp_sa->transport, &dst);
if (sockaddr2text(dst, &addr, 0) == -1)
addr = 0;
LOG_DBG((LOG_MESSAGE, 30, "dpd_event: sending R_U_THERE to %s seq %u",
addr ? addr : "<unknown>", isakmp_sa->dpd_seq));
if (addr)
free(addr);
message_send_dpd_notify(isakmp_sa, ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE,
isakmp_sa->dpd_seq);
/* And set the short timer. */
dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_CHECK);
}
/*
* Called by the timer. If this function is called, it means we did not
* received any R_U_THERE_ACK confirmation from the other peer.
*/
static void
dpd_check_event(void *v_sa)
{
struct sa *isakmp_sa = v_sa;
struct sa *sa;
isakmp_sa->dpd_event = 0;
if (++isakmp_sa->dpd_failcount < DPD_RETRANS_MAX) {
LOG_DBG((LOG_MESSAGE, 10, "dpd_check_event: "
"peer not responding, retry %u of %u",
isakmp_sa->dpd_failcount, DPD_RETRANS_MAX));
message_send_dpd_notify(isakmp_sa,
ISAKMP_NOTIFY_STATUS_DPD_R_U_THERE, isakmp_sa->dpd_seq);
dpd_timer_reset(isakmp_sa, 0, DPD_TIMER_CHECK);
return;
}
/*
* Peer is considered dead. Delete all SAs created under isakmp_sa.
*/
LOG_DBG((LOG_MESSAGE, 10, "dpd_check_event: peer is dead, "
"deleting all SAs connected to SA %p", isakmp_sa));
while ((sa = sa_find(dpd_find_sa, isakmp_sa)) != 0) {
LOG_DBG((LOG_MESSAGE, 30, "dpd_check_event: deleting SA %p",
sa));
sa_delete(sa, 0);
}
LOG_DBG((LOG_MESSAGE, 30, "dpd_check_event: deleting ISAKMP SA %p",
isakmp_sa));
sa_delete(isakmp_sa, 0);
}