Add support for INVALID_KE_PAYLOAD in CREATE_CHILD_SA

exchange.  In the case of an invalid KE error, retry
CREATE_CHILD_SA exchange with different group instead
of restarting the full IKE handshake.

ok markus@

3 files changed, 104 insertions, 37 deletions

diff --git a/sbin/iked/config.c b/sbin/iked/config.c
index a77e5320381..7df23d84bba 100644
--- a/sbin/iked/config.c
+++ b/sbin/iked/config.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: config.c,v 1.74 2020/11/29 21:00:43 tobhe Exp $	*/
+/*	$OpenBSD: config.c,v 1.75 2021/01/21 16:46:47 tobhe Exp $	*/
 
 /*
  * Copyright (c) 2019 Tobias Heider <tobias.heider@stusta.de>
@@ -84,8 +84,7 @@ config_free_kex(struct iked_kex *kex)
 	ibuf_release(kex->kex_inonce);
 	ibuf_release(kex->kex_rnonce);
 
-	if (kex->kex_dhgroup != NULL)
-		group_free(kex->kex_dhgroup);
+	group_free(kex->kex_dhgroup);
 	ibuf_release(kex->kex_dhiexchange);
 	ibuf_release(kex->kex_dhrexchange);
 
@@ -140,8 +139,7 @@ config_free_sa(struct iked *env, struct iked_sa *sa)
 	ibuf_release(sa->sa_inonce);
 	ibuf_release(sa->sa_rnonce);
 
-	if (sa->sa_dhgroup != NULL)
-		group_free(sa->sa_dhgroup);
+	group_free(sa->sa_dhgroup);
 	ibuf_release(sa->sa_dhiexchange);
 	ibuf_release(sa->sa_dhrexchange);
 
@@ -408,7 +406,7 @@ config_add_transform(struct iked_proposal *prop, unsigned int type,
 }
 
 struct iked_transform *
-config_findtransform(struct iked_proposals *props, uint8_t type,
+config_findtransform_ext(struct iked_proposals *props, uint8_t type, int id,
     unsigned int proto)
 {
 	struct iked_proposal	*prop;
@@ -422,6 +420,9 @@ config_findtransform(struct iked_proposals *props, uint8_t type,
 			continue;
 		for (i = 0; i < prop->prop_nxforms; i++) {
 			xform = prop->prop_xforms + i;
+			/* optional lookup of specific transform */
+			if (id >= 0 && xform->xform_id != id)
+				continue;
 			if (xform->xform_type == type)
 				return (xform);
 		}
@@ -430,6 +431,13 @@ config_findtransform(struct iked_proposals *props, uint8_t type,
 	return (NULL);
 }
 
+struct iked_transform *
+config_findtransform(struct iked_proposals *props, uint8_t type,
+    unsigned int proto)
+{
+	return config_findtransform_ext(props, type, -1, proto);
+}
+
 struct iked_user *
 config_new_user(struct iked *env, struct iked_user *new)
 {
diff --git a/sbin/iked/iked.h b/sbin/iked/iked.h
index 242ceef109b..a8578d8ee51 100644
--- a/sbin/iked/iked.h
+++ b/sbin/iked/iked.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: iked.h,v 1.179 2020/12/21 22:49:36 tobhe Exp $	*/
+/*	$OpenBSD: iked.h,v 1.180 2021/01/21 16:46:47 tobhe Exp $	*/
 
 /*
  * Copyright (c) 2019 Tobias Heider <tobias.heider@stusta.de>
@@ -479,7 +479,7 @@ struct iked_sa {
 	struct iked_sa			*sa_previ;	/* matching back pointer */
 	struct iked_sa			*sa_nextr;	/* simultaneous rekey */
 	struct iked_sa			*sa_prevr;	/* matching back pointer */
-	uint64_t			 sa_rekeyspi;	/* peerspi CSA rekey*/
+	uint64_t			 sa_rekeyspi;	/* peerspi CSA rekey */
 	struct ibuf			*sa_simult;	/* simultaneous rekey */
 
 	struct iked_ipcomp		 sa_ipcompi;	/* IPcomp initator */
@@ -800,6 +800,8 @@ uint64_t
 	 config_getspi(void);
 struct iked_transform *
 	 config_findtransform(struct iked_proposals *, uint8_t, unsigned int);
+struct iked_transform *
+	 config_findtransform_ext(struct iked_proposals *, uint8_t,int, unsigned int);
 void	 config_free_policy(struct iked *, struct iked_policy *);
 struct iked_proposal *
 	 config_add_proposal(struct iked_proposals *, unsigned int,
diff --git a/sbin/iked/ikev2.c b/sbin/iked/ikev2.c
index 5a2a2c52dbe..2f7b781a195 100644
--- a/sbin/iked/ikev2.c
+++ b/sbin/iked/ikev2.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ikev2.c,v 1.295 2021/01/20 18:44:28 tobhe Exp $	*/
+/*	$OpenBSD: ikev2.c,v 1.296 2021/01/21 16:46:47 tobhe Exp $	*/
 
 /*
  * Copyright (c) 2019 Tobias Heider <tobias.heider@stusta.de>
@@ -103,7 +103,7 @@ ssize_t	 ikev2_handle_delete(struct iked *, struct iked_message *,
 	    struct ibuf *, struct ikev2_payload **, uint8_t *);
 
 int	 ikev2_send_create_child_sa(struct iked *, struct iked_sa *,
-	    struct iked_spi *, uint8_t);
+	    struct iked_spi *, uint8_t, uint16_t);
 int	 ikev2_ikesa_enable(struct iked *, struct iked_sa *, struct iked_sa *);
 void	 ikev2_ikesa_delete(struct iked *, struct iked_sa *, int);
 int	 ikev2_nonce_cmp(struct ibuf *, struct ibuf *);
@@ -593,6 +593,7 @@ ikev2_recv(struct iked *env, struct iked_message *msg)
 
 	initiator = (hdr->ike_flags & IKEV2_FLAG_INITIATOR) ? 0 : 1;
 	msg->msg_response = (hdr->ike_flags & IKEV2_FLAG_RESPONSE) ? 1 : 0;
+	msg->msg_exchange = hdr->ike_exchange;
 	msg->msg_sa = sa_lookup(env,
 	    betoh64(hdr->ike_ispi), betoh64(hdr->ike_rspi),
 	    initiator);
@@ -2952,7 +2953,10 @@ ikev2_handle_notifies(struct iked *env, struct iked_message *msg)
 {
 	struct iked_ipcomp	*ic;
 	struct iked_sa		*sa;
-	uint16_t		 group;
+	struct iked_spi		 rekey;
+	struct group		*group;
+	uint16_t		 groupid;
+	unsigned int		 protoid;
 
 	if ((sa = msg->msg_sa) == NULL)
 		return (-1);
@@ -2980,39 +2984,85 @@ ikev2_handle_notifies(struct iked *env, struct iked_message *msg)
 	}
 
 	if (msg->msg_flags & IKED_MSG_FLAGS_INVALID_KE) {
-		/* XXX chould also happen for PFS */
-		group = betoh16(msg->msg_group);
-		if (!sa->sa_hdr.sh_initiator) {
-			log_debug("%s: not an initiator", __func__);
+		groupid = betoh16(msg->msg_group);
+		if (group_getid(groupid) == NULL) {
+			log_debug("%s: unable to select DH group %u",
+			    __func__, groupid);
 			ikev2_ike_sa_setreason(sa,
-			    "received invalid KE as responder");
+			    "unable to select DH group");
 			sa_state(env, sa, IKEV2_STATE_CLOSED);
 			msg->msg_sa = NULL;
 			return (-1);
 		}
-		if (group_getid(group) == NULL) {
-			log_debug("%s: unable to select DH group %u", __func__,
-			    group);
+		log_debug("%s: responder selected DH group %u", __func__,
+		    groupid);
+		switch (msg->msg_exchange) {
+		case IKEV2_EXCHANGE_IKE_SA_INIT:
+			protoid = IKEV2_SAPROTO_ESP;
+			if (!sa->sa_hdr.sh_initiator) {
+				log_debug("%s: not an initiator", __func__);
+				ikev2_ike_sa_setreason(sa,
+				    "received invalid KE as responder");
+				sa_state(env, sa, IKEV2_STATE_CLOSED);
+				msg->msg_sa = NULL;
+				return (-1);
+			}
+			if (config_findtransform_ext(&msg->msg_policy->pol_proposals,
+			    IKEV2_XFORMTYPE_DH, groupid, protoid) == NULL) {
+				log_debug("%s: DH group %u denied by policy",
+				    __func__, groupid);
+				ikev2_ike_sa_setreason(sa,
+				    "unsupported group in INVALID_KE message");
+				sa_state(env, sa, IKEV2_STATE_CLOSED);
+				msg->msg_sa = NULL;
+				return (-1);
+			}
 			ikev2_ike_sa_setreason(sa,
-			    "unable to select DH group");
+			    "reinitiating with new DH group");
 			sa_state(env, sa, IKEV2_STATE_CLOSED);
 			msg->msg_sa = NULL;
+			msg->msg_policy->pol_peerdh = groupid;
+			timer_set(env, &env->sc_inittmr, ikev2_init_ike_sa, NULL);
+			timer_add(env, &env->sc_inittmr, IKED_INITIATOR_INITIAL);
+			return (-1);
+		case IKEV2_EXCHANGE_CREATE_CHILD_SA:
+			if (!(sa->sa_stateflags & IKED_REQ_CHILDSA)) {
+				log_debug("%s: IKED_REQ_CHILDSA missing",
+				     __func__);
+				return (-1);
+			}
+			sa->sa_stateflags &= ~IKED_REQ_CHILDSA;
+			protoid = sa->sa_rekeyspi ?
+			    IKEV2_SAPROTO_ESP : IKEV2_SAPROTO_IKE;
+			if (config_findtransform_ext(&msg->msg_policy->pol_proposals,
+			    IKEV2_XFORMTYPE_DH, groupid, protoid) == NULL) {
+				log_debug("%s: DH group %u denied by policy",
+				    __func__, groupid);
+				ikev2_ike_sa_setreason(sa,
+				    "unsupported group in INVALID_KE message");
+				sa_state(env, sa, IKEV2_STATE_CLOSED);
+				msg->msg_sa = NULL;
+				return (-1);
+			}
+			if (protoid == IKEV2_SAPROTO_ESP) {
+				/* CHILDSA */
+				rekey.spi = sa->sa_rekeyspi;
+				rekey.spi_size = 4;
+				rekey.spi_protoid = protoid;
+				(void)ikev2_send_create_child_sa(env, sa,
+				    &rekey, rekey.spi_protoid, groupid);
+			} else {
+				/* IKESA */
+				if ((group = group_get(groupid)) == NULL)
+					return -1;
+				group_free(sa->sa_dhgroup);
+				sa->sa_dhgroup = group;
+				timer_set(env, &sa->sa_rekey,
+				    ikev2_ike_sa_rekey, sa);
+				timer_add(env, &sa->sa_rekey, 0);
+			}
 			return (-1);
 		}
-		msg->msg_policy->pol_peerdh = group;
-		log_debug("%s: responder selected DH group %u", __func__,
-		    group);
-		ikev2_ike_sa_setreason(sa,
-		    "reinitiating with new DH group");
-		sa_state(env, sa, IKEV2_STATE_CLOSED);
-		msg->msg_sa = NULL;
-
-		/*
-		 * XXX should also happen for PFS so we have to check state.
-		 */
-		timer_set(env, &env->sc_inittmr, ikev2_init_ike_sa, NULL);
-		timer_add(env, &env->sc_inittmr, IKED_INITIATOR_INITIAL);
-		return (-1);
 	}
 
 	if (msg->msg_flags & IKED_MSG_FLAGS_IPCOMP_SUPPORTED) {
@@ -3762,7 +3812,7 @@ ikev2_set_sa_proposal(struct iked_sa *sa, struct iked_policy *pol,
 
 int
 ikev2_send_create_child_sa(struct iked *env, struct iked_sa *sa,
-    struct iked_spi *rekey, uint8_t protoid)
+    struct iked_spi *rekey, uint8_t protoid, uint16_t proposed_group)
 {
 	struct iked_policy		*pol = sa->sa_policy;
 	struct iked_childsa		*csa = NULL, *csb = NULL;
@@ -3862,6 +3912,13 @@ ikev2_send_create_child_sa(struct iked *env, struct iked_sa *sa,
 	    protoid)) {
 		log_debug("%s: enable PFS", __func__);
 		ikev2_sa_cleanup_dh(sa);
+		if (proposed_group) {
+			if ((sa->sa_dhgroup =
+			    group_get(proposed_group)) == NULL) {
+				log_debug("%s: failed to get group", __func__);
+				goto done;
+			}
+		}
 		if (ikev2_sa_initiator_dh(sa, NULL, protoid, NULL) < 0) {
 			log_debug("%s: failed to setup DH", __func__);
 			goto done;
@@ -6357,7 +6414,7 @@ ikev2_child_sa_acquire(struct iked *env, struct iked_flow *acquire)
 		if (sa->sa_stateflags & (IKED_REQ_CHILDSA|IKED_REQ_INF))
 			return (-1);	/* busy, retry later */
 		if (ikev2_send_create_child_sa(env, sa, NULL,
-		    flow->flow_saproto) != 0)
+		    flow->flow_saproto, 0) != 0)
 			log_warnx("%s: failed to initiate a "
 			    "CREATE_CHILD_SA exchange", SPI_SA(sa, __func__));
 	}
@@ -6407,7 +6464,7 @@ ikev2_child_sa_rekey(struct iked *env, struct iked_spi *rekey)
 		return (-1);	/* peer is busy, retry later */
 	if (csa->csa_allocated)	/* Peer SPI died first, get the local one */
 		rekey->spi = csa->csa_peerspi;
-	if (ikev2_send_create_child_sa(env, sa, rekey, rekey->spi_protoid))
+	if (ikev2_send_create_child_sa(env, sa, rekey, rekey->spi_protoid, 0))
 		log_warnx("%s: failed to initiate a CREATE_CHILD_SA exchange",
 		    SPI_SA(sa, __func__));
 	return (0);