Reject Group Key message 1/2 prior to completion of 4-way handshake

Previously, it would have been possible to complete RSN connection by
skipping the msg 3/4 and 4/4 completely. This would have resulted in
pairwise key not being configured. This is obviously not supposed to
happen in practice and could result in unexpected behavior, so reject
group key message before the initial 4-way handshake has been completed.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/rsn_supp/wpa.c

@@ -1244,6 +1244,7 @@ static void wpa_supplicant_process_3_of_4(struct wpa_sm *sm,
 			sm->cur_pmksa = sa;
 	}
 
+	sm->msg_3_of_4_ok = 1;
 	return;
 
 failed:
@@ -1436,6 +1437,12 @@ static void wpa_supplicant_process_1_of_2(struct wpa_sm *sm,
 	int rekey, ret;
 	struct wpa_gtk_data gd;
 
+	if (!sm->msg_3_of_4_ok) {
+		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
+			"WPA: Group Key Handshake started prior to completion of 4-way handshake");
+		goto failed;
+	}
+
 	os_memset(&gd, 0, sizeof(gd));
 
 	rekey = wpa_sm_get_state(sm) == WPA_COMPLETED;
@@ -2295,6 +2302,8 @@ void wpa_sm_notify_disassoc(struct wpa_sm *sm)
 
 	/* Keys are not needed in the WPA state machine anymore */
 	wpa_sm_drop_sa(sm);
+
+	sm->msg_3_of_4_ok = 0;
 }
 
 

src/rsn_supp/wpa_i.h

@@ -23,6 +23,7 @@ struct wpa_sm {
 	size_t pmk_len;
 	struct wpa_ptk ptk, tptk;
 	int ptk_set, tptk_set;
+	unsigned int msg_3_of_4_ok:1;
 	u8 snonce[WPA_NONCE_LEN];
 	u8 anonce[WPA_NONCE_LEN]; /* ANonce from the last 1/4 msg */
 	int renew_snonce;