mac80211: drop unencrypted frames in mesh fwding

commit d0c22119 upstream.

The mesh forwarding path was not checking that data
frames were protected when running an encrypted network;
add the necessary check.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

net/mac80211/rx.c

@@ -2076,6 +2076,9 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 	hdr = (struct ieee80211_hdr *) skb->data;
 	mesh_hdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);
 
+	if (ieee80211_drop_unencrypted(rx, hdr->frame_control))
+		return RX_DROP_MONITOR;
+
 	/* frame is in RMC, don't forward */
 	if (ieee80211_is_data(hdr->frame_control) &&
 	    is_multicast_ether_addr(hdr->addr1) &&