mac80211: accept deauth frames in IBSS mode

We can process deauth frames and all, but we drop them very
early in the RX path today - this could never have worked.

Fixes: 2cc59e78 ("mac80211: reply to AUTH with DEAUTH if sta allocation fails in IBSS")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20191004123706.15768-2-luca@coelho.fiSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rx.c

@@ -3467,9 +3467,18 @@ ieee80211_rx_h_mgmt(struct ieee80211_rx_data *rx)
 	case cpu_to_le16(IEEE80211_STYPE_PROBE_RESP):
 		/* process for all: mesh, mlme, ibss */
 		break;
+	case cpu_to_le16(IEEE80211_STYPE_DEAUTH):
+		if (is_multicast_ether_addr(mgmt->da) &&
+		    !is_broadcast_ether_addr(mgmt->da))
+			return RX_DROP_MONITOR;
+
+		/* process only for station/IBSS */
+		if (sdata->vif.type != NL80211_IFTYPE_STATION &&
+		    sdata->vif.type != NL80211_IFTYPE_ADHOC)
+			return RX_DROP_MONITOR;
+		break;
 	case cpu_to_le16(IEEE80211_STYPE_ASSOC_RESP):
 	case cpu_to_le16(IEEE80211_STYPE_REASSOC_RESP):
-	case cpu_to_le16(IEEE80211_STYPE_DEAUTH):
 	case cpu_to_le16(IEEE80211_STYPE_DISASSOC):
 		if (is_multicast_ether_addr(mgmt->da) &&
 		    !is_broadcast_ether_addr(mgmt->da))