mac80211: send delBA on unexpected BlockAck data frames

When we receive data frames with ACK policy BlockAck, send
delBA as requested by the 802.11 spec. Since this would be
happening for every frame inside an A-MPDU if it's really
received outside a session, limit it to a single attempt.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/agg-rx.c

@@ -409,8 +409,10 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 	}
 
 end:
-	if (status == WLAN_STATUS_SUCCESS)
+	if (status == WLAN_STATUS_SUCCESS) {
 		__set_bit(tid, sta->ampdu_mlme.agg_session_valid);
+		__clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
+	}
 	mutex_unlock(&sta->ampdu_mlme.mtx);
 
 end_no_lock:

net/mac80211/rx.c

@@ -1122,8 +1122,15 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx,
 	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 
 	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
-	if (!tid_agg_rx)
+	if (!tid_agg_rx) {
+		if (ack_policy == IEEE80211_QOS_CTL_ACK_POLICY_BLOCKACK &&
+		    !test_bit(tid, rx->sta->ampdu_mlme.agg_session_valid) &&
+		    !test_and_set_bit(tid, rx->sta->ampdu_mlme.unexpected_agg))
+			ieee80211_send_delba(rx->sdata, rx->sta->sta.addr, tid,
+					     WLAN_BACK_RECIPIENT,
+					     WLAN_REASON_QSTA_REQUIRE_SETUP);
 		goto dont_reorder;
+	}
 
 	/* qos null data frames are excluded */
 	if (unlikely(hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_NULLFUNC)))

net/mac80211/sta_info.h

@@ -230,6 +230,8 @@ struct tid_ampdu_rx {
  * @tid_rx_stop_requested:  bitmap indicating which BA sessions per TID the
  *	driver requested to close until the work for it runs
  * @agg_session_valid: bitmap indicating which TID has a rx BA session open on
+ * @unexpected_agg: bitmap indicating which TID already sent a delBA due to
+ *	unexpected aggregation related frames outside a session
  * @work: work struct for starting/stopping aggregation
  * @tid_tx: aggregation info for Tx per TID
  * @tid_start_tx: sessions where start was requested
@@ -244,6 +246,7 @@ struct sta_ampdu_mlme {
 	unsigned long tid_rx_timer_expired[BITS_TO_LONGS(IEEE80211_NUM_TIDS)];
 	unsigned long tid_rx_stop_requested[BITS_TO_LONGS(IEEE80211_NUM_TIDS)];
 	unsigned long agg_session_valid[BITS_TO_LONGS(IEEE80211_NUM_TIDS)];
+	unsigned long unexpected_agg[BITS_TO_LONGS(IEEE80211_NUM_TIDS)];
 	/* tx */
 	struct work_struct work;
 	struct tid_ampdu_tx __rcu *tid_tx[IEEE80211_NUM_TIDS];