mac80211: QoS multicast frames have No Ack policy

Previously QoS multicast frames had the Normal Acknowledgment QoS
control bits set. This would cause broadcast frames to be discarded by
peers with which we have a BA session, since their sequence number would
fall outside the allowed range. Set No Ack QoS control bits on multicast
QoS frames and filter these in de-aggregation code.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>

v2: Use proper QoS Ack Policy ctl field mask (Christian)

v3: Clean up conditional (Johannes)
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 3173dcf..72c1eb4 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -747,7 +747,7 @@
 	struct sta_info *sta = rx->sta;
 	struct tid_ampdu_rx *tid_agg_rx;
 	u16 sc;
-	int tid;
+	u8 tid, ack_policy;
 
 	if (!ieee80211_is_data_qos(hdr->frame_control))
 		goto dont_reorder;
@@ -760,6 +760,8 @@
 	if (!sta)
 		goto dont_reorder;
 
+	ack_policy = *ieee80211_get_qos_ctl(hdr) &
+		     IEEE80211_QOS_CTL_ACK_POLICY_MASK;
 	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 
 	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
@@ -770,6 +772,11 @@
 	if (unlikely(hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_NULLFUNC)))
 		goto dont_reorder;
 
+	/* not part of a BA session */
+	if (ack_policy != IEEE80211_QOS_CTL_ACK_POLICY_BLOCKACK &&
+	    ack_policy != IEEE80211_QOS_CTL_ACK_POLICY_NORMAL)
+		goto dont_reorder;
+
 	/* new, potentially un-ordered, ampdu frame - process it */
 
 	/* reset session timer */