mac80211: fix enabling 4-address mode on a sta vif after assoc

Notify the driver about the 4-address mode change and also send a nulldata
packet to the AP to notify it about the change

Fixes: 1ff4e8f2de ("mac80211: notify the driver when a sta uses 4-address mode")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210702050111.47546-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -152,6 +152,8 @@ static int ieee80211_change_iface(struct wiphy *wiphy,
 				  struct vif_params *params)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
 	int ret;
 
 	ret = ieee80211_if_change_type(sdata, type);
@@ -162,7 +164,24 @@ static int ieee80211_change_iface(struct wiphy *wiphy,
 		RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
 		ieee80211_check_fast_rx_iface(sdata);
 	} else if (type == NL80211_IFTYPE_STATION && params->use_4addr >= 0) {
+		struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+
+		if (params->use_4addr == ifmgd->use_4addr)
+			return 0;
+
 		sdata->u.mgd.use_4addr = params->use_4addr;
+		if (!ifmgd->associated)
+			return 0;
+
+		mutex_lock(&local->sta_mtx);
+		sta = sta_info_get(sdata, ifmgd->bssid);
+		if (sta)
+			drv_sta_set_4addr(local, sdata, &sta->sta,
+					  params->use_4addr);
+		mutex_unlock(&local->sta_mtx);
+
+		if (params->use_4addr)
+			ieee80211_send_4addr_nullfunc(local, sdata);
 	}
 
 	if (sdata->vif.type == NL80211_IFTYPE_MONITOR) {

net/mac80211/ieee80211_i.h

@@ -2201,6 +2201,8 @@ void ieee80211_dynamic_ps_timer(struct timer_list *t);
 void ieee80211_send_nullfunc(struct ieee80211_local *local,
 			     struct ieee80211_sub_if_data *sdata,
 			     bool powersave);
+void ieee80211_send_4addr_nullfunc(struct ieee80211_local *local,
+				   struct ieee80211_sub_if_data *sdata);
 void ieee80211_sta_tx_notify(struct ieee80211_sub_if_data *sdata,
 			     struct ieee80211_hdr *hdr, bool ack, u16 tx_time);
 

net/mac80211/mlme.c

@@ -1095,8 +1095,8 @@ void ieee80211_send_nullfunc(struct ieee80211_local *local,
 	ieee80211_tx_skb(sdata, skb);
 }
 
-static void ieee80211_send_4addr_nullfunc(struct ieee80211_local *local,
-					  struct ieee80211_sub_if_data *sdata)
+void ieee80211_send_4addr_nullfunc(struct ieee80211_local *local,
+				   struct ieee80211_sub_if_data *sdata)
 {
 	struct sk_buff *skb;
 	struct ieee80211_hdr *nullfunc;