mac80211: MBSSID support in interface handling

Configure multiple BSSID and enhanced multi-BSSID advertisement (EMA)
parameters in mac80211 for AP mode.

For each interface, 'mbssid_tx_vif' points to the transmitting interface of
the MBSSID set. The pointer is set to NULL if MBSSID is disabled.

Function ieee80211_stop() is modified to always bring down all the
non-transmitting interfaces first and the transmitting interface last.

Signed-off-by: John Crispin <[e-mail]>
Co-developed-by: Aloka Dixit <[e-mail]>
Signed-off-by: Aloka Dixit <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[slightly change logic to be more obvious]
Signed-off-by: Johannes Berg <[e-mail]>

include/net/mac80211.h

···
  *	write-protected by sdata_lock and local->mtx so holding either is fine
  *	for read access.
  * @color_change_color: the bss color that will be used after the change.
+ * @mbssid_tx_vif: Pointer to the transmitting interface if MBSSID is enabled.
  */
 struct ieee80211_vif {
 	enum nl80211_iftype type;
···
 
 	bool color_change_active;
 	u8 color_change_color;
+
+	struct ieee80211_vif *mbssid_tx_vif;
 
 	/* must be last */
 	u8 drv_priv[] __aligned(sizeof(void *));

net/mac80211/cfg.c

···
 	return 0;
 }
 
+static int ieee80211_set_ap_mbssid_options(struct ieee80211_sub_if_data *sdata,
+					   struct cfg80211_mbssid_config params)
+{
+	struct ieee80211_sub_if_data *tx_sdata;
+
+	sdata->vif.mbssid_tx_vif = NULL;
+	sdata->vif.bss_conf.bssid_index = 0;
+	sdata->vif.bss_conf.nontransmitted = false;
+	sdata->vif.bss_conf.ema_ap = false;
+
+	if (sdata->vif.type != NL80211_IFTYPE_AP || !params.tx_wdev)
+		return -EINVAL;
+
+	tx_sdata = IEEE80211_WDEV_TO_SUB_IF(params.tx_wdev);
+	if (!tx_sdata)
+		return -EINVAL;
+
+	if (tx_sdata == sdata) {
+		sdata->vif.mbssid_tx_vif = &sdata->vif;
+	} else {
+		sdata->vif.mbssid_tx_vif = &tx_sdata->vif;
+		sdata->vif.bss_conf.nontransmitted = true;
+		sdata->vif.bss_conf.bssid_index = params.index;
+	}
+	if (params.ema)
+		sdata->vif.bss_conf.ema_ap = true;
+
+	return 0;
+}
+
 static struct wireless_dev *ieee80211_add_iface(struct wiphy *wiphy,
 						const char *name,
 						unsigned char name_assign_type,
···
 
 		if (params->he_bss_color.enabled)
 			changed |= BSS_CHANGED_HE_BSS_COLOR;
+	}
+
+	if (sdata->vif.type == NL80211_IFTYPE_AP &&
+	    params->mbssid_config.tx_wdev) {
+		err = ieee80211_set_ap_mbssid_options(sdata,
+						      params->mbssid_config);
+		if (err)
+			return err;
 	}
 
 	mutex_lock(&local->mtx);

net/mac80211/iface.c

···
 		ieee80211_add_virtual_monitor(local);
 }
 
+static void ieee80211_stop_mbssid(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_sub_if_data *tx_sdata, *non_tx_sdata, *tmp_sdata;
+	struct ieee80211_vif *tx_vif = sdata->vif.mbssid_tx_vif;
+
+	if (!tx_vif)
+		return;
+
+	tx_sdata = vif_to_sdata(tx_vif);
+	sdata->vif.mbssid_tx_vif = NULL;
+
+	list_for_each_entry_safe(non_tx_sdata, tmp_sdata,
+				 &tx_sdata->local->interfaces, list) {
+		if (non_tx_sdata != sdata && non_tx_sdata != tx_sdata &&
+		    non_tx_sdata->vif.mbssid_tx_vif == tx_vif &&
+		    ieee80211_sdata_running(non_tx_sdata)) {
+			non_tx_sdata->vif.mbssid_tx_vif = NULL;
+			dev_close(non_tx_sdata->wdev.netdev);
+		}
+	}
+
+	if (sdata != tx_sdata && ieee80211_sdata_running(tx_sdata)) {
+		tx_sdata->vif.mbssid_tx_vif = NULL;
+		dev_close(tx_sdata->wdev.netdev);
+	}
+}
+
 static int ieee80211_stop(struct net_device *dev)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
-	/* close all dependent VLAN interfaces before locking wiphy */
+	/* close dependent VLAN and MBSSID interfaces before locking wiphy */
 	if (sdata->vif.type == NL80211_IFTYPE_AP) {
 		struct ieee80211_sub_if_data *vlan, *tmpsdata;
 
 		list_for_each_entry_safe(vlan, tmpsdata, &sdata->u.ap.vlans,
 					 u.vlan.list)
 			dev_close(vlan->dev);
+
+		ieee80211_stop_mbssid(sdata);
 	}
 
 	wiphy_lock(sdata->local->hw.wiphy);