Allow add-BSS operation to re-use existing netdev

When removing and re-adding the first wlan# netdev to hostapd
dynamically, the netdev is already present and should not be removed and
re-added to maintain its state as not-added-by-hostapd so that it does
not get removed automatically.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

src/ap/ap_drv_ops.c

@@ -286,7 +286,7 @@ int hostapd_vlan_if_add(struct hostapd_data *hapd, const char *ifname)
 	char force_ifname[IFNAMSIZ];
 	u8 if_addr[ETH_ALEN];
 	return hostapd_if_add(hapd, WPA_IF_AP_VLAN, ifname, hapd->own_addr,
-			      NULL, NULL, force_ifname, if_addr, NULL);
+			      NULL, NULL, force_ifname, if_addr, NULL, 0);
 }
 
 
@@ -417,13 +417,13 @@ int hostapd_set_ssid(struct hostapd_data *hapd, const u8 *buf, size_t len)
 int hostapd_if_add(struct hostapd_data *hapd, enum wpa_driver_if_type type,
 		   const char *ifname, const u8 *addr, void *bss_ctx,
 		   void **drv_priv, char *force_ifname, u8 *if_addr,
-		   const char *bridge)
+		   const char *bridge, int use_existing)
 {
 	if (hapd->driver == NULL || hapd->driver->if_add == NULL)
 		return -1;
 	return hapd->driver->if_add(hapd->drv_priv, type, ifname, addr,
 				    bss_ctx, drv_priv, force_ifname, if_addr,
-				    bridge);
+				    bridge, use_existing);
 }
 
 

src/ap/ap_drv_ops.h

@@ -48,7 +48,7 @@ int hostapd_set_ssid(struct hostapd_data *hapd, const u8 *buf, size_t len);
 int hostapd_if_add(struct hostapd_data *hapd, enum wpa_driver_if_type type,
 		   const char *ifname, const u8 *addr, void *bss_ctx,
 		   void **drv_priv, char *force_ifname, u8 *if_addr,
-		   const char *bridge);
+		   const char *bridge, int use_existing);
 int hostapd_if_remove(struct hostapd_data *hapd, enum wpa_driver_if_type type,
 		      const char *ifname);
 int hostapd_set_ieee8021x(struct hostapd_data *hapd,

src/ap/hostapd.c

@@ -608,7 +608,8 @@ hostapd_das_disconnect(void *ctx, struct radius_das_attrs *attr)
 /**
  * hostapd_setup_bss - Per-BSS setup (initialization)
  * @hapd: Pointer to BSS data
- * @first: Whether this BSS is the first BSS of an interface
+ * @first: Whether this BSS is the first BSS of an interface; -1 = not first,
+ *	but interface may exist
  *
  * This function is used to initialize all per-BSS data structures and
  * resources. This gets called in a loop for each BSS when an interface is
@@ -623,7 +624,7 @@ static int hostapd_setup_bss(struct hostapd_data *hapd, int first)
 	char force_ifname[IFNAMSIZ];
 	u8 if_addr[ETH_ALEN];
 
-	if (!first) {
+	if (!first || first == -1) {
 		if (hostapd_mac_comp_empty(hapd->conf->bssid) == 0) {
 			/* Allocate the next available BSSID. */
 			do {
@@ -647,7 +648,7 @@ static int hostapd_setup_bss(struct hostapd_data *hapd, int first)
 				   hapd->conf->iface, hapd->own_addr, hapd,
 				   &hapd->drv_priv, force_ifname, if_addr,
 				   hapd->conf->bridge[0] ? hapd->conf->bridge :
-				   NULL)) {
+				   NULL, first == -1)) {
 			wpa_printf(MSG_ERROR, "Failed to add BSS (BSSID="
 				   MACSTR ")", MAC2STR(hapd->own_addr));
 			return -1;
@@ -1578,7 +1579,7 @@ int hostapd_add_iface(struct hapd_interfaces *interfaces, char *buf)
 			os_memcpy(hapd->own_addr, hapd_iface->bss[0]->own_addr,
 				  ETH_ALEN);
 
-			if (hostapd_setup_bss(hapd, 0)) {
+			if (hostapd_setup_bss(hapd, -1)) {
 				hapd_iface->conf->num_bss--;
 				hapd_iface->num_bss--;
 				os_free(hapd);

src/drivers/driver.h

@@ -1955,12 +1955,13 @@ struct wpa_driver_ops {
 	 *	(this may differ from the requested addr if the driver cannot
 	 *	change interface address)
 	 * @bridge: Bridge interface to use or %NULL if no bridge configured
+	 * @use_existing: Whether to allow existing interface to be used
 	 * Returns: 0 on success, -1 on failure
 	 */
 	int (*if_add)(void *priv, enum wpa_driver_if_type type,
 		      const char *ifname, const u8 *addr, void *bss_ctx,
 		      void **drv_priv, char *force_ifname, u8 *if_addr,
-		      const char *bridge);
+		      const char *bridge, int use_existing);
 
 	/**
 	 * if_remove - Remove a virtual interface

src/drivers/driver_nl80211.c

@@ -7064,7 +7064,7 @@ static int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,
 				const char *ifname, enum nl80211_iftype iftype,
 				const u8 *addr, int wds,
 				int (*handler)(struct nl_msg *, void *),
-				void *arg)
+				void *arg, int use_existing)
 {
 	int ret;
 
@@ -7073,6 +7073,11 @@ static int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,
 
 	/* if error occurred and interface exists already */
 	if (ret == -ENFILE && if_nametoindex(ifname)) {
+		if (use_existing) {
+			wpa_printf(MSG_DEBUG, "nl80211: Continue using existing interface %s",
+				   ifname);
+			return -ENFILE;
+		}
 		wpa_printf(MSG_INFO, "Try to remove and re-create %s", ifname);
 
 		/* Try to remove the interface that was already there. */
@@ -7438,7 +7443,7 @@ nl80211_create_monitor_interface(struct wpa_driver_nl80211_data *drv)
 
 	drv->monitor_ifidx =
 		nl80211_create_iface(drv, buf, NL80211_IFTYPE_MONITOR, NULL,
-				     0, NULL, NULL);
+				     0, NULL, NULL, 0);
 
 	if (drv->monitor_ifidx == -EOPNOTSUPP) {
 		/*
@@ -8979,7 +8984,8 @@ static int i802_set_wds_sta(void *priv, const u8 *addr, int aid, int val,
 		if (!if_nametoindex(name)) {
 			if (nl80211_create_iface(drv, name,
 						 NL80211_IFTYPE_AP_VLAN,
-						 bss->addr, 1, NULL, NULL) < 0)
+						 bss->addr, 1, NULL, NULL, 0) <
+			    0)
 				return -1;
 			if (bridge_ifname &&
 			    linux_br_add_if(drv->global->ioctl_sock,
@@ -9276,12 +9282,13 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 				     const char *ifname, const u8 *addr,
 				     void *bss_ctx, void **drv_priv,
 				     char *force_ifname, u8 *if_addr,
-				     const char *bridge)
+				     const char *bridge, int use_existing)
 {
 	enum nl80211_iftype nlmode;
 	struct i802_bss *bss = priv;
 	struct wpa_driver_nl80211_data *drv = bss->drv;
 	int ifidx;
+	int added = 1;
 
 	if (addr)
 		os_memcpy(if_addr, addr, ETH_ALEN);
@@ -9292,7 +9299,7 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 		os_memset(&p2pdev_info, 0, sizeof(p2pdev_info));
 		ifidx = nl80211_create_iface(drv, ifname, nlmode, addr,
 					     0, nl80211_wdev_handler,
-					     &p2pdev_info);
+					     &p2pdev_info, use_existing);
 		if (!p2pdev_info.wdev_id_set || ifidx != 0) {
 			wpa_printf(MSG_ERROR, "nl80211: Failed to create a P2P Device interface %s",
 				   ifname);
@@ -9308,8 +9315,11 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 			   (long long unsigned int) p2pdev_info.wdev_id);
 	} else {
 		ifidx = nl80211_create_iface(drv, ifname, nlmode, addr,
-					     0, NULL, NULL);
-		if (ifidx < 0) {
+					     0, NULL, NULL, use_existing);
+		if (use_existing && ifidx == -ENFILE) {
+			added = 0;
+			ifidx = if_nametoindex(ifname);
+		} else if (ifidx < 0) {
 			return -1;
 		}
 	}
@@ -9319,7 +9329,8 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 			os_memcpy(if_addr, bss->addr, ETH_ALEN);
 		else if (linux_get_ifhwaddr(drv->global->ioctl_sock,
 					    bss->ifname, if_addr) < 0) {
-			nl80211_remove_iface(drv, ifidx);
+			if (added)
+				nl80211_remove_iface(drv, ifidx);
 			return -1;
 		}
 	}
@@ -9357,7 +9368,8 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 	if (type == WPA_IF_AP_BSS) {
 		struct i802_bss *new_bss = os_zalloc(sizeof(*new_bss));
 		if (new_bss == NULL) {
-			nl80211_remove_iface(drv, ifidx);
+			if (added)
+				nl80211_remove_iface(drv, ifidx);
 			return -1;
 		}
 
@@ -9366,7 +9378,8 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 			wpa_printf(MSG_ERROR, "nl80211: Failed to add the new "
 				   "interface %s to a bridge %s",
 				   ifname, bridge);
-			nl80211_remove_iface(drv, ifidx);
+			if (added)
+				nl80211_remove_iface(drv, ifidx);
 			os_free(new_bss);
 			return -1;
 		}
@@ -9384,7 +9397,7 @@ static int wpa_driver_nl80211_if_add(void *priv, enum wpa_driver_if_type type,
 		new_bss->next = drv->first_bss->next;
 		new_bss->freq = drv->first_bss->freq;
 		new_bss->ctx = bss_ctx;
-		new_bss->added_if = 1;
+		new_bss->added_if = added;
 		drv->first_bss->next = new_bss;
 		if (drv_priv)
 			*drv_priv = new_bss;
@@ -9410,8 +9423,8 @@ static int wpa_driver_nl80211_if_remove(struct i802_bss *bss,
 	struct wpa_driver_nl80211_data *drv = bss->drv;
 	int ifindex = if_nametoindex(ifname);
 
-	wpa_printf(MSG_DEBUG, "nl80211: %s(type=%d ifname=%s) ifindex=%d",
-		   __func__, type, ifname, ifindex);
+	wpa_printf(MSG_DEBUG, "nl80211: %s(type=%d ifname=%s) ifindex=%d added_if=%d",
+		   __func__, type, ifname, ifindex, bss->added_if);
 	if (ifindex > 0 && bss->added_if)
 		nl80211_remove_iface(drv, ifindex);
 
@@ -9436,6 +9449,7 @@ static int wpa_driver_nl80211_if_remove(struct i802_bss *bss,
 	if (bss != drv->first_bss) {
 		struct i802_bss *tbss;
 
+		wpa_printf(MSG_DEBUG, "nl80211: Not the first BSS - remove it");
 		for (tbss = drv->first_bss; tbss; tbss = tbss->next) {
 			if (tbss->next == bss) {
 				tbss->next = bss->next;
@@ -9451,10 +9465,13 @@ static int wpa_driver_nl80211_if_remove(struct i802_bss *bss,
 			wpa_printf(MSG_INFO, "nl80211: %s - could not find "
 				   "BSS %p in the list", __func__, bss);
 	} else {
+		wpa_printf(MSG_DEBUG, "nl80211: First BSS - reassign context");
 		nl80211_teardown_ap(bss);
-		wpa_driver_nl80211_del_beacon(drv);
+		if (!bss->added_if && !drv->first_bss->next)
+			wpa_driver_nl80211_del_beacon(drv);
 		nl80211_destroy_bss(bss);
-		i802_set_iface_flags(bss, 0);
+		if (!bss->added_if)
+			i802_set_iface_flags(bss, 0);
 		if (drv->first_bss->next) {
 			drv->first_bss = drv->first_bss->next;
 			drv->ctx = drv->first_bss->ctx;

src/drivers/driver_test.c

@@ -1059,7 +1059,7 @@ static int test_driver_if_add(void *priv, enum wpa_driver_if_type type,
 			      const char *ifname, const u8 *addr,
 			      void *bss_ctx, void **drv_priv,
 			      char *force_ifname, u8 *if_addr,
-			      const char *bridge)
+			      const char *bridge, int use_existing)
 {
 	struct test_driver_bss *dbss = priv;
 	struct wpa_driver_test_data *drv = dbss->drv;

wpa_supplicant/driver_i.h

@@ -380,7 +380,7 @@ static inline int wpa_drv_if_add(struct wpa_supplicant *wpa_s,
 	if (wpa_s->driver->if_add)
 		return wpa_s->driver->if_add(wpa_s->drv_priv, type, ifname,
 					     addr, bss_ctx, NULL, force_ifname,
-					     if_addr, bridge);
+					     if_addr, bridge, 0);
 	return -1;
 }