AP MLD: De-initialize/disable link BSS properly

When the first link BSS of an interface was de-initialized/disabled, the
whole MLD was brought down. All other links were stopped beaconing and
links were removed. And if the non-first link BSS was
de-initialized/disabled, nothing happened. Even beaconing was not
stopped which is wrong.

Fix this by properly bringing down the intended link alone from the
interface.

Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>

hostapd/main.c

@@ -195,6 +195,7 @@ static int hostapd_driver_init(struct hostapd_iface *iface)
 		}
 
 		hapd->drv_priv = h_hapd->drv_priv;
+		hapd->interface_added = h_hapd->interface_added;
 
 		/*
 		 * All interfaces participating in the AP MLD would have

src/ap/hostapd.c

@@ -397,27 +397,6 @@ static int hostapd_broadcast_wep_set(struct hostapd_data *hapd)
 #endif /* CONFIG_WEP */
 
 
-static void hostapd_clear_drv_priv(struct hostapd_data *hapd)
-{
-#ifdef CONFIG_IEEE80211BE
-	unsigned int i;
-
-	for (i = 0; i < hapd->iface->interfaces->count; i++) {
-		struct hostapd_iface *iface = hapd->iface->interfaces->iface[i];
-
-		if (hapd->iface == iface || !iface)
-			continue;
-
-		if (iface->bss && iface->bss[0] &&
-		    hostapd_mld_get_first_bss(iface->bss[0]) == hapd)
-			iface->bss[0]->drv_priv = NULL;
-	}
-#endif /* CONFIG_IEEE80211BE */
-
-	hapd->drv_priv = NULL;
-}
-
-
 #ifdef CONFIG_IEEE80211BE
 #ifdef CONFIG_TESTING_OPTIONS
 
@@ -554,10 +533,20 @@ void hostapd_free_hapd_data(struct hostapd_data *hapd)
 			 * driver wrapper may have removed its internal instance
 			 * and hapd->drv_priv is not valid anymore.
 			 */
-			hostapd_clear_drv_priv(hapd);
+			hapd->drv_priv = NULL;
 		}
 	}
 
+#ifdef CONFIG_IEEE80211BE
+	/* If the interface was not added as well as it is not the first BSS,
+	 * at least the link should be removed here since deinit will take care
+	 * of only the first BSS. */
+	if (hapd->conf->mld_ap && !hapd->interface_added &&
+	    hapd->iface->bss[0] != hapd)
+		hostapd_if_link_remove(hapd, WPA_IF_AP_BSS, hapd->conf->iface,
+				       hapd->mld_link_id);
+#endif /* CONFIG_IEEE80211BE */
+
 	wpabuf_free(hapd->time_adv);
 	hapd->time_adv = NULL;
 
@@ -3304,6 +3293,37 @@ hostapd_interface_init_bss(struct hapd_interfaces *interfaces, const char *phy,
 }
 
 
+static void hostapd_cleanup_driver(const struct wpa_driver_ops *driver,
+				   void *drv_priv, struct hostapd_iface *iface)
+{
+#ifdef CONFIG_IEEE80211BE
+	if (!driver || !driver->hapd_deinit || !drv_priv)
+		return;
+
+	/* In case of non-ML operation, de-init. But if ML operation exist,
+	 * even if that's the last BSS in the interface, the driver (drv) could
+	 * be in use for a different AP MLD. Hence, need to check if drv is
+	 * still being used by some other BSS before de-initiallizing. */
+	if (!iface->bss[0]->conf->mld_ap) {
+		driver->hapd_deinit(drv_priv);
+	} else if (hostapd_mld_is_first_bss(iface->bss[0]) &&
+		   driver->is_drv_shared &&
+		   !driver->is_drv_shared(drv_priv, iface->bss[0])) {
+		driver->hapd_deinit(drv_priv);
+	} else if (hostapd_if_link_remove(iface->bss[0],
+					  WPA_IF_AP_BSS,
+					  iface->bss[0]->conf->iface,
+					  iface->bss[0]->mld_link_id)) {
+		wpa_printf(MSG_WARNING, "Failed to remove BSS interface %s",
+			   iface->bss[0]->conf->iface);
+	}
+#else /* CONFIG_IEEE80211BE */
+	driver->hapd_deinit(drv_priv);
+#endif /* CONFIG_IEEE80211BE */
+	iface->bss[0]->drv_priv = NULL;
+}
+
+
 void hostapd_interface_deinit_free(struct hostapd_iface *iface)
 {
 	const struct wpa_driver_ops *driver;
@@ -3320,11 +3340,7 @@ void hostapd_interface_deinit_free(struct hostapd_iface *iface)
 	hostapd_interface_deinit(iface);
 	wpa_printf(MSG_DEBUG, "%s: driver=%p drv_priv=%p -> hapd_deinit",
 		   __func__, driver, drv_priv);
-	if (driver && driver->hapd_deinit && drv_priv) {
+	hostapd_cleanup_driver(driver, drv_priv, iface);
-		if (hostapd_mld_is_first_bss(iface->bss[0]))
-			driver->hapd_deinit(drv_priv);
-		hostapd_clear_drv_priv(iface->bss[0]);
-	}
 	hostapd_interface_free(iface);
 }
 
@@ -3337,15 +3353,16 @@ static void hostapd_deinit_driver(const struct wpa_driver_ops *driver,
 
 	wpa_printf(MSG_DEBUG, "%s: driver=%p drv_priv=%p -> hapd_deinit",
 		   __func__, driver, drv_priv);
+
+	hostapd_cleanup_driver(driver, drv_priv, hapd_iface);
+
 	if (driver && driver->hapd_deinit && drv_priv) {
-		if (hostapd_mld_is_first_bss(hapd_iface->bss[0]))
-			driver->hapd_deinit(drv_priv);
 		for (j = 0; j < hapd_iface->num_bss; j++) {
 			wpa_printf(MSG_DEBUG, "%s:bss[%d]->drv_priv=%p",
 				   __func__, (int) j,
 				   hapd_iface->bss[j]->drv_priv);
 			if (hapd_iface->bss[j]->drv_priv == drv_priv) {
-				hostapd_clear_drv_priv(hapd_iface->bss[j]);
+				hapd_iface->bss[j]->drv_priv = NULL;
 				hapd_iface->extended_capa = NULL;
 				hapd_iface->extended_capa_mask = NULL;
 				hapd_iface->extended_capa_len = 0;

src/drivers/driver.h

@@ -5165,6 +5165,19 @@ struct wpa_driver_ops {
 	int (*link_remove)(void *priv, enum wpa_driver_if_type type,
 			   const char *ifname, u8 link_id);
 
+	/**
+	 * is_drv_shared - Check whether the driver interface is shared
+	 * @priv: Private driver interface data from init()
+	 * @bss_ctx: BSS context for %WPA_IF_AP_BSS interfaces
+	 *
+	 * Checks whether the driver interface is being used by other partner
+	 * BSS(s) or not. This is used to decide whether the driver interface
+	 * needs to be deinitilized when one interface is getting deinitialized.
+	 *
+	 * Returns: true if it is being used or else false.
+	 */
+	bool (*is_drv_shared)(void *priv, void *bss_ctx);
+
 #ifdef CONFIG_TESTING_OPTIONS
 	int (*register_frame)(void *priv, u16 type,
 			      const u8 *match, size_t match_len,

src/drivers/driver_nl80211.c

@@ -10715,6 +10715,7 @@ static int driver_nl80211_if_remove(void *priv, enum wpa_driver_if_type type,
 
 
 #ifdef CONFIG_IEEE80211BE
+
 static int driver_nl80211_link_remove(void *priv, enum wpa_driver_if_type type,
 				      const char *ifname, u8 link_id)
 {
@@ -10744,6 +10745,39 @@ static int driver_nl80211_link_remove(void *priv, enum wpa_driver_if_type type,
 
 	return 0;
 }
+
+
+static bool nl80211_is_drv_shared(void *priv, void *bss_ctx)
+{
+	struct i802_bss *bss = priv;
+	struct wpa_driver_nl80211_data *drv = bss->drv;
+	unsigned int num_bss = 0;
+
+	/* If any other BSS exist, someone else is using this since at this
+	 * time, we would have removed all BSSs created by this driver and only
+	 * this BSS should be remaining if the driver is not shared by anyone.
+	 */
+	for (bss = drv->first_bss; bss; bss = bss->next) {
+		num_bss++;
+		if (num_bss > 1)
+			return true;
+	}
+
+	/* This is the only BSS present */
+	bss = priv;
+
+	/* If only one/no link is there no one is sharing */
+	if (bss->valid_links <= 1)
+		return false;
+
+	/* More than one link means someone is still using. To check if
+	 * only 1 bit is set, power of 2 condition can be checked. */
+	if (!(bss->valid_links & (bss->valid_links - 1)))
+		return false;
+
+	return true;
+}
+
 #endif /* CONFIG_IEEE80211BE */
 
 
@@ -14078,6 +14112,7 @@ const struct wpa_driver_ops wpa_driver_nl80211_ops = {
 	.link_add = nl80211_link_add,
 #ifdef CONFIG_IEEE80211BE
 	.link_remove = driver_nl80211_link_remove,
+	.is_drv_shared = nl80211_is_drv_shared,
 #endif /* CONFIG_IEEE80211BE */
 #ifdef CONFIG_TESTING_OPTIONS
 	.register_frame = testing_nl80211_register_frame,