cfg80211: NL80211_ATTR_SOCKET_OWNER support for CMD_CONNECT

Disconnect or deauthenticate when the owning socket is closed if this
flag is supplied to CMD_CONNECT or CMD_ASSOCIATE.  This may be used
to ensure userspace daemon doesn't leave an unmanaged connection behind.

In some situations it would be possible to account for that, to some
degree, in the deamon restart code or in the up/down scripts without
the use of this attribute.  But there will be systems where the daemon
can go away for varying periods without a warning due to local resource
management.
Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -3865,6 +3865,9 @@ struct cfg80211_cached_keys;
  * @conn: (private) cfg80211 software SME connection state machine data
  * @connect_keys: (private) keys to set after connection is established
  * @conn_bss_type: connecting/connected BSS type
+ * @conn_owner_nlportid: (private) connection owner socket port ID
+ * @disconnect_wk: (private) auto-disconnect work
+ * @disconnect_bssid: (private) the BSSID to use for auto-disconnect
  * @ibss_fixed: (private) IBSS is using fixed BSSID
  * @ibss_dfs_possible: (private) IBSS may change to a DFS channel
  * @event_list: (private) list for internal event processing
@@ -3896,6 +3899,10 @@ struct wireless_dev {
 	struct cfg80211_conn *conn;
 	struct cfg80211_cached_keys *connect_keys;
 	enum ieee80211_bss_type conn_bss_type;
+	u32 conn_owner_nlportid;
+
+	struct work_struct disconnect_wk;
+	u8 disconnect_bssid[ETH_ALEN];
 
 	struct list_head event_list;
 	spinlock_t event_lock;

include/uapi/linux/nl80211.h

@@ -1820,6 +1820,8 @@ enum nl80211_commands {
  *	and remove functions. NAN notifications will be sent in unicast to that
  *	socket. Without this attribute, any socket can add functions and the
  *	notifications will be sent to the %NL80211_MCGRP_NAN multicast group.
+ *	If set during %NL80211_CMD_ASSOCIATE or %NL80211_CMD_CONNECT the
+ *	station will deauthenticate when the socket is closed.
  *
  * @NL80211_ATTR_TDLS_INITIATOR: flag attribute indicating the current end is
  *	the TDLS link initiator.

net/wireless/core.c

@@ -1142,6 +1142,8 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		     wdev->iftype == NL80211_IFTYPE_ADHOC) && !wdev->use_4addr)
 			dev->priv_flags |= IFF_DONT_BRIDGE;
 
+		INIT_WORK(&wdev->disconnect_wk, cfg80211_autodisconnect_wk);
+
 		nl80211_notify_iface(rdev, wdev, NL80211_CMD_NEW_INTERFACE);
 		break;
 	case NETDEV_GOING_DOWN:
@@ -1230,6 +1232,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 #ifdef CONFIG_CFG80211_WEXT
 			kzfree(wdev->wext.keys);
 #endif
+			flush_work(&wdev->disconnect_wk);
 		}
 		/*
 		 * synchronise (so that we won't find this netdev

net/wireless/core.h

@@ -400,6 +400,7 @@ void __cfg80211_roamed(struct wireless_dev *wdev,
 		       const u8 *resp_ie, size_t resp_ie_len);
 int cfg80211_mgd_wext_connect(struct cfg80211_registered_device *rdev,
 			      struct wireless_dev *wdev);
+void cfg80211_autodisconnect_wk(struct work_struct *work);
 
 /* SME implementation */
 void cfg80211_conn_work(struct work_struct *work);

net/wireless/mlme.c

@@ -345,6 +345,11 @@ int cfg80211_mlme_deauth(struct cfg80211_registered_device *rdev,
 	     !ether_addr_equal(wdev->current_bss->pub.bssid, bssid)))
 		return 0;
 
+	if (ether_addr_equal(wdev->disconnect_bssid, bssid) ||
+	    (wdev->current_bss &&
+	     ether_addr_equal(wdev->current_bss->pub.bssid, bssid)))
+		wdev->conn_owner_nlportid = 0;
+
 	return rdev_deauth(rdev, dev, &req);
 }
 

net/wireless/nl80211.c

@@ -8050,8 +8050,17 @@ static int nl80211_associate(struct sk_buff *skb, struct genl_info *info)
 	err = nl80211_crypto_settings(rdev, info, &req.crypto, 1);
 	if (!err) {
 		wdev_lock(dev->ieee80211_ptr);
+
 		err = cfg80211_mlme_assoc(rdev, dev, chan, bssid,
 					  ssid, ssid_len, &req);
+
+		if (!err && info->attrs[NL80211_ATTR_SOCKET_OWNER]) {
+			dev->ieee80211_ptr->conn_owner_nlportid =
+				info->snd_portid;
+			memcpy(dev->ieee80211_ptr->disconnect_bssid,
+			       bssid, ETH_ALEN);
+		}
+
 		wdev_unlock(dev->ieee80211_ptr);
 	}
 
@@ -8770,11 +8779,24 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	wdev_lock(dev->ieee80211_ptr);
+
 	err = cfg80211_connect(rdev, dev, &connect, connkeys,
 			       connect.prev_bssid);
-	wdev_unlock(dev->ieee80211_ptr);
 	if (err)
 		kzfree(connkeys);
+
+	if (!err && info->attrs[NL80211_ATTR_SOCKET_OWNER]) {
+		dev->ieee80211_ptr->conn_owner_nlportid = info->snd_portid;
+		if (connect.bssid)
+			memcpy(dev->ieee80211_ptr->disconnect_bssid,
+			       connect.bssid, ETH_ALEN);
+		else
+			memset(dev->ieee80211_ptr->disconnect_bssid,
+			       0, ETH_ALEN);
+	}
+
+	wdev_unlock(dev->ieee80211_ptr);
+
 	return err;
 }
 
@@ -14491,6 +14513,8 @@ static int nl80211_netlink_notify(struct notifier_block * nb,
 
 			if (wdev->owner_nlportid == notify->portid)
 				schedule_destroy_work = true;
+			else if (wdev->conn_owner_nlportid == notify->portid)
+				schedule_work(&wdev->disconnect_wk);
 		}
 
 		spin_lock_bh(&rdev->beacon_registrations_lock);

net/wireless/sme.c

@@ -727,6 +727,7 @@ void __cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
 		kzfree(wdev->connect_keys);
 		wdev->connect_keys = NULL;
 		wdev->ssid_len = 0;
+		wdev->conn_owner_nlportid = 0;
 		if (bss) {
 			cfg80211_unhold_bss(bss_from_pub(bss));
 			cfg80211_put_bss(wdev->wiphy, bss);
@@ -955,6 +956,7 @@ void __cfg80211_disconnected(struct net_device *dev, const u8 *ie,
 
 	wdev->current_bss = NULL;
 	wdev->ssid_len = 0;
+	wdev->conn_owner_nlportid = 0;
 
 	nl80211_send_disconnected(rdev, dev, reason, ie, ie_len, from_ap);
 
@@ -1098,6 +1100,8 @@ int cfg80211_disconnect(struct cfg80211_registered_device *rdev,
 	kzfree(wdev->connect_keys);
 	wdev->connect_keys = NULL;
 
+	wdev->conn_owner_nlportid = 0;
+
 	if (wdev->conn)
 		err = cfg80211_sme_disconnect(wdev, reason);
 	else if (!rdev->ops->disconnect)
@@ -1107,3 +1111,32 @@ int cfg80211_disconnect(struct cfg80211_registered_device *rdev,
 
 	return err;
 }
+
+/*
+ * Used to clean up after the connection / connection attempt owner socket
+ * disconnects
+ */
+void cfg80211_autodisconnect_wk(struct work_struct *work)
+{
+	struct wireless_dev *wdev =
+		container_of(work, struct wireless_dev, disconnect_wk);
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+
+	wdev_lock(wdev);
+
+	if (wdev->conn_owner_nlportid) {
+		/*
+		 * Use disconnect_bssid if still connecting and ops->disconnect
+		 * not implemented.  Otherwise we can use cfg80211_disconnect.
+		 */
+		if (rdev->ops->disconnect || wdev->current_bss)
+			cfg80211_disconnect(rdev, wdev->netdev,
+					    WLAN_REASON_DEAUTH_LEAVING, true);
+		else
+			cfg80211_mlme_deauth(rdev, wdev->netdev,
+					     wdev->disconnect_bssid, NULL, 0,
+					     WLAN_REASON_DEAUTH_LEAVING, false);
+	}
+
+	wdev_unlock(wdev);
+}