Merge tag 'mac80211-next-for-net-next-2021-02-02' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next

Johannes Berg says:

====================
This time, only RTNL locking reduction fallout.
 - cfg80211_dev_rename() requires RTNL
 - cfg80211_change_iface() and cfg80211_set_encryption()
   require wiphy mutex (was missing in wireless extensions)
 - cfg80211_destroy_ifaces() requires wiphy mutex
 - netdev registration can fail due to notifiers, and then
   notifiers are "unrolled", need to handle this properly

* tag 'mac80211-next-for-net-next-2021-02-02' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next:
  cfg80211: fix netdev registration deadlock
  cfg80211: call cfg80211_destroy_ifaces() with wiphy lock held
  wext: call cfg80211_set_encryption() with wiphy lock held
  wext: call cfg80211_change_iface() with wiphy lock held
  nl80211: call cfg80211_dev_rename() under RTNL
====================

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

include/net/cfg80211.h

@@ -5299,6 +5299,8 @@ static inline void wiphy_unlock(struct wiphy *wiphy)
  * @wiphy: pointer to hardware description
  * @iftype: interface type
  * @registered: is this wdev already registered with cfg80211
+ * @registering: indicates we're doing registration under wiphy lock
+ *	for the notifier
  * @list: (private) Used to collect the interfaces
  * @netdev: (private) Used to reference back to the netdev, may be %NULL
  * @identifier: (private) Identifier used in nl80211 to identify this
@@ -5382,7 +5384,7 @@ struct wireless_dev {
 
 	struct mutex mtx;
 
-	bool use_4addr, is_running, registered;
+	bool use_4addr, is_running, registered, registering;
 
 	u8 address[ETH_ALEN] __aligned(sizeof(u16));
 

net/wireless/core.c

@@ -334,6 +334,7 @@ void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev)
 	struct wireless_dev *wdev, *tmp;
 
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(&rdev->wiphy);
 
 	list_for_each_entry_safe(wdev, tmp, &rdev->wiphy.wdev_list, list) {
 		if (wdev->nl_owner_dead)
@@ -349,7 +350,9 @@ static void cfg80211_destroy_iface_wk(struct work_struct *work)
 			    destroy_work);
 
 	rtnl_lock();
+	wiphy_lock(&rdev->wiphy);
 	cfg80211_destroy_ifaces(rdev);
+	wiphy_unlock(&rdev->wiphy);
 	rtnl_unlock();
 }
 
@@ -1343,6 +1346,7 @@ int cfg80211_register_netdevice(struct net_device *dev)
 
 	/* we'll take care of this */
 	wdev->registered = true;
+	wdev->registering = true;
 	ret = register_netdevice(dev);
 	if (ret)
 		goto out;
@@ -1358,6 +1362,7 @@ int cfg80211_register_netdevice(struct net_device *dev)
 	cfg80211_register_wdev(rdev, wdev);
 	ret = 0;
 out:
+	wdev->registering = false;
 	if (ret)
 		wdev->registered = false;
 	return ret;
@@ -1400,7 +1405,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		 * It is possible to get NETDEV_UNREGISTER multiple times,
 		 * so check wdev->registered.
 		 */
-		if (wdev->registered) {
+		if (wdev->registered && !wdev->registering) {
 			wiphy_lock(&rdev->wiphy);
 			_cfg80211_unregister_wdev(wdev, false);
 			wiphy_unlock(&rdev->wiphy);

net/wireless/nl80211.c

@@ -3220,7 +3220,6 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 		wdev = netdev->ieee80211_ptr;
 
 	wiphy_lock(&rdev->wiphy);
-	rtnl_unlock();
 
 	/*
 	 * end workaround code, by now the rdev is available
@@ -3230,6 +3229,7 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[NL80211_ATTR_WIPHY_NAME])
 		result = cfg80211_dev_rename(
 			rdev, nla_data(info->attrs[NL80211_ATTR_WIPHY_NAME]));
+	rtnl_unlock();
 
 	if (result)
 		goto out;

net/wireless/wext-compat.c

@@ -39,6 +39,7 @@ int cfg80211_wext_siwmode(struct net_device *dev, struct iw_request_info *info,
 	struct cfg80211_registered_device *rdev;
 	struct vif_params vifparams;
 	enum nl80211_iftype type;
+	int ret;
 
 	rdev = wiphy_to_rdev(wdev->wiphy);
 
@@ -61,7 +62,11 @@ int cfg80211_wext_siwmode(struct net_device *dev, struct iw_request_info *info,
 
 	memset(&vifparams, 0, sizeof(vifparams));
 
-	return cfg80211_change_iface(rdev, dev, type, &vifparams);
+	wiphy_lock(wdev->wiphy);
+	ret = cfg80211_change_iface(rdev, dev, type, &vifparams);
+	wiphy_unlock(wdev->wiphy);
+
+	return ret;
 }
 EXPORT_WEXT_HANDLER(cfg80211_wext_siwmode);
 
@@ -650,6 +655,7 @@ static int cfg80211_wext_siwencodeext(struct net_device *dev,
 	bool remove = false;
 	struct key_params params;
 	u32 cipher;
+	int ret;
 
 	if (wdev->iftype != NL80211_IFTYPE_STATION &&
 	    wdev->iftype != NL80211_IFTYPE_ADHOC)
@@ -721,12 +727,16 @@ static int cfg80211_wext_siwencodeext(struct net_device *dev,
 		params.seq_len = 6;
 	}
 
-	return cfg80211_set_encryption(
+	wiphy_lock(wdev->wiphy);
+	ret = cfg80211_set_encryption(
 			rdev, dev,
 			!(ext->ext_flags & IW_ENCODE_EXT_GROUP_KEY),
 			addr, remove,
 			ext->ext_flags & IW_ENCODE_EXT_SET_TX_KEY,
 			idx, &params);
+	wiphy_unlock(wdev->wiphy);
+
+	return ret;
 }
 
 static int cfg80211_wext_giwencode(struct net_device *dev,