cfg80211: correct bridge/4addr mode check

Without the patch we fail:

$ sudo brctl addbr br0
$ sudo brctl addif br0 wlp1s0
$ sudo iw wlp1s0 set 4addr on
command failed: Device or resource busy (-16)

Last command failed but iface was already in 4addr mode.

Fixes: ad4bb6f8883a ("cfg80211: disallow bridging managed/adhoc interfaces")
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@gmail.com>
Link: https://lore.kernel.org/r/20211024201546.614379-1-janusz.dziedzic@gmail.com
[add fixes tag, fix indentation, edit commit log]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 18dba3d7c638bd0b606f360a46395efa302e528c..a1a99a5749844a7314f48f7bb99b9be7988c75b0 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1028,14 +1028,14 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
            !(rdev->wiphy.interface_modes & (1 << ntype)))
                return -EOPNOTSUPP;
 
-       /* if it's part of a bridge, reject changing type to station/ibss */
-       if (netif_is_bridge_port(dev) &&
-           (ntype == NL80211_IFTYPE_ADHOC ||
-            ntype == NL80211_IFTYPE_STATION ||
-            ntype == NL80211_IFTYPE_P2P_CLIENT))
-               return -EBUSY;
-
        if (ntype != otype) {
+               /* if it's part of a bridge, reject changing type to station/ibss */
+               if (netif_is_bridge_port(dev) &&
+                   (ntype == NL80211_IFTYPE_ADHOC ||
+                    ntype == NL80211_IFTYPE_STATION ||
+                    ntype == NL80211_IFTYPE_P2P_CLIENT))
+                       return -EBUSY;
+
                dev->ieee80211_ptr->use_4addr = false;
                dev->ieee80211_ptr->mesh_id_up_len = 0;
                wdev_lock(dev->ieee80211_ptr);