4 files changed, 47 insertions, 4 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index a6f74b2b9571..a2cbe61f6e65 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -390,6 +390,10 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
         if (dev->br_port != NULL)
                 return -EBUSY;
 
+        /* No bridging devices that dislike that (e.g. wireless) */
+        if (dev->priv_flags & IFF_DONT_BRIDGE)
+                return -EOPNOTSUPP;
+
         p = new_nbp(br, dev);
         if (IS_ERR(p))
                 return PTR_ERR(p);
diff --git a/net/wireless/core.c b/net/wireless/core.c
index e2cc6e7522dd..fc5e9b508607 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -697,6 +697,10 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
 #endif
                 if (!dev->ethtool_ops)
                         dev->ethtool_ops = &cfg80211_ethtool_ops;
+
+                if ((wdev->iftype == NL80211_IFTYPE_STATION ||
+                     wdev->iftype == NL80211_IFTYPE_ADHOC) && !wdev->use_4addr)
+                        dev->priv_flags |= IFF_DONT_BRIDGE;
                 break;
         case NETDEV_GOING_DOWN:
                 switch (wdev->iftype) {
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index b7b0f67b0c61..149539ade15e 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -969,10 +969,14 @@ static int parse_monitor_flags(struct nlattr *nla, u32 *mntrflags)
 }
 
 static int nl80211_valid_4addr(struct cfg80211_registered_device *rdev,
-                               u8 use_4addr, enum nl80211_iftype iftype)
+                               struct net_device *netdev, u8 use_4addr,
+                               enum nl80211_iftype iftype)
 {
-        if (!use_4addr)
+        if (!use_4addr) {
+                if (netdev && netdev->br_port)
+                        return -EBUSY;
                 return 0;
+        }
 
         switch (iftype) {
         case NL80211_IFTYPE_AP_VLAN:
@@ -1033,7 +1037,7 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_4ADDR]) {
                 params.use_4addr = !!nla_get_u8(info->attrs[NL80211_ATTR_4ADDR]);
                 change = true;
-                err = nl80211_valid_4addr(rdev, params.use_4addr, ntype);
+                err = nl80211_valid_4addr(rdev, dev, params.use_4addr, ntype);
                 if (err)
                         goto unlock;
         } else {
@@ -1111,7 +1115,7 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 
         if (info->attrs[NL80211_ATTR_4ADDR]) {
                 params.use_4addr = !!nla_get_u8(info->attrs[NL80211_ATTR_4ADDR]);
-                err = nl80211_valid_4addr(rdev, params.use_4addr, type);
+                err = nl80211_valid_4addr(rdev, NULL, params.use_4addr, type);
                 if (err)
                         goto unlock;
         }
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 17a7a4cfc617..59361fdcb5d0 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -658,6 +658,11 @@ 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 (dev->br_port && (ntype == NL80211_IFTYPE_ADHOC ||
+                             ntype == NL80211_IFTYPE_STATION))
+                return -EBUSY;
+
         if (ntype != otype) {
                 dev->ieee80211_ptr->use_4addr = false;
 
@@ -687,5 +692,31 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
         if (!err && params && params->use_4addr != -1)
                 dev->ieee80211_ptr->use_4addr = params->use_4addr;
 
+        if (!err) {
+                dev->priv_flags &= ~IFF_DONT_BRIDGE;
+                switch (ntype) {
+                case NL80211_IFTYPE_STATION:
+                        if (dev->ieee80211_ptr->use_4addr)
+                                break;
+                        /* fall through */
+                case NL80211_IFTYPE_ADHOC:
+                        dev->priv_flags |= IFF_DONT_BRIDGE;
+                        break;
+                case NL80211_IFTYPE_AP:
+                case NL80211_IFTYPE_AP_VLAN:
+                case NL80211_IFTYPE_WDS:
+                case NL80211_IFTYPE_MESH_POINT:
+                        /* bridging OK */
+                        break;
+                case NL80211_IFTYPE_MONITOR:
+                        /* monitor can't bridge anyway */
+                        break;
+                case NL80211_IFTYPE_UNSPECIFIED:
+                case __NL80211_IFTYPE_AFTER_LAST:
+                        /* not happening */
+                        break;
+                }
+        }
+
         return err;
 }