3 files changed, 43 insertions, 4 deletions

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;
 }