net: forbid underlaying devices to change its type

It's not desired for underlaying devices to change type. At the time,
there is for example possible to have bond with changed type from
Ethernet to Infiniband as a port of a bridge. This patch fixes this.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 453512266ea1..c39a5f41169c 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -530,6 +530,10 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
                 }
                 unregister_netdevice_many(&list);
                 break;
+
+        case NETDEV_PRE_TYPE_CHANGE:
+                /* Forbid underlaying device to change its type. */
+                return NOTIFY_BAD;
         }
 
 out: