Hey guys, It's possible to create a tun device in a process in namespace A and then move that interface to namespace B. The controlling process in A needs to receive notifications on when the interface is brought up or down. It can receive these notifications via netlink while the interface lives in A but not when it moves to B.
Any tricks or APIs to get around this? The best I've come up with is, in a sleep loop, writing to the tun device's fd something with a NULL or invalid payload. If the interface is down, the kernel returns -EIO. If the interface is up, the kernel returns -EFAULT. This seems to be a reliable distinguisher, but is a pretty insane way of doing it. And sleep loops are somewhat different from events too. If there aren't any current APIs for receiving events directly from the fd of a tun interface, would this list be happy with a patch that adds one? Thanks, Jason
