network: retrieve correct names and ifindices

network: retrieve correct names and ifindices

On privileged network creation we only retrieved the names and ifindeces of
network devices in the host's network namespace. This meant that the monitor
process was acting on possibly incorrect information. With this commit we have
the child send back the correct device names and ifindeces in the container's
network namespace.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>