Any services that have method_call EmitEvent privs on the D-Bus com.ubuntu.Upstart send_destination (com.ubuntu.Upstart0_6 send_interface) can cause arc-sensor.conf to run the mknod command in the context of the namespace of any arbitrary process, which is bad in the case that said namespace bind mounts (controls) the program at /system/bin/mknod.

We should add some kind of sanity checking here if possible. This is a follow-up of crbug.com/884917.