/usr/lib/ganeti/kvm-ifup-os is in ganeti 2.15.2-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ganeti/default/usr/lib/ganeti/kvm-ifup-os
/usr/lib/ganeti/default/usr/lib/ganeti/kvm-ifup-os