For improving the security of Linux services, Lennart added ReadOnlySystem and ProtectedHome settings for services. ReadOnlySystem will mount /usr and /boot as read-only for the specific service. The ProtectedHome setting mounts /home and /run/user as read-only or replaces it with an empty, inaccessible directory.
Lennart wrote on Google+, "With these easy options we hence can make sure now that specific services don't get the chance to modify the operating system itself, or to get access to the user's personal data. I have also now enabled this functionality for all of systemd's own long-running services. Of course, ideally we get all of Fedora to enable these settings for all long-running services. This should improve our security quite a bit by default, in particular for network-facing services."
These new service unit security features were commited to systemd Git yesterday and will be part of the systemd 214 release.