Seasoned Linux administrators and security engineers already know that they need to put some trust in the users and processes on their system in order for the system to remain secure. This is partially because users can attempt to exploit vulnerabilities found in the software running on the system, but a large contribution to this trust level is because the secure state of the system depends on the behavior of the users. A Linux user with access to sensitive information could easily leak that out to the public, manipulate the behavior of the applications he or she launches, and do many other things that affect the security of the system. The default access controls that are active on a regular Linux system are discretionary; it is up to the users how the access controls should behave.
The Linux discretionary access control (DAC) mechanism is based on the user and/or group information of the process and is matched against the user and/or group information of...