Isolation and Protection: Ensuring Process Security

This lecture discusses the critical concepts of isolation and protection in computer systems. It begins by outlining the hardware requirements necessary for efficient process execution without trusting the processes themselves. The instructor emphasizes the importance of protecting processes from one another, as well as safeguarding the operating system from potentially malicious or misbehaving processes. Key techniques such as limited direct execution and trap architecture are introduced, highlighting how the operating system manages resources and enforces security. The lecture also covers the roles of the operating system as both an illusionist, providing the appearance of exclusive resource access to each process, and as a referee, ensuring fair resource allocation. The distinction between time sharing and space sharing for resource virtualization is explained, along with the necessity for the operating system to run untrusted processes with restricted rights. The lecture concludes with a discussion on the enforcement mechanisms required to maintain isolation and protect system integrity, even in the presence of uncooperative applications.