TAILIEUCHUNG - Lecture Operating system concepts (Sixth ed) - Chapter 18: Protection

The various processes in an operating system must be protected from one another’s activities. For that purpose, various mechanisms exist that can be used to ensure that the files, memory segments, CPU, and other resources can be operated on by only those processes that have gained proper authorization from the operating system. In this chapter, we examine the problem of protection in great detail and develop a unifying model for implementing protection. | Module 18 Protection Goals of Protection Domain of Protection Access Matrix Implementation of Access Matrix Revocation of Access Rights Capability-Based Systems Language-Based Protection 4 Operating System Concepts Operating System Concepts Silberschatz Galvin and Gagne 2002 Protection Operating system consists of a collection of objects hardware or software Each object has a unique name and can be accessed through a well-defined set of operations. Protection problem - ensure that each object is accessed correctly and only by those processes that are allowed to do so. 4J Operating System Concepts Silberschatz Galvin and Gagne 2002 Access-right object-name rights-set where rights-set is a subset of all valid operations that can be performed on the object. Domain set of access-rights Operating System Concepts Silberschatz Galvin and Gagne 2002 p Domain Implementation UNIX System consists of 2 domains User Supervisor UNIX Domain user-id Domain switch accomplished via file system. Each file has associated with it a domain bit setuid bit . When file is executed and setuid on then user-id is set to owner of the file being executed. When execution completes user-id is reset. Operating System Concepts Silberschatz Galvin and Gagne 2002 Domain Implementation Multics Let D and Djbe any two domain rings. If j I Dị Dj ring 0 ring 1 4 Operating System Concepts Silberschatz Galvin and Gagne 2002 Multics Rings Multics Rings Silberschatz Galvin and Gagne 2002 Access Matrix View protection as a matrix access matrix Rows represent domains Columns represent objects Access ị j is the set of operations that a process executing in Domaini can invoke on Objectj 4 Operating System Concepts Silberschatz Galvin and Gagne 2002 4 Operating System Concepts Silberschatz Galvin and Gagne .

• Hệ điều hành
• Operating system concepts
• Lecture Operating system concepts
• Operating system
• Operating system structure
• Hệ điều hành
• Access matrix
• Operating system services
• Operating system structures
• Operating system design
• Computer system organization
• Operating System Debugging
• Operating System Generation
• Types of System Calls
• Computer system structures
• File system interface
• File system implementation
• Computer system architecture
• The Linux system