To implement an access matrix, we must first understand what it is. An access matrix is a protection model within an operating system consisting of objects and domains. The access matrix determines which processes interact with objects within the domain. Objects within the domain can consist of both hardware and software. The lists below show the advantages and disadvantages of access lists associated with objects, and capabilities with domains.
Access lists associated with objects
- Advantages
- Corresponds directly to the user’s needs.
- Easy revocation and review of access.
- Disadvantages
- Difficult to determine access rights for a domain.
- Takes time to search the domain for access rights.
Capabilities with domains
- Advantages
- Useful for localizing information for a process.
- Secured against unauthorized access.
- Disadvantages
- Inefficient at the revocation of capabilities.
- Does not correspond directly to the user’s needs.
Even though each implementation has its own strengths and weaknesses, most computer systems tend to use both types. Silberschatz et al. (2014, pages. 612-613) describe an access list as a “list for each object consisting of the domains with a nonempty set of access rights for that object.” while defining a capability list as “a list of objects together with the operations allowed on those objects” for each domain. The best implementation to use moving forward would be the lock-key mechanism as it uses both access and capability lists. The only disadvantage of the lock-key implementation is that it does not correspond directly to the needs of the users as the users cannot view or modify the list of locks or keys.
References:
Silberschatz, A., Galvin, P. B., & Gagne, G. (2014). Operating system concepts essentials (2nd ed.). Retrieved from https://redshelf.com/
Implementation of Access Matrix in Distributed OS. GeeksforGeeks. (2020, January 8). Retrieved January 27, 2022, from https://www.geeksforgeeks.org/implementation-of-access-matrix-in-distributed-os/?ref=lbp
Comments
Post a Comment