4. Access Control and Rootly Powers


Access control is an area of active research, and it has long been one of the major challenges of operating system design. Generically speaking, operating systems define accounts for individual users, and they offer those users a smorgasbord of possible operations: editing text files, logging into remote computers, setting the system’s hostname, installing new software, and so on. The access control system is the black box that considers potential actions (user/operation pairs) and issues rulings as to whether each action is permissible.

In the case of UNIX and Linux, there isn’t really a single black box that ...

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