File system calls open execute directory traversal a

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Unformatted text preview: Efficiency Simplicity Flexibility CS 236 Online Lecture 3 Page 31 An Example Reference Monitor • The Linux code that mediates file access • Applied on relatively few of the file system calls – Open, execute, directory traversal, a few others – Not on read and write CS 236 Online Lecture 3 Page 32 Another Example Reference Monitor • A firewall • It examines every packet for certain characteristics • Typically, either any subject can do something or no subject can • But sometimes packets from particular source addresses can do more – Essentially, the source address identifies a privileged subject CS 236 Online Lecture 3 Page 33 Thinking More Broadly About Access Control • From one perspective, access control is the core of all computer security • All security is about who can access what • So where do security problems come from? – Not applying access control – Not applying access control properly CS 236 Online Lecture 3 Page 34 What Is the Most Common Access Control Mechanism? • T...
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This document was uploaded on 11/01/2013.

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