Category: CMUTR
Institution: Department of Computer Science, Carnegie
        Mellon University
Abstract: This dissertation pushes the boundary between textual and visual
        expression in a new way.
        We focus on the issue of writing specifications using a visual 
        notation, and we describe two visual languages for this purpose.
        These languages provide users with the ability to formally 
        specify security properties of a file system. 
        Relative to previous text-based approaches to security 
        specification, our use of a visual notation yields 
        specifications that are more clear and concise.
        Moreover, since we formally define the semantics of our 
        languages, every well-formed picture languages can be practical 
        and useful, even on a large scale, if they are targeted to 
        sufficiently restricted domains of interest.
        
        We focus on two different aspects of the security domain. 
        First, we use the instance language to specify security 
        configurations, that is, fixed access relationships between 
        users and files on a file system. 
        Since these specifications can be both read and written, they 
        give users the ability to determine the access rights granted on
        their files and to modify those rights. Second, we use the 
        constraint language to specify security policies, each of which
        determines a (possibly infinite) set of legal configurations.
        Systems administrators can use the constraint language to 
        experiment with different policies.
        In fact, one important application of the constraint language is
        that it provides systems administrators with a vocabulary for 
        specifying and automatically detecting potential security holes.
        
        The semantics of both the instance language and the constraint 
        language suggest natural computational problems, each of which 
        raises interesting algorithmic questions.
        Central to our work is the design and implementation of 
        efficient algorithms for processing pictures drawn in these 
        languages.
        We describe a set of software tools we have developed, including  		visual language compiler. 
        In conjunction with the visual languages themselves, these tools 
        give users an easy way to specify and process security 
        configurations and policies.
Number: CMU-CS-91-201
Bibtype: TechReport
Month: jan
Author: C. Allan Heydon
Title: Processing Visual Specifications of File System Security
Year: 1992
Address: Pittsburgh, PA
Super: @CMUTR