Protection Errors in Operating Systems: Validation of Critical Conditions
Abstract
This report describes a class of operation system protection errors known as \"insufficient validation of critical conditions,\" or simply \"validaion errors,\" and outlines a scheme for finding them. This class of errors is recognized as a very broad one, lying outside the scope of the basic protection mechanisms of existing systems; the extent of the problem is illustrated by a set of validation errors taken from current systems. Considerations for validity conditions and their attachment to variables and to various types of control points in procedures are explored, and categories of validation methods noted. The notion of critiality itself is analyzed, and criteria suggested for determining which variables and control points are most critical in the protection sense. Because a search for validation errors can involve substantial information processing, the report references existing or developing tools and techniques applicable to this task.
Institution
Univeristy of Southern California
Organization
Information Sciences Institute
Publication Date
0000-00-00
Contents
Abstract...........................................v
Acknowledgements....................vi
1. Introduction...............................1
2. Motivation for the Study...........3
3. Validation as a Branch of
Protection...................................6
4. Target System
Normalization............................8
4.1 Target System Definition
and Identification.................8
4.2 System communication
Graph....................................8
4.3 Production of the
Comunication Graph.......10
5. Validation Policy....................12
5.1 Validity Conditions and
Critical Items.....................12
5.2 Input and Output
Conditions.........................12
5.3 Functional Validity versus
Integrity...............................13
6. Criticality Criteria...................15
6.1 The Chicken-and-egg
View.....................................15
6.2 Fundamental
Criticality.............................15
6.3 Influentiality....................16
6.4 Influencibility..................17
6.5 Incompleteness of
Criticality Criteria...............18
7. Validation Mechanisms and
Their Specification..................19
7.1 Enforcement of
Specifications....................19
7.2 Explicit Input and Output
Validation...........................19
7.3 Generalized
Validation...........................21
8. Sufficiency Evaluation...........22
8.1 Overall Scheme.............22
8.2 Section Evaluation:
Derivation of Conditions...22
8.3 Condition Derivation
Across Loops....................24
8.4 Termination and
Continuation
Considerations.................25
References.................................27
Keywords
criticality, errors, validation of critical conditions
Location
A hard-copy of this is in the Papers Cabinet
Subject
Critical conditions, operating system errors
