Role Based Access Control Models

1. Role Based Access Control Models Presented By Ankit Shah 2nd Year Master’s Student

2. Problems • Mandatory Access Control (MAC) • Central authority determines access control • Discretionary Access Control (DAC) • Decentralized • Access control decisions lie with the owner of an object • Access control on a per user basis • Access control needs are unique • Existing products lack flexibility

3. Solution • Role Based Access Control • Permission associated with roles and users assigned to appropriate roles • Motivation • Organization style • Competency • Authority and responsibility • Duty assignments - Security administration and review - Simple role-permission relationship - Ability to meet the changing needs of an organization

4. Role related concepts • What is the difference between roles and groups? • User – permission distinction • Eg. Unix operating system • RBAC is policy neutral but supports • Least privilege • Separation of duties • Data Abstraction

5. Four Reference Models

6. Base Model (RBAC0) • User • Typically a human being • Role • Job title • Permission • Approval of a mode of access to some object • Variety of permissions from coarse grain to fine grain • Depends on implementation details of the system • Session • Mapping of one user to many roles • Multiple sessions • Each session may map single or multiple roles of the users subset

7. RBAC Models

8. Role Hierarchies (RBAC1) • Reflects an organization’s role structure • Supports inheritance of permissions • Hierarchies are a partial order • Useful to limit scope of inheritance • Private roles

9. Role Hierarchy Examples

10. Role Hierarchy Examples Continued

11. Constraints (RBAC2) • Argued to be the principal motivation • Is a convenience when RBAC is centralized • When decentralized becomes a mechanism for restriction • Types of Constraints • Mutually exclusive roles/ permissions • Cardinality constraints • Prerequisite roles • Effective only if suitable discipline is observed • Mapping one user to more than one u-id • Mapping one permission to more than one p-id • Role Hierarchies can be considered a constraint

12. Consolidated Model (RBAC3) • Combines Constraints and Role Hierarchies • Issues raised • Constraints can apply to the role hierarchy itself • Violation of mutual exclusion constraint may be acceptable • Specify mutual exclusion of private roles without any conflict

13. Management Model • Till now, we assumed the presence of a single security officer • Normally have a small administrative team to mange RBAC • Propagation of rights

14. Management Model

15. Management Model Proposed • Administrative roles and permissions are disjoint from regular roles and permissions • Administrative authority can be viewed as the ability to modify user assignments, permissions, assignment and role hierarchy relations. • Mirror copy of the top half with ARBAC0-3 for different levels of sophistication • Issues • How to scope administrative authority in administrative roles • Scope permissions and users of an administrative role

16. Management Model Continued

17. Critique • Was published in 1996 and a lot of improvements have been proposed to these models • Issues are raised in the consolidated and management models but no solution is proposed • Lacked a related work section giving us an overview of similar work done and how the proposed model is superior

18. Questions