Role Based Access Control Models

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Role Based Access Control Models

• Presented By
• Ankit Shah
• 2nd Year Masters Student

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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

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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

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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

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Four Reference Models
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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

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RBAC Models
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Role Hierarchies (RBAC1)

• Reflects an organizations role structure
• Supports inheritance of permissions
• Hierarchies are a partial order
• Useful to limit scope of inheritance
• Private roles

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Role Hierarchy Examples
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Role Hierarchy Examples Continued
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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

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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

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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

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Management Model
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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

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Management Model Continued
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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

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Questions