ROLE-BASED ACCESS CONTROL:A MULTI-DIMENSIONAL VIEW
Ravi Sandhu, Edward Coyne,Hal Feinstein and Charles Youman
Seta CorporationMcLean, VA
Ravi Sandhu is also affiliated withGeorge Mason University, Fairfax, VA
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RBAC
• An alternative to classical MAC and DAC
• Substantial history and tradition
• Often used to separate administrative functions
• Extend this concept into application domain
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
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PRIVILEGES
• Primitive privileges
• read, write, append, execute
• Abstract privileges
• credit, debit, inquiry
• Generic privileges
• auditor
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USERS
• Users are human beings
• Each individual should be known as exactly one user
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POLICY VERSUS MECHANISM
• Roles are a policy concept
• Several mechanisms can be used to implement roles
• Roles
• Groups
• Compartments
• Some mechanisms are better suited than others
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WHAT IS THE POLICY IN RBAC?
• There is no information flow policy
• RBAC is a framework to help in articulating policy
• The main point of RBAC is to facilitate security management
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INTERACTION OF RBAC, MAC AND DAC
RBAC
MAC DAC
permitted accesses
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
ROLEHIERARCHIES
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HIERARCHICAL ROLES
Health-Care Provider
Physician
Primary-CarePhysician
SpecialistPhysician
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HIERARCHICAL ROLES
Engineer
HardwareEngineer
SoftwareEngineer
SupervisingEngineer
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SCOPED INHERITANCE
Department Head
Project 1 Manager Project 2 Manager
Department Public
Project 1 Public Project 2 Public
Project 1Programmers
Project 1Testing
Project 2Programmers
Project 2Testing
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RBAC
ROLEUSERS PRIVILEGES
ROLEHIERARCHIES
CONSTRAINTS
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
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CONSTRAINTS
• Mutually Exclusive Roles
• Static Exclusion: The same individual can never hold both roles
• Dynamic Exclusion: The same individual can never hold both roles in the same context
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CONSTRAINTS
• Mutually Exclusive Privileges
• Static Exclusion: The same role should never be assigned both privileges
• Dynamic Exclusion: The same role can never hold both privileges in the same context
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CONSTRAINTS
• Cardinality Constraints on User-Role Assignment
• At most k users can belong to the role
• At least k users must belong to the role
• Exactly k users must belong to the role
• Cardinality Constraints on Privilege-Role Assignment
• At most k roles can get the privilege
• At least k roles must get the privilege
• Exactly k roles must get the privilege
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
ROLEHIERARCHIES
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SCALE
• Hundreds of roles
• User-role assignment will change frequently
• Privilege-role assignment will change frequently
• Role hierarchy will change occasionally
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RBAC SUMMARY
• RBAC is a sophisticated and multi-dimensional concept
• Different products will support variations of RBAC (even if standards emerge)
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BELL-LAPADULA AND RBAC
• Can BLP be practically and conveniently done in RBAC?
YES
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IS RBAC A PANACEA?
• NO
