Role-Based Access Control (RBAC)

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Role-based access control (RBAC) is an access control model where resources are protected by ACLs that are managed by administrators and that provide user permissions based on job functions (roles).

• Each set of permissions is a role
• Each principal is allocated to one or more roles
  • a user or service account
• right to modify the permissions assigned to each role is reserved to a system owner
• system is nondiscretionary
  • each principal cannot modify the ACL of a resource
  • though they can change the resource in other ways
• Principals gain rights implicitly, rather than explicitly
  • through being assigned to a role vs being assigned the right directly
• filesystem ACLs are where these permissions are stored and enforced
  • locally or networked storage

Security Groups

• a security group account partially turns a discretionary system into a role-based one
  • rather assigning rights directly to user accounts
    • system owner assigns user accounts to security group accounts
  • principals gain rights by being made a member of a security group
    • can be a member of multiple groups
    • can receive rights and permissions from several sources
      
  • RBAC can be partially implemented by mapping security groups onto roles
    • but are not identical schemes
  • membership in security groups is discretionary
    • assigned by admins rather than determined by the system
  • ideally, a principal should only inherit the permissions of a role to complete a particular task
    • not retain them permanently
  • admins should be prevented from escalating their own privileges
    • e.g.,
      • assigning roles to their own accounts arbitrarily
      • boosting a role’s permissions