Authorization refers to rules that determine who is allowed to do what. Scope and role are two key concepts in authorization that determine what a user is allowed to access or do. Understanding the difference between scope and role is important for properly securing an application.
Scope
Scope refers to the specific resources and actions that a user is allowed to access. Scopes represent fine-grained privileges that can be assigned to a user.
For example, in an application, you may define separate scopes for:
– Read access to blog posts
– Write access to create new blog posts
– Ability to delete blog posts
– Access to view user profiles
– Ability to edit user profiles
So if a user is assigned the “blog.read” scope, they would only be allowed to view blog posts but not make any modifications. The scopes assigned to a user determine the specific actions they can perform within the application.
Some key things to note about scopes:
– Scopes represent granular privileges for accessing resources and actions.
– Users can be assigned multiple scopes based on their role.
– Scopes are additive – a user with multiple scopes has the combined privileges of all assigned scopes.
– Scope assignments are flexible and can be changed as needed for a user.
Common Scopes
Some common scopes used in applications include:
– read – Allows read access to a resource
– write – Allows modifying or creating a resource
– delete – Allows deleting a resource
– admin – A broad scope for full administrative access
Scopes may also relate to specific resources or actions like “order.create”, “user.profile.update”, etc.
Role
A role refers to a named set of privileges that users can be assigned. Roles represent coarse-grained privileges and are used to manage access for groups of users.
For example, common roles in an application may include:
– Admin – Broad privileges to manage all resources and users
– Editor – Ability to create, update and publish content
– User – Basic privileges to view content and their own profile
Some key things to note about roles:
– Roles represent broad privileges used to manage groups of users.
– Roles comprise one or more scopes that define their privileges.
– Users are assigned roles to efficiently manage access.
– Role assignments can be changed more easily than scope assignments.
Role-Based Access Control
Most authorization implementations are based on role-based access control (RBAC). With RBAC, privileges are organized into roles, and roles are assigned to specific users based on their responsibilities and job functions.
For example, an “Editor” role may contain scopes like “blog.write”, “user.profile.read”, etc. An admin would assign users to the “Editor” role to grant them the necessary access.
RBAC allows managing authorization at the role level rather than individual user and scope level, which is more efficient and scalable. Roles can be updated to change permissions for all users assigned to that role.
Scope vs Role Summary
Here is a summary of the key differences between scope and role:
Scope | Role |
---|---|
Fine-grained privilege | Coarse-grained privilege |
Represents a specific resource or action | Represents a group of related privileges |
Directly assigned to users | Assigned to users through roles |
More flexible but complex to manage | Simpler to manage with role-based access |
Example: user.profile.update | Example: Editor |
So in summary:
– Scope represents a specific privilege like ability to edit a resource.
– Role represents a group of scopes/privileges like Editor, Admin etc.
– Scopes are directly assigned to users.
– Roles comprise scopes and are assigned to users.
Scope and Role Usage
In practice, scope and role are used together to manage authorization:
– Scopes represent individual privileges like read, write, delete etc.
– Roles group related scopes like Editor, User, Admin.
– Users are assigned roles based on their function.
– The scopes within a role determine the user’s privileges.
This provides the flexibility to manage privileges at both scope and role level. Some key advantages:
– Scopes allow granular privilege assignments.
– Roles allow efficient management for groups of users.
– Separating scope and role allows reusing scopes in different roles.
– The same scopes can be added to multiple roles.
– New scopes can be introduced without changing roles.
For example, an Editor role may contain read and write scopes for content. A new “publish” scope could be added to Editor without changing the role structure.
Authorization Patterns
Some common patterns include:
– Role-based access control (RBAC) – Using predefined roles with scopes.
– Attribute-based access control (ABAC) – Using policies that combine attributes like user, resource and environment.
– Access control lists (ACL) – Low level list of users and privileges for each resource.
RBAC is the most common as it balances ease of use and flexibility. However, scopes and roles can be combined with other patterns like ABAC for more complex needs.
Implementing Scope and Role
Here are some best practices for implementing scope and role:
– Identify key resources, actions and privileges for scopes. Name scopes meaningfully.
– Group related privileges into roles that represent job functions.
– Avoid too many overlapping scopes between roles. Reuse common scopes where possible.
– Assign users minimum necessary scopes and roles. Start with restrictive privileges.
– Audit scope and role assignments periodically for unused privileges.
– Implement role hierarchies where higher roles inherit scopes from lower roles.
– Externalize authorization logic from application code where possible.
On the code side, here are some tips:
– Define constants/enums for scopes and roles.
– Use access control lists (ACLs), policies or claims to enforce authorization.
– Check user’s scopes or roles before allowing access to APIs/pages.
– Raise 403 Forbidden for unauthorized access attempts.
– Centralize authorization logic in middleware components.
– Consider using a authorization frameworks or services if available.
Authorization Frameworks
Some popular open source frameworks and standards for implementing authorization include:
– OAuth 2.0 – Industry standard protocol for access delegation and scopes.
– OpenID Connect – Built on top of OAuth 2.0 with identity layer.
– JSON Web Tokens (JWT) – Compact tokens for securely transmitting claims.
– Keycloak – Provides authentication, authorization and user federation.
– Apache Shiro – Java framework with built-in authorization.
– Spring Security – Popular Java/Spring framework.
– Auth0 – Simple APIs and UI for implementing authorization.
Cloud providers like AWS, Azure and GCP also provide authorization services to manage scope and role.
Conclusion
In summary,
– Scope represents granular privileges to access resources and actions.
– Role represents a group of privileges that match a user function.
– Scopes provide flexibility while roles simplify management.
– OAuth 2.0 and OpenID Connect use scopes to delegate access.
– Role based access control (RBAC) is a common authorization model.
– Authorization frameworks help implement scope and role correctly.
Getting the balance right between scopes and roles is important for an authorization model that is secure, easy to use and maintainable in the long run.