DB2 - Roles

Db2 - Roles and Privileges

Introduction to Roles

In modern database management, a role is a named collection of privileges. Instead of granting individual permissions (like SELECT, INSERT, etc.) to each user, you grant them to a role. You then grant the role to users or even other roles. This approach, known as Role-Based Access Control (RBAC), is a cornerstone of the principle of least privilege, simplifying security administration and reducing the risk of error.

Key Concepts and Restrictions

• Ownership: A role cannot own database objects like tables or views. Ownership is always assigned to a user (authorization ID).
• Static SQL Considerations: When creating objects that contain static SQL (such as views, MQTs, triggers, or SQL routines), Db2 checks the privileges of the object’s creator directly. Privileges granted via a role are not considered during the creation of these specific objects, unless a trusted context is in use (an advanced security feature).

Practical Workflow: Creating and Using Roles

Let’s walk through a common scenario: setting up a read-only role for business analysts.

Step 1: Create a New Role

First, a user with SECADM (Security Administrator) authority creates the role.

CREATE ROLE ANALYST_READONLY;

Example:

db2 "CREATE ROLE ANALYST_READONLY"

Output:

DB20000I  The SQL command completed successfully.

Step 2: Grant Privileges to the Role

Next, the data owner or a user with DBADM authority grants the necessary permissions on specific objects to the newly created role.

GRANT SELECT ON TABLE <schema_name>.<table_name> TO ROLE <role_name>;

Example: Granting SELECT access on the SALES.TRANSACTIONS table.

db2 "GRANT SELECT ON TABLE SALES.TRANSACTIONS TO ROLE ANALYST_READONLY"

Output:

DB20000I  The SQL command completed successfully.

Step 3: Grant the Role to a User

Finally, the security administrator grants the role to a user or a group. This user now inherits all privileges assigned to the role.

GRANT ROLE <role_name> TO USER <username>;

Example: Granting the ANALYST_READONLY role to user bpatel.

db2 "GRANT ROLE ANALYST_READONLY TO USER bpatel"

Output:

DB20000I  The SQL command completed successfully.

Role Hierarchies

Roles can be granted to other roles, creating a hierarchy. This is useful for building layered access levels. A role inherits all the privileges of the roles granted to it.

Syntax:

GRANT ROLE <child_role_name> TO ROLE <parent_role_name>;

Example: Let’s create a MANAGER role that includes all analyst permissions plus the ability to manage a specific reporting table.

-- First, create the new role
 db2 "CREATE ROLE MANAGER"

-- Grant the existing analyst role to the manager role
 db2 "GRANT ROLE ANALYST_READONLY TO ROLE MANAGER"

-- Add additional manager-specific privileges
 db2 "GRANT INSERT, UPDATE ON TABLE REPORTING.SUMMARY TO ROLE MANAGER"

-- Now, grant the MANAGER role to a user
 db2 "GRANT ROLE MANAGER TO USER sjones"

Best Practices and Further Learning

• Semantic Naming: Use clear, descriptive names for roles (e.g., APP_SERVICE_ACCOUNT, FINANCE_AUDITOR, DEV_READ_WRITE).
• Auditing: Regularly audit role memberships and the privileges assigned to each role using system catalog views like SYSCAT.ROLEAUTH and SYSCAT.TABAUTH.
• Trusted Contexts: For complex application security models, explore Db2 Trusted Contexts, which allow privileges from a role to be used when creating static SQL objects under specific, trusted conditions.