SQL Developer Security: Roles

Understanding Database Roles

Database roles are essential components of SQL Server security. They allow you to group database permissions and assign these groups to users. This simplifies the management of access control and ensures that users have the appropriate privileges without granting them individually.

Roles can be broadly categorized into two types:

Fixed Server Roles: Predefined roles that grant specific server-level permissions (e.g., sysadmin, serveradmin).
Fixed Database Roles: Predefined roles that grant specific database-level permissions (e.g., db_owner, db_datareader, db_datawriter).
User-Defined Roles: Roles that you create to tailor permissions to your specific application needs.

Creating and Managing User-Defined Roles

User-defined roles offer granular control over access. You can create custom roles and then grant specific permissions to these roles. Subsequently, you assign users or other roles to your custom roles.

Creating a New Role

You can create a new role using SQL Server Management Studio (SSMS) or Transact-SQL (T-SQL).

Using T-SQL:

CREATE ROLE MyCustomRole;
GO

Granting Permissions to a Role

Once a role is created, you can grant it specific permissions. For example, granting `SELECT` permission on a table:

GRANT SELECT ON dbo.MyTable TO MyCustomRole;
GO

Adding Members to a Role

You can add existing database users or other roles as members to your custom role.

ALTER ROLE MyCustomRole ADD MEMBER AnotherUser;
GO

Best Practice: Avoid granting permissions directly to users. Instead, use roles to manage permissions. This makes it easier to add or remove permissions for a group of users by simply modifying the role's membership or permissions.

Common Database Roles and Their Permissions

SQL Server provides a set of built-in fixed database roles. Understanding their scope is crucial for effective security management.

db_owner: Members of this role can perform all configuration and maintenance activities on the database. They are also the members of the db_ddladmin, db_securityadmin, and db_accessadmin fixed database roles.
db_accessadmin: Members of this role can manage member access and the database roles themselves.
db_securityadmin: Members of this role can manage the permissions and security policies.
db_ddladmin: Members of this role can run any Data Definition Language (DDL) command.
db_dataholder: Members of this role can view all data in all user tables.
db_datareader: Members of this role can read all data from all user tables.
db_datawriter: Members of this role can add, delete, or change data in all user tables.
db_denydatareader: Members of this role cannot read any data from any user table.
db_denydatawriter: Members of this role cannot add, delete, or change any data in any user table.

Tip: For most application development scenarios, using roles like db_datareader and db_datawriter (or custom roles with specific SELECT, INSERT, UPDATE, DELETE permissions) is a secure approach.

Best Practices for Role Management

Principle of Least Privilege: Grant users and roles only the permissions they absolutely need to perform their tasks.
Use Custom Roles: Create user-defined roles for your applications rather than relying solely on fixed database roles, especially for granting access to specific tables or operations.
Regular Audits: Periodically review role memberships and permissions to ensure they are still appropriate.
Avoid Public Role: Be cautious when assigning permissions to the public role, as all users are members of this role by default.
Segregate Duties: Use roles to separate duties among different groups of users (e.g., developers, administrators, end-users).

MSDN Documentation

Understanding Database Roles

Creating and Managing User-Defined Roles

Creating a New Role

Using T-SQL:

Granting Permissions to a Role

Adding Members to a Role

Common Database Roles and Their Permissions

Best Practices for Role Management

Further Reading