Custom roles and policies in GCP

Custom Roles and Policies in Google Cloud Platform (GCP): A Detailed Guide

Introduction

As organizations increasingly adopt cloud computing, security becomes a paramount concern. Cloud providers like Google Cloud Platform (GCP) offer robust Identity and Access Management (IAM) tools to help organizations control and manage access to their resources. In GCP, IAM enables administrators to grant specific roles and permissions to users and service accounts to ensure only authorized entities can access or modify cloud resources.

In addition to predefined roles, GCP provides the ability to create custom roles and policies tailored to specific organizational needs. Understanding how to design, implement, and manage these roles and policies is crucial for ensuring secure and efficient cloud operations. This guide will delve deep into custom roles and policies in GCP, providing a step-by-step explanation, use cases, and best practices to help you make the most out of these IAM features.

What are Roles and Policies in GCP?

1. Roles in Google Cloud Platform

In GCP, roles are collections of permissions that define what actions a user or service account can perform on a particular resource or group of resources. Roles help administrators manage access to cloud resources efficiently.

There are three types of roles in GCP:

Primitive Roles: These are basic roles that include broad permissions and are suitable for simple use cases.
- Owner: Provides full administrative rights over all resources in the project.
- Editor: Allows the creation, modification, and deletion of resources, but without the ability to change permissions.
- Viewer: Provides read-only access to all resources, but does not allow modification.
Predefined Roles: These roles are more granular and tailored to specific GCP services. For example, the Cloud Storage Admin role includes permissions specific to managing Cloud Storage resources, and the Compute Instance Admin role provides permissions for managing compute instances.
Custom Roles: These roles are user-defined and allow administrators to assign only the specific permissions required for a particular user or service account. Custom roles are designed to meet the unique security and operational needs of organizations that cannot be satisfied with predefined roles.

2. Policies in Google Cloud Platform

In GCP, policies are the rules that define how roles are assigned to identities (users, groups, service accounts, etc.). These policies are typically managed using the IAM policy bindings, which specify which members (identities) are granted specific roles on resources. The IAM policy allows for fine-grained control over who can access cloud resources and what actions they can perform.

A policy in GCP consists of:

Bindings: A binding is the relationship between a member and a role. For example, a binding might state that a user is granted the “Viewer” role on a specific project.
Members: These are the users, groups, or service accounts who are assigned the roles.
Roles: The roles associated with the members specify what permissions the members are granted.

Why Use Custom Roles and Policies?

While predefined roles in GCP provide a quick and convenient way to assign permissions, they may be too broad for certain use cases, potentially violating the principle of least privilege. The principle of least privilege recommends granting only the minimum permissions necessary for users to perform their tasks, and custom roles help achieve this by providing fine-grained control.

Custom roles also allow for:

Tailored permissions: Providing only the exact permissions needed by the user.
Granular control: Minimizing the risk of users having excessive access to cloud resources.
Compliance: Ensuring that specific regulatory or organizational security requirements are met.

Creating Custom Roles in GCP

The process of creating custom roles in GCP consists of several stages: understanding the required permissions, defining the role, and implementing the custom role.

1. Identify the Required Permissions

Before creating a custom role, it is essential to determine which permissions are required. Permissions in GCP are action verbs that are tied to specific resources. For example, to allow a user to view a Cloud Storage bucket, you might need the storage.buckets.get permission. To list objects in a bucket, the permission storage.objects.list is required.

The key to creating a custom role is understanding which permissions align with the tasks the user will perform. It’s helpful to start with a predefined role and modify it according to your needs, or you can start from scratch if your needs are unique.

To identify permissions:

Review the available predefined roles that come with GCP.
Identify which permissions they contain and determine if they fit the user’s needs.
Customize and narrow down the permissions as necessary.

2. Define the Custom Role

Once you’ve identified the permissions needed, it’s time to define the custom role.

To create a custom role in GCP:

Navigate to IAM & Admin Console: Go to the IAM & Admin section in the GCP Console.
- In the left sidebar, click on Roles.
Create a New Role: Click Create Role to initiate the creation of a custom role.
Fill in Role Details:
- Name: Give the role a unique name that reflects its purpose (e.g., CustomStorageViewer).
- Description: Provide a description that outlines the role’s purpose and its permissions.
- Launch Stage: Set the launch stage to “General Availability” or “Beta” based on the role’s readiness.
Assign Permissions:
- Under the Permissions section, add the required permissions for the role. Use the permission search feature to find and add permissions to the role.
- Permissions should be as minimal as possible to adhere to the principle of least privilege.
Save the Custom Role: After defining the role, click Create to finalize the custom role.

3. Assign the Custom Role to Users or Service Accounts

After creating the custom role, it’s time to assign it to users, service accounts, or groups to give them the necessary permissions.

Navigate to IAM: Go to the IAM & Admin section and click on IAM.
Assign a Role: Find the user or service account to whom you wish to assign the custom role. If the user is not listed, you can add them by clicking the Add button.
Select the Custom Role: In the “Role” dropdown, scroll down and select your custom role under the appropriate category (e.g., Custom).
Save Changes: After assigning the role, click Save to apply the changes.

4. Review and Test the Role

Once the custom role is assigned, it’s crucial to verify that the user or service account has the expected level of access. Testing the permissions can help identify any potential gaps in access or excessive permissions.

Testing involves:

Login as the User: Log in as the user assigned the custom role or impersonate the service account.
Perform Expected Actions: Ensure that the user can perform the intended actions (e.g., viewing a bucket or listing objects).
Verify Restricted Access: Ensure that the user cannot access resources or perform actions that are outside the scope of the custom role’s permissions.

Managing and Updating Custom Roles

As your organization’s cloud infrastructure evolves, you may need to update custom roles to reflect new permissions, services, or compliance requirements. Updating custom roles is straightforward, but careful attention is required to avoid accidentally granting excessive permissions.

1. Editing Custom Roles

To edit a custom role:

Navigate to the IAM & Admin Console: Go to the Roles section in IAM & Admin.
Select the Role: Find the custom role you wish to modify.
Add/Remove Permissions: You can add or remove permissions based on the changes to your security requirements.
Save Changes: After updating the role, click Save to apply the modifications.

2. Versioning Custom Roles

GCP allows you to manage versions of custom roles. If you make significant changes to a custom role, it’s often a good practice to create a new version of the role rather than modifying the existing one.

Create a New Version: When updating a role, consider creating a new version to ensure backward compatibility with applications or users relying on the previous version.
Track Changes: Always document the changes made to the custom roles, especially when updating permissions, so you have a clear history of what changes were made and why.

3. Deleting Custom Roles

If a custom role is no longer needed, you can delete it:

Navigate to IAM & Admin: In the GCP console, go to the Roles section.
Select the Role: Find the custom role to delete.
Delete Role: Click on the trash icon to delete the custom role.

It’s important to ensure that no active users or service accounts rely on the role before deletion. If necessary, reassign users to different roles before removing the custom role.

Best Practices for Custom Roles and Policies

Use Least Privilege: Always assign only the permissions required for the user’s task. Do not provide overly broad roles if more granular access is possible.
Review Roles Regularly: Periodically review custom roles to ensure they remain aligned with your organization’s security and operational needs.
Use Groups for Role Assignments: Instead of assigning roles to individual users, assign roles to groups. This simplifies the management of access control and ensures consistency.
Audit Access Control: Regularly audit IAM policies to ensure that no users or service accounts have excessive privileges.
Leverage Policy Bindings: For more dynamic access control, use IAM policy bindings to assign roles to members at the project, folder, or organization level.

Custom roles and policies are powerful tools for managing access control in GCP, allowing organizations to implement security controls tailored to their specific needs. By understanding the intricacies of creating and managing custom roles and policies, you can ensure that your cloud resources are secure and that your users have the necessary access to perform their tasks without compromising the principle of least privilege.

By following the steps outlined in this guide, you can effectively implement custom roles in GCP and maintain a secure and well-managed cloud infrastructure.