CMEK organization policies

Google Cloud offers two organization policy constraints to help ensure CMEK usage across an organization:

• constraints/gcp.restrictNonCmekServices is used to require CMEK protection.
• constraints/gcp.restrictCmekCryptoKeyProjects is used to limit which Cloud KMS keys are used for CMEK protection.

CMEK organization policies only apply to newly created resources within supported Google Cloud services.

Required roles

To ensure that each user has the necessary permissions to check organization policies when creating resources, ask your administrator to grant each user the Organization Policy Viewer (roles/orgpolicy.policyViewer) IAM role on your organization. For more information about granting roles, see Manage access to projects, folders, and organizations.

This predefined role contains the permissions required to check organization policies when creating resources. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to check organization policies when creating resources:

• To view full organization policy details: orgpolicy.policy.get
• To check organization policy when creating resources: orgpolicy.policies.check

Your administrator might also be able to give each user these permissions with custom roles or other predefined roles.

When organization policies are active, the orgpolicy.policies.check permission is required for Google Cloud console users who create resources that are protected by CMEK keys. Users without this permission can create CMEK-protected resources using the Google Cloud console, but they can select a CMEK key that isn't allowed by the restrictCmekCryptoKeyProjects constraint. When a key that does not meet this constraint is selected, resource creation eventually fails.

Require CMEK protection

To require CMEK protection for your organization, configure the constraints/gcp.restrictNonCmekServices organization policy.

As a list constraint, the accepted values for this constraint are Google Cloud service names (for example, sqladmin.googleapis.com). Use this constraint by providing a list of Google Cloud service names and setting the constraint to Deny. This configuration blocks the creation of resources in these services if the resource is not protected by CMEK. In other words, requests to create a resource in the service do not succeed without specifying a Cloud KMS key. Additionally, this constraint blocks the removal of CMEK protection from resources in these services. This constraint can only be applied to supported services.

Limit the use of Cloud KMS keys for CMEK

To limit which Cloud KMS keys are used for CMEK protection, configure the constraints/gcp.restrictCmekCryptoKeyProjects constraint.

As a list constraint, the accepted values are resource hierarchy indicators (for example, projects/PROJECT_ID, under:folders/FOLDER_ID, and under:organizations/ORGANIZATION_ID). Use this constraint by configuring a list of resource hierarchy indicators and setting the constraint to Allow. This configuration restricts supported services so that CMEK keys can be chosen only from the listed projects, folders, and organizations. Requests to create CMEK-protected resources in configured services don't succeed without a Cloud KMS key from one of the allowed resources. Where configured, this constraint applies to all supported services.

Supported services

CMEK organization policies and the Storage Transfer Service

Although the Storage Transfer Service doesn't have a CMEK integration, it can be used with CMEK organization policies. If you use the Storage Transfer Service and want to ensure that the database credentials stored in Secret Manager are protected by CMEK, then you must add both storagetransfer.googleapis.com and secretmanager.googleapis.com to the constraints/gcp.restrictNonCmekServices constraint. For more information, see the Storage Transfer Service CMEK documentation.

Enforcement exceptions by resource type

CMEK organization policy constraints are enforced when creating a new resource or when changing (where supported) the Cloud KMS key on an existing resource. Generally, they are enforced on all of a service's resource types that support CMEK and based solely on the resource's configuration. Some notable exceptions are summarized here:

Configuration examples

In the configuration examples, assume the sample organization has the following resource hierarchy:

Require CMEK and limit keys for a project

Suppose you want to require CMEK protection for all Cloud Storage resources under projects/5 and ensure that only keys coming from projects/4 can be used.

To require CMEK protection for all new Cloud Storage resources, use the following organization policy setting:

• Organization policy: constraints/gcp.restrictNonCmekServices
• Binding at: projects/5
• Policy type: Deny
• Policy value: storage.googleapis.com

To ensure only keys from projects/4 are used, use the following configuration:

• Organization policy: constraints/gcp.restrictCmekCryptoKeyProjects
• Binding at: projects/5
• Policy type: Allow
• Policy value: projects/4

Require CMEK and limit keys to within a folder

Alternatively, suppose you're expecting to add additional Cloud KMS projects under folders/2 in the future and want to require CMEK more broadly within folders/3. For this scenario, you need slightly different configurations.

To require additional CMEK protection for new Cloud SQL and Cloud Storage resources anywhere under folders/3:

• Organization policy: constraints/gcp.restrictNonCmekServices
• Binding at: folders/3
• Policy type: Deny
• Policy values: sqladmin.googleapis.com, storage.googleapis.com

To ensure only keys from Cloud KMS projects under folders/2 are used:

• Organization policy: constraints/gcp.restrictCmekCryptoKeyProjects
• Binding at: folders/3
• Policy type: Allow
• Policy value: under:folders/2

Require CMEK for an organization

To require CMEK everywhere in the organization (in supported services), configure the constraints/gcp.restrictNonCmekServices constraint with the following setting:

• Organization policy: constraints/gcp.restrictNonCmekServices
• Binding at: organizations/1
• Policy type: Deny
• Policy values: (all supported services)

Limitations

If you use Google Cloud console to create a resource, you may notice that you can't use any encryption options other than CMEK when constraints/gcp.restrictNonCmekServices is configured for a project and service. The CMEK organization policy restriction is only visible when the customer account has been granted the orgpolicy.policy.get IAM permission on the project.

What's next

See Introduction to the Organization Policy Service to learn more about the benefits and common use cases for organization policies.

For more examples on creating an organization policy with particular constraints, see Using constraints.