Use custom organization policies

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This page shows you how to use Organization Policy Service custom constraints to restrict specific operations on the following Google Cloud resources:

• binaryauthorization.googleapis.com/Policy
• binaryauthorization.googleapis.com/Attestor

To learn more about Organization Policy, see Custom organization policies.

About organization policies and constraints

The Google Cloud Organization Policy Service gives you centralized, programmatic control over your organization's resources. As the organization policy administrator, you can define an organization policy, which is a set of restrictions called constraints that apply to Google Cloud resources and descendants of those resources in the Google Cloud resource hierarchy. You can enforce organization policies at the organization, folder, or project level.

Organization Policy provides predefined constraints for various Google Cloud services. However, if you want more granular, customizable control over the specific fields that are restricted in your organization policies, you can also create custom constraints and use those custom constraints in an organization policy.

Policy inheritance

By default, organization policies are inherited by the descendants of the resources on which you enforce the policy. For example, if you enforce a policy on a folder, Google Cloud enforces the policy on all projects in the folder. To learn more about this behavior and how to change it, refer to Hierarchy evaluation rules.

Benefits

Use custom organization policies to do the following with Binary Authorization policies:

• Enforce security requirements by mandating user authorization for system image deployment.
• Ensure that attestation is required for all pod deployments within Binary Authorization policy.
• Ensure that specific attestors are included in the Binary Authorization policy used for attestation verification.
• Restrict allowed operations to a defined allowlist pattern within the Binary Authorization policy.

Use custom organization policies to do the following with Binary Authorization attestations:

• Ensure attestors are created with descriptive metadata to clearly define their purpose.
• Ensure that the cryptographic key associated with each attestor is generated using a specific, predetermined signature algorithm.

Before you begin

1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Go to project selector

3. Make sure that billing is enabled for your Google Cloud project.

4. Install the Google Cloud CLI.

5. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

6. To initialize the gcloud CLI, run the following command:

   gcloud init

7. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Go to project selector

8. Make sure that billing is enabled for your Google Cloud project.

9. Install the Google Cloud CLI.

10. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

11. To initialize the gcloud CLI, run the following command:

    gcloud init

12. Ensure that you know your organization ID.

Required roles

To get the permissions that you need to manage organization policies, ask your administrator to grant you the following IAM roles:

• Organization Policy Administrator (roles/orgpolicy.policyAdmin) on the organization resource
• To update a policy: Binary Authorization Policy Roles (roles/binaryauthorization.policyEditor) on the project
• To create and update an attestor: Binary Authorization Attestor Roles (roles/binaryauthorization.attestorsAdmin) on the project

For more information about granting roles, see Manage access to projects, folders, and organizations.

These predefined roles contain the permissions required to manage organization policies. To see the exact permissions that are required, expand the Required permissions section:

You might also be able to get these permissions with custom roles or other predefined roles.

Create a custom constraint

A custom constraint is defined in a YAML file by the resources, methods, conditions, and actions that are supported by the service on which you are enforcing the organization policy. Conditions for your custom constraints are defined using Common Expression Language (CEL). For more information about how to build conditions in custom constraints using CEL, see the CEL section of Creating and managing custom constraints.

To create a custom constraint, create a YAML file using the following format:

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resourceTypes:
- RESOURCE_NAME
methodTypes:
- CREATE
- UPDATE
condition: "CONDITION"
actionType: ACTION
displayName: DISPLAY_NAME
description: DESCRIPTION

Replace the following:

• ORGANIZATION_ID: your organization ID, such as 123456789.

• CONSTRAINT_NAME: the name you want for your new custom constraint. A custom constraint must start with custom., and can only include uppercase letters, lowercase letters, or numbers. For example, custom.ensureBinaryAuthorizationEnforcementEnabled. The maximum length of this field is 70 characters.

• RESOURCE_NAME: the fully qualified name of the Google Cloud resource containing the object and field you want to restrict. For example, binaryauthorization.googleapis.com/Policy.

• CONDITION: a CEL condition that is written against a representation of a supported service resource. This field has a maximum length of 1000 characters. See Supported resources for more information about the resources available to write conditions against. For example, "resource.defaultAdmissionRule.enforcementMode == 'ENFORCED_BLOCK_AND_AUDIT_LOG'".

• ACTION: the action to take if the condition is met. Possible values are ALLOW and DENY.

• DISPLAY_NAME: a human-friendly name for the constraint. This field has a maximum length of 200 characters.

• DESCRIPTION: a human-friendly description of the constraint to display as an error message when the policy is violated. This field has a maximum length of 2000 characters.

For more information about how to create a custom constraint, see Defining custom constraints.

Set up a custom constraint

gcloud org-policies set-custom-constraint CONSTRAINT_PATH

gcloud org-policies list-custom-constraints --organization=ORGANIZATION_ID

Enforce a custom organization policy

      name: projects/PROJECT_ID/policies/CONSTRAINT_NAME
      spec:
        rules:
        - enforce: true
    

    gcloud org-policies set-policy POLICY_PATH
    

Test the custom organization policy

The following example shows how to create a custom constraint and policy that ensures Binary Authorization policy enforcement within a project, preventing deployments when attestations are missing.

Before you begin, ensure the following:

• Enable the Binary Authorization API, once per project.
• Know your organization ID.
• Know your project ID.

Create the constraint

1. Save the following file as constraint.yaml:

   name: organizations/ORGANIZATION_ID/customConstraints/custom.ensureBinaryAuthorizationEnforcementEnabled
   resourceTypes:
   - binaryauthorization.googleapis.com/Policy
   methodTypes:
   - CREATE
   - UPDATE
   condition: "resource.defaultAdmissionRule.enforcementMode == 'ENFORCED_BLOCK_AND_AUDIT_LOG'"
   actionType: ALLOW
   displayName: Ensure Binary Authorization Enforcement is enabled
   description: Binary Authorization policy must have enforcement enabled to block deployments if one or more required attestations are missing.
   

   This constraint prevents Binary Authorization policy updates unless the defaultAdmissionRule.enforcementMode is set to ENFORCED_BLOCK_AND_AUDIT_LOG.

2. Apply the constraint:

   gcloud org-policies set-custom-constraint ~/constraint.yaml
   

3. Verify that the constraint exists:

   gcloud org-policies list-custom-constraints --organization=ORGANIZATION_ID
   

   The output is similar to the following:

   CUSTOM_CONSTRAINT: custom.ensureBinaryAuthorizationEnforcementEnabled
   ACTION_TYPE: DENY
   METHOD_TYPES: CREATE,UPDATE
   RESOURCE_TYPES: binaryauthorization.googleapis.com/Policy
   DISPLAY_NAME: Ensure Binary Authorization Enforcement is enabled
   

Create the policy

1. Save the following file as policy.yaml:

   name: projects/PROJECT_ID/policies/custom.ensureBinaryAuthorizationEnforcementEnabled
   spec:
     rules:
     - enforce: true
   

   Replace PROJECT_ID with your project ID.

2. Apply the policy:

   gcloud org-policies set-policy ~/policy.yaml
   

3. Verify that the policy exists:

   gcloud org-policies list --project=PROJECT_ID
   

   The output is similar to the following:

   CONSTRAINT: custom.ensureBinaryAuthorizationEnforcementEnabled
   LIST_POLICY: -
   BOOLEAN_POLICY: SET
   ETAG: CJSetr4GEPil1JAB-
   

After you apply the policy, wait for about two minutes for Google Cloud to start enforcing the policy.

Test the policy

cat > binauthzPolicy.yaml << EOM
globalPolicyEvaluationMode: DISABLE
defaultAdmissionRule:
  evaluationMode: ALWAYS_DENY
  enforcementMode: DRYRUN_AUDIT_LOG_ONLY
EOM

gcloud container binauthz policy import binauthzPolicy.yaml '--format=json'

The output is the following:

Operation denied by org policy: ["customConstraints/custom.ensureBinaryAuthorizationEnforcementEnabled": "Pod deployment should be blocked when admission rule are not satisfied."].

Example custom organization policies for common use cases

The following table provides the syntax of some custom constraints for common use cases:

  name: organizations/ORGANIZATION_ID/customConstraints/custom.podCreationRequireAttestations
  resourceTypes:
  - binaryauthorization.googleapis.com/Policy
  methodTypes:
  - CREATE
  - UPDATE
  condition: "resource.defaultAdmissionRule.evaluationMode == 'REQUIRE_ATTESTATION'"
  actionType: ALLOW
  displayName: Attestations are required in Binary Authorization Policy
  description: Binary Authorization Policy evaluation requires attestations.
  

  name: organizations/ORGANIZATION_ID/customConstraints/custom.policyWithParticularAttestor
  resourceTypes:
  - binaryauthorization.googleapis.com/Policy
  methodTypes:
  - CREATE
  - UPDATE
  condition: "resource.defaultAdmissionRule.requireAttestationsBy.size() > 0 && resource.defaultAdmissionRule.requireAttestationsBy.exists(value, value.matches(r'^projects/[^/]+/attestors/qa-attestor$'))"
  actionType: ALLOW
  displayName: Ensure Binary Authorization policy contains qa-attestor.
  description: Ensure Binary Authorization policy contains qa-attestor.
  

    name: organizations/ORGANIZATION_ID/customConstraints/custom.enforceAttestorDescription
    resourceTypes:
    - binaryauthorization.googleapis.com/Attestor
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.description == ''"
    actionType: DENY
    displayName: Deny Attestor creation that have no description.
    description: Binary Authorization Attestor should have description associated with it.
    

    name: organizations/ORGANIZATION_ID/customConstraints/custom.allowParticularKeySignatureAlgorithm
    resourceTypes:
    - binaryauthorization.googleapis.com/Attestor
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.userOwnedGrafeasNote.publicKeys.all(publicKey, publicKey.pkixPublicKey.signatureAlgorithm == 'ECDSA_P256_SHA256')"
    actionType: ALLOW
    displayName: Allow particular signature algorithm
    description: Only particular signature Algorithm is allowed.
    

Binary Authorization supported resources

What's next

• Learn more about Organization Policy Service.
• Learn more about how to create and manage organization policies.
• See the full list of predefined organization policy constraints.