Manage security posture by using custom constraints

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

securityposture.googleapis.com/Posture
securityposture.googleapis.com/PostureDeployment

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

You can use custom organization policies with security posture to do the following:

Allow posture to be created with a certain STATE
Allow posture creation with a certain type of Policy
Allow posture deployment to certain target resources
Allow posture deployment for specific postures

Before you begin

Ensure that you know your organization ID.

Install and initialize the Google Cloud CLI.

Install the Google Cloud CLI.
To initialize the gcloud CLI, run the following command:
```
gcloud init
```

Required roles

To get the permissions that you need to manage custom organization policies, ask your administrator to grant you the Organization Policy Administrator (roles/orgpolicy.policyAdmin) IAM role on the organization resource. For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through 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.LbTrafficExtensionDenyBodyEvents. 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, networkservices.googleapis.com/LbTrafficExtension.
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.extensionChains.all(value, value.extensions.all(value, value.supportedEvents.all(value, value.contains("BODY"))))".
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

After you have created the YAML file for a new custom constraint, you must set it up to make it available for organization policies in your organization. To set up a custom constraint, use the gcloud org-policies set-custom-constraint command:

gcloud org-policies set-custom-constraint CONSTRAINT_PATH

Replace CONSTRAINT_PATH with the full path to your custom constraint file. For example, /home/user/customconstraint.yaml. Once completed, your custom constraints are available as organization policies in your list of Google Cloud organization policies. To verify that the custom constraint exists, use the gcloud org-policies list-custom-constraints command:

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

Replace ORGANIZATION_ID with the ID of your organization resource. For more information, see Viewing organization policies.

Enforce a custom organization policy

You can enforce a boolean constraint by creating an organization policy that references it, and then applying that organization policy to a Google Cloud resource.

Console

In the Google Cloud console, go to the Organization policies page.
Go to Organization policies
From the project picker, select the project for which you want to set the organization policy.
From the list on the Organization policies page, select your constraint to view the Policy details page for that constraint.
To configure the organization policy for this resource, click Manage policy.
On the Edit policy page, select Override parent's policy.
Click Add a rule.
In the Enforcement section, select whether enforcement of this organization policy is on or off.
Optional: To make the organization policy conditional on a tag, click Add condition. Note that if you add a conditional rule to an organization policy, you must add at least one unconditional rule or the policy cannot be saved. For more information, see Setting an organization policy with tags.
If this is a custom constraint, you can click Test changes to simulate the effect of this organization policy. For more information, see Test organization policy changes with Policy Simulator.
To finish and apply the organization policy, click Set policy. The policy requires up to 15 minutes to take effect.

gcloud

To create an organization policy that enforces a boolean constraint, create a policy YAML file that references the constraint:

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

Replace the following:

PROJECT_ID: the project on which you want to enforce your constraint.
CONSTRAINT_NAME: the name you defined for your custom constraint. For example, custom.LbTrafficExtensionDenyBodyEvents.

To enforce the organization policy containing the constraint, run the following command:

    gcloud org-policies set-policy POLICY_PATH

Replace POLICY_PATH with the full path to your organization policy YAML file. The policy requires up to 15 minutes to take effect.

Test the custom organization policy

The following example creates a custom constraint that prevents creation of security posture with DRAFT state.

Create the constraint

To define the constraint, create a file named constraint-active-postures.yaml with the following contents:

name: organizations/ORGANIZATION_ID/customConstraints/custom.createActivePosturesOnly
resourceTypes:
- securityposture.googleapis.com/Posture
methodTypes:
- CREATE
- UPDATE
condition: resource.state.contains('ACTIVE')
actionType: ALLOW
displayName: Create only ACTIVE postures.
description: Create only ACTIVE postures.

Replace ORGANIZATION_ID with your organization ID.

Apply the constraint:

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

Verify that the constraint exists:

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

The output is similar to the following:

CUSTOM_CONSTRAINT ACTION_TYPE  METHOD_TYPES   RESOURCE_TYPES                                   DISPLAY_NAME
custom.Posture    ALLOW        CREATE,UPDATE  securityposture.googleapis.com/Posture           Create only ACTIVE postures.

Create the policy

Create a file named policy-active-postures.yaml file with the following policy:
```
name: projects/PROJECT_ID/policies/custom.createActivePosturesOnly
spec:
  rules:
  - enforce: true
```
Replace PROJECT_ID with your project ID.

Apply the policy:

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

Verify that the policy exists:

gcloud org-policies list --project=PROJECT_ID

The output is similar to the following:

CONSTRAINT                       LIST_POLICY    BOOLEAN_POLICY    ETAG
custom.createActivePosturesOnly  -              SET               COCsm5QGENiXi2E=

After you apply the policy, wait for about two minutes for security posture to start enforcing the policy.

Test the policy

Test the policy by creating a security posture with DRAFT state:

gcloud scc postures create POSTURE_NAME \
    --posture-from-file=PATH_TO_POSTURE_YAML_FILE

Replace the following:

POSTURE_NAME: a unique name for the security posture
PATH_TO_POSTURE_YAML_FILE: the path of the posture file

The output is similar to the following:

ERROR: (google.cloud.securityposture.v1.SecurityPosture.CreatePosture)
FAILED_PRECONDITION: Operation denied by org policy on resource
'organizations/996122346870/locations/global':
["customConstraints/custom.createActivePosturesOnly":
"Create only ACTIVE postures."].

Example custom organization policies for common use cases

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

Description	Constraint syntax
Require all security posture to have ACTIVE state	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createActivePosturesOnly resourceTypes: - securityposture.googleapis.com/Posture methodTypes: - CREATE - UPDATE condition: "resource.state.contains('ACTIVE')" actionType: ALLOW displayName: Require all security posture to have ACTIVE state description: All security posture must have ACTIVE state

Description

Constraint syntax

Require all security posture to have ACTIVE state

    name: organizations/ORGANIZATION_ID/customConstraints/custom.createActivePosturesOnly
    resourceTypes:
    - securityposture.googleapis.com/Posture
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.state.contains('ACTIVE')"
    actionType: ALLOW
    displayName: Require all security posture to
    have ACTIVE state
    description: All security posture must have ACTIVE state

Security Command Center supported resources

The following table lists the Security Command Center resources that you can reference in custom constraints.

Resource	Field
securityposture.googleapis.com/Posture	`resource.annotations`
	`resource.description`
	`resource.name`
	`resource.policySets.description`
	`resource.policySets.policies.complianceStandards.control`
	`resource.policySets.policies.complianceStandards.standard`
	`resource.policySets.policies.constraint.orgPolicyConstraint.cannedConstraintId`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.allowAll`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.denyAll`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.enforce`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.parameters.fields`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.resourceTypes.included`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.values.allowedValues`
	`resource.policySets.policies.constraint.orgPolicyConstraint.policyRules.values.deniedValues`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.actionType`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.condition`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.description`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.displayName`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.methodTypes`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.name`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.customConstraint.resourceTypes`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.allowAll`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.denyAll`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.enforce`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.parameters.fields`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.resourceTypes.included`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.values.allowedValues`
	`resource.policySets.policies.constraint.orgPolicyConstraintCustom.policyRules.values.deniedValues`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.config.customOutput.properties.name`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.config.description`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.config.recommendation`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.config.resourceSelector.resourceTypes`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.config.severity`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.displayName`
	`resource.policySets.policies.constraint.securityHealthAnalyticsCustomModule.moduleEnablementState`
	`resource.policySets.policies.constraint.securityHealthAnalyticsModule.moduleEnablementState`
	`resource.policySets.policies.constraint.securityHealthAnalyticsModule.moduleName`
	`resource.policySets.policies.description`
	`resource.policySets.policies.policyId`
	`resource.policySets.policySetId`
	`resource.state`
securityposture.googleapis.com/PostureDeployment	`resource.annotations`
	`resource.description`
	`resource.name`
	`resource.postureId`
	`resource.postureRevisionId`
	`resource.targetResource`

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.