Manage VPC firewall rule resources by using custom constraints

Google Cloud Organization Policy 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 enforce those custom constraints in a custom 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, see Hierarchy evaluation rules.

Cloud NGFW supported resources

For VPC firewall rules, you can set custom constraints on the following resources and fields.

  • Firewall: compute.googleapis.com/Firewall
    • Name: resource.name
    • Description: resource.description
    • Network: resource.network
    • Priority: resource.priority
    • Source ranges: resource.sourceRanges[]
    • Destination ranges: resource.destinationRanges[]
    • Source tags: resource.sourceTags[]
    • Target tags: resource.targetTags[]
    • Allow rules: resource.allowed[]
      • Protocol: resource.allowed[].IPProtocol
      • Ports: resource.allowed[].ports[]
    • Deny rules: resource.denied[]
      • Protocol: resource.denied[].IPProtocol
      • Ports: resource.denied[].ports[]
    • Direction: resource.direction
    • Is disabled: resource.disabled

Defining custom constraints

A custom constraint is defined 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 organization policies.

In addition to the standard CEL functions, you can use the custom CEL function containsFirewallPort to create custom constraints for firewall rules. You can use this function to create a constraint that refers to a particular protocol, or a protocol and port combination.

  • Protocol only: resource.allowed.containsFirewallPort('PROTOCOL')
  • Protocol and port: resource.allowed.containsFirewallPort('PROTOCOL', 'PORT_NUMBER')

For information about allowed protocols, see Protocols and ports.

Before you begin

  • If you haven't already, set up authentication. Authentication verifies your identity for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:

    Select the tab for how you plan to use the samples on this page:

    Console

    When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.

    gcloud

    1. Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command: 

      gcloud init

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

    2. Set a default region and zone.

    REST

    To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

      Install the Google Cloud CLI.

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

    For more information, see Authenticate for using REST in the Google Cloud authentication documentation.

* Ensure that you know your organization ID.

Required roles

To get the permissions that you need to manage organization policies for Cloud Next Generation Firewall resources, ask your administrator to grant you the following IAM roles:

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 for Cloud Next Generation Firewall resources. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to manage organization policies for Cloud Next Generation Firewall resources:

  • orgpolicy.constraints.list
  • orgpolicy.policies.create
  • orgpolicy.policies.delete
  • orgpolicy.policies.list
  • orgpolicy.policies.update
  • orgpolicy.policy.get
  • orgpolicy.policy.set

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

Set up a custom constraint

You can create a custom constraint and set it up for use in organization policies by using the Google Cloud console or Google Cloud CLI.

Console

  1. In the Google Cloud console, go to the Organization policies page.

    Go to Organization policies

  2. Select the Project picker at the top of the page.

  3. From the Project picker, select the resource for which you want to set the organization policy.

  4. Click Custom constraint.

  5. In the Display name box, enter a human-friendly name for the constraint. This field has a maximum length of 200 characters. Don't use PII or sensitive data in constraint names, because they could be exposed in error messages.

  6. In the Constraint ID box, enter 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.httpFirewallRule. The maximum length of this field is 70 characters, not counting the prefix, for example, organizations/123456789/customConstraints/custom..

  7. In the Description box, enter 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 2,000 characters.

  8. In the Resource type box, select the name of the Google Cloud REST resource containing the object and field you want to restrict. For example, compute.googleapis.com/Firewall.

  9. Under Enforcement method, select whether to enforce the constraint on the REST CREATE method only or on both the REST CREATE and UPDATE methods.

  10. To define a condition, click Edit condition.

    1. In the Add condition panel, create a CEL condition that refers to a supported service resource. This field has a maximum length of 1,000 characters.

    2. Click Save.

  11. Under Action, select whether to allow or deny the evaluated method if the previous condition is met.

  12. Click Create constraint.

When you have entered a value into each field, the equivalent YAML configuration for this custom constraint appears on the right.

gcloud

To create a custom constraint using the Google Cloud CLI, create a YAML file.

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resource_types: compute.googleapis.com/RESOURCE_NAME
method_types:
– METHOD1
– METHOD2
condition: "CONDITION"
action_type: ACTION
display_name: DISPLAY_NAME
description: DESCRIPTION

Replace the following:

  • ORGANIZATION_ID: the organization ID, such as 123456789.

  • CONSTRAINT_NAME: the name for the custom constraint to create. A custom constraint ID must start with custom. and can contain only uppercase letters, lowercase letters, and numbers. For example, custom.httpFirewallRule.

    The maximum length of this field is 70 characters, not counting the prefix. For example, organizations/123456789/customConstraints/custom.

  • RESOURCE_NAME: the name (not the URI) of the Compute Engine API REST resource containing the object and field to restrict. For example, compute.googleapis.com/Firewall.

  • METHOD1, METHOD2, ...: a list of RESTful methods for which to enforce the constraint. Can be CREATE or CREATE and UPDATE.

  • CONDITION: a CEL condition that is written against a representation of a supported service resource. This field has a maximum length of 1,000 characters. See Supported resources for more information about the resources available to write conditions against.

  • ACTION: the action to take if the condition is met. This can be either ALLOW or 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 2,000 characters.

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

Console

To create a custom constraint, do the following:

  1. In the Google Cloud console, go to the Organization policies page.

    Go to Organization policies

  2. From the project picker, select the project that you want to set the organization policy for.
  3. Click Custom constraint.
  4. In the Display name box, enter a human-readable name for the constraint. This name is used in error messages and can be used for identification and debugging. Don't use personally identifiable information (PII) or sensitive data in display names because this name could be exposed in error messages. This field can contain up to 200 characters.
  5. In the Constraint ID box, enter the ID that you want for your new custom constraint. A custom constraint can only contain letters (including upper and lowercase) or numbers, for example custom.httpFirewallRule. This field can contain up to 70 characters, not counting the prefix (custom.), for example, organizations/123456789/customConstraints/custom. Don't include PII or sensitive data in your constraint ID, because it could be exposed in error messages.
  6. In the Description box, enter a human-readable description of the constraint. This description is used as an error message when the policy is violated. Include details about why the policy violation occurred and how to resolve the policy violation. Don't include PII or sensitive data in your description, because it could be exposed in error messages. This field can contain up to 2000 characters.
  7. In the Resource type box, select the name of the Google Cloud REST resource containing the object and field that you want to restrict—for example, container.googleapis.com/NodePool. Most resource types support up to 20 custom constraints. If you attempt to create more custom constraints, the operation fails.
  8. This constraint can only be enforced on the REST CREATE method.

    9. To see supported methods for each service, find the service in Services that support custom constraints.

  9. To define a condition, click Edit condition.