Use custom organization policies

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 organization policies.

Benefits

You can use custom organization policies that reference IAM attributes to control how your allow policies can be modified. Specifically, you can control the following:

Who can be granted roles
Who can have their roles revoked
Which roles can be granted
Which roles can be revoked

For example, you can prevent roles that contain the word admin from being granted to principals whose email addresses end in @gmail.com.

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.

Pricing

The Organization Policy Service, including predefined and custom organization policies, is offered at no charge.

Limitations

Custom organization policies in dry-run mode that reference IAM attributes have some limitations. Namely, audit logs for violations that involve the setiamPolicy method might be missing the following fields:

resourceName
serviceName
methodName

Before you begin

Ensure that you know your organization ID.
If you want to test out custom organization policies that reference IAM resources, create a new project. Testing these organization policies in an existing project could disrupt security workflows.
1. In the Google Cloud console, go to the project selector page.
  
  Go to project selector
2. Select or create a Google Cloud project.
  
  Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

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
Modify your project's IAM policy: Project IAM Admin (roles/resourcemanager.projectIamAdmin) 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:

Required permissions

The following permissions are required to manage organization policies:

orgpolicy.constraints.list
orgpolicy.policies.create
orgpolicy.policies.delete
orgpolicy.policies.list
orgpolicy.policies.update
orgpolicy.policy.get
orgpolicy.policy.set
resourcemanager.projects.setIamPolicy

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 YAML file for a custom constraint:

name: organizations/ORG_ID/customConstraints/CONSTRAINT_NAME
resourceTypes: iam.googleapis.com/AllowPolicy
methodTypes:
  METHOD_TYPE
condition: "CONDITION"
actionType: ACTION
displayName: DISPLAY_NAME
description: DESCRIPTION

Replace the following:

ORG_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.denyProjectIAMAdmin. The maximum length of this field is 70 characters, not counting the prefix, for example, organizations/123456789/customConstraints/custom.
METHOD_TYPE: the type of action that you want to the constraint to apply for. If you want the constraint to apply when someone tries to grant a role to a principal, use the following values:
```
- CREATE
- UPDATE
```
Note: You must include both values to properly enforce the constraint.

If you want the constraint to apply when someone tries to revoke a principal's role, use the following value:
```
- REMOVE_GRANT
```
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 attributes for more information about the attributes available to write conditions against. For example, resource.bindings.exists(binding, RoleNameMatches(binding.role, ['roles/resourcemanager.projectIamAdmin'])).
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: optional. 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.denyProjectIAMAdmin.

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

Optionally, you can test the organization policy by setting the policy and then trying to take an action that the policy should prevent.

This section describes how to test the following organization policy constraint:

name: organizations/ORG_ID/customConstraints/custom.denyProjectIAMAdmin
resourceTypes: iam.googleapis.com/AllowPolicy
methodTypes:
  - CREATE
  - UPDATE
condition:
  "resource.bindings.exists(
    binding,
    RoleNameMatches(binding.role, ['roles/resourcemanager.projectIamAdmin']) &&
    binding.members.exists(member,
      MemberSubjectMatches(member, ['user:EMAIL_ADDRESS'])
    )
  )"
actionType: DENY
displayName: Do not allow EMAIL_ADDRESS to be granted the Project IAM Admin role.

If you want to test this custom constraint, do the following:

Copy the constraint into a YAML file and replace the following values:
- ORG_ID: the numeric ID of your Google Cloud organization.
- MEMBER_EMAIL_ADDRESS: the email address of the principal that you want to use to test the custom constraint. While the constraint is active, this principal won't be able to be granted the Project IAM Admin role (roles/resourcemanager.projectIamAdmin) on the project that you enforce the constraint for.
Set up the custom constraint and enforce it for the project that you created to test the custom organization policy constraint.
Try to grant the Project IAM Admin role (roles/resourcemanager.projectIamAdmin) to the principal whose email address you included in the custom constraint. Before running the command, replace the following values:
- PROJECT_ID: The ID of the Google Cloud project where you enforced the constraint
- EMAIL_ADDRESS: The email address of the principal that you specified when you created the organization policy constraint.

gcloud projects add-iam-policy-binding PROJECT_ID \
    --member=user:EMAIL_ADDRESS --role=roles/resourcemanager.projectIamAdmin

The output is the following:

Operation denied by custom org policies: ["customConstraints/custom.denyProjectIAMAdmin": "EMAIL_ADDRESS can't be granted the Project IAM Admin role."]

Identity and Access Management supported attributes

IAM supports the resources.bindings attribute. This attribute is returned for all methods that modify a resource's allow policy. All of these methods end with setIamPolicy.

The resource.bindings attribute has the following structure, where BINDINGS is an array of role bindings that were modified during a change to an allow policy:

{
  "bindings": {
    BINDINGS
  }
}

Each binding in resource.bindings has the following structure, where ROLE is the name of the role in the role binding and MEMBERS is a list of identifiers for the principals that were added to or removed from the role binding:

{
  "role": "ROLE"
  "members": {
    MEMBERS
  }
}

To see the formats that principal identifiers can have, see Principal identifiers.

You can only evaluate the resource.bindings attribute and its fields using the supported functions. Other operators and functions—like ==, !=, in, contains, startsWith, and endsWith—are not supported.

Supported functions

You can use the following CEL functions to evaluate the role and members fields of binding resources. When using these functions, you can also use the logical operators && (and) and || (or) to write multipart conditions.

Function	Description
`RoleNameMatches( role, roleNames: list )` `bool`	Returns `true` if the role `role` fully matches at least one of the roles listed in `roleNames`. Parameters `role`: the role to evaluate. `roleNames`: a list of role names to match against. Example Returns `true` if the `role` in the specified `binding` is `roles/storage.admin` or `roles/compute.admin`: RoleNameMatches(binding.role, ['roles/storage.admin', 'roles/compute.admin'])
`RoleNameStartsWith( role, rolePrefixes: list )` `bool`	Returns `true` if the role `role` starts with at least one of the strings listed in `rolePrefixes`. Parameters `role`: the role to evaluate. `rolePrefixes`: a list of strings to match the start of the role against. Example Returns `true` if the `role` in the specified `binding` starts with `roles/storage`: RoleNameStartsWith(binding.role, ['roles/storage'])
`RoleNameEndsWith( role, roleSuffixes: list )` `bool`	Returns `true` if the role `role` ends with at least one of the strings listed in `roleSuffixes`. Parameters `role`: the role to evaluate. `roleSuffixes`: a list of strings to match the end of the role against. Example Returns `true` if the `role` in the specified `binding` ends with `.admin`: RoleNameEndsWith(binding.role, ['.admin'])
`RoleNameContains( role, roleSubstrings: list )` `bool`	Returns `true` if the role `role` contains at least one of the strings listed in `roleSubstrings`. Parameters `role`: the role to evaluate. `roleSubstrings`: a list of strings to match any part of the role to. Example Returns `true` if the `role` in the specified `binding` contains the string `admin`: RoleNameContains(binding.role, ['admin'])
`MemberSubjectMatches( member, memberNames: list )` `bool`	Returns `true` if the member `member` fully matches at least one of the members listed in `memberNames`. If the identifier for `member` is an email address, this function evaluates only that email address—it doesn't evaluate any aliases for that email address. Parameters `member`: the member to evaluate. `memberNames`: a list of member names to match against. Example Returns `true` if the member `member` is `rosario@example.com`: MemberSubjectMatches(member, ['user:rosario@example.com'])
`MemberSubjectEndsWith( member, memberSuffixes: list )` `bool`	Returns `true` if the member `member` ends with at least one of the strings listed in `memberSuffixes`. If the identifier for `member` is an email address, this function evaluates only that email address—it doesn't evaluate any aliases for that email address. Parameters `member`: the member to evaluate. `memberSuffixes`: a list of strings to match the end of the member name against. Example Returns `true` if the member `member` ends with `@example.com`: MemberSubjectEndsWith(member, ['@example.com'])

Example custom organization policies for common use cases

The following table provides the syntax of some custom organization policies that you might find useful.

The following examples use the CEL macros all and exists. For more information about these macros, see Macros.

Description	Constraint syntax
Block the ability to grant a specific role.	name: organizations/`ORG_ID`/customConstraints/custom.denyRole resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.exists( binding, RoleNameMatches(binding.role, ['`ROLE`']) )" actionType: DENY displayName: Do not allow the `ROLE` role to be granted
Only allow specific roles to be granted.	name: organizations/`ORG_ID`/customConstraints/custom.specificRolesOnly resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.all( binding, RoleNameMatches(binding.role, ['`ROLE_1`', '`ROLE_2`']) )" actionType: ALLOW displayName: Only allow the `ROLE_1` role and `ROLE_2` role to be granted
Prevent any roles that start with `roles/storage.` from being granted.	name: organizations/`ORG_ID`/customConstraints/custom.dontgrantStorageRoles resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.exists( binding, RoleNameStartsWith(binding.role, ['roles/storage.']) )" actionType: DENY displayName: Prevent roles that start with "roles/storage." from being granted
Prevent any roles with `admin` in the name from being revoked.	name: organizations/`ORG_ID`/customConstraints/custom.dontRevokeAdminRoles resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - REMOVE_GRANT condition: "resource.bindings.exists( binding, RoleNameContains(binding.role, ['admin']) )" actionType: DENY displayName: Prevent roles with "admin" in their names from being revoked
Only allow specific principals to be granted roles.	name: organizations/`ORG_ID`/customConstraints/custom.allowSpecificPrincipals resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.all( binding, binding.members.all(member, MemberSubjectMatches(member, ['user:`USER`','serviceAccount:`SERVICE_ACCOUNT`']) ) )" actionType: ALLOW displayName: Only allow roles to be granted to `USER` and `SERVICE_ACCOUNT`
Prevent any roles from being revoked from specific principals.	name: organizations/`ORG_ID`/customConstraints/custom.denyRemovalOfSpecificPrincipals resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - REMOVE_GRANT condition: "resource.bindings.exists( binding, binding.members.exists(member, MemberSubjectMatches(member, ['user:`USER_1`','user:`USER_2`']) ) )" actionType: DENY displayName: Do not allow roles to be revoked from `USER_1` or `USER_2`
Prevent principals with email addresses ending in `@gmail.com` from being granted roles.	name: organizations/`ORG_ID`/customConstraints/custom.dontGrantToGmail resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.exists( binding, binding.members.exists(member, MemberSubjectEndsWith(member, ['@gmail.com']) ) )" actionType: DENY displayName: Do not allow members whose email addresses end with "@gmail.com" to be granted roles
Only allow specific roles to be granted, and only to specific principals.	name: organizations/`ORG_ID`/customConstraints/custom.allowSpecificRolesAndPrincipals resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.all( binding, RoleNameMatches(binding.role, ['`ROLE_1`', '`ROLE_2`']) && binding.members.all(member, MemberSubjectMatches(member, ['serviceAccount:`SERVICE_ACCOUNT`', 'group:`GROUP`']) ) )" actionType: ALLOW displayName: Only allow `ROLE_1` and `ROLE_2` to be granted to `SERVICE_ACCOUNT` and `GROUP`
Prevent Cloud Storage roles from being granted to `allUsers` and `allAuthenticatedUsers`.	name: organizations/`ORG_ID`/customConstraints/custom.denyStorageRolesForPrincipalAllUsers resourceTypes: iam.googleapis.com/AllowPolicy methodTypes: - CREATE - UPDATE condition: "resource.bindings.exists( binding, RoleNameStartsWith(binding.role, ['roles/storage.']) && binding.members.exists(member, MemberSubjectMatches(member, ['allUsers', 'allAuthenticatedUsers']) ) )" actionType: DENY displayName: Do not allow storage roles to be granted to allUsers or allAuthenticatedUsers

What's next

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