Use custom organization policies for allow policies

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

• iam.googleapis.com/AllowPolicy

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 built-in managed 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 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 .

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

• Audit logs aren't generated for all IAM-related custom organization policy violations. Namely, if a custom organization policy causes a setIamPolicy operation on the organization resource to fail, then Google Cloud doesn't generate an audit log for that event.

• Custom organization policies that reference IAM attributes don't affect the following:

  • Default grants by Cloud Storage ACLs .
  • Automatic role grants for Cloud Storage convenience values and BigQuery default dataset access .
  • Roles granted by default allow policies —for example, a project creator automatically being granted the Owner role ( roles/owner ) on the project.

• Users can be sent invitations to become owners, even if you have a custom organization policy that prevents the Owner role ( roles/owner ) from being granted. However, while the custom organization policy doesn't prevent an invitation from being sent, it does prevent invited users from being granted the Owner role. If invited users try to accept the invitation, they'll encounter an error and won't be granted the Owner role.

• Some actions in Google Cloud, such as creating resources or enabling APIs, involve automatically granting a role to a service agent or default service account . If an action involves automatically granting a role and an organization policy prevents that role from being granted, then the entire operation might fail.

  If you encounter this issue, you can use tags to temporarily disable the constraint that prevents the role grant. Then, perform the action. After the action finishes, re-enable the constraint.

Before you begin

• 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.

     Roles required to select or create a project

     • Select a project : Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
     • Create a project : To create a project, you need the Project Creator role ( roles/resourcemanager.projectCreator ), which contains the resourcemanager.projects.create permission. Learn how to grant roles .

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
• Test the organization policies described on this page: 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 permissionssection:

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

Set up 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 .

Enforce a custom organization policy

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.

Create the constraint

1. Save the following file as constraint-deny-project-iam-admin .

     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. 
    
   

   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.

2. Apply the constraint:

    gcloud  
   org-policies  
   set-custom-constraint  
   ~/constraint-deny-project-iam-admin.yaml 
   

3. Verify that the constraint exists:

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

Create the policy

1. Save the following file as policy-deny-project-iam-admin.yaml :

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

   Replace PROJECT_ID with your project ID.

2. Apply the policy:

    gcloud  
   org-policies  
   set-policy  
   ~/policy-deny-project-iam-admin.yaml 
   

3. Verify that the policy exists:

    gcloud  
   org-policies  
   list  
   --project = 
    PROJECT_ID 
    
   

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

Test the policy

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."] 

Example custom organization policies for common use cases

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

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

 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 

 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 

 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 

 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 

 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 
 

 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 
 

 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 

 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 
 

 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 

 name 
 : 
  
 organizations/ ORG_ID 
/customConstraints/custom.allowInternaldentitiesOnly 
 resourceTypes 
 : 
  
 iam.googleapis.com/AllowPolicy 
 methodTypes 
 : 
  
 - 
  
 CREATE 
  
 - 
  
 UPDATE 
 condition 
 : 
  
 "resource.bindings.all( 
  
 binding, 
  
 binding.members.all(member, 
  
 MemberInPrincipalSet(member, 
  
 ['//cloudresourcemanager.googleapis.com/organizations/ ORG_ID 
']) 
  
 ) 
  
 )" 
 actionType 
 : 
  
 ALLOW 
 displayName 
 : 
  
 Only allow organization members to be granted roles 

 name 
 : 
  
 organizations/ ORG_ID 
/customConstraints/custom.allowServiceAccountsOnly 
 resourceTypes 
 : 
  
 iam.googleapis.com/AllowPolicy 
 methodTypes 
 : 
  
 - 
  
 CREATE 
  
 - 
  
 UPDATE 
 condition 
 : 
  
 "resource.bindings.all( 
  
 binding, 
  
 binding.members.all(member, 
  
 MemberTypeMatches(member, 
  
 ['iam.googleapis.com/ServiceAccount']) 
  
 ) 
  
 )" 
 actionType 
 : 
  
 ALLOW 
 displayName 
 : 
  
 Only allow service accounts to be granted roles 

 name 
 : 
  
 organizations/ ORG_ID 
/customConstraints/custom.denyRemovalOfGoogleManagedServiceAgents 
 resource_types 
 : 
  
 iam.googleapis.com/AllowPolicy 
 method_types 
 : 
  
 - 
  
 REMOVE_GRANT 
 condition 
 : 
  
 |- 
  
 resource.bindings.all( 
  
 binding, 
  
 binding.members.all(member, 
  
 MemberTypeMatches(member, ['iam.googleapis.com/ServiceAgent']) 
  
 ) 
  
 ) 
 action_type 
 : 
  
 DENY 
 display_name 
 : 
  
 Deny Removal Of Google-Managed Service Agents 
 description 
 : 
  
 Restricts the removal of Google-managed service agents from role bindings. Please reach out to your organization admins for if you have any questions. 

Conditional organization policies

You can make a custom organization policy conditional using tags . For example, imagine that you wrote the following custom constraint to 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 
 

To enforce the constraint conditionally, you could create an organization policy like the following:

  name 
 : 
  
 organizations/ORG_ID/policies/custom.dontgrantStorageRoles 
 spec 
 : 
  
 rules 
 : 
  
 - 
  
 condition 
 : 
  
 expression 
 : 
  
 "resource.matchTag('ORG_ID/environment', 
  
 'dev')" 
  
 enforce 
 : 
  
 true 
  
 - 
  
 enforce 
 : 
  
 false 
 

This organization policy prevents roles that start with roles/storage. from being granted on any resource that also has the tag environment=dev .

Identity and Access Management supported resources

IAM supports the AllowPolicy resource. This resource has the attribute resources.bindings attribute, which is returned for all methods that modify a resource's allow policy. All of the methods that modify a resource's allow policy 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 all 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 individual roles and members in a binding.

To evaluate all bindings in the bindings array or all members in the members array, use the all and exists macros. For more information, see Macros to evaluate lists on this page.

You can also use the logical operators && ( and ) and || ( or ) to write multipart conditions.

Macros to evaluate lists

Use the all and exists macros to evaluate a condition expression for a list of items.

Conditions with nested lists

In general, if your condition includes nested lists, you should use the same macro for all lists in the condition.

Consider the following examples:

• If your policy has the actionType ALLOW , then use the all macro for both the members list and the bindings list to ensure that policy modifications are only allowed if all members in all modified bindings satisfy the condition.
• If your policy has the actionType DENY , then use the exists macro for both the members list and the bindings list to ensure that policy modifications aren't allowed if any member in any modified binding satisfies the condition.

Mixing macros in a single condition might result in a condition that doesn't behave how you intended.

For example, imagine that you want to prevent roles from being granted to members outside of the example.com organization. The example.com organization has the ID 123456789012 .

To accomplish this goal, you write the following condition:

Not recommended — misconfigured condition

"resource.bindings. all(
  binding,
  binding.members. exists(member,
    MemberInPrincipalSet(member, ['//cloudresourcemanager.googleapis.com/organizations/123456789012'])
  )
)"

This condition appears to prevent roles from being granted to members outside of the example.com organization. However, the condition evaluates to true if any member in each of the modified role bindings is in the example.com organization. As a result, you can still grant roles to members outside of the example.com organization if you also grant the same role to a member in the example.com organization.

For example, the condition evaluates to true for the following set of bindings, even though one of the members isn't in the example.com organization:

  
 "bindings" 
 : 
  
 [ 
  
 { 
  
 "members" 
 : 
  
 [ 
  
 " user:raha@altostrat.com" 
 , 
  
 "user:jie@example.com" 
  
 ], 
  
 "role" 
 : 
  
 "roles/resourcemanager.projectCreator" 
  
 } 
  
 ], 

Instead, you should write a condition like the following:

Recommended — correctly configured condition

"resource.bindings. all(
  binding,
  binding.members. all(member,
    MemberInPrincipalSet(member, ['//cloudresourcemanager.googleapis.com/organizations/123456789012'])
  )
)"

Using the all macro for both the members.bindings array and the resource.bindings array ensures that the condition evaluates to true only if all members in all bindings are in the example.com principal set.

Supported principal types for MemberTypeMatches

The MemberTypeMatches function requires you to specify which principal type the specified member must match.

The following table lists the principal types that you can enter and a description of what the principal type represents. It also lists the principal identifiers that correspond with each principal type. These identifiers are the values that are used in IAM policies.

What's next

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