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Hierarchical firewall policies

Hierarchical firewall policies let you create and enforce a consistent firewall policy across your organization. You can assign hierarchical firewall policies to the organization as a whole or to individual folders. These policies contain rules that can explicitly deny or allow connections, as do Virtual Private Cloud (VPC) firewall rules. In addition, hierarchical firewall policy rules can delegate evaluation to lower-level policies or VPC network firewall rules with a goto_next action.

Lower-level rules cannot override a rule from a higher place in the resource hierarchy. This lets organization-wide admins manage critical firewall rules in one place.

Specifications

  • Hierarchical firewall policies are created at organization and folder nodes. Creating a policy does not automatically apply the rules to the node.
  • Policies, once created, can be applied to (associated with) any nodes in the organization.
  • Hierarchical firewall policies are containers for firewall rules. When you associate a policy with the organization or a folder, all rules are immediately applied. You can swap policies for a node, which atomically swaps all the firewall rules applied to virtual machine (VM) instances under that node.
  • Rule evaluation is hierarchical based on resource hierarchy. All rules associated with the organization node are evaluated, followed by those of the first level of folders, and so on.
  • Hierarchical firewall policy rules have a new goto_next action that you can use to delegate connection evaluation to lower levels of the hierarchy.
  • Hierarchical firewall policy rules can be targeted to specific VPC networks and VMs by using target resources for networks and target service accounts for VMs. This lets you create exceptions for groups of VMs. Hierarchical firewall policy rules do not support targeting by instance tags.
  • Each hierarchical firewall policy rule can include either IPv4 or IPv6 ranges, but not both.
  • To help with compliance and debugging, firewall rules applied to a VM instance can be audited by using the VPC network details page and the VM instance's network interface details page.

Resource hierarchy

You create and apply firewall policies as separate steps. You can create and apply firewall policies at the organization or folder nodes of the resource hierarchy. A firewall policy rule can block connections, allow connections, or defer firewall rule evaluation to lower-level folders or VPC firewall rules defined in VPC networks.

  • Organization is the top-level node in the resource hierarchy in Google Cloud where you can create or associate hierarchical firewall policies. All folders and VPC networks in the organization inherit this policy.

  • Folders are mid-level nodes in the Google Cloud resource hierarchy, between the organization and projects, where you can create or assign hierarchical firewall policies. All folders and VPC networks in a folder inherit its associated policy.

  • A project lives under a folder or the organization. You can move projects between nodes in an organization. Projects contain VPC networks. Hierarchical firewall policies cannot be assigned to projects, only to the organization or folders.

  • A VPC network is the Google Cloud partition for isolated internal IP space communication. This is the level at which routes, network firewall policies, and traditional VPC firewall rules are specified and applied. Hierarchical firewall policy rules can override or delegate connection evaluation to global network firewall policies and rules.

By default, all hierarchical firewall policy rules apply to all VMs in all projects under the organization or folder where the policy is associated. However, you can restrict which VMs get a given rule by specifying target networks or target service accounts.

The levels of the hierarchy at which firewall rules can now be applied are represented in the following diagram. The yellow boxes represent hierarchical firewall policies that contain firewall rules, while the white boxes represent VPC firewall rules.

Hierarchical firewall policies containing rules (yellow boxes)
        at the organization and folder levels and VPC firewall
        rules at the VPC network level
Hierarchical firewall policies containing rules (yellow boxes) are applied at the organization and folder levels. VPC firewall rules are applied at the VPC network level.

Hierarchical firewall policy details

Hierarchical firewall policy rules are defined in a firewall policy resource that acts as a container for firewall rules. The rules defined in a firewall policy are not enforced until the policy is associated with a node (an organization or a folder).

A single policy can be associated with multiple nodes. If you modify a rule in a policy, that rule change applies to all currently associated nodes.

Only one firewall policy can be associated with a node. Hierarchical firewall policy rules and VPC firewall rules are evaluated in a well-defined order.

A firewall policy that is not associated with any nodes is an unassociated hierarchical firewall policy.

Policy names

When you create a new policy, Google Cloud automatically generates an ID for the policy. In addition, you also specify a short name for the policy. When using the gcloud interface to update an existing policy, you can reference either the system-generated ID or a combination of the short name and your organization ID. When using the API to update the policy, you must provide the system-generated ID.

Hierarchical firewall policy rule details

Hierarchical firewall policy rules work the same as firewall policy rules and VPC firewall rules, but there are a few differences:

  • Hierarchical firewall policies support target networks, while global network firewall policies don't. You can specify target networks to restrict a firewall policy rule to VMs in the specified networks. Specifying VPC networks in the rule gives you control over which networks are configured with that rule.

    Combined with goto_next or allow, specifying target networks lets you create exceptions for specific networks when you want to define an otherwise restrictive policy.

  • Hierarchical firewall policies don't have secure tag integration.

  • Hierarchical firewall policies are organization-level resources, while global network firewall policies are project-level resources.

Pre-defined rules

All hierarchical firewall policies have four pre-defined goto_next rules with lowest priority. These rules are applied to any connections that do not match an explicitly defined rule in the policy, causing such connections to be passed down to lower-level policies or network rules.

IPv4 rules:

  • An egress rule whose destination is 0.0.0.0/0, with very low priority (2147483646), that sends processing of the connection to the next lower level of evaluation (goto_next).

  • An ingress rule whose source is 0.0.0.0/0, with a very low priority (2147483647), that sends processing of the connection to the next lower level of evaluation (goto_next).

IPv6 rules:

  • An egress rule whose destination is ::/0, with very low priority (2147483644), that sends processing of the connection to the next lower level of evaluation (goto_next).

  • An ingress rule whose source is ::/0, with a very low priority (2147483645), that sends processing of the connection to the next lower level of evaluation (goto_next).

These pre-defined rules are visible, but cannot be modified or deleted. These rules are different from the implied and pre-populated rules of a VPC network.

Identity and Access Management (IAM) roles

IAM roles govern the following actions with regard to hierarchical firewall policies:

  • Creating a policy that lives at a particular node
  • Associating a policy with a particular node
  • Modifying an existing policy
  • Viewing the effective firewall rules for a particular network or VM

The following table describes which roles are necessary for each step:

Ability Necessary role
Create a new hierarchical firewall policy compute.orgFirewallPolicyAdmin role on the node where the policy will live
Associate a policy with a node compute.orgSecurityResourceAdmin role on the target node, and either compute.orgFirewallPolicyAdmin or compute.orgFirewallPolicyUser role on the node where the policy lives or on the policy itself
Modify the policy by adding, updating, or deleting policy firewall rules compute.orgFirewallPolicyAdmin role either on the node where the policy lives or on the policy itself
Delete the policy compute.orgFirewallPolicyAdmin role either on the node where the policy lives or on the policy itself
View effective firewall rules for a VPC network Any of the following roles for the network:
compute.networkAdmin
compute.networkViewer
compute.securityAdmin
compute.securityReadOnly
compute.viewer
View effective firewall rules for a VM in a network Any of the following roles for the VM:
compute.instanceAdmin
compute.securityAdmin
compute.securityReadOnly
compute.viewer

The following roles are relevant to hierarchical firewall policies.

Role name Description
compute.orgFirewallPolicyAdmin Can be granted on a node or on an individual policy. If granted at a node, allows users to create, update, and delete hierarchical firewall policies and their rules. If granted on an individual policy, allows the user to update the policy rules, but not create or delete the policy. This role also allows the user to associate a policy with a node if they also have the compute.orgSecurityResourceAdmin role on that node.
compute.orgSecurityResourceAdmin Granted at the organization level or to a folder, allows folder-level administrators to associate a policy with that node. Administrators must also have the compute.orgFirewallPolicyUser or compute.orgFirewallPolicyAdmin role on the node that owns the policy or on the policy itself in order to make use of it.
compute.orgFirewallPolicyUser Granted on a node or on an individual policy, allows administrators to make use of the individual policy or policies associated with the node. Users must also have the compute.orgSecurityResourceAdmin role on the target node to associate a policy with that node.
compute.securityAdmin
compute.viewer
compute.networkUser
compute.networkViewer
Allows users to view the firewall rules applied to the network or instance.
Includes the compute.networks.getEffectiveFirewalls permission for networks and the compute.instances.getEffectiveFirewalls for instances.

In the following example, Joe can create, modify, and delete any hierarchical firewall policy in the policies folder, but he cannot attach the hierarchical firewall policy to a folder because he does not have the orgSecurityResourceAdmin role on any folder.

However, because Joe granted Mary permissions to use policy-1, she can list and associate that hierarchical firewall policy with the dev-projects folder or any of its descendants. The orgFirewallPolicyUser role does not grant permission to associate the policies to any folders; the user must also have the orgSecurityResourceAdmin role on the target folder.

policy-1 example
policy-1 example

Manage hierarchical firewall policy resources

Because a hierarchical firewall policy only defines a set of firewall rules and not where they are applied, you can create these resources in a different part of the hierarchy from the nodes that they apply to. This lets you associate a single hierarchical firewall policy resource with multiple folders in the organization.

In the following example, policy-1 is applied to the dev-projects and corp-projects folders and so is enforced on all projects in those folders.

Policy location and association
Policy location and association

Modify a policy's rules

You can add, remove, and modify rules in a policy. Each change is done individually; there is no mechanism for batch updating rules in a policy. Changes are applied in roughly the order that the commands are executed, although this is not guaranteed.

If you are making extensive changes to a hierarchical firewall policy and need to ensure that they're applied at the same time, you can clone the policy to a temporary policy and assign the temporary policy to the same nodes. You can then make your changes to the original, and then assign the original back to the nodes. For the steps to do this, see Cloning rules from one policy to another.

In the following example, policy-1 is attached to the dev-projects folder, and you would like to make several changes that apply atomically. Create a new policy named scratch-policy, and then copy all of the existing rules from policy-1 to scratch-policy for editing. After you finish editing, copy all the rules from scratch-policy back to policy-1.

Modify a policy
Modify a policy

Move a policy

Hierarchical firewall policies, like projects, are parented by a folder or organization resource. As your folder scheme evolves, you might need to move a hierarchical firewall policy to a new folder, perhaps before a folder deletion. Policies owned by a folder are deleted if the folder is deleted.

The following diagram illustrates moving a policy between nodes associations or the evaluation of rules in the policy.

Move a policy
Move a policy

Associate a hierarchical firewall policy with a folder

A hierarchical firewall policy is not enforced unless it is associated with an organization or folder node. After it is associated, it is applied to all VMs in all networks under that organization or folder.

Associate a policy
Associate a policy

Changes to the resource hierarchy

Changes to the resource hierarchy might take some time to propagate through the system. We recommend that you avoid simultaneous updates to the hierarchical firewall policy attachments and the resource hierarchy because networks might not immediately inherit the hierarchical firewall policy defined in the new location in the hierarchy.

Moving a policy
Moving a policy

For example, if you are moving the dept-A folder from the dev-projects folder to the eng-projects folder and changing the association of policy-1 to eng-projects instead of dev-projects, be sure to not disassociate policy-1 from dev-projects at the same time. If the dev-projects folder loses its hierarchical firewall policy association before all VPC networks under it have had their ancestry updated, for a short period of time those VPC networks are not protected by policy-1.

Use hierarchical firewall policies with Shared VPC

In Shared VPC scenarios, a VM interface connected to a host project network is governed by the hierarchical firewall policy rules of the host project, not the service project.

VM in Shared VPC
VM in Shared VPC

Even if the service projects are under a different folder than the host project, the VM interfaces in the shared network still inherit from the host project folder rules.

Service project VMs inherit rules from host project
Service project VMs inherit rules from host project

Use hierarchical firewall policies with VPC Network Peering

In VPC Network Peering scenarios, the VM interface associated to each of the VPC networks inherits the policies in the hierarchy in the respective VPC networks. The following is a VPC Network Peering example where the VPC peered networks belong to different organizations.

VMs inherit from respective networks
VMs inherit from respective networks

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