gcp_compute_disk_resource_policies_v1.yaml

# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

# This template is for policies auditing Persistent Disk resource
# policies (eg. snapshot schedules). It supports allowlist or denylist
# modes, as well as exempting selected assets from the list.

apiVersion: templates.gatekeeper.sh/v1alpha1
kind: ConstraintTemplate
metadata:
  name: gcp-compute-disk-resource-policies-v1
spec:
  crd:
    spec:
      names:
        kind: GCPComputeDiskResourcePoliciesConstraintV1
      validation:
        openAPIV3Schema:
          properties:
            mode:
              type: string
              enum: [denylist, allowlist]
              description: "String identifying the operational mode, allowlist or denylist. In allowlist mode, 
              disk resource policies are only allowed in the policies specified in the 'resource_policies' parameter. 
              In denylist mode, all disk resources policies are allowed except those listed in the 'resource_policies' 
              parameter."
            exemptions:
              type: array
              items:
                type: string
              description: "Array of disk assets to exempt from resource policies restriction. String values in the array 
              should correspond to the full name values of exempted policies."
            resourcePolicies:
              type: array
              items:
                type: string
              description: "Array of resource policies to be allowed or denied. Should be the full URL syntax,
              e.g. https://www.googleapis.com/compute/v1/projects/my-project/regions/europe-north1/resourcePolicies/snapshot-schedule."
  targets:
    validation.gcp.forsetisecurity.org:
      rego: | #INLINE("validator/compute_disk_resource_policies.rego")
           #
           # Copyright 2020 Google LLC
           #
           # Licensed under the Apache License, Version 2.0 (the "License");
           # you may not use this file except in compliance with the License.
           # You may obtain a copy of the License at
           #
           #      http://www.apache.org/licenses/LICENSE-2.0
           #
           # Unless required by applicable law or agreed to in writing, software
           # distributed under the License is distributed on an "AS IS" BASIS,
           # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
           # See the License for the specific language governing permissions and
           # limitations under the License.
           #
           
           package templates.gcp.GCPComputeDiskResourcePoliciesConstraintV1
           
           import data.validator.gcp.lib as lib
           
           #####################################
           # Find Compute Persistent Disk Resource Policy Violations
           #####################################
           deny[{
           	"msg": message,
           	"details": metadata,
           }] {
           	constraint := input.constraint
           	lib.get_constraint_params(constraint, params)
           
           	# Verify that resource is Disk or RegionDisk
           	asset := input.asset
           	{asset.asset_type} == {asset.asset_type} & {"compute.googleapis.com/Disk", "compute.googleapis.com/RegionDisk"}
           
           	# Check if resource is in exempt list
           	exempt_list := params.exemptions
           	matches := {asset.name} & cast_set(exempt_list)
           	count(matches) == 0
           
           	# Check that resource policy is in allowlist/denylist
           	asset_resource_policies := lib.get_default(asset.resource.data, "resourcePolicies", [""])
           	target_resource_policies := params.resourcePolicies
           	resource_policies_matches := cast_set(asset_resource_policies) & cast_set(target_resource_policies)
           	target_resource_policies_match_count(params.mode, desired_count)
           	count(resource_policies_matches) == desired_count
           
           	message := sprintf("%v has an empty or disallowed resource policy.", [asset.name])
           	metadata := {"resource": asset.name, "resource_policies": asset_resource_policies}
           }
           
           #################
           # Rule Utilities
           #################
           
           # Determine the overlap between resource policies under test and constraint
           # By default (allowlist), we violate if there isn't overlap
           target_resource_policies_match_count(mode) = 0 {
           	mode != "denylist"
           }
           
           target_resource_policies_match_count(mode) = 1 {
           	mode == "denylist"
           }
           #ENDINLINE