gcp_storage_location_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 restricting the locations
# of Cloud Storage buckets to specific locations in GCP.
# Location names need to be exact match. It supports
# allowlist or denylist modes, as well as exempting selected
# buckets from the list.

apiVersion: templates.gatekeeper.sh/v1alpha1
kind: ConstraintTemplate
metadata:
  name: gcp-storage-location-v1
spec:
  crd:
    spec:
      names:
        kind: GCPStorageLocationConstraintV1
      validation:
        openAPIV3Schema:
          properties:
            mode:
              type: string
              enum: [denylist, allowlist]
              description: "String identifying the operational mode, allowlist or denylist. In allowlist mode,
              datasets are only allowed in the locations specified in the 'locations' parameter. In denylist mode,
              resources are allowed in all locations except those listed in the 'locations' parameter."
            exemptions:
              type: array
              items:
                type: string
              description: "Array of storage buckets to exempt from location restriction. String values in the array should
              correspond to the full name values of exempted storage buckets."
            locations:
              type: array
              items:
                type: string
              description: "Array of location names to be allowed or denied. Should be the the location name, whether regional
              (e.g. us-west2), multi-regional (e.g. EU), or dual-region (e.g. eur4), as defined at
              https://cloud.google.com/storage/docs/locations. Location names need to be exact match."
  targets:
    validation.gcp.forsetisecurity.org:
      rego: | #INLINE("validator/storage_location.rego")
          #
          # 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.
          #
          
          package templates.gcp.GCPStorageLocationConstraintV1
          
          import data.validator.gcp.lib as lib
          
          deny[{
          	"msg": message,
          	"details": metadata,
          }] {
          	constraint := input.constraint
          	lib.get_constraint_params(constraint, params)
          
          	asset := input.asset
          	asset.asset_type == "storage.googleapis.com/Bucket"
          
          	# Check if resource is in exempt list
          	exempt_list := lib.get_default(params, "exemptions", [])
          	matches := {asset.name} & cast_set(exempt_list)
          	count(matches) == 0
          
          	# Check that location is in allowlist/denylist
          	target_locations := params.locations
          	asset_location := asset.resource.data.location
          	location_matches := ({upper(asset_location)} & cast_set(target_locations)) | ({lower(asset_location)} & cast_set(target_locations))
          	target_location_match_count(params.mode, desired_count)
          	count(location_matches) == desired_count
          
          	message := sprintf("%v is in a disallowed location.", [asset.name])
          	metadata := {"location": asset_location, "resource": asset.name}
          }
          
          ###########################
          # Rule Utilities
          ###########################
          
          # Determine the overlap between locations under test and constraint
          # By default (allowlist), we violate if there isn't overlap
          target_location_match_count(mode) = 0 {
          	mode != "denylist"
          }
          
          target_location_match_count(mode) = 1 {
          	mode == "denylist"
          }
          #ENDINLINE