# Copyright 2021 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
#
#     https://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 BigQuery datasets to specific locations in GCP. It supports
# allowlist or denylist modes, as well as exempting selected
# datasets from the list.

apiVersion: templates.gatekeeper.sh/v1alpha1
kind: ConstraintTemplate
metadata:
  name: gcp-bigquery-dataset-location-v1
spec:
  crd:
    spec:
      names:
        kind: GCPBigQueryDatasetLocationConstraintV1
      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 datasets to exempt from location restriction.
                String values in the array should correspond to the full name values
                of exempted datasets."
            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) or multi-regional
                (e.g. EU), as defined at https://cloud.google.com/bigquery/docs/locations."
  targets:
    validation.gcp.forsetisecurity.org:
      rego: |2

        #

        # Copyright 2021 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

        #

        #     https://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.GCPBigQueryDatasetLocationConstraintV1



        import data.validator.gcp.lib as lib



        ############################################

        # Find BigQuery Dataset Location Violations

        ############################################

        deny[{

        	"msg": message,

        	"details": metadata,

        }] {

        	constraint := input.constraint

        	lib.get_constraint_params(constraint, params)



        	# Verify that resource is BigQuery dataset

        	asset := input.asset

        	asset.asset_type == "bigquery.googleapis.com/Dataset"



        	# 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 := {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
