Add --no-cross-namespace-refs flag

This uses the helper in fluxcd/runtime/acl to bind the cross-ns flag,
passes it to the controller, and checks it when resolving the
potentially cross-namespace reference.

Signed-off-by: Michael Bridgen <michael@weave.works>

controllers/imagepolicy_controller.go

@@ -57,6 +57,7 @@ type ImagePolicyReconciler struct {
 	ExternalEventRecorder *events.Recorder
 	MetricsRecorder       *metrics.Recorder
 	Database              DatabaseReader
+	ACLOptions            acl.Options
 }
 
 type ImagePolicyReconcilerOptions struct {
@@ -97,6 +98,23 @@ func (r *ImagePolicyReconciler) Reconcile(ctx context.Context, req ctrl.Request)
 	if pol.Spec.ImageRepositoryRef.Namespace != "" {
 		repoNamespacedName.Namespace = pol.Spec.ImageRepositoryRef.Namespace
 	}
+
+	// check if we're allowed to reference across namespaces, before trying to fetch it
+	if r.ACLOptions.NoCrossNamespaceRefs && repoNamespacedName.Namespace != pol.GetNamespace() {
+		err := fmt.Errorf("cannot access '%s/%s', cross-namespace references have been blocked", imagev1.ImageRepositoryKind, repoNamespacedName)
+		imagev1.SetImagePolicyReadiness(
+			&pol,
+			metav1.ConditionFalse,
+			aclapi.AccessDeniedReason,
+			err.Error(),
+		)
+		if err := r.patchStatus(ctx, req, pol.Status); err != nil {
+			return ctrl.Result{Requeue: true}, err
+		}
+		log.Error(err, "access denied to cross-namespace ImageRepository")
+		return ctrl.Result{}, nil // this cannot proceed until the spec changes, so no need to requeue explicitly
+	}
+
 	if err := r.Get(ctx, repoNamespacedName, &repo); err != nil {
 		if client.IgnoreNotFound(err) == nil {
 			imagev1.SetImagePolicyReadiness(

main.go

@@ -29,6 +29,7 @@ import (
 	ctrl "sigs.k8s.io/controller-runtime"
 	crtlmetrics "sigs.k8s.io/controller-runtime/pkg/metrics"
 
+	"github.com/fluxcd/pkg/runtime/acl"
 	"github.com/fluxcd/pkg/runtime/client"
 	"github.com/fluxcd/pkg/runtime/events"
 	"github.com/fluxcd/pkg/runtime/leaderelection"
@@ -72,6 +73,7 @@ func main() {
 		awsAutoLogin            bool
 		gcpAutoLogin            bool
 		azureAutoLogin          bool
+		aclOptions              acl.Options
 	)
 
 	flag.StringVar(&metricsAddr, "metrics-addr", ":8080", "The address the metric endpoint binds to.")
@@ -89,6 +91,7 @@ func main() {
 	clientOptions.BindFlags(flag.CommandLine)
 	logOptions.BindFlags(flag.CommandLine)
 	leaderElectionOptions.BindFlags(flag.CommandLine)
+	aclOptions.BindFlags(flag.CommandLine)
 	flag.Parse()
 
 	log := logger.NewLogger(logOptions)
@@ -167,6 +170,7 @@ func main() {
 		ExternalEventRecorder: eventRecorder,
 		MetricsRecorder:       metricsRecorder,
 		Database:              db,
+		ACLOptions:            aclOptions,
 	}).SetupWithManager(mgr, controllers.ImagePolicyReconcilerOptions{
 		MaxConcurrentReconciles: concurrent,
 	}); err != nil {