fix: validate regex patterns in annotations #510

pkg/webhook/tenant/forbidden_annotations_regex.go

@@ -0,0 +1,76 @@
+// Copyright 2020-2021 Clastix Labs
+// SPDX-License-Identifier: Apache-2.0
+
+package tenant
+
+import (
+	"context"
+	"regexp"
+
+	"k8s.io/client-go/tools/record"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	capsulev1beta1 "github.com/clastix/capsule/api/v1beta1"
+	capsulewebhook "github.com/clastix/capsule/pkg/webhook"
+	"github.com/clastix/capsule/pkg/webhook/utils"
+)
+
+type forbiddenAnnotationsRegexHandler struct {
+}
+
+func ForbiddenAnnotationsRegexHandler() capsulewebhook.Handler {
+	return &forbiddenAnnotationsRegexHandler{}
+}
+
+func (h *forbiddenAnnotationsRegexHandler) validate(decoder *admission.Decoder, req admission.Request) *admission.Response {
+	tenant := &capsulev1beta1.Tenant{}
+	if err := decoder.Decode(req, tenant); err != nil {
+		return utils.ErroredResponse(err)
+	}
+
+	if tenant.Annotations == nil {
+		return nil
+	}
+
+	annotationsToCheck := []string{
+		capsulev1beta1.ForbiddenNamespaceAnnotationsRegexpAnnotation,
+		capsulev1beta1.ForbiddenNamespaceLabelsRegexpAnnotation,
+	}
+
+	for _, annotation := range annotationsToCheck {
+		if _, err := regexp.Compile(tenant.Annotations[annotation]); err != nil {
+			response := admission.Denied("unable to compile " + annotation + " regex annotation")
+
+			return &response
+		}
+	}
+
+	return nil
+}
+
+func (h *forbiddenAnnotationsRegexHandler) OnCreate(_ client.Client, decoder *admission.Decoder, _ record.EventRecorder) capsulewebhook.Func {
+	return func(ctx context.Context, req admission.Request) *admission.Response {
+		if err := h.validate(decoder, req); err != nil {
+			return err
+		}
+
+		return nil
+	}
+}
+
+func (h *forbiddenAnnotationsRegexHandler) OnDelete(client.Client, *admission.Decoder, record.EventRecorder) capsulewebhook.Func {
+	return func(context.Context, admission.Request) *admission.Response {
+		return nil
+	}
+}
+
+func (h *forbiddenAnnotationsRegexHandler) OnUpdate(client client.Client, decoder *admission.Decoder, recorder record.EventRecorder) capsulewebhook.Func {
+	return func(ctx context.Context, req admission.Request) *admission.Response {
+		if response := h.validate(decoder, req); response != nil {
+			return response
+		}
+
+		return nil
+	}
+}