nfd-master: add validation of label names and values

Validate labels before trying to update the node. Makes us fail early
nad prevent useless retries in case invalid labels are tried.

(backported from commit 2a3c7e4c93)

pkg/nfd-master/nfd-master-internal_test.go

@@ -367,8 +367,10 @@ func TestSetLabels(t *testing.T) {
 				"random.denied.ns/feature-3":     "val-3",
 				"kubernetes.io/feature-4":        "val-4",
 				"sub.ns.kubernetes.io/feature-5": "val-5",
-				vendorFeatureLabel:               " val-6",
-				vendorProfileLabel:               " val-7"}
+				vendorFeatureLabel:               "val-6",
+				vendorProfileLabel:               "val-7",
+				"--invalid-name--":               "valid-val",
+				"valid-name":                     "--invalid-val--"}
 			expectedPatches := []apihelper.JsonPatch{
 				apihelper.NewJsonPatch("add", "/metadata/annotations", instance+"."+nfdv1alpha1.WorkerVersionAnnotation, workerVer),
 				apihelper.NewJsonPatch("add", "/metadata/annotations",

pkg/nfd-master/nfd-master.go

@@ -39,6 +39,7 @@ import (
 	corev1 "k8s.io/api/core/v1"
 	k8sQuantity "k8s.io/apimachinery/pkg/api/resource"
 	k8sLabels "k8s.io/apimachinery/pkg/labels"
+	k8svalidation "k8s.io/apimachinery/pkg/util/validation"
 	"k8s.io/client-go/kubernetes"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/klog/v2"
@@ -462,6 +463,12 @@ func (m *nfdMaster) filterFeatureLabels(labels Labels) (Labels, ExtendedResource
 		// Add possibly missing default ns
 		label := addNs(label, nfdv1alpha1.FeatureLabelNs)
 
+		//Validate label name
+		if errs := k8svalidation.IsQualifiedName(label); len(errs) > 0 {
+			klog.Errorf("ignoring label %q, invalid name: %s", label, strings.Join(errs, "; "))
+			continue
+		}
+
 		ns, name := splitNs(label)
 
 		// Check label namespace, filter out if ns is not whitelisted
@@ -481,6 +488,12 @@ func (m *nfdMaster) filterFeatureLabels(labels Labels) (Labels, ExtendedResource
 			klog.Errorf("%s (%s) does not match the whitelist (%s) and will not be published.", name, label, m.config.LabelWhiteList.Regexp.String())
 			continue
 		}
+
+		// Validate the label value
+		if errs := k8svalidation.IsValidLabelValue(value); len(errs) > 0 {
+			klog.Errorf("ignoring label %q, invalid value %q: %s", label, value, strings.Join(errs, "; "))
+			continue
+		}
 		outLabels[label] = value
 	}