nfd-master: implement --verify-node-name

Make NodeName based authorization of the workers optional (off by
default). This makes it possible for all nfd-worker pods in the cluster
to use one shared secret, making NFD deployment much easier. However,
this also opens a way for nfd-workers to label other nodes (than what it
is running on), too.

cmd/nfd-master/main.go

@@ -73,6 +73,7 @@ type Args struct {
 	labelWhiteList *regexp.Regexp
 	noPublish      bool
 	port           int
+	verifyNodeName bool
 }
 
 func main() {
@@ -145,6 +146,7 @@ func argsParse(argv []string) (Args, error) {
   Usage:
   %s [--no-publish] [--label-whitelist=<pattern>] [--port=<port>]
      [--ca-file=<path>] [--cert-file=<path>] [--key-file=<path>]
+     [--verify-node-name]
   %s -h | --help
   %s --version
 
@@ -159,6 +161,9 @@ func argsParse(argv []string) (Args, error) {
                               [Default: ]
   --key-file=<path>           Private key matching --cert-file
                               [Default: ]
+  --verify-node-name		  Verify worker node name against CN from the TLS
+                              certificate. Only has effect when TLS authentication
+                              has been enabled.
   --no-publish                Do not publish feature labels
   --label-whitelist=<pattern> Regular expression to filter label names to
                               publish to the Kubernetes API server. [Default: ]`,
@@ -185,6 +190,7 @@ func argsParse(argv []string) (Args, error) {
 	if err != nil {
 		return args, fmt.Errorf("error parsing whitelist regex (%s): %s", arguments["--label-whitelist"], err)
 	}
+	args.verifyNodeName = arguments["--verify-node-name"].(bool)
 
 	// Check TLS related args
 	if args.certFile != "" || args.keyFile != "" || args.caFile != "" {
@@ -242,28 +248,29 @@ type labelerServer struct {
 
 // Service SetLabels
 func (s *labelerServer) SetLabels(c context.Context, r *pb.SetLabelsRequest) (*pb.SetLabelsReply, error) {
-	// Client authorization.
+	if s.args.verifyNodeName {
-	// Check that the node name matches the CN from the TLS cert
+		// Client authorization.
-	client, ok := peer.FromContext(c)
+		// Check that the node name matches the CN from the TLS cert
-	if !ok {
+		client, ok := peer.FromContext(c)
-		stderrLogger.Printf("gRPC request error: failed to get peer (client)")
+		if !ok {
-		return &pb.SetLabelsReply{}, fmt.Errorf("failed to get peer (client)")
+			stderrLogger.Printf("gRPC request error: failed to get peer (client)")
+			return &pb.SetLabelsReply{}, fmt.Errorf("failed to get peer (client)")
+		}
+		tlsAuth, ok := client.AuthInfo.(credentials.TLSInfo)
+		if !ok {
+			stderrLogger.Printf("gRPC request error: incorrect client credentials from '%v'", client.Addr)
+			return &pb.SetLabelsReply{}, fmt.Errorf("incorrect client credentials")
+		}
+		if len(tlsAuth.State.VerifiedChains) == 0 || len(tlsAuth.State.VerifiedChains[0]) == 0 {
+			stderrLogger.Printf("gRPC request error: client certificate verification for '%v' failed", client.Addr)
+			return &pb.SetLabelsReply{}, fmt.Errorf("client certificate verification failed")
+		}
+		cn := tlsAuth.State.VerifiedChains[0][0].Subject.CommonName
+		if cn != r.NodeName {
+			stderrLogger.Printf("gRPC request error: authorization for %v failed: cert valid for '%s', requested node name '%s'", client.Addr, cn, r.NodeName)
+			return &pb.SetLabelsReply{}, fmt.Errorf("request authorization failed: cert valid for '%s', requested node name '%s'", cn, r.NodeName)
+		}
 	}
-	tlsAuth, ok := client.AuthInfo.(credentials.TLSInfo)
-	if !ok {
-		stderrLogger.Printf("gRPC request error: incorrect client credentials from '%v'", client.Addr)
-		return &pb.SetLabelsReply{}, fmt.Errorf("incorrect client credentials")
-	}
-	if len(tlsAuth.State.VerifiedChains) == 0 || len(tlsAuth.State.VerifiedChains[0]) == 0 {
-		stderrLogger.Printf("gRPC request error: client certificate verification for '%v' failed", client.Addr)
-		return &pb.SetLabelsReply{}, fmt.Errorf("client certificate verification failed")
-	}
-	cn := tlsAuth.State.VerifiedChains[0][0].Subject.CommonName
-	if cn != r.NodeName {
-		stderrLogger.Printf("gRPC request error: authorization for %v failed: cert valid for '%s', requested node name '%s'", client.Addr, cn, r.NodeName)
-		return &pb.SetLabelsReply{}, fmt.Errorf("request authorization failed: cert valid for '%s', requested node name '%s'", cn, r.NodeName)
-	}
-
 	stdoutLogger.Printf("REQUEST Node: %s NFD-version: %s Labels: %s", r.NodeName, r.NfdVersion, r.Labels)
 
 	if !s.args.noPublish {