auth, etcdserver: attaching a fake root token when calling LeaseRevoke

fix LeaseRevoke may fail to apply when authentication is enabled
and upgrading cluster from etcd-3.2 to etcd-3.3 (#11691)

auth/store.go

@@ -162,6 +162,9 @@ type AuthStore interface {
 
 	// AuthInfoFromTLS gets AuthInfo from TLS info of gRPC's context
 	AuthInfoFromTLS(ctx context.Context) *AuthInfo
+
+	// WithRoot generates and installs a token that can be used as a root credential
+	WithRoot(ctx context.Context) context.Context
 }
 
 type TokenProvider interface {
@@ -1070,3 +1073,40 @@ func NewTokenProvider(tokenOpts string, indexWaiter func(uint64) <-chan struct{}
 		return nil, ErrInvalidAuthOpts
 	}
 }
+
+func (as *authStore) WithRoot(ctx context.Context) context.Context {
+	if !as.isAuthEnabled() {
+		return ctx
+	}
+
+	var ctxForAssign context.Context
+	if ts, ok := as.tokenProvider.(*tokenSimple); ok && ts != nil {
+		ctx1 := context.WithValue(ctx, "index", uint64(0))
+		prefix, err := ts.genTokenPrefix()
+		if err != nil {
+			plog.Errorf("failed to generate prefix of internally used token")
+			return ctx
+		}
+		ctxForAssign = context.WithValue(ctx1, "simpleToken", prefix)
+	} else {
+		ctxForAssign = ctx
+	}
+
+	token, err := as.tokenProvider.assign(ctxForAssign, "root", as.Revision())
+	if err != nil {
+		// this must not happen
+		plog.Errorf("failed to assign token for lease revoking: %s", err)
+		return ctx
+	}
+
+	mdMap := map[string]string{
+		"token": token,
+	}
+	tokenMD := metadata.New(mdMap)
+
+	// clean up tls info to ensure using root credential
+	ctx = peer.NewContext(ctx, nil)
+
+	// use "mdIncomingKey{}" since it's called from local etcdserver
+	return metadata.NewIncomingContext(ctx, tokenMD)
+}

etcdserver/v3_server.go

@@ -222,6 +222,9 @@ func (s *EtcdServer) LeaseGrant(ctx context.Context, r *pb.LeaseGrantRequest) (*
 }
 
 func (s *EtcdServer) LeaseRevoke(ctx context.Context, r *pb.LeaseRevokeRequest) (*pb.LeaseRevokeResponse, error) {
+	// fix: LeaseRevoke may fail to apply when authentication is enabled and upgrading cluster from etcd-3.2 to etcd-3.3
+	// see https://github.com/etcd-io/etcd/issues/11689
+	ctx = s.authStore.WithRoot(ctx)
 	resp, err := s.raftRequestOnce(ctx, pb.InternalRaftRequest{LeaseRevoke: r})
 	if err != nil {
 		return nil, err