hscontrol: refuse a key expiry that cannot be encoded

handleRegister, the OIDC auth path and SetNodeExpiry refuse it. Expiries
are stored in UTC, which SQLite can read back, and loaded in UTC, as
PostgreSQL returns the server's zone. The v1 API answers 400.

Fixes ANT-2026-QMCAFJ1Q

(cherry picked from commit 15a8c7584e, adapted: gRPC ExpireNode instead of REST v1)

hscontrol/auth.go

@@ -40,6 +40,14 @@ func (h *Headscale) handleRegister(
 	req tailcfg.RegisterRequest,
 	machineKey key.MachinePublic,
 ) (*tailcfg.RegisterResponse, error) {
+	// Every path below may store the client's expiry and send it to peers.
+	expiry, err := types.ValidateExpiry(req.Expiry)
+	if err != nil {
+		return nil, NewHTTPError(http.StatusBadRequest, err.Error(), err)
+	}
+
+	req.Expiry = expiry
+
 	// Check for logout/expiry FIRST, before checking auth key.
 	// Tailscale clients may send logout requests with BOTH a past expiry AND an auth key.
 	// A past expiry takes precedence - it's a logout regardless of other fields.

hscontrol/auth_test.go

@@ -4327,3 +4327,57 @@ func TestFollowupWaitPrefersCompletedAuthOverExpiredContext(t *testing.T) {
 		timeouts, iterations)
 	assert.Equal(t, iterations, authorized, "every completed registration must be returned as authorized")
 }
+
+// TestRegisterRejectsUnencodableExpiry proves a registration cannot store a key
+// expiry that is in range in its own zone but outside the years [0,9999] in
+// UTC, which every map carrying the node would fail to encode.
+func TestRegisterRejectsUnencodableExpiry(t *testing.T) {
+	app := createTestApp(t)
+
+	user := app.state.CreateUserForTest("expiry-range-user")
+	pak, err := app.state.CreatePreAuthKey(user.TypedID(), true, false, nil, nil)
+	require.NoError(t, err)
+
+	register := func(expiry time.Time) (key.NodePublic, error) {
+		nodeKey := key.NewNode().Public()
+
+		_, err := app.handleRegister(context.Background(), tailcfg.RegisterRequest{
+			Auth:     &tailcfg.RegisterResponseAuth{AuthKey: pak.Key},
+			NodeKey:  nodeKey,
+			Hostinfo: &tailcfg.Hostinfo{Hostname: "expiry-range-node"},
+			Expiry:   expiry,
+		}, key.NewMachine().Public())
+
+		return nodeKey, err
+	}
+
+	for _, raw := range []string{
+		"9999-12-31T23:59:59-23:59",
+		"0000-01-01T00:00:00+23:59",
+	} {
+		expiry, err := time.Parse(time.RFC3339, raw)
+		require.NoError(t, err)
+
+		nodeKey, err := register(expiry)
+
+		httpErr, ok := errors.AsType[HTTPError](err)
+		require.True(t, ok, "expiry %s: want an HTTPError, got %v", raw, err)
+		require.Equal(t, http.StatusBadRequest, httpErr.Code)
+
+		_, found := app.state.GetNodeByNodeKey(nodeKey)
+		require.False(t, found, "expiry %s must not create a node", raw)
+	}
+
+	// The latest encodable expiry still registers, and SQLite reads it back
+	// although it is in the year 10000 east of UTC.
+	latest := time.Date(9999, time.December, 31, 23, 59, 59, 0, time.UTC)
+	nodeKey, err := register(latest.In(time.FixedZone("", 60*60)))
+	require.NoError(t, err, "the latest encodable expiry must still register")
+
+	node, found := app.state.GetNodeByNodeKey(nodeKey)
+	require.True(t, found)
+
+	stored, err := app.state.DB().GetNodeByID(node.ID())
+	require.NoError(t, err)
+	assert.True(t, latest.Equal(*stored.Expiry))
+}

hscontrol/grpcv1.go

@@ -486,6 +486,10 @@ func (api headscaleV1APIServer) ExpireNode(
 	node, nodeChange, err := api.h.state.SetNodeExpiry(
 		types.NodeID(request.GetNodeId()), &expiry,
 	)
+	if errors.Is(err, types.ErrExpiryOutOfRange) {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
 	if err != nil {
 		return nil, err
 	}

hscontrol/grpcv1_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
 )
@@ -817,3 +818,36 @@ func TestDeleteApiKey_BothIdentifiers(t *testing.T) {
 	assert.Equal(t, codes.InvalidArgument, st.Code())
 	assert.Contains(t, st.Message(), "provide either id or prefix, not both")
 }
+
+// TestExpireNode_RefusesUnencodableExpiry proves ExpireNode refuses a key
+// expiry outside the years [0,9999] in UTC as invalid input, which
+// grpc-gateway answers with 400.
+func TestExpireNode_RefusesUnencodableExpiry(t *testing.T) {
+	t.Parallel()
+
+	app := createTestApp(t)
+	apiServer := newHeadscaleV1APIServer(app)
+
+	user := app.state.CreateUserForTest("expire-range-user")
+	node := app.state.CreateRegisteredNodeForTest(user, "expire-range-node")
+	app.state.PutNodeInStoreForTest(*node)
+
+	beyond, err := time.Parse(time.RFC3339, "9999-12-31T23:59:59-23:59")
+	require.NoError(t, err)
+
+	_, err = apiServer.ExpireNode(context.Background(), &v1.ExpireNodeRequest{
+		NodeId: uint64(node.ID),
+		Expiry: timestamppb.New(beyond),
+	})
+	require.Error(t, err)
+	st, ok := status.FromError(err)
+	require.True(t, ok, "error should be a gRPC status error")
+	assert.Equal(t, codes.InvalidArgument, st.Code())
+
+	latest := time.Date(9999, time.December, 31, 23, 59, 59, 0, time.UTC)
+	_, err = apiServer.ExpireNode(context.Background(), &v1.ExpireNodeRequest{
+		NodeId: uint64(node.ID),
+		Expiry: timestamppb.New(latest),
+	})
+	require.NoError(t, err)
+}

hscontrol/state/persist_test.go

@@ -710,3 +710,111 @@ func TestUpdatePolicyManagerUsersUnchangedKeepsSnapshot(t *testing.T) {
 	require.NotSame(t, before, s.nodeStore.data.Load(),
 		"a user change must rebuild the peer map")
 }
+
+// TestSetNodeExpiryRejectsUnencodableExpiry proves an admin cannot store a key
+// expiry that every map carrying the node would fail to encode.
+func TestSetNodeExpiryRejectsUnencodableExpiry(t *testing.T) {
+	_, s, nodeID := persistTestSetup(t)
+	t.Cleanup(func() { _ = s.Close() })
+
+	beyond, err := time.Parse(time.RFC3339, "9999-12-31T23:59:59-23:59")
+	require.NoError(t, err)
+
+	before := s.nodeStore.data.Load()
+
+	_, _, err = s.SetNodeExpiry(nodeID, &beyond)
+	require.ErrorIs(t, err, types.ErrExpiryOutOfRange)
+	require.Same(t, before, s.nodeStore.data.Load(),
+		"a refused expiry must not reach the NodeStore")
+
+	latest := time.Date(9999, time.December, 31, 23, 59, 59, 0, time.UTC)
+	_, _, err = s.SetNodeExpiry(nodeID, &latest)
+	require.NoError(t, err)
+}
+
+// TestAuthPathRejectsUnencodableExpiry proves an expiry handed to the auth
+// path, such as an OIDC token's, cannot store what SetNodeExpiry refuses.
+func TestAuthPathRejectsUnencodableExpiry(t *testing.T) {
+	_, s, _ := persistTestSetup(t)
+	t.Cleanup(func() { _ = s.Close() })
+
+	user := s.CreateUserForTest("auth-path-user")
+	nodeKey := key.NewNode().Public()
+	authID := types.MustAuthID()
+	s.SetAuthCacheEntry(authID, types.NewRegisterAuthRequest(&types.RegistrationData{
+		MachineKey: key.NewMachine().Public(),
+		NodeKey:    nodeKey,
+		Hostname:   "auth-path-node",
+	}))
+
+	// How go-oidc reads an exp claim in the year 10000.
+	beyond := time.Unix(253402300800, 0)
+
+	_, _, err := s.HandleNodeFromAuthPath(
+		authID, types.UserID(user.ID), &beyond, util.RegisterMethodOIDC,
+	)
+	require.ErrorIs(t, err, types.ErrExpiryOutOfRange)
+
+	_, found := s.GetNodeByNodeKey(nodeKey)
+	require.False(t, found, "a refused expiry must not create a node")
+}
+
+// TestAcceptedExpirySurvivesRestart proves an accepted expiry that is already in
+// the year 10000 in its own zone is stored so SQLite can load it at the next
+// start. go-oidc reads a token's exp in the server's zone, east of UTC here.
+func TestAcceptedExpirySurvivesRestart(t *testing.T) {
+	latest := time.Date(9999, time.December, 31, 23, 59, 59, 0, time.UTC)
+	east := latest.In(time.FixedZone("", 60*60))
+
+	dbPath, s, adminID := persistTestSetup(t)
+
+	_, _, err := s.SetNodeExpiry(adminID, &east)
+	require.NoError(t, err)
+
+	user := s.CreateUserForTest("oidc-user")
+	authID := types.MustAuthID()
+	s.SetAuthCacheEntry(authID, types.NewRegisterAuthRequest(&types.RegistrationData{
+		MachineKey: key.NewMachine().Public(),
+		NodeKey:    key.NewNode().Public(),
+		Hostname:   "oidc-node",
+	}))
+
+	oidcNode, _, err := s.HandleNodeFromAuthPath(
+		authID, types.UserID(user.ID), &east, util.RegisterMethodOIDC,
+	)
+	require.NoError(t, err)
+	require.NoError(t, s.Close())
+
+	s = persistTestReopen(t, dbPath)
+
+	for _, id := range []types.NodeID{adminID, oidcNode.ID()} {
+		nv, ok := s.GetNodeByID(id)
+		require.True(t, ok)
+		assert.True(t, latest.Equal(nv.Expiry().Get()), "node %d", id)
+	}
+}
+
+// TestLoadedExpiryIsUTC proves an expiry the database returns in another zone is
+// served in UTC. PostgreSQL returns the server's zone, where the latest accepted
+// expiry is in the year 10000 and cannot be encoded.
+func TestLoadedExpiryIsUTC(t *testing.T) {
+	dbPath, s, nodeID := persistTestSetup(t)
+	require.NoError(t, s.Close())
+
+	expiry := time.Date(2030, time.January, 1, 0, 0, 0, 0, time.UTC)
+
+	database, err := db.NewHeadscaleDatabase(persistTestConfig(dbPath))
+	require.NoError(t, err)
+	require.NoError(t, database.DB.Model(&types.Node{}).Where("id = ?", nodeID).
+		Update("expiry", expiry.In(time.FixedZone("", 60*60))).Error)
+	require.NoError(t, database.Close())
+
+	s = persistTestReopen(t, dbPath)
+
+	nv, ok := s.GetNodeByID(nodeID)
+	require.True(t, ok)
+
+	got := nv.Expiry().Get()
+	assert.True(t, expiry.Equal(got))
+	assert.Equal(t, time.UTC, got.Location())
+}

hscontrol/state/state.go

@@ -253,6 +253,12 @@ func NewState(cfg *types.Config) (*State, error) {
 	// This ensures we don't have stale online status from previous runs
 	for _, node := range nodes {
 		node.IsOnline = new(false)
+
+		// PostgreSQL returns the server's zone, where the latest accepted
+		// expiry is in the year 10000 and cannot be encoded.
+		if node.Expiry != nil {
+			node.Expiry = new(node.Expiry.UTC())
+		}
 	}
 
 	users, err := db.ListUsers()
@@ -912,6 +918,15 @@ func (s *State) ListEphemeralNodes() views.Slice[types.NodeView] {
 // SetNodeExpiry updates the expiration time for a node.
 // If expiry is nil, the node's expiry is disabled (node will never expire).
 func (s *State) SetNodeExpiry(nodeID types.NodeID, expiry *time.Time) (types.NodeView, change.Change, error) {
+	if expiry != nil {
+		utc, err := types.ValidateExpiry(*expiry)
+		if err != nil {
+			return types.NodeView{}, change.Change{}, err
+		}
+
+		expiry = &utc
+	}
+
 	var onlineChanged bool
 
 	// Update [NodeStore] before database to ensure consistency. The [NodeStore] update
@@ -2216,6 +2231,16 @@ func (s *State) HandleNodeFromAuthPath(
 	expiry *time.Time,
 	registrationMethod string,
 ) (types.NodeView, change.Change, error) {
+	// An OIDC token's expiry arrives here without passing handleRegister.
+	if expiry != nil {
+		utc, err := types.ValidateExpiry(*expiry)
+		if err != nil {
+			return types.NodeView{}, change.Change{}, err
+		}
+
+		expiry = &utc
+	}
+
 	// Get the registration entry from cache
 	regEntry, ok := s.GetAuthCacheEntry(authID)
 	if !ok {

hscontrol/types/node.go

@@ -619,6 +619,10 @@ func ValidateGivenName(givenName, baseDomain string) error {
 // or an error when it cannot be sent to clients. [time.Time.MarshalJSON] refuses
 // a year outside [0,9999], failing every map response that carries it. A time
 // that is in range in its own zone can still leave the range in UTC.
+//
+// Callers store the returned value: SQLite writes a time in its own zone and
+// cannot read back a year outside [0,9999], which that zone can reach when UTC
+// does not.
 func ValidateExpiry(expiry time.Time) (time.Time, error) {
 	utc := expiry.UTC()
 	if year := utc.Year(); year < 0 || year > 9999 {