drop Initial and Handshake keys when receiving the first 1-RTT ACK

internal/ackhandler/sent_packet_handler.go

@@ -105,17 +105,12 @@ func NewSentPacketHandler(
 func (h *sentPacketHandler) DropPackets(encLevel protocol.EncryptionLevel) {
 	// remove outstanding packets from bytes_in_flight
 	pnSpace := h.getPacketNumberSpace(encLevel)
-	var packets []*Packet
 	pnSpace.history.Iterate(func(p *Packet) (bool, error) {
-		packets = append(packets, p)
 		if p.includedInBytesInFlight {
 			h.bytesInFlight -= p.Length
 		}
 		return true, nil
 	})
-	for _, p := range packets {
-		pnSpace.history.Remove(p.PacketNumber)
-	}
 	// remove packets from the retransmission queue
 	var queue []*Packet
 	for _, packet := range h.retransmissionQueue {
@@ -124,6 +119,15 @@ func (h *sentPacketHandler) DropPackets(encLevel protocol.EncryptionLevel) {
 		}
 	}
 	h.retransmissionQueue = queue
+	// drop the packet history
+	switch encLevel {
+	case protocol.EncryptionInitial:
+		h.initialPackets = nil
+	case protocol.EncryptionHandshake:
+		h.handshakePackets = nil
+	default:
+		panic(fmt.Sprintf("Cannot drop keys for encryption level %s", encLevel))
+	}
 }
 
 func (h *sentPacketHandler) SetMaxAckDelay(mad time.Duration) {
@@ -312,7 +316,14 @@ func (h *sentPacketHandler) determineNewlyAckedPackets(
 }
 
 func (h *sentPacketHandler) hasOutstandingCryptoPackets() bool {
-	return h.initialPackets.history.HasOutstandingPackets() || h.handshakePackets.history.HasOutstandingPackets()
+	var hasInitial, hasHandshake bool
+	if h.initialPackets != nil {
+		hasInitial = h.initialPackets.history.HasOutstandingPackets()
+	}
+	if h.handshakePackets != nil {
+		hasHandshake = h.handshakePackets.history.HasOutstandingPackets()
+	}
+	return hasInitial || hasHandshake
 }
 
 func (h *sentPacketHandler) hasOutstandingPackets() bool {
@@ -536,8 +547,13 @@ func (h *sentPacketHandler) PopPacketNumber(encLevel protocol.EncryptionLevel) p
 }
 
 func (h *sentPacketHandler) SendMode() SendMode {
-	numTrackedPackets := len(h.retransmissionQueue) + h.initialPackets.history.Len() +
-		h.handshakePackets.history.Len() + h.oneRTTPackets.history.Len()
+	numTrackedPackets := len(h.retransmissionQueue) + h.oneRTTPackets.history.Len()
+	if h.initialPackets != nil {
+		numTrackedPackets += h.initialPackets.history.Len()
+	}
+	if h.handshakePackets != nil {
+		numTrackedPackets += h.handshakePackets.history.Len()
+	}
 
 	// Don't send any packets if we're keeping track of the maximum number of packets.
 	// Note that since MaxOutstandingSentPackets is smaller than MaxTrackedSentPackets,

internal/ackhandler/sent_packet_handler_test.go

@@ -861,7 +861,7 @@ var _ = Describe("SentPacketHandler", func() {
 			handler.queuePacketForRetransmission(lostPacket, handler.getPacketNumberSpace(protocol.EncryptionHandshake))
 			handler.DropPackets(protocol.EncryptionInitial)
 			Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(10)))
-			Expect(handler.initialPackets.history.Len()).To(BeZero())
+			Expect(handler.initialPackets).To(BeNil())
 			Expect(handler.handshakePackets.history.Len()).ToNot(BeZero())
 			packet := handler.DequeuePacketForRetransmission()
 			Expect(packet).To(Equal(lostPacket))
@@ -882,7 +882,7 @@ var _ = Describe("SentPacketHandler", func() {
 			handler.queuePacketForRetransmission(lostPacket, handler.getPacketNumberSpace(protocol.EncryptionHandshake))
 			handler.DropPackets(protocol.EncryptionHandshake)
 			Expect(handler.bytesInFlight).To(Equal(protocol.ByteCount(10)))
-			Expect(handler.handshakePackets.history.Len()).To(BeZero())
+			Expect(handler.handshakePackets).To(BeNil())
 			packet := handler.DequeuePacketForRetransmission()
 			Expect(packet).To(Equal(lostPacket))
 		})

internal/handshake/crypto_setup.go

@@ -53,10 +53,15 @@ func (m messageType) String() string {
 	}
 }
 
-// ErrOpenerNotYetAvailable is returned when an opener is requested for an encryption level,
-// but the corresponding opener has not yet been initialized
-// This can happen when packets arrive out of order.
-var ErrOpenerNotYetAvailable = errors.New("CryptoSetup: opener at this encryption level not yet available")
+var (
+	// ErrOpenerNotYetAvailable is returned when an opener is requested for an encryption level,
+	// but the corresponding opener has not yet been initialized
+	// This can happen when packets arrive out of order.
+	ErrOpenerNotYetAvailable = errors.New("CryptoSetup: opener at this encryption level not yet available")
+	// ErrKeysDropped is returned when an opener or a sealer is requested for an encryption level,
+	// but the corresponding keys have already been dropped.
+	ErrKeysDropped = errors.New("CryptoSetup: keys were already dropped")
+)
 
 type cryptoSetup struct {
 	tlsConf *qtls.Config
@@ -67,6 +72,8 @@ type cryptoSetup struct {
 	paramsChan           <-chan []byte
 	handleParamsCallback func([]byte)
 
+	dropKeyCallback func(protocol.EncryptionLevel)
+
 	alertChan chan uint8
 	// HandleData() sends errors on the messageErrChan
 	messageErrChan chan error
@@ -121,6 +128,7 @@ func NewCryptoSetupClient(
 	remoteAddr net.Addr,
 	tp *TransportParameters,
 	handleParams func([]byte),
+	dropKeys func(protocol.EncryptionLevel),
 	tlsConf *tls.Config,
 	logger utils.Logger,
 ) (CryptoSetup, <-chan struct{} /* ClientHello written */, error) {
@@ -131,6 +139,7 @@ func NewCryptoSetupClient(
 		connID,
 		tp,
 		handleParams,
+		dropKeys,
 		tlsConf,
 		logger,
 		protocol.PerspectiveClient,
@@ -151,6 +160,7 @@ func NewCryptoSetupServer(
 	remoteAddr net.Addr,
 	tp *TransportParameters,
 	handleParams func([]byte),
+	dropKeys func(protocol.EncryptionLevel),
 	tlsConf *tls.Config,
 	logger utils.Logger,
 ) (CryptoSetup, error) {
@@ -161,6 +171,7 @@ func NewCryptoSetupServer(
 		connID,
 		tp,
 		handleParams,
+		dropKeys,
 		tlsConf,
 		logger,
 		protocol.PerspectiveServer,
@@ -179,6 +190,7 @@ func newCryptoSetup(
 	connID protocol.ConnectionID,
 	tp *TransportParameters,
 	handleParams func([]byte),
+	dropKeys func(protocol.EncryptionLevel),
 	tlsConf *tls.Config,
 	logger utils.Logger,
 	perspective protocol.Perspective,
@@ -197,6 +209,7 @@ func newCryptoSetup(
 		readEncLevel:           protocol.EncryptionInitial,
 		writeEncLevel:          protocol.EncryptionInitial,
 		handleParamsCallback:   handleParams,
+		dropKeyCallback:        dropKeys,
 		paramsChan:             extHandler.TransportParameters(),
 		logger:                 logger,
 		perspective:            perspective,
@@ -225,6 +238,24 @@ func (h *cryptoSetup) ChangeConnectionID(id protocol.ConnectionID) error {
 	return nil
 }
 
+func (h *cryptoSetup) Received1RTTAck() {
+	// drop initial keys
+	// TODO: do this earlier
+	if h.initialOpener != nil {
+		h.initialOpener = nil
+		h.initialSealer = nil
+		h.dropKeyCallback(protocol.EncryptionInitial)
+		h.logger.Debugf("Dropping Initial keys.")
+	}
+	// drop handshake keys
+	if h.handshakeOpener != nil {
+		h.handshakeOpener = nil
+		h.handshakeSealer = nil
+		h.logger.Debugf("Dropping Handshake keys.")
+		h.dropKeyCallback(protocol.EncryptionHandshake)
+	}
+}
+
 func (h *cryptoSetup) RunHandshake() error {
 	// Handle errors that might occur when HandleData() is called.
 	handshakeComplete := make(chan struct{})
@@ -554,10 +585,17 @@ func (h *cryptoSetup) GetOpener(level protocol.EncryptionLevel) (Opener, error)
 
 	switch level {
 	case protocol.EncryptionInitial:
+		if h.initialOpener == nil {
+			return nil, ErrKeysDropped
+		}
 		return h.initialOpener, nil
 	case protocol.EncryptionHandshake:
 		if h.handshakeOpener == nil {
-			return nil, ErrOpenerNotYetAvailable
+			if h.initialOpener != nil {
+				return nil, ErrOpenerNotYetAvailable
+			}
+			// if the initial opener is also not available, the keys were already dropped
+			return nil, ErrKeysDropped
 		}
 		return h.handshakeOpener, nil
 	case protocol.Encryption1RTT:

internal/handshake/crypto_setup_test.go

@@ -87,6 +87,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			nil,
 			&TransportParameters{},
 			func([]byte) {},
+			func(protocol.EncryptionLevel) {},
 			tlsConf,
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -115,6 +116,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			nil,
 			&TransportParameters{},
 			func([]byte) {},
+			func(protocol.EncryptionLevel) {},
 			testdata.GetTLSConfig(),
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -149,6 +151,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			nil,
 			&TransportParameters{},
 			func([]byte) {},
+			func(protocol.EncryptionLevel) {},
 			testdata.GetTLSConfig(),
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -177,6 +180,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 			nil,
 			&TransportParameters{},
 			func([]byte) {},
+			func(protocol.EncryptionLevel) {},
 			testdata.GetTLSConfig(),
 			utils.DefaultLogger.WithPrefix("server"),
 		)
@@ -256,6 +260,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				nil,
 				&TransportParameters{},
 				func([]byte) {},
+				func(protocol.EncryptionLevel) {},
 				clientConf,
 				utils.DefaultLogger.WithPrefix("client"),
 			)
@@ -271,6 +276,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				nil,
 				&TransportParameters{StatelessResetToken: &token},
 				func([]byte) {},
+				func(protocol.EncryptionLevel) {},
 				serverConf,
 				utils.DefaultLogger.WithPrefix("server"),
 			)
@@ -313,6 +319,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				nil,
 				&TransportParameters{},
 				func([]byte) {},
+				func(protocol.EncryptionLevel) {},
 				&tls.Config{InsecureSkipVerify: true},
 				utils.DefaultLogger.WithPrefix("client"),
 			)
@@ -350,6 +357,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				nil,
 				cTransportParameters,
 				func(p []byte) { sTransportParametersRcvd = p },
+				func(protocol.EncryptionLevel) {},
 				clientConf,
 				utils.DefaultLogger.WithPrefix("client"),
 			)
@@ -369,6 +377,7 @@ var _ = Describe("Crypto Setup TLS", func() {
 				nil,
 				sTransportParameters,
 				func(p []byte) { cTransportParametersRcvd = p },
+				func(protocol.EncryptionLevel) {},
 				testdata.GetTLSConfig(),
 				utils.DefaultLogger.WithPrefix("server"),
 			)

internal/handshake/interface.go

@@ -36,6 +36,7 @@ type CryptoSetup interface {
 	ChangeConnectionID(protocol.ConnectionID) error
 
 	HandleMessage([]byte, protocol.EncryptionLevel) bool
+	Received1RTTAck()
 	ConnectionState() tls.ConnectionState
 
 	GetSealer() (protocol.EncryptionLevel, Sealer)

internal/mocks/crypto_setup.go

@@ -137,6 +137,18 @@ func (mr *MockCryptoSetupMockRecorder) HandleMessage(arg0, arg1 interface{}) *go
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HandleMessage", reflect.TypeOf((*MockCryptoSetup)(nil).HandleMessage), arg0, arg1)
 }
 
+// Received1RTTAck mocks base method
+func (m *MockCryptoSetup) Received1RTTAck() {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "Received1RTTAck")
+}
+
+// Received1RTTAck indicates an expected call of Received1RTTAck
+func (mr *MockCryptoSetupMockRecorder) Received1RTTAck() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Received1RTTAck", reflect.TypeOf((*MockCryptoSetup)(nil).Received1RTTAck))
+}
+
 // RunHandshake mocks base method
 func (m *MockCryptoSetup) RunHandshake() error {
 	m.ctrl.T.Helper()

session.go

@@ -49,6 +49,7 @@ type streamManager interface {
 type cryptoStreamHandler interface {
 	RunHandshake() error
 	ChangeConnectionID(protocol.ConnectionID) error
+	Received1RTTAck()
 	io.Closer
 	ConnectionState() tls.ConnectionState
 }
@@ -129,9 +130,8 @@ type session struct {
 	handshakeCompleteChan chan struct{} // is closed when the handshake completes
 	handshakeComplete     bool
 
-	receivedRetry                    bool
-	receivedFirstPacket              bool
-	receivedFirstForwardSecurePacket bool
+	receivedRetry       bool
+	receivedFirstPacket bool
 
 	sessionCreationTime time.Time
 	// The idle timeout is set based on the max of the time we received the last packet...
@@ -199,6 +199,7 @@ var newSession = func(
 		conn.RemoteAddr(),
 		params,
 		s.processTransportParameters,
+		s.dropEncryptionLevel,
 		tlsConf,
 		logger,
 	)
@@ -267,6 +268,7 @@ var newClientSession = func(
 		conn.RemoteAddr(),
 		params,
 		s.processTransportParameters,
+		s.dropEncryptionLevel,
 		tlsConf,
 		logger,
 	)
@@ -485,8 +487,6 @@ func (s *session) handleHandshakeComplete() {
 	// independent from the application protocol.
 	if s.perspective == protocol.PerspectiveServer {
 		s.queueControlFrame(&wire.PingFrame{})
-		s.sentPacketHandler.DropPackets(protocol.EncryptionInitial)
-		s.sentPacketHandler.DropPackets(protocol.EncryptionHandshake)
 	}
 }
 
@@ -560,16 +560,19 @@ func (s *session) handleSinglePacket(p *receivedPacket, hdr *wire.Header) bool /
 
 	packet, err := s.unpacker.Unpack(hdr, p.data)
 	if err != nil {
-		if err == handshake.ErrOpenerNotYetAvailable {
+		switch err {
+		case handshake.ErrKeysDropped:
+			s.logger.Debugf("Dropping packet because we already dropped the keys.")
+		case handshake.ErrOpenerNotYetAvailable:
 			// Sealer for this encryption level not yet available.
 			// Try again later.
 			wasQueued = true
 			s.tryQueueingUndecryptablePacket(p)
-			return false
+		default:
+			// This might be a packet injected by an attacker.
+			// Drop it.
+			s.logger.Debugf("Dropping packet that could not be unpacked. Unpack error: %s", err)
 		}
-		// This might be a packet injected by an attacker.
-		// Drop it.
-		s.logger.Debugf("Dropping packet that could not be unpacked. Unpack error: %s", err)
 		return false
 	}
 
@@ -642,16 +645,6 @@ func (s *session) handleUnpackedPacket(packet *unpackedPacket, rcvTime time.Time
 	s.firstAckElicitingPacketAfterIdleSentTime = time.Time{}
 	s.keepAlivePingSent = false
 
-	// The client completes the handshake first (after sending the CFIN).
-	// We know that the server completed the handshake as soon as we receive a forward-secure packet.
-	if s.perspective == protocol.PerspectiveClient {
-		if !s.receivedFirstForwardSecurePacket && packet.encryptionLevel == protocol.Encryption1RTT {
-			s.receivedFirstForwardSecurePacket = true
-			s.sentPacketHandler.DropPackets(protocol.EncryptionInitial)
-			s.sentPacketHandler.DropPackets(protocol.EncryptionHandshake)
-		}
-	}
-
 	r := bytes.NewReader(packet.data)
 	var isAckEliciting bool
 	for {
@@ -834,6 +827,7 @@ func (s *session) handleAckFrame(frame *wire.AckFrame, pn protocol.PacketNumber,
 	}
 	if encLevel == protocol.Encryption1RTT {
 		s.receivedPacketHandler.IgnoreBelow(s.sentPacketHandler.GetLowestPacketNotConfirmedAcked())
+		s.cryptoStreamHandler.Received1RTTAck()
 	}
 	return nil
 }
@@ -924,6 +918,11 @@ func (s *session) handleCloseError(closeErr closeError) {
 	}
 }
 
+func (s *session) dropEncryptionLevel(encLevel protocol.EncryptionLevel) {
+	s.sentPacketHandler.DropPackets(encLevel)
+	s.receivedPacketHandler.DropPackets(encLevel)
+}
+
 func (s *session) processTransportParameters(data []byte) {
 	var params *handshake.TransportParameters
 	var err error

session_test.go

@@ -161,6 +161,7 @@ var _ = Describe("Session", func() {
 			})
 
 			It("tells the ReceivedPacketHandler to ignore low ranges", func() {
+				cryptoSetup.EXPECT().Received1RTTAck()
 				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 2, Largest: 3}}}
 				sph := mockackhandler.NewMockSentPacketHandler(mockCtrl)
 				sph.EXPECT().ReceivedAck(gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any())