noise: add an option to allow unknown peer ID in SecureOutbound

p2p/security/noise/crypto_test.go

@@ -93,7 +93,7 @@ func TestCryptoFailsIfHandshakeIncomplete(t *testing.T) {
 	init, resp := net.Pipe()
 	_ = resp.Close()
 
-	session, _ := newSecureSession(initTransport, context.TODO(), init, "remote-peer", nil, nil, nil, true)
+	session, _ := newSecureSession(initTransport, context.TODO(), init, "remote-peer", nil, nil, nil, true, true)
 	_, err := session.encrypt(nil, []byte("hi"))
 	if err == nil {
 		t.Error("expected encryption error when handshake incomplete")

p2p/security/noise/handshake.go

@@ -272,11 +272,8 @@ func (s *secureSession) handleRemoteHandshakePayload(payload []byte, remoteStati
 		return nil, err
 	}
 
-	// check the peer ID for:
-	// * all outbound connection
-	// * inbound connections, if we know which peer we want to connect to (SecureInbound called with a peer ID)
-	if (s.initiator && s.remoteID != id) || (!s.initiator && s.remoteID != "" && s.remoteID != id) {
-		// use Pretty() as it produces the full b58-encoded string, rather than abbreviated forms.
+	// check the peer ID if enabled
+	if s.checkPeerID && s.remoteID != id {
 		return nil, fmt.Errorf("peer id mismatch: expected %s, but remote key matches %s", s.remoteID.Pretty(), id.Pretty())
 	}
 

p2p/security/noise/session.go

@@ -15,7 +15,8 @@ import (
 )
 
 type secureSession struct {
-	initiator bool
+	initiator   bool
+	checkPeerID bool
 
 	localID   peer.ID
 	localKey  crypto.PrivKey
@@ -47,7 +48,7 @@ type secureSession struct {
 
 // newSecureSession creates a Noise session over the given insecureConn Conn, using
 // the libp2p identity keypair from the given Transport.
-func newSecureSession(tpt *Transport, ctx context.Context, insecure net.Conn, remote peer.ID, prologue []byte, initiatorEDH, responderEDH EarlyDataHandler, initiator bool) (*secureSession, error) {
+func newSecureSession(tpt *Transport, ctx context.Context, insecure net.Conn, remote peer.ID, prologue []byte, initiatorEDH, responderEDH EarlyDataHandler, initiator, checkPeerID bool) (*secureSession, error) {
 	s := &secureSession{
 		insecureConn:              insecure,
 		insecureReader:            bufio.NewReader(insecure),
@@ -58,6 +59,7 @@ func newSecureSession(tpt *Transport, ctx context.Context, insecure net.Conn, re
 		prologue:                  prologue,
 		initiatorEarlyDataHandler: initiatorEDH,
 		responderEarlyDataHandler: responderEDH,
+		checkPeerID:               checkPeerID,
 	}
 
 	// the go-routine we create to run the handshake will

p2p/security/noise/session_transport.go

@@ -50,22 +50,34 @@ func EarlyData(initiator, responder EarlyDataHandler) SessionOption {
 	}
 }
 
+// DisablePeerIDCheck disables checking the remote peer ID for a noise connection.
+// For outbound connections, this is the equivalent of calling `SecureInbound` with an empty
+// peer ID. This is susceptible to MITM attacks since we do not verify the identity of the remote
+// peer.
+func DisablePeerIDCheck() SessionOption {
+	return func(s *SessionTransport) error {
+		s.disablePeerIdCheck = true
+		return nil
+	}
+}
+
 var _ sec.SecureTransport = &SessionTransport{}
 
 // SessionTransport can be used
 // to provide per-connection options
 type SessionTransport struct {
 	t *Transport
 	// options
-	prologue []byte
+	prologue           []byte
+	disablePeerIdCheck bool
 
 	initiatorEarlyDataHandler, responderEarlyDataHandler EarlyDataHandler
 }
 
 // SecureInbound runs the Noise handshake as the responder.
 // If p is empty, connections from any peer are accepted.
 func (i *SessionTransport) SecureInbound(ctx context.Context, insecure net.Conn, p peer.ID) (sec.SecureConn, error) {
-	c, err := newSecureSession(i.t, ctx, insecure, p, i.prologue, i.initiatorEarlyDataHandler, i.responderEarlyDataHandler, false)
+	c, err := newSecureSession(i.t, ctx, insecure, p, i.prologue, i.initiatorEarlyDataHandler, i.responderEarlyDataHandler, false, p != "" || i.disablePeerIdCheck)
 	if err != nil {
 		addr, maErr := manet.FromNetAddr(insecure.RemoteAddr())
 		if maErr == nil {
@@ -77,5 +89,5 @@ func (i *SessionTransport) SecureInbound(ctx context.Context, insecure net.Conn,
 
 // SecureOutbound runs the Noise handshake as the initiator.
 func (i *SessionTransport) SecureOutbound(ctx context.Context, insecure net.Conn, p peer.ID) (sec.SecureConn, error) {
-	return newSecureSession(i.t, ctx, insecure, p, i.prologue, i.initiatorEarlyDataHandler, i.responderEarlyDataHandler, true)
+	return newSecureSession(i.t, ctx, insecure, p, i.prologue, i.initiatorEarlyDataHandler, i.responderEarlyDataHandler, true, !i.disablePeerIdCheck)
 }

p2p/security/noise/transport.go

@@ -54,7 +54,7 @@ func New(privkey crypto.PrivKey, muxers []protocol.ID) (*Transport, error) {
 // If p is empty, connections from any peer are accepted.
 func (t *Transport) SecureInbound(ctx context.Context, insecure net.Conn, p peer.ID) (sec.SecureConn, error) {
 	responderEDH := newTransportEDH(t)
-	c, err := newSecureSession(t, ctx, insecure, p, nil, nil, responderEDH, false)
+	c, err := newSecureSession(t, ctx, insecure, p, nil, nil, responderEDH, false, p != "")
 	if err != nil {
 		addr, maErr := manet.FromNetAddr(insecure.RemoteAddr())
 		if maErr == nil {
@@ -67,15 +67,15 @@ func (t *Transport) SecureInbound(ctx context.Context, insecure net.Conn, p peer
 // SecureOutbound runs the Noise handshake as the initiator.
 func (t *Transport) SecureOutbound(ctx context.Context, insecure net.Conn, p peer.ID) (sec.SecureConn, error) {
 	initiatorEDH := newTransportEDH(t)
-	c, err := newSecureSession(t, ctx, insecure, p, nil, initiatorEDH, nil, true)
+	c, err := newSecureSession(t, ctx, insecure, p, nil, initiatorEDH, nil, true, true)
 	if err != nil {
 		return c, err
 	}
 	return SessionWithConnState(c, initiatorEDH.MatchMuxers(true)), err
 }
 
-func (t *Transport) WithSessionOptions(opts ...SessionOption) (sec.SecureTransport, error) {
-	st := &SessionTransport{t: t}
+func (t *Transport) WithSessionOptions(opts ...SessionOption) (*SessionTransport, error) {
+	st := &SessionTransport{t: t, disablePeerIdCheck: false}
 	for _, opt := range opts {
 		if err := opt(st); err != nil {
 			return nil, err

p2p/security/noise/transport_test.go

@@ -232,6 +232,26 @@ func TestPeerIDMismatchInboundFailsHandshake(t *testing.T) {
 	<-done
 }
 
+func TestPeerIDOutboundNoCheck(t *testing.T) {
+	initTransport := newTestTransport(t, crypto.Ed25519, 2048)
+	respTransport := newTestTransport(t, crypto.Ed25519, 2048)
+	init, resp := newConnPair(t)
+
+	initSessionTransport, err := initTransport.WithSessionOptions(DisablePeerIDCheck())
+	require.NoError(t, err)
+
+	errChan := make(chan error)
+	go func() {
+		_, err := initSessionTransport.SecureOutbound(context.Background(), init, "test")
+		errChan <- err
+	}()
+
+	_, err = respTransport.SecureInbound(context.Background(), resp, "")
+	require.NoError(t, err)
+	initErr := <-errChan
+	require.NoError(t, initErr)
+}
+
 func makeLargePlaintext(size int) []byte {
 	buf := make([]byte, size)
 	rand.Read(buf)