vendor: golang.org/x/crypto v0.17.0

update the package, which contains a fix in the ssh package.

full diff: https://github.com/golang/crypto/compare/v0.16.0...v0.17.0

from the security mailing:

> Hello gophers,
>
> Version v0.17.0 of golang.org/x/crypto fixes a protocol weakness in the
> golang.org/x/crypto/ssh package that allowed a MITM attacker to compromise
> the integrity of the secure channel before it was established, allowing
> them to prevent transmission of a number of messages immediately after
> the secure channel was established without either side being aware.
>
> The impact of this attack is relatively limited, as it does not compromise
> confidentiality of the channel. Notably this attack would allow an attacker
> to prevent the transmission of the SSH2_MSG_EXT_INFO message, disabling a
> handful of newer security features.
>
> This protocol weakness was also fixed in OpenSSH 9.6.
>
> Thanks to Fabian Bäumer, Marcus Brinkmann, and Jörg Schwenk from Ruhr
> University Bochum for reporting this issue.
>
> This is CVE-2023-48795 and Go issue https://go.dev/issue/64784.
>
> Cheers,
> Roland on behalf of the Go team

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.mod

@@ -202,7 +202,7 @@ require (
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.8.0 // indirect
 	go.uber.org/zap v1.21.0 // indirect
-	golang.org/x/crypto v0.16.0 // indirect
+	golang.org/x/crypto v0.17.0 // indirect
 	golang.org/x/oauth2 v0.10.0 // indirect
 	golang.org/x/tools v0.10.0 // indirect
 	google.golang.org/api v0.126.0 // indirect

vendor.sum

@@ -1394,8 +1394,8 @@ golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392/go.mod h1:jdWPYTVW3xRLrWP
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.0.0-20220314234659-1baeb1ce4c0b/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/crypto v0.0.0-20220411220226-7b82a4e95df4/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
-golang.org/x/crypto v0.16.0 h1:mMMrFzRSCF0GvB7Ne27XVtVAaXLrPmgPC7/v0tkwHaY=
-golang.org/x/crypto v0.16.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
+golang.org/x/crypto v0.17.0 h1:r8bRNjWL3GshPW3gkd+RpvzWrZAwPS49OmTGZ/uhM4k=
+golang.org/x/crypto v0.17.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190125153040-c74c464bbbf2/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=

vendor/golang.org/x/crypto/ssh/channel.go

@@ -187,9 +187,11 @@ type channel struct {
 	pending    *buffer
 	extPending *buffer
 
-	// windowMu protects myWindow, the flow-control window.
-	windowMu sync.Mutex
-	myWindow uint32
+	// windowMu protects myWindow, the flow-control window, and myConsumed,
+	// the number of bytes consumed since we last increased myWindow
+	windowMu   sync.Mutex
+	myWindow   uint32
+	myConsumed uint32
 
 	// writeMu serializes calls to mux.conn.writePacket() and
 	// protects sentClose and packetPool. This mutex must be
@@ -332,14 +334,24 @@ func (ch *channel) handleData(packet []byte) error {
 	return nil
 }
 
-func (c *channel) adjustWindow(n uint32) error {
+func (c *channel) adjustWindow(adj uint32) error {
 	c.windowMu.Lock()
-	// Since myWindow is managed on our side, and can never exceed
-	// the initial window setting, we don't worry about overflow.
-	c.myWindow += uint32(n)
+	// Since myConsumed and myWindow are managed on our side, and can never
+	// exceed the initial window setting, we don't worry about overflow.
+	c.myConsumed += adj
+	var sendAdj uint32
+	if (channelWindowSize-c.myWindow > 3*c.maxIncomingPayload) ||
+		(c.myWindow < channelWindowSize/2) {
+		sendAdj = c.myConsumed
+		c.myConsumed = 0
+		c.myWindow += sendAdj
+	}
 	c.windowMu.Unlock()
+	if sendAdj == 0 {
+		return nil
+	}
 	return c.sendMessage(windowAdjustMsg{
-		AdditionalBytes: uint32(n),
+		AdditionalBytes: sendAdj,
 	})
 }
 

vendor/golang.org/x/crypto/ssh/client.go

@@ -82,7 +82,7 @@ func NewClientConn(c net.Conn, addr string, config *ClientConfig) (Conn, <-chan
 
 	if err := conn.clientHandshake(addr, &fullConf); err != nil {
 		c.Close()
-		return nil, nil, nil, fmt.Errorf("ssh: handshake failed: %v", err)
+		return nil, nil, nil, fmt.Errorf("ssh: handshake failed: %w", err)
 	}
 	conn.mux = newMux(conn.transport)
 	return conn, conn.mux.incomingChannels, conn.mux.incomingRequests, nil

vendor/golang.org/x/crypto/ssh/handshake.go

@@ -35,6 +35,16 @@ type keyingTransport interface {
 	// direction will be effected if a msgNewKeys message is sent
 	// or received.
 	prepareKeyChange(*algorithms, *kexResult) error
+
+	// setStrictMode sets the strict KEX mode, notably triggering
+	// sequence number resets on sending or receiving msgNewKeys.
+	// If the sequence number is already > 1 when setStrictMode
+	// is called, an error is returned.
+	setStrictMode() error
+
+	// setInitialKEXDone indicates to the transport that the initial key exchange
+	// was completed
+	setInitialKEXDone()
 }
 
 // handshakeTransport implements rekeying on top of a keyingTransport
@@ -100,6 +110,10 @@ type handshakeTransport struct {
 
 	// The session ID or nil if first kex did not complete yet.
 	sessionID []byte
+
+	// strictMode indicates if the other side of the handshake indicated
+	// that we should be following the strict KEX protocol restrictions.
+	strictMode bool
 }
 
 type pendingKex struct {
@@ -209,7 +223,10 @@ func (t *handshakeTransport) readLoop() {
 			close(t.incoming)
 			break
 		}
-		if p[0] == msgIgnore || p[0] == msgDebug {
+		// If this is the first kex, and strict KEX mode is enabled,
+		// we don't ignore any messages, as they may be used to manipulate
+		// the packet sequence numbers.
+		if !(t.sessionID == nil && t.strictMode) && (p[0] == msgIgnore || p[0] == msgDebug) {
 			continue
 		}
 		t.incoming <- p
@@ -441,6 +458,11 @@ func (t *handshakeTransport) readOnePacket(first bool) ([]byte, error) {
 	return successPacket, nil
 }
 
+const (
+	kexStrictClient = "kex-strict-c-v00@openssh.com"
+	kexStrictServer = "kex-strict-s-v00@openssh.com"
+)
+
 // sendKexInit sends a key change message.
 func (t *handshakeTransport) sendKexInit() error {
 	t.mu.Lock()
@@ -454,7 +476,6 @@ func (t *handshakeTransport) sendKexInit() error {
 	}
 
 	msg := &kexInitMsg{
-		KexAlgos:                t.config.KeyExchanges,
 		CiphersClientServer:     t.config.Ciphers,
 		CiphersServerClient:     t.config.Ciphers,
 		MACsClientServer:        t.config.MACs,
@@ -464,6 +485,13 @@ func (t *handshakeTransport) sendKexInit() error {
 	}
 	io.ReadFull(rand.Reader, msg.Cookie[:])
 
+	// We mutate the KexAlgos slice, in order to add the kex-strict extension algorithm,
+	// and possibly to add the ext-info extension algorithm. Since the slice may be the
+	// user owned KeyExchanges, we create our own slice in order to avoid using user
+	// owned memory by mistake.
+	msg.KexAlgos = make([]string, 0, len(t.config.KeyExchanges)+2) // room for kex-strict and ext-info
+	msg.KexAlgos = append(msg.KexAlgos, t.config.KeyExchanges...)
+
 	isServer := len(t.hostKeys) > 0
 	if isServer {
 		for _, k := range t.hostKeys {
@@ -488,17 +516,24 @@ func (t *handshakeTransport) sendKexInit() error {
 				msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, keyFormat)
 			}
 		}
+
+		if t.sessionID == nil {
+			msg.KexAlgos = append(msg.KexAlgos, kexStrictServer)
+		}
 	} else {
 		msg.ServerHostKeyAlgos = t.hostKeyAlgorithms
 
 		// As a client we opt in to receiving SSH_MSG_EXT_INFO so we know what
 		// algorithms the server supports for public key authentication. See RFC
 		// 8308, Section 2.1.
+		//
+		// We also send the strict KEX mode extension algorithm, in order to opt
+		// into the strict KEX mode.
 		if firstKeyExchange := t.sessionID == nil; firstKeyExchange {
-			msg.KexAlgos = make([]string, 0, len(t.config.KeyExchanges)+1)
-			msg.KexAlgos = append(msg.KexAlgos, t.config.KeyExchanges...)
 			msg.KexAlgos = append(msg.KexAlgos, "ext-info-c")
+			msg.KexAlgos = append(msg.KexAlgos, kexStrictClient)
 		}
+
 	}
 
 	packet := Marshal(msg)
@@ -604,6 +639,13 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 		return err
 	}
 
+	if t.sessionID == nil && ((isClient && contains(serverInit.KexAlgos, kexStrictServer)) || (!isClient && contains(clientInit.KexAlgos, kexStrictClient))) {
+		t.strictMode = true
+		if err := t.conn.setStrictMode(); err != nil {
+			return err
+		}
+	}
+
 	// We don't send FirstKexFollows, but we handle receiving it.
 	//
 	// RFC 4253 section 7 defines the kex and the agreement method for
@@ -679,6 +721,12 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 		return unexpectedMessageError(msgNewKeys, packet[0])
 	}
 
+	if firstKeyExchange {
+		// Indicates to the transport that the first key exchange is completed
+		// after receiving SSH_MSG_NEWKEYS.
+		t.conn.setInitialKEXDone()
+	}
+
 	return nil
 }
 

vendor/golang.org/x/crypto/ssh/server.go

@@ -213,6 +213,7 @@ func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewCha
 	} else {
 		for _, algo := range fullConf.PublicKeyAuthAlgorithms {
 			if !contains(supportedPubKeyAuthAlgos, algo) {
+				c.Close()
 				return nil, nil, nil, fmt.Errorf("ssh: unsupported public key authentication algorithm %s", algo)
 			}
 		}
@@ -220,6 +221,7 @@ func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewCha
 	// Check if the config contains any unsupported key exchanges
 	for _, kex := range fullConf.KeyExchanges {
 		if _, ok := serverForbiddenKexAlgos[kex]; ok {
+			c.Close()
 			return nil, nil, nil, fmt.Errorf("ssh: unsupported key exchange %s for server", kex)
 		}
 	}

vendor/golang.org/x/crypto/ssh/transport.go

@@ -49,6 +49,9 @@ type transport struct {
 	rand      io.Reader
 	isClient  bool
 	io.Closer
+
+	strictMode     bool
+	initialKEXDone bool
 }
 
 // packetCipher represents a combination of SSH encryption/MAC
@@ -74,6 +77,18 @@ type connectionState struct {
 	pendingKeyChange chan packetCipher
 }
 
+func (t *transport) setStrictMode() error {
+	if t.reader.seqNum != 1 {
+		return errors.New("ssh: sequence number != 1 when strict KEX mode requested")
+	}
+	t.strictMode = true
+	return nil
+}
+
+func (t *transport) setInitialKEXDone() {
+	t.initialKEXDone = true
+}
+
 // prepareKeyChange sets up key material for a keychange. The key changes in
 // both directions are triggered by reading and writing a msgNewKey packet
 // respectively.
@@ -112,11 +127,12 @@ func (t *transport) printPacket(p []byte, write bool) {
 // Read and decrypt next packet.
 func (t *transport) readPacket() (p []byte, err error) {
 	for {
-		p, err = t.reader.readPacket(t.bufReader)
+		p, err = t.reader.readPacket(t.bufReader, t.strictMode)
 		if err != nil {
 			break
 		}
-		if len(p) == 0 || (p[0] != msgIgnore && p[0] != msgDebug) {
+		// in strict mode we pass through DEBUG and IGNORE packets only during the initial KEX
+		if len(p) == 0 || (t.strictMode && !t.initialKEXDone) || (p[0] != msgIgnore && p[0] != msgDebug) {
 			break
 		}
 	}
@@ -127,7 +143,7 @@ func (t *transport) readPacket() (p []byte, err error) {
 	return p, err
 }
 
-func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
+func (s *connectionState) readPacket(r *bufio.Reader, strictMode bool) ([]byte, error) {
 	packet, err := s.packetCipher.readCipherPacket(s.seqNum, r)
 	s.seqNum++
 	if err == nil && len(packet) == 0 {
@@ -140,6 +156,9 @@ func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
 			select {
 			case cipher := <-s.pendingKeyChange:
 				s.packetCipher = cipher
+				if strictMode {
+					s.seqNum = 0
+				}
 			default:
 				return nil, errors.New("ssh: got bogus newkeys message")
 			}
@@ -170,10 +189,10 @@ func (t *transport) writePacket(packet []byte) error {
 	if debugTransport {
 		t.printPacket(packet, true)
 	}
-	return t.writer.writePacket(t.bufWriter, t.rand, packet)
+	return t.writer.writePacket(t.bufWriter, t.rand, packet, t.strictMode)
 }
 
-func (s *connectionState) writePacket(w *bufio.Writer, rand io.Reader, packet []byte) error {
+func (s *connectionState) writePacket(w *bufio.Writer, rand io.Reader, packet []byte, strictMode bool) error {
 	changeKeys := len(packet) > 0 && packet[0] == msgNewKeys
 
 	err := s.packetCipher.writeCipherPacket(s.seqNum, w, rand, packet)
@@ -188,6 +207,9 @@ func (s *connectionState) writePacket(w *bufio.Writer, rand io.Reader, packet []
 		select {
 		case cipher := <-s.pendingKeyChange:
 			s.packetCipher = cipher
+			if strictMode {
+				s.seqNum = 0
+			}
 		default:
 			panic("ssh: no key material for msgNewKeys")
 		}

vendor/modules.txt

@@ -1217,7 +1217,7 @@ go.uber.org/zap/internal/bufferpool
 go.uber.org/zap/internal/color
 go.uber.org/zap/internal/exit
 go.uber.org/zap/zapcore
-# golang.org/x/crypto v0.16.0
+# golang.org/x/crypto v0.17.0
 ## explicit; go 1.18
 golang.org/x/crypto/blowfish
 golang.org/x/crypto/chacha20