| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package main |
| |
| import ( |
| "bytes" |
| "crypto" |
| "crypto/ecdsa" |
| "crypto/elliptic" |
| "crypto/rsa" |
| "crypto/subtle" |
| "crypto/x509" |
| "encoding/asn1" |
| "errors" |
| "fmt" |
| "io" |
| "math/big" |
| ) |
| |
| // serverHandshakeState contains details of a server handshake in progress. |
| // It's discarded once the handshake has completed. |
| type serverHandshakeState struct { |
| c *Conn |
| clientHello *clientHelloMsg |
| hello *serverHelloMsg |
| suite *cipherSuite |
| ellipticOk bool |
| ecdsaOk bool |
| sessionState *sessionState |
| finishedHash finishedHash |
| masterSecret []byte |
| certsFromClient [][]byte |
| cert *Certificate |
| } |
| |
| // serverHandshake performs a TLS handshake as a server. |
| func (c *Conn) serverHandshake() error { |
| config := c.config |
| |
| // If this is the first server handshake, we generate a random key to |
| // encrypt the tickets with. |
| config.serverInitOnce.Do(config.serverInit) |
| |
| c.sendHandshakeSeq = 0 |
| c.recvHandshakeSeq = 0 |
| |
| hs := serverHandshakeState{ |
| c: c, |
| } |
| isResume, err := hs.readClientHello() |
| if err != nil { |
| return err |
| } |
| |
| // For an overview of TLS handshaking, see https://tools.ietf.org/html/rfc5246#section-7.3 |
| if isResume { |
| // The client has included a session ticket and so we do an abbreviated handshake. |
| if err := hs.doResumeHandshake(); err != nil { |
| return err |
| } |
| if err := hs.establishKeys(); err != nil { |
| return err |
| } |
| if c.config.Bugs.RenewTicketOnResume { |
| if err := hs.sendSessionTicket(); err != nil { |
| return err |
| } |
| } |
| if err := hs.sendFinished(); err != nil { |
| return err |
| } |
| if err := hs.readFinished(isResume); err != nil { |
| return err |
| } |
| c.didResume = true |
| } else { |
| // The client didn't include a session ticket, or it wasn't |
| // valid so we do a full handshake. |
| if err := hs.doFullHandshake(); err != nil { |
| return err |
| } |
| if err := hs.establishKeys(); err != nil { |
| return err |
| } |
| if err := hs.readFinished(isResume); err != nil { |
| return err |
| } |
| if c.config.Bugs.ExpectFalseStart { |
| if err := c.readRecord(recordTypeApplicationData); err != nil { |
| return err |
| } |
| } |
| if err := hs.sendSessionTicket(); err != nil { |
| return err |
| } |
| if err := hs.sendFinished(); err != nil { |
| return err |
| } |
| } |
| c.handshakeComplete = true |
| |
| return nil |
| } |
| |
| // readClientHello reads a ClientHello message from the client and decides |
| // whether we will perform session resumption. |
| func (hs *serverHandshakeState) readClientHello() (isResume bool, err error) { |
| config := hs.c.config |
| c := hs.c |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return false, err |
| } |
| var ok bool |
| hs.clientHello, ok = msg.(*clientHelloMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return false, unexpectedMessageError(hs.clientHello, msg) |
| } |
| if config.Bugs.RequireFastradioPadding && len(hs.clientHello.raw) < 1000 { |
| return false, errors.New("tls: ClientHello record size should be larger than 1000 bytes when padding enabled.") |
| } |
| |
| if c.isDTLS && !config.Bugs.SkipHelloVerifyRequest { |
| // Per RFC 6347, the version field in HelloVerifyRequest SHOULD |
| // be always DTLS 1.0 |
| helloVerifyRequest := &helloVerifyRequestMsg{ |
| vers: VersionTLS10, |
| cookie: make([]byte, 32), |
| } |
| if _, err := io.ReadFull(c.config.rand(), helloVerifyRequest.cookie); err != nil { |
| c.sendAlert(alertInternalError) |
| return false, errors.New("dtls: short read from Rand: " + err.Error()) |
| } |
| c.writeRecord(recordTypeHandshake, helloVerifyRequest.marshal()) |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return false, err |
| } |
| newClientHello, ok := msg.(*clientHelloMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return false, unexpectedMessageError(hs.clientHello, msg) |
| } |
| if !bytes.Equal(newClientHello.cookie, helloVerifyRequest.cookie) { |
| return false, errors.New("dtls: invalid cookie") |
| } |
| |
| // Apart from the cookie, the two ClientHellos must |
| // match. Note that clientHello.equal compares the |
| // serialization, so we make a copy. |
| oldClientHelloCopy := *hs.clientHello |
| oldClientHelloCopy.raw = nil |
| oldClientHelloCopy.cookie = nil |
| newClientHelloCopy := *newClientHello |
| newClientHelloCopy.raw = nil |
| newClientHelloCopy.cookie = nil |
| if !oldClientHelloCopy.equal(&newClientHelloCopy) { |
| return false, errors.New("dtls: retransmitted ClientHello does not match") |
| } |
| hs.clientHello = newClientHello |
| } |
| |
| if config.Bugs.RequireSameRenegoClientVersion && c.clientVersion != 0 { |
| if c.clientVersion != hs.clientHello.vers { |
| return false, fmt.Errorf("tls: client offered different version on renego") |
| } |
| } |
| c.clientVersion = hs.clientHello.vers |
| |
| // Reject < 1.2 ClientHellos with signature_algorithms. |
| if c.clientVersion < VersionTLS12 && len(hs.clientHello.signatureAndHashes) > 0 { |
| return false, fmt.Errorf("tls: client included signature_algorithms before TLS 1.2") |
| } |
| |
| c.vers, ok = config.mutualVersion(hs.clientHello.vers) |
| if !ok { |
| c.sendAlert(alertProtocolVersion) |
| return false, fmt.Errorf("tls: client offered an unsupported, maximum protocol version of %x", hs.clientHello.vers) |
| } |
| c.haveVers = true |
| |
| hs.hello = new(serverHelloMsg) |
| hs.hello.isDTLS = c.isDTLS |
| |
| supportedCurve := false |
| preferredCurves := config.curvePreferences() |
| Curves: |
| for _, curve := range hs.clientHello.supportedCurves { |
| for _, supported := range preferredCurves { |
| if supported == curve { |
| supportedCurve = true |
| break Curves |
| } |
| } |
| } |
| |
| supportedPointFormat := false |
| for _, pointFormat := range hs.clientHello.supportedPoints { |
| if pointFormat == pointFormatUncompressed { |
| supportedPointFormat = true |
| break |
| } |
| } |
| hs.ellipticOk = supportedCurve && supportedPointFormat |
| |
| foundCompression := false |
| // We only support null compression, so check that the client offered it. |
| for _, compression := range hs.clientHello.compressionMethods { |
| if compression == compressionNone { |
| foundCompression = true |
| break |
| } |
| } |
| |
| if !foundCompression { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: client does not support uncompressed connections") |
| } |
| |
| hs.hello.vers = c.vers |
| hs.hello.random = make([]byte, 32) |
| _, err = io.ReadFull(config.rand(), hs.hello.random) |
| if err != nil { |
| c.sendAlert(alertInternalError) |
| return false, err |
| } |
| |
| if !bytes.Equal(c.clientVerify, hs.clientHello.secureRenegotiation) { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: renegotiation mismatch") |
| } |
| |
| if len(c.clientVerify) > 0 && !c.config.Bugs.EmptyRenegotiationInfo { |
| hs.hello.secureRenegotiation = append(hs.hello.secureRenegotiation, c.clientVerify...) |
| hs.hello.secureRenegotiation = append(hs.hello.secureRenegotiation, c.serverVerify...) |
| if c.config.Bugs.BadRenegotiationInfo { |
| hs.hello.secureRenegotiation[0] ^= 0x80 |
| } |
| } else { |
| hs.hello.secureRenegotiation = hs.clientHello.secureRenegotiation |
| } |
| |
| hs.hello.compressionMethod = compressionNone |
| hs.hello.duplicateExtension = c.config.Bugs.DuplicateExtension |
| if len(hs.clientHello.serverName) > 0 { |
| c.serverName = hs.clientHello.serverName |
| } |
| |
| if len(hs.clientHello.alpnProtocols) > 0 { |
| if selectedProto, fallback := mutualProtocol(hs.clientHello.alpnProtocols, c.config.NextProtos); !fallback { |
| hs.hello.alpnProtocol = selectedProto |
| c.clientProtocol = selectedProto |
| c.usedALPN = true |
| } |
| } else { |
| // Although sending an empty NPN extension is reasonable, Firefox has |
| // had a bug around this. Best to send nothing at all if |
| // config.NextProtos is empty. See |
| // https://code.google.com/p/go/issues/detail?id=5445. |
| if hs.clientHello.nextProtoNeg && len(config.NextProtos) > 0 { |
| hs.hello.nextProtoNeg = true |
| hs.hello.nextProtos = config.NextProtos |
| } |
| } |
| hs.hello.extendedMasterSecret = c.vers >= VersionTLS10 && hs.clientHello.extendedMasterSecret && !c.config.Bugs.NoExtendedMasterSecret |
| |
| if len(config.Certificates) == 0 { |
| c.sendAlert(alertInternalError) |
| return false, errors.New("tls: no certificates configured") |
| } |
| hs.cert = &config.Certificates[0] |
| if len(hs.clientHello.serverName) > 0 { |
| hs.cert = config.getCertificateForName(hs.clientHello.serverName) |
| } |
| if expected := c.config.Bugs.ExpectServerName; expected != "" && expected != hs.clientHello.serverName { |
| return false, errors.New("tls: unexpected server name") |
| } |
| |
| if hs.clientHello.channelIDSupported && config.RequestChannelID { |
| hs.hello.channelIDRequested = true |
| } |
| |
| if hs.clientHello.srtpProtectionProfiles != nil { |
| SRTPLoop: |
| for _, p1 := range c.config.SRTPProtectionProfiles { |
| for _, p2 := range hs.clientHello.srtpProtectionProfiles { |
| if p1 == p2 { |
| hs.hello.srtpProtectionProfile = p1 |
| c.srtpProtectionProfile = p1 |
| break SRTPLoop |
| } |
| } |
| } |
| } |
| |
| if c.config.Bugs.SendSRTPProtectionProfile != 0 { |
| hs.hello.srtpProtectionProfile = c.config.Bugs.SendSRTPProtectionProfile |
| } |
| |
| _, hs.ecdsaOk = hs.cert.PrivateKey.(*ecdsa.PrivateKey) |
| |
| if hs.checkForResumption() { |
| return true, nil |
| } |
| |
| var scsvFound bool |
| |
| for _, cipherSuite := range hs.clientHello.cipherSuites { |
| if cipherSuite == fallbackSCSV { |
| scsvFound = true |
| break |
| } |
| } |
| |
| if !scsvFound && config.Bugs.FailIfNotFallbackSCSV { |
| return false, errors.New("tls: no fallback SCSV found when expected") |
| } else if scsvFound && !config.Bugs.FailIfNotFallbackSCSV { |
| return false, errors.New("tls: fallback SCSV found when not expected") |
| } |
| |
| var preferenceList, supportedList []uint16 |
| if c.config.PreferServerCipherSuites { |
| preferenceList = c.config.cipherSuites() |
| supportedList = hs.clientHello.cipherSuites |
| } else { |
| preferenceList = hs.clientHello.cipherSuites |
| supportedList = c.config.cipherSuites() |
| } |
| |
| for _, id := range preferenceList { |
| if hs.suite = c.tryCipherSuite(id, supportedList, c.vers, hs.ellipticOk, hs.ecdsaOk); hs.suite != nil { |
| break |
| } |
| } |
| |
| if hs.suite == nil { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: no cipher suite supported by both client and server") |
| } |
| |
| return false, nil |
| } |
| |
| // checkForResumption returns true if we should perform resumption on this connection. |
| func (hs *serverHandshakeState) checkForResumption() bool { |
| c := hs.c |
| |
| if len(hs.clientHello.sessionTicket) > 0 { |
| if c.config.SessionTicketsDisabled { |
| return false |
| } |
| |
| var ok bool |
| if hs.sessionState, ok = c.decryptTicket(hs.clientHello.sessionTicket); !ok { |
| return false |
| } |
| } else { |
| if c.config.ServerSessionCache == nil { |
| return false |
| } |
| |
| var ok bool |
| sessionId := string(hs.clientHello.sessionId) |
| if hs.sessionState, ok = c.config.ServerSessionCache.Get(sessionId); !ok { |
| return false |
| } |
| } |
| |
| // Never resume a session for a different SSL version. |
| if !c.config.Bugs.AllowSessionVersionMismatch && c.vers != hs.sessionState.vers { |
| return false |
| } |
| |
| cipherSuiteOk := false |
| // Check that the client is still offering the ciphersuite in the session. |
| for _, id := range hs.clientHello.cipherSuites { |
| if id == hs.sessionState.cipherSuite { |
| cipherSuiteOk = true |
| break |
| } |
| } |
| if !cipherSuiteOk { |
| return false |
| } |
| |
| // Check that we also support the ciphersuite from the session. |
| hs.suite = c.tryCipherSuite(hs.sessionState.cipherSuite, c.config.cipherSuites(), hs.sessionState.vers, hs.ellipticOk, hs.ecdsaOk) |
| if hs.suite == nil { |
| return false |
| } |
| |
| sessionHasClientCerts := len(hs.sessionState.certificates) != 0 |
| needClientCerts := c.config.ClientAuth == RequireAnyClientCert || c.config.ClientAuth == RequireAndVerifyClientCert |
| if needClientCerts && !sessionHasClientCerts { |
| return false |
| } |
| if sessionHasClientCerts && c.config.ClientAuth == NoClientCert { |
| return false |
| } |
| |
| return true |
| } |
| |
| func (hs *serverHandshakeState) doResumeHandshake() error { |
| c := hs.c |
| |
| hs.hello.cipherSuite = hs.suite.id |
| // We echo the client's session ID in the ServerHello to let it know |
| // that we're doing a resumption. |
| hs.hello.sessionId = hs.clientHello.sessionId |
| hs.hello.ticketSupported = c.config.Bugs.RenewTicketOnResume |
| |
| hs.finishedHash = newFinishedHash(c.vers, hs.suite) |
| hs.finishedHash.discardHandshakeBuffer() |
| hs.writeClientHash(hs.clientHello.marshal()) |
| hs.writeServerHash(hs.hello.marshal()) |
| |
| c.writeRecord(recordTypeHandshake, hs.hello.marshal()) |
| |
| if len(hs.sessionState.certificates) > 0 { |
| if _, err := hs.processCertsFromClient(hs.sessionState.certificates); err != nil { |
| return err |
| } |
| } |
| |
| hs.masterSecret = hs.sessionState.masterSecret |
| c.extendedMasterSecret = hs.sessionState.extendedMasterSecret |
| |
| return nil |
| } |
| |
| func (hs *serverHandshakeState) doFullHandshake() error { |
| config := hs.c.config |
| c := hs.c |
| |
| isPSK := hs.suite.flags&suitePSK != 0 |
| if !isPSK && hs.clientHello.ocspStapling && len(hs.cert.OCSPStaple) > 0 { |
| hs.hello.ocspStapling = true |
| } |
| |
| if hs.clientHello.sctListSupported && len(hs.cert.SignedCertificateTimestampList) > 0 { |
| hs.hello.sctList = hs.cert.SignedCertificateTimestampList |
| } |
| |
| hs.hello.ticketSupported = hs.clientHello.ticketSupported && !config.SessionTicketsDisabled && c.vers > VersionSSL30 |
| hs.hello.cipherSuite = hs.suite.id |
| c.extendedMasterSecret = hs.hello.extendedMasterSecret |
| |
| // Generate a session ID if we're to save the session. |
| if !hs.hello.ticketSupported && config.ServerSessionCache != nil { |
| hs.hello.sessionId = make([]byte, 32) |
| if _, err := io.ReadFull(config.rand(), hs.hello.sessionId); err != nil { |
| c.sendAlert(alertInternalError) |
| return errors.New("tls: short read from Rand: " + err.Error()) |
| } |
| } |
| |
| hs.finishedHash = newFinishedHash(c.vers, hs.suite) |
| hs.writeClientHash(hs.clientHello.marshal()) |
| hs.writeServerHash(hs.hello.marshal()) |
| |
| c.writeRecord(recordTypeHandshake, hs.hello.marshal()) |
| |
| if !isPSK { |
| certMsg := new(certificateMsg) |
| certMsg.certificates = hs.cert.Certificate |
| if !config.Bugs.UnauthenticatedECDH { |
| hs.writeServerHash(certMsg.marshal()) |
| c.writeRecord(recordTypeHandshake, certMsg.marshal()) |
| } |
| } |
| |
| if hs.hello.ocspStapling { |
| certStatus := new(certificateStatusMsg) |
| certStatus.statusType = statusTypeOCSP |
| certStatus.response = hs.cert.OCSPStaple |
| hs.writeServerHash(certStatus.marshal()) |
| c.writeRecord(recordTypeHandshake, certStatus.marshal()) |
| } |
| |
| keyAgreement := hs.suite.ka(c.vers) |
| skx, err := keyAgreement.generateServerKeyExchange(config, hs.cert, hs.clientHello, hs.hello) |
| if err != nil { |
| c.sendAlert(alertHandshakeFailure) |
| return err |
| } |
| if skx != nil && !config.Bugs.SkipServerKeyExchange { |
| hs.writeServerHash(skx.marshal()) |
| c.writeRecord(recordTypeHandshake, skx.marshal()) |
| } |
| |
| if config.ClientAuth >= RequestClientCert { |
| // Request a client certificate |
| certReq := &certificateRequestMsg{ |
| certificateTypes: config.ClientCertificateTypes, |
| } |
| if certReq.certificateTypes == nil { |
| certReq.certificateTypes = []byte{ |
| byte(CertTypeRSASign), |
| byte(CertTypeECDSASign), |
| } |
| } |
| if c.vers >= VersionTLS12 { |
| certReq.hasSignatureAndHash = true |
| if !config.Bugs.NoSignatureAndHashes { |
| certReq.signatureAndHashes = config.signatureAndHashesForServer() |
| } |
| } |
| |
| // An empty list of certificateAuthorities signals to |
| // the client that it may send any certificate in response |
| // to our request. When we know the CAs we trust, then |
| // we can send them down, so that the client can choose |
| // an appropriate certificate to give to us. |
| if config.ClientCAs != nil { |
| certReq.certificateAuthorities = config.ClientCAs.Subjects() |
| } |
| hs.writeServerHash(certReq.marshal()) |
| c.writeRecord(recordTypeHandshake, certReq.marshal()) |
| } |
| |
| helloDone := new(serverHelloDoneMsg) |
| hs.writeServerHash(helloDone.marshal()) |
| c.writeRecord(recordTypeHandshake, helloDone.marshal()) |
| |
| var pub crypto.PublicKey // public key for client auth, if any |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| |
| var ok bool |
| // If we requested a client certificate, then the client must send a |
| // certificate message, even if it's empty. |
| if config.ClientAuth >= RequestClientCert { |
| var certMsg *certificateMsg |
| if certMsg, ok = msg.(*certificateMsg); !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(certMsg, msg) |
| } |
| hs.writeClientHash(certMsg.marshal()) |
| |
| if len(certMsg.certificates) == 0 { |
| // The client didn't actually send a certificate |
| switch config.ClientAuth { |
| case RequireAnyClientCert, RequireAndVerifyClientCert: |
| c.sendAlert(alertBadCertificate) |
| return errors.New("tls: client didn't provide a certificate") |
| } |
| } |
| |
| pub, err = hs.processCertsFromClient(certMsg.certificates) |
| if err != nil { |
| return err |
| } |
| |
| msg, err = c.readHandshake() |
| if err != nil { |
| return err |
| } |
| } |
| |
| // Get client key exchange |
| ckx, ok := msg.(*clientKeyExchangeMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(ckx, msg) |
| } |
| hs.writeClientHash(ckx.marshal()) |
| |
| preMasterSecret, err := keyAgreement.processClientKeyExchange(config, hs.cert, ckx, c.vers) |
| if err != nil { |
| c.sendAlert(alertHandshakeFailure) |
| return err |
| } |
| if c.extendedMasterSecret { |
| hs.masterSecret = extendedMasterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.finishedHash) |
| } else { |
| if c.config.Bugs.RequireExtendedMasterSecret { |
| return errors.New("tls: extended master secret required but not supported by peer") |
| } |
| hs.masterSecret = masterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.clientHello.random, hs.hello.random) |
| } |
| |
| // If we received a client cert in response to our certificate request message, |
| // the client will send us a certificateVerifyMsg immediately after the |
| // clientKeyExchangeMsg. This message is a digest of all preceding |
| // handshake-layer messages that is signed using the private key corresponding |
| // to the client's certificate. This allows us to verify that the client is in |
| // possession of the private key of the certificate. |
| if len(c.peerCertificates) > 0 { |
| msg, err = c.readHandshake() |
| if err != nil { |
| return err |
| } |
| certVerify, ok := msg.(*certificateVerifyMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(certVerify, msg) |
| } |
| |
| // Determine the signature type. |
| var signatureAndHash signatureAndHash |
| if certVerify.hasSignatureAndHash { |
| signatureAndHash = certVerify.signatureAndHash |
| if !isSupportedSignatureAndHash(signatureAndHash, config.signatureAndHashesForServer()) { |
| return errors.New("tls: unsupported hash function for client certificate") |
| } |
| } else { |
| // Before TLS 1.2 the signature algorithm was implicit |
| // from the key type, and only one hash per signature |
| // algorithm was possible. Leave the hash as zero. |
| switch pub.(type) { |
| case *ecdsa.PublicKey: |
| signatureAndHash.signature = signatureECDSA |
| case *rsa.PublicKey: |
| signatureAndHash.signature = signatureRSA |
| } |
| } |
| |
| switch key := pub.(type) { |
| case *ecdsa.PublicKey: |
| if signatureAndHash.signature != signatureECDSA { |
| err = errors.New("tls: bad signature type for client's ECDSA certificate") |
| break |
| } |
| ecdsaSig := new(ecdsaSignature) |
| if _, err = asn1.Unmarshal(certVerify.signature, ecdsaSig); err != nil { |
| break |
| } |
| if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 { |
| err = errors.New("ECDSA signature contained zero or negative values") |
| break |
| } |
| var digest []byte |
| digest, _, err = hs.finishedHash.hashForClientCertificate(signatureAndHash, hs.masterSecret) |
| if err != nil { |
| break |
| } |
| if !ecdsa.Verify(key, digest, ecdsaSig.R, ecdsaSig.S) { |
| err = errors.New("ECDSA verification failure") |
| break |
| } |
| case *rsa.PublicKey: |
| if signatureAndHash.signature != signatureRSA { |
| err = errors.New("tls: bad signature type for client's RSA certificate") |
| break |
| } |
| var digest []byte |
| var hashFunc crypto.Hash |
| digest, hashFunc, err = hs.finishedHash.hashForClientCertificate(signatureAndHash, hs.masterSecret) |
| if err != nil { |
| break |
| } |
| err = rsa.VerifyPKCS1v15(key, hashFunc, digest, certVerify.signature) |
| } |
| if err != nil { |
| c.sendAlert(alertBadCertificate) |
| return errors.New("could not validate signature of connection nonces: " + err.Error()) |
| } |
| |
| hs.writeClientHash(certVerify.marshal()) |
| } |
| |
| hs.finishedHash.discardHandshakeBuffer() |
| |
| return nil |
| } |
| |
| func (hs *serverHandshakeState) establishKeys() error { |
| c := hs.c |
| |
| clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV := |
| keysFromMasterSecret(c.vers, hs.suite, hs.masterSecret, hs.clientHello.random, hs.hello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen) |
| |
| var clientCipher, serverCipher interface{} |
| var clientHash, serverHash macFunction |
| |
| if hs.suite.aead == nil { |
| clientCipher = hs.suite.cipher(clientKey, clientIV, true /* for reading */) |
| clientHash = hs.suite.mac(c.vers, clientMAC) |
| serverCipher = hs.suite.cipher(serverKey, serverIV, false /* not for reading */) |
| serverHash = hs.suite.mac(c.vers, serverMAC) |
| } else { |
| clientCipher = hs.suite.aead(clientKey, clientIV) |
| serverCipher = hs.suite.aead(serverKey, serverIV) |
| } |
| |
| c.in.prepareCipherSpec(c.vers, clientCipher, clientHash) |
| c.out.prepareCipherSpec(c.vers, serverCipher, serverHash) |
| |
| return nil |
| } |
| |
| func (hs *serverHandshakeState) readFinished(isResume bool) error { |
| c := hs.c |
| |
| c.readRecord(recordTypeChangeCipherSpec) |
| if err := c.in.error(); err != nil { |
| return err |
| } |
| |
| if hs.hello.nextProtoNeg { |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| nextProto, ok := msg.(*nextProtoMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(nextProto, msg) |
| } |
| hs.writeClientHash(nextProto.marshal()) |
| c.clientProtocol = nextProto.proto |
| } |
| |
| if hs.hello.channelIDRequested { |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| encryptedExtensions, ok := msg.(*encryptedExtensionsMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(encryptedExtensions, msg) |
| } |
| x := new(big.Int).SetBytes(encryptedExtensions.channelID[0:32]) |
| y := new(big.Int).SetBytes(encryptedExtensions.channelID[32:64]) |
| r := new(big.Int).SetBytes(encryptedExtensions.channelID[64:96]) |
| s := new(big.Int).SetBytes(encryptedExtensions.channelID[96:128]) |
| if !elliptic.P256().IsOnCurve(x, y) { |
| return errors.New("tls: invalid channel ID public key") |
| } |
| channelID := &ecdsa.PublicKey{elliptic.P256(), x, y} |
| var resumeHash []byte |
| if isResume { |
| resumeHash = hs.sessionState.handshakeHash |
| } |
| if !ecdsa.Verify(channelID, hs.finishedHash.hashForChannelID(resumeHash), r, s) { |
| return errors.New("tls: invalid channel ID signature") |
| } |
| c.channelID = channelID |
| |
| hs.writeClientHash(encryptedExtensions.marshal()) |
| } |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| clientFinished, ok := msg.(*finishedMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(clientFinished, msg) |
| } |
| |
| verify := hs.finishedHash.clientSum(hs.masterSecret) |
| if len(verify) != len(clientFinished.verifyData) || |
| subtle.ConstantTimeCompare(verify, clientFinished.verifyData) != 1 { |
| c.sendAlert(alertHandshakeFailure) |
| return errors.New("tls: client's Finished message is incorrect") |
| } |
| c.clientVerify = append(c.clientVerify[:0], clientFinished.verifyData...) |
| |
| hs.writeClientHash(clientFinished.marshal()) |
| return nil |
| } |
| |
| func (hs *serverHandshakeState) sendSessionTicket() error { |
| c := hs.c |
| state := sessionState{ |
| vers: c.vers, |
| cipherSuite: hs.suite.id, |
| masterSecret: hs.masterSecret, |
| certificates: hs.certsFromClient, |
| handshakeHash: hs.finishedHash.server.Sum(nil), |
| } |
| |
| if !hs.hello.ticketSupported || hs.c.config.Bugs.SkipNewSessionTicket { |
| if c.config.ServerSessionCache != nil && len(hs.hello.sessionId) != 0 { |
| c.config.ServerSessionCache.Put(string(hs.hello.sessionId), &state) |
| } |
| return nil |
| } |
| |
| m := new(newSessionTicketMsg) |
| |
| var err error |
| m.ticket, err = c.encryptTicket(&state) |
| if err != nil { |
| return err |
| } |
| |
| hs.writeServerHash(m.marshal()) |
| c.writeRecord(recordTypeHandshake, m.marshal()) |
| |
| return nil |
| } |
| |
| func (hs *serverHandshakeState) sendFinished() error { |
| c := hs.c |
| |
| finished := new(finishedMsg) |
| finished.verifyData = hs.finishedHash.serverSum(hs.masterSecret) |
| c.serverVerify = append(c.serverVerify[:0], finished.verifyData...) |
| postCCSBytes := finished.marshal() |
| hs.writeServerHash(postCCSBytes) |
| |
| if c.config.Bugs.FragmentAcrossChangeCipherSpec { |
| c.writeRecord(recordTypeHandshake, postCCSBytes[:5]) |
| postCCSBytes = postCCSBytes[5:] |
| } |
| |
| if !c.config.Bugs.SkipChangeCipherSpec { |
| c.writeRecord(recordTypeChangeCipherSpec, []byte{1}) |
| } |
| |
| c.writeRecord(recordTypeHandshake, postCCSBytes) |
| |
| c.cipherSuite = hs.suite.id |
| |
| return nil |
| } |
| |
| // processCertsFromClient takes a chain of client certificates either from a |
| // Certificates message or from a sessionState and verifies them. It returns |
| // the public key of the leaf certificate. |
| func (hs *serverHandshakeState) processCertsFromClient(certificates [][]byte) (crypto.PublicKey, error) { |
| c := hs.c |
| |
| hs.certsFromClient = certificates |
| certs := make([]*x509.Certificate, len(certificates)) |
| var err error |
| for i, asn1Data := range certificates { |
| if certs[i], err = x509.ParseCertificate(asn1Data); err != nil { |
| c.sendAlert(alertBadCertificate) |
| return nil, errors.New("tls: failed to parse client certificate: " + err.Error()) |
| } |
| } |
| |
| if c.config.ClientAuth >= VerifyClientCertIfGiven && len(certs) > 0 { |
| opts := x509.VerifyOptions{ |
| Roots: c.config.ClientCAs, |
| CurrentTime: c.config.time(), |
| Intermediates: x509.NewCertPool(), |
| KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth}, |
| } |
| |
| for _, cert := range certs[1:] { |
| opts.Intermediates.AddCert(cert) |
| } |
| |
| chains, err := certs[0].Verify(opts) |
| if err != nil { |
| c.sendAlert(alertBadCertificate) |
| return nil, errors.New("tls: failed to verify client's certificate: " + err.Error()) |
| } |
| |
| ok := false |
| for _, ku := range certs[0].ExtKeyUsage { |
| if ku == x509.ExtKeyUsageClientAuth { |
| ok = true |
| break |
| } |
| } |
| if !ok { |
| c.sendAlert(alertHandshakeFailure) |
| return nil, errors.New("tls: client's certificate's extended key usage doesn't permit it to be used for client authentication") |
| } |
| |
| c.verifiedChains = chains |
| } |
| |
| if len(certs) > 0 { |
| var pub crypto.PublicKey |
| switch key := certs[0].PublicKey.(type) { |
| case *ecdsa.PublicKey, *rsa.PublicKey: |
| pub = key |
| default: |
| c.sendAlert(alertUnsupportedCertificate) |
| return nil, fmt.Errorf("tls: client's certificate contains an unsupported public key of type %T", certs[0].PublicKey) |
| } |
| c.peerCertificates = certs |
| return pub, nil |
| } |
| |
| return nil, nil |
| } |
| |
| func (hs *serverHandshakeState) writeServerHash(msg []byte) { |
| // writeServerHash is called before writeRecord. |
| hs.writeHash(msg, hs.c.sendHandshakeSeq) |
| } |
| |
| func (hs *serverHandshakeState) writeClientHash(msg []byte) { |
| // writeClientHash is called after readHandshake. |
| hs.writeHash(msg, hs.c.recvHandshakeSeq-1) |
| } |
| |
| func (hs *serverHandshakeState) writeHash(msg []byte, seqno uint16) { |
| if hs.c.isDTLS { |
| // This is somewhat hacky. DTLS hashes a slightly different format. |
| // First, the TLS header. |
| hs.finishedHash.Write(msg[:4]) |
| // Then the sequence number and reassembled fragment offset (always 0). |
| hs.finishedHash.Write([]byte{byte(seqno >> 8), byte(seqno), 0, 0, 0}) |
| // Then the reassembled fragment (always equal to the message length). |
| hs.finishedHash.Write(msg[1:4]) |
| // And then the message body. |
| hs.finishedHash.Write(msg[4:]) |
| } else { |
| hs.finishedHash.Write(msg) |
| } |
| } |
| |
| // tryCipherSuite returns a cipherSuite with the given id if that cipher suite |
| // is acceptable to use. |
| func (c *Conn) tryCipherSuite(id uint16, supportedCipherSuites []uint16, version uint16, ellipticOk, ecdsaOk bool) *cipherSuite { |
| for _, supported := range supportedCipherSuites { |
| if id == supported { |
| var candidate *cipherSuite |
| |
| for _, s := range cipherSuites { |
| if s.id == id { |
| candidate = s |
| break |
| } |
| } |
| if candidate == nil { |
| continue |
| } |
| // Don't select a ciphersuite which we can't |
| // support for this client. |
| if (candidate.flags&suiteECDHE != 0) && !ellipticOk { |
| continue |
| } |
| if (candidate.flags&suiteECDSA != 0) != ecdsaOk { |
| continue |
| } |
| if !c.config.Bugs.SkipCipherVersionCheck && version < VersionTLS12 && candidate.flags&suiteTLS12 != 0 { |
| continue |
| } |
| if c.isDTLS && candidate.flags&suiteNoDTLS != 0 { |
| continue |
| } |
| return candidate |
| } |
| } |
| |
| return nil |
| } |
