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path: root/src/pkg/crypto/tls/handshake_server.go
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Diffstat (limited to 'src/pkg/crypto/tls/handshake_server.go')
-rw-r--r--src/pkg/crypto/tls/handshake_server.go534
1 files changed, 393 insertions, 141 deletions
diff --git a/src/pkg/crypto/tls/handshake_server.go b/src/pkg/crypto/tls/handshake_server.go
index 76adc540c..730991016 100644
--- a/src/pkg/crypto/tls/handshake_server.go
+++ b/src/pkg/crypto/tls/handshake_server.go
@@ -13,31 +13,120 @@ import (
"io"
)
+// 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
+ sessionState *sessionState
+ finishedHash finishedHash
+ masterSecret []byte
+ certsFromClient [][]byte
+}
+
+// serverHandshake performs a TLS handshake as a server.
func (c *Conn) serverHandshake() error {
config := c.config
- msg, err := c.readHandshake()
+
+ // If this is the first server handshake, we generate a random key to
+ // encrypt the tickets with.
+ config.serverInitOnce.Do(func() {
+ if config.SessionTicketsDisabled {
+ return
+ }
+
+ // If the key has already been set then we have nothing to do.
+ for _, b := range config.SessionTicketKey {
+ if b != 0 {
+ return
+ }
+ }
+
+ if _, err := io.ReadFull(config.rand(), config.SessionTicketKey[:]); err != nil {
+ config.SessionTicketsDisabled = true
+ }
+ })
+
+ hs := serverHandshakeState{
+ c: c,
+ }
+ isResume, err := hs.readClientHello()
if err != nil {
return err
}
- clientHello, ok := msg.(*clientHelloMsg)
+
+ // 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 err := hs.sendFinished(); err != nil {
+ return err
+ }
+ if err := hs.readFinished(); 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(); 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 {
- return c.sendAlert(alertUnexpectedMessage)
+ return false, c.sendAlert(alertUnexpectedMessage)
}
- vers, ok := mutualVersion(clientHello.vers)
+ c.vers, ok = mutualVersion(hs.clientHello.vers)
if !ok {
- return c.sendAlert(alertProtocolVersion)
+ return false, c.sendAlert(alertProtocolVersion)
}
- c.vers = vers
c.haveVers = true
- finishedHash := newFinishedHash(vers)
- finishedHash.Write(clientHello.marshal())
+ hs.finishedHash = newFinishedHash(c.vers)
+ hs.finishedHash.Write(hs.clientHello.marshal())
- hello := new(serverHelloMsg)
+ hs.hello = new(serverHelloMsg)
supportedCurve := false
Curves:
- for _, curve := range clientHello.supportedCurves {
+ for _, curve := range hs.clientHello.supportedCurves {
switch curve {
case curveP256, curveP384, curveP521:
supportedCurve = true
@@ -46,110 +135,182 @@ Curves:
}
supportedPointFormat := false
- for _, pointFormat := range clientHello.supportedPoints {
+ for _, pointFormat := range hs.clientHello.supportedPoints {
if pointFormat == pointFormatUncompressed {
supportedPointFormat = true
break
}
}
-
- ellipticOk := supportedCurve && supportedPointFormat
-
- var suite *cipherSuite
-FindCipherSuite:
- for _, id := range clientHello.cipherSuites {
- for _, supported := range config.cipherSuites() {
- 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.elliptic && !ellipticOk {
- continue
- }
- suite = candidate
- break FindCipherSuite
- }
- }
- }
+ hs.ellipticOk = supportedCurve && supportedPointFormat
foundCompression := false
// We only support null compression, so check that the client offered it.
- for _, compression := range clientHello.compressionMethods {
+ for _, compression := range hs.clientHello.compressionMethods {
if compression == compressionNone {
foundCompression = true
break
}
}
- if suite == nil || !foundCompression {
- return c.sendAlert(alertHandshakeFailure)
+ if !foundCompression {
+ return false, c.sendAlert(alertHandshakeFailure)
}
- hello.vers = vers
- hello.cipherSuite = suite.id
+ hs.hello.vers = c.vers
t := uint32(config.time().Unix())
- hello.random = make([]byte, 32)
- hello.random[0] = byte(t >> 24)
- hello.random[1] = byte(t >> 16)
- hello.random[2] = byte(t >> 8)
- hello.random[3] = byte(t)
- _, err = io.ReadFull(config.rand(), hello.random[4:])
+ hs.hello.random = make([]byte, 32)
+ hs.hello.random[0] = byte(t >> 24)
+ hs.hello.random[1] = byte(t >> 16)
+ hs.hello.random[2] = byte(t >> 8)
+ hs.hello.random[3] = byte(t)
+ _, err = io.ReadFull(config.rand(), hs.hello.random[4:])
if err != nil {
- return c.sendAlert(alertInternalError)
+ return false, c.sendAlert(alertInternalError)
+ }
+ hs.hello.compressionMethod = compressionNone
+ if len(hs.clientHello.serverName) > 0 {
+ c.serverName = hs.clientHello.serverName
+ }
+ if hs.clientHello.nextProtoNeg {
+ hs.hello.nextProtoNeg = true
+ hs.hello.nextProtos = config.NextProtos
+ }
+
+ if hs.checkForResumption() {
+ return true, nil
+ }
+
+ 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, hs.ellipticOk); hs.suite != nil {
+ break
+ }
+ }
+
+ if hs.suite == nil {
+ return false, c.sendAlert(alertHandshakeFailure)
+ }
+
+ return false, nil
+}
+
+// checkForResumption returns true if we should perform resumption on this connection.
+func (hs *serverHandshakeState) checkForResumption() bool {
+ c := hs.c
+
+ var ok bool
+ if hs.sessionState, ok = c.decryptTicket(hs.clientHello.sessionTicket); !ok {
+ return false
}
- hello.compressionMethod = compressionNone
- if clientHello.nextProtoNeg {
- hello.nextProtoNeg = true
- hello.nextProtos = config.NextProtos
+
+ if hs.sessionState.vers > hs.clientHello.vers {
+ return false
+ }
+ if vers, ok := mutualVersion(hs.sessionState.vers); !ok || 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.ellipticOk)
+ 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.finishedHash.Write(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
+
+ return nil
+}
+
+func (hs *serverHandshakeState) doFullHandshake() error {
+ config := hs.c.config
+ c := hs.c
+
if len(config.Certificates) == 0 {
return c.sendAlert(alertInternalError)
}
cert := &config.Certificates[0]
- if len(clientHello.serverName) > 0 {
- c.serverName = clientHello.serverName
- cert = config.getCertificateForName(clientHello.serverName)
+ if len(hs.clientHello.serverName) > 0 {
+ cert = config.getCertificateForName(hs.clientHello.serverName)
}
- if clientHello.ocspStapling && len(cert.OCSPStaple) > 0 {
- hello.ocspStapling = true
+ if hs.clientHello.ocspStapling && len(cert.OCSPStaple) > 0 {
+ hs.hello.ocspStapling = true
}
- finishedHash.Write(hello.marshal())
- c.writeRecord(recordTypeHandshake, hello.marshal())
+ hs.hello.ticketSupported = hs.clientHello.ticketSupported && !config.SessionTicketsDisabled
+ hs.hello.cipherSuite = hs.suite.id
+ hs.finishedHash.Write(hs.hello.marshal())
+ c.writeRecord(recordTypeHandshake, hs.hello.marshal())
certMsg := new(certificateMsg)
certMsg.certificates = cert.Certificate
- finishedHash.Write(certMsg.marshal())
+ hs.finishedHash.Write(certMsg.marshal())
c.writeRecord(recordTypeHandshake, certMsg.marshal())
- if hello.ocspStapling {
+ if hs.hello.ocspStapling {
certStatus := new(certificateStatusMsg)
certStatus.statusType = statusTypeOCSP
certStatus.response = cert.OCSPStaple
- finishedHash.Write(certStatus.marshal())
+ hs.finishedHash.Write(certStatus.marshal())
c.writeRecord(recordTypeHandshake, certStatus.marshal())
}
- keyAgreement := suite.ka()
- skx, err := keyAgreement.generateServerKeyExchange(config, cert, clientHello, hello)
+ keyAgreement := hs.suite.ka()
+ skx, err := keyAgreement.generateServerKeyExchange(config, cert, hs.clientHello, hs.hello)
if err != nil {
c.sendAlert(alertHandshakeFailure)
return err
}
if skx != nil {
- finishedHash.Write(skx.marshal())
+ hs.finishedHash.Write(skx.marshal())
c.writeRecord(recordTypeHandshake, skx.marshal())
}
@@ -166,28 +327,29 @@ FindCipherSuite:
if config.ClientCAs != nil {
certReq.certificateAuthorities = config.ClientCAs.Subjects()
}
- finishedHash.Write(certReq.marshal())
+ hs.finishedHash.Write(certReq.marshal())
c.writeRecord(recordTypeHandshake, certReq.marshal())
}
helloDone := new(serverHelloDoneMsg)
- finishedHash.Write(helloDone.marshal())
+ hs.finishedHash.Write(helloDone.marshal())
c.writeRecord(recordTypeHandshake, helloDone.marshal())
var pub *rsa.PublicKey // public key for client auth, if any
- msg, err = c.readHandshake()
+ 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 {
if certMsg, ok = msg.(*certificateMsg); !ok {
return c.sendAlert(alertHandshakeFailure)
}
- finishedHash.Write(certMsg.marshal())
+ hs.finishedHash.Write(certMsg.marshal())
if len(certMsg.certificates) == 0 {
// The client didn't actually send a certificate
@@ -198,54 +360,9 @@ FindCipherSuite:
}
}
- certs := make([]*x509.Certificate, len(certMsg.certificates))
- for i, asn1Data := range certMsg.certificates {
- if certs[i], err = x509.ParseCertificate(asn1Data); err != nil {
- c.sendAlert(alertBadCertificate)
- return 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(),
- }
-
- for i, cert := range certs {
- if i == 0 {
- continue
- }
- opts.Intermediates.AddCert(cert)
- }
-
- chains, err := certs[0].Verify(opts)
- if err != nil {
- c.sendAlert(alertBadCertificate)
- return 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 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 {
- if pub, ok = certs[0].PublicKey.(*rsa.PublicKey); !ok {
- return c.sendAlert(alertUnsupportedCertificate)
- }
- c.peerCertificates = certs
+ pub, err = hs.processCertsFromClient(certMsg.certificates)
+ if err != nil {
+ return err
}
msg, err = c.readHandshake()
@@ -259,7 +376,7 @@ FindCipherSuite:
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
- finishedHash.Write(ckx.marshal())
+ hs.finishedHash.Write(ckx.marshal())
// If we received a client cert in response to our certificate request message,
// the client will send us a certificateVerifyMsg immediately after the
@@ -278,15 +395,15 @@ FindCipherSuite:
}
digest := make([]byte, 0, 36)
- digest = finishedHash.serverMD5.Sum(digest)
- digest = finishedHash.serverSHA1.Sum(digest)
+ digest = hs.finishedHash.serverMD5.Sum(digest)
+ digest = hs.finishedHash.serverSHA1.Sum(digest)
err = rsa.VerifyPKCS1v15(pub, crypto.MD5SHA1, digest, certVerify.signature)
if err != nil {
c.sendAlert(alertBadCertificate)
return errors.New("could not validate signature of connection nonces: " + err.Error())
}
- finishedHash.Write(certVerify.marshal())
+ hs.finishedHash.Write(certVerify.marshal())
}
preMasterSecret, err := keyAgreement.processClientKeyExchange(config, cert, ckx, c.vers)
@@ -294,20 +411,38 @@ FindCipherSuite:
c.sendAlert(alertHandshakeFailure)
return err
}
+ hs.masterSecret = masterFromPreMasterSecret(c.vers, preMasterSecret, hs.clientHello.random, hs.hello.random)
+
+ return nil
+}
+
+func (hs *serverHandshakeState) establishKeys() error {
+ c := hs.c
- masterSecret, clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
- keysFromPreMasterSecret(c.vers, preMasterSecret, clientHello.random, hello.random, suite.macLen, suite.keyLen, suite.ivLen)
+ clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
+ keysFromMasterSecret(c.vers, hs.masterSecret, hs.clientHello.random, hs.hello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen)
- clientCipher := suite.cipher(clientKey, clientIV, true /* for reading */)
- clientHash := suite.mac(c.vers, clientMAC)
+ clientCipher := hs.suite.cipher(clientKey, clientIV, true /* for reading */)
+ clientHash := hs.suite.mac(c.vers, clientMAC)
c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
+
+ serverCipher := hs.suite.cipher(serverKey, serverIV, false /* not for reading */)
+ serverHash := hs.suite.mac(c.vers, serverMAC)
+ c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
+
+ return nil
+}
+
+func (hs *serverHandshakeState) readFinished() error {
+ c := hs.c
+
c.readRecord(recordTypeChangeCipherSpec)
if err := c.error(); err != nil {
return err
}
- if hello.nextProtoNeg {
- msg, err = c.readHandshake()
+ if hs.hello.nextProtoNeg {
+ msg, err := c.readHandshake()
if err != nil {
return err
}
@@ -315,11 +450,11 @@ FindCipherSuite:
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
- finishedHash.Write(nextProto.marshal())
+ hs.finishedHash.Write(nextProto.marshal())
c.clientProtocol = nextProto.proto
}
- msg, err = c.readHandshake()
+ msg, err := c.readHandshake()
if err != nil {
return err
}
@@ -328,25 +463,142 @@ FindCipherSuite:
return c.sendAlert(alertUnexpectedMessage)
}
- verify := finishedHash.clientSum(masterSecret)
+ verify := hs.finishedHash.clientSum(hs.masterSecret)
if len(verify) != len(clientFinished.verifyData) ||
subtle.ConstantTimeCompare(verify, clientFinished.verifyData) != 1 {
return c.sendAlert(alertHandshakeFailure)
}
- finishedHash.Write(clientFinished.marshal())
+ hs.finishedHash.Write(clientFinished.marshal())
+ return nil
+}
+
+func (hs *serverHandshakeState) sendSessionTicket() error {
+ if !hs.hello.ticketSupported {
+ return nil
+ }
+
+ c := hs.c
+ m := new(newSessionTicketMsg)
+
+ var err error
+ state := sessionState{
+ vers: c.vers,
+ cipherSuite: hs.suite.id,
+ masterSecret: hs.masterSecret,
+ certificates: hs.certsFromClient,
+ }
+ m.ticket, err = c.encryptTicket(&state)
+ if err != nil {
+ return err
+ }
+
+ hs.finishedHash.Write(m.marshal())
+ c.writeRecord(recordTypeHandshake, m.marshal())
+
+ return nil
+}
+
+func (hs *serverHandshakeState) sendFinished() error {
+ c := hs.c
- serverCipher := suite.cipher(serverKey, serverIV, false /* not for reading */)
- serverHash := suite.mac(c.vers, serverMAC)
- c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
finished := new(finishedMsg)
- finished.verifyData = finishedHash.serverSum(masterSecret)
+ finished.verifyData = hs.finishedHash.serverSum(hs.masterSecret)
+ hs.finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
- c.handshakeComplete = true
- c.cipherSuite = suite.id
+ 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) (*rsa.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 {
+ pub, ok := certs[0].PublicKey.(*rsa.PublicKey)
+ if !ok {
+ return nil, c.sendAlert(alertUnsupportedCertificate)
+ }
+ c.peerCertificates = certs
+ return pub, nil
+ }
+
+ return nil, nil
+}
+
+// tryCipherSuite returns a cipherSuite with the given id if that cipher suite
+// is acceptable to use.
+func (c *Conn) tryCipherSuite(id uint16, supportedCipherSuites []uint16, ellipticOk 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.elliptic && !ellipticOk {
+ continue
+ }
+ return candidate
+ }
+ }
return nil
}
generated by cgit v1.2.3 (git 2.46.0) at 2025-10-16 16:48:23 +0000