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13.go
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13.go
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package qtls
import (
"bytes"
"crypto"
"crypto/cipher"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/hmac"
"crypto/rsa"
"crypto/subtle"
"encoding/hex"
"errors"
"fmt"
"hash"
"io"
"log"
"os"
"runtime"
"runtime/debug"
"strings"
"sync/atomic"
"time"
"v2ray.com/core/external/github.com/cloudflare/sidh/sidh"
"golang.org/x/crypto/curve25519"
)
// numSessionTickets is the number of different session tickets the
// server sends to a TLS 1.3 client, who will use each only once.
const numSessionTickets = 2
type secretLabel int
const (
x25519SharedSecretSz = 32
P503PubKeySz = 378
P503PrvKeySz = 32
P503SharedSecretSz = 126
SIDHp503Curve25519PubKeySz = x25519SharedSecretSz + P503PubKeySz
SIDHp503Curve25519PrvKeySz = x25519SharedSecretSz + P503PrvKeySz
SIDHp503Curve25519SharedKeySz = x25519SharedSecretSz + P503SharedSecretSz
)
const (
secretResumptionPskBinder secretLabel = iota
secretEarlyClient
secretHandshakeClient
secretHandshakeServer
secretApplicationClient
secretApplicationServer
secretResumption
)
type keySchedule13 struct {
suite *cipherSuite
transcriptHash hash.Hash // uses the cipher suite hash algo
secret []byte // Current secret as used for Derive-Secret
handshakeCtx []byte // cached handshake context, invalidated on updates.
clientRandom []byte // Used for keylogging, nil if keylogging is disabled.
config *Config // Used for KeyLogWriter callback, nil if keylogging is disabled.
}
// Interface implemented by DH key exchange strategies
type dhKex interface {
// c - context of current TLS handshake, groupId - ID of an algorithm
// (curve/field) being chosen for key agreement. Methods implmenting an
// interface always assume that provided groupId is correct.
//
// In case of success, function returns secret key and ephemeral key. Otherwise
// error is set.
generate(c *Conn, groupId CurveID) ([]byte, keyShare, error)
// c - context of current TLS handshake, ks - public key received
// from the other side of the connection, secretKey - is a private key
// used for DH key agreement. Function returns shared secret in case
// of success or empty slice otherwise.
derive(c *Conn, ks keyShare, secretKey []byte) []byte
}
// Key Exchange strategies per curve type
type kexNist struct{} // Used by NIST curves; P-256, P-384, P-512
type kexX25519 struct{} // Used by X25519
type kexSIDHp503 struct{} // Used by SIDH/P503
type kexHybridSIDHp503X25519 struct {
classicKEX kexX25519
pqKEX kexSIDHp503
} // Used by SIDH-ECDH hybrid scheme
// Routing map for key exchange strategies
var dhKexStrat = map[CurveID]dhKex{
CurveP256: &kexNist{},
CurveP384: &kexNist{},
CurveP521: &kexNist{},
X25519: &kexX25519{},
HybridSIDHp503Curve25519: &kexHybridSIDHp503X25519{},
}
func newKeySchedule13(suite *cipherSuite, config *Config, clientRandom []byte) *keySchedule13 {
if config.KeyLogWriter == nil {
clientRandom = nil
config = nil
}
return &keySchedule13{
suite: suite,
transcriptHash: hashForSuite(suite).New(),
clientRandom: clientRandom,
config: config,
}
}
// setSecret sets the early/handshake/master secret based on the given secret
// (IKM). The salt is based on previous secrets (nil for the early secret).
func (ks *keySchedule13) setSecret(secret []byte) {
hash := hashForSuite(ks.suite)
salt := ks.secret
if salt != nil {
h0 := hash.New().Sum(nil)
salt = hkdfExpandLabel(hash, salt, h0, "derived", hash.Size())
}
ks.secret = hkdfExtract(hash, secret, salt)
}
// Depending on role returns pair of key variant to be used by
// local and remote process.
func getSidhKeyVariant(isClient bool) (sidh.KeyVariant, sidh.KeyVariant) {
if isClient {
return sidh.KeyVariant_SIDH_A, sidh.KeyVariant_SIDH_B
}
return sidh.KeyVariant_SIDH_B, sidh.KeyVariant_SIDH_A
}
// write appends the data to the transcript hash context.
func (ks *keySchedule13) write(data []byte) {
ks.handshakeCtx = nil
ks.transcriptHash.Write(data)
}
func (ks *keySchedule13) getLabel(secretLabel secretLabel) (label, keylogType string) {
switch secretLabel {
case secretResumptionPskBinder:
label = "res binder"
case secretEarlyClient:
label = "c e traffic"
keylogType = "CLIENT_EARLY_TRAFFIC_SECRET"
case secretHandshakeClient:
label = "c hs traffic"
keylogType = "CLIENT_HANDSHAKE_TRAFFIC_SECRET"
case secretHandshakeServer:
label = "s hs traffic"
keylogType = "SERVER_HANDSHAKE_TRAFFIC_SECRET"
case secretApplicationClient:
label = "c ap traffic"
keylogType = "CLIENT_TRAFFIC_SECRET_0"
case secretApplicationServer:
label = "s ap traffic"
keylogType = "SERVER_TRAFFIC_SECRET_0"
case secretResumption:
label = "res master"
}
return
}
// deriveSecret returns the secret derived from the handshake context and label.
func (ks *keySchedule13) deriveSecret(secretLabel secretLabel) []byte {
label, keylogType := ks.getLabel(secretLabel)
if ks.handshakeCtx == nil {
ks.handshakeCtx = ks.transcriptHash.Sum(nil)
}
hash := hashForSuite(ks.suite)
secret := hkdfExpandLabel(hash, ks.secret, ks.handshakeCtx, label, hash.Size())
if keylogType != "" && ks.config != nil {
ks.config.writeKeyLog(keylogType, ks.clientRandom, secret)
}
return secret
}
func (ks *keySchedule13) prepareCipher(trafficSecret []byte) cipher.AEAD {
hash := hashForSuite(ks.suite)
key := hkdfExpandLabel(hash, trafficSecret, nil, "key", ks.suite.keyLen)
iv := hkdfExpandLabel(hash, trafficSecret, nil, "iv", ks.suite.ivLen)
return ks.suite.aead(key, iv)
}
func (hs *serverHandshakeState) doTLS13Handshake() error {
config := hs.c.config
c := hs.c
hs.c.cipherSuite, hs.hello.cipherSuite = hs.suite.id, hs.suite.id
hs.c.clientHello = hs.clientHello.marshal()
// When picking the group for the handshake, priority is given to groups
// that the client provided a keyShare for, so to avoid a round-trip.
// After that the order of CurvePreferences is respected.
var ks keyShare
CurvePreferenceLoop:
for _, curveID := range config.curvePreferences() {
for _, keyShare := range hs.clientHello.keyShares {
if curveID == keyShare.group {
ks = keyShare
break CurvePreferenceLoop
}
}
}
if ks.group == 0 {
c.sendAlert(alertInternalError)
return errors.New("tls: HelloRetryRequest not implemented") // TODO(filippo)
}
privateKey, serverKS, err := c.generateKeyShare(ks.group)
if err != nil {
c.sendAlert(alertInternalError)
return err
}
hs.hello.keyShare = serverKS
hash := hashForSuite(hs.suite)
hashSize := hash.Size()
hs.keySchedule = newKeySchedule13(hs.suite, config, hs.clientHello.random)
// Check for PSK and update key schedule with new early secret key
isResumed, pskAlert := hs.checkPSK()
switch {
case pskAlert != alertSuccess:
c.sendAlert(pskAlert)
return errors.New("tls: invalid client PSK")
case !isResumed:
// apply an empty PSK if not resumed.
hs.keySchedule.setSecret(nil)
case isResumed:
c.didResume = true
}
hs.keySchedule.write(hs.clientHello.marshal())
earlyClientTrafficSecret := hs.keySchedule.deriveSecret(secretEarlyClient)
ecdheSecret := c.deriveDHESecret(ks, privateKey)
if ecdheSecret == nil {
c.sendAlert(alertIllegalParameter)
return errors.New("tls: bad ECDHE client share")
}
hs.keySchedule.write(hs.hello.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
return err
}
// middlebox compatibility mode: send CCS after first handshake message
if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
return err
}
hs.keySchedule.setSecret(ecdheSecret)
hs.hsClientTrafficSecret = hs.keySchedule.deriveSecret(secretHandshakeClient)
hsServerTrafficSecret := hs.keySchedule.deriveSecret(secretHandshakeServer)
c.out.exportKey(hs.keySchedule.suite, hsServerTrafficSecret)
c.out.setKey(c.vers, hs.keySchedule.suite, hsServerTrafficSecret)
serverFinishedKey := hkdfExpandLabel(hash, hsServerTrafficSecret, nil, "finished", hashSize)
hs.clientFinishedKey = hkdfExpandLabel(hash, hs.hsClientTrafficSecret, nil, "finished", hashSize)
// EncryptedExtensions
hs.keySchedule.write(hs.hello13Enc.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hs.hello13Enc.marshal()); err != nil {
return err
}
// TODO: we should have 2 separated methods - one for full-handshake and the other for PSK-handshake
if !c.didResume {
// Server MUST NOT send CertificateRequest if authenticating with PSK
if c.config.ClientAuth >= RequestClientCert {
certReq := new(certificateRequestMsg13)
// extension 'signature_algorithms' MUST be specified
certReq.supportedSignatureAlgorithms = supportedSignatureAlgorithms13
certReq.supportedSignatureAlgorithmsCert = supportedSigAlgorithmsCert(supportedSignatureAlgorithms13)
hs.keySchedule.write(certReq.marshal())
if _, err := hs.c.writeRecord(recordTypeHandshake, certReq.marshal()); err != nil {
return err
}
}
if err := hs.sendCertificate13(); err != nil {
return err
}
}
verifyData := hmacOfSum(hash, hs.keySchedule.transcriptHash, serverFinishedKey)
serverFinished := &finishedMsg{
verifyData: verifyData,
}
hs.keySchedule.write(serverFinished.marshal())
if _, err := c.writeRecord(recordTypeHandshake, serverFinished.marshal()); err != nil {
return err
}
hs.keySchedule.setSecret(nil) // derive master secret
serverAppTrafficSecret := hs.keySchedule.deriveSecret(secretApplicationServer)
c.out.exportKey(hs.keySchedule.suite, serverAppTrafficSecret)
c.out.setKey(c.vers, hs.keySchedule.suite, serverAppTrafficSecret)
if c.hand.Len() > 0 {
return c.sendAlert(alertUnexpectedMessage)
}
hs.appClientTrafficSecret = hs.keySchedule.deriveSecret(secretApplicationClient)
if hs.hello13Enc.earlyData {
c.in.exportKey(hs.keySchedule.suite, earlyClientTrafficSecret)
c.in.setKey(c.vers, hs.keySchedule.suite, earlyClientTrafficSecret)
c.phase = readingEarlyData
} else {
c.in.exportKey(hs.keySchedule.suite, hs.hsClientTrafficSecret)
c.in.setKey(c.vers, hs.keySchedule.suite, hs.hsClientTrafficSecret)
if hs.clientHello.earlyData {
c.phase = discardingEarlyData
} else {
c.phase = waitingClientFinished
}
}
return nil
}
// readClientFinished13 is called during the server handshake (when no early
// data it available) or after reading all early data. It discards early data if
// the server did not accept it and then verifies the Finished message. Once
// done it sends the session tickets. Under c.in lock.
func (hs *serverHandshakeState) readClientFinished13(hasConfirmLock bool) error {
c := hs.c
// If the client advertised and sends early data while the server does
// not accept it, it must be fully skipped until the Finished message.
for c.phase == discardingEarlyData {
if err := c.readRecord(recordTypeApplicationData); err != nil {
return err
}
// Assume receipt of Finished message (will be checked below).
if c.hand.Len() > 0 {
c.phase = waitingClientFinished
break
}
}
// If the client sends early data followed by a Finished message (but
// no end_of_early_data), the server MUST terminate the connection.
if c.phase != waitingClientFinished {
c.sendAlert(alertUnexpectedMessage)
return errors.New("tls: did not expect Client Finished yet")
}
c.phase = readingClientFinished
msg, err := c.readHandshake()
if err != nil {
return err
}
// client authentication
// (4.4.2) Client MUST send certificate msg if requested by server
if c.config.ClientAuth >= RequestClientCert && !c.didResume {
certMsg, ok := msg.(*certificateMsg13)
if !ok {
c.sendAlert(alertCertificateRequired)
return unexpectedMessageError(certMsg, msg)
}
hs.keySchedule.write(certMsg.marshal())
certs := getCertsFromEntries(certMsg.certificates)
pubKey, err := hs.processCertsFromClient(certs)
if err != nil {
return err
}
if len(certs) > 0 {
// 4.4.3: CertificateVerify MUST appear immediately after Certificate msg
msg, err = c.readHandshake()
if err != nil {
return err
}
certVerify, ok := msg.(*certificateVerifyMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(certVerify, msg)
}
err, alertCode := verifyPeerHandshakeSignature(
certVerify,
pubKey,
supportedSignatureAlgorithms13,
hs.keySchedule.transcriptHash.Sum(nil),
"TLS 1.3, client CertificateVerify")
if err != nil {
c.sendAlert(alertCode)
return err
}
hs.keySchedule.write(certVerify.marshal())
}
// Read next chunk
msg, err = c.readHandshake()
if err != nil {
return err
}
}
clientFinished, ok := msg.(*finishedMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(clientFinished, msg)
}
hash := hashForSuite(hs.suite)
expectedVerifyData := hmacOfSum(hash, hs.keySchedule.transcriptHash, hs.clientFinishedKey)
if len(expectedVerifyData) != len(clientFinished.verifyData) ||
subtle.ConstantTimeCompare(expectedVerifyData, clientFinished.verifyData) != 1 {
c.sendAlert(alertDecryptError)
return errors.New("tls: client's Finished message is incorrect")
}
hs.keySchedule.write(clientFinished.marshal())
c.hs = nil // Discard the server handshake state
if c.hand.Len() > 0 {
return c.sendAlert(alertUnexpectedMessage)
}
c.in.exportKey(hs.keySchedule.suite, hs.appClientTrafficSecret)
c.in.setKey(c.vers, hs.keySchedule.suite, hs.appClientTrafficSecret)
c.in.traceErr, c.out.traceErr = nil, nil
c.phase = handshakeConfirmed
atomic.StoreInt32(&c.handshakeConfirmed, 1)
// Any read operation after handshakeRunning and before handshakeConfirmed
// will be holding this lock, which we release as soon as the confirmation
// happens, even if the Read call might do more work.
// If a Handshake is pending, c.confirmMutex will never be locked as
// ConfirmHandshake will wait for the handshake to complete. If a
// handshake was complete, and this was a confirmation, unlock
// c.confirmMutex now to allow readers to proceed.
if hasConfirmLock {
c.confirmMutex.Unlock()
}
return hs.sendSessionTicket13() // TODO: do in a goroutine
}
func (hs *serverHandshakeState) sendCertificate13() error {
c := hs.c
certEntries := []certificateEntry{}
for _, cert := range hs.cert.Certificate {
certEntries = append(certEntries, certificateEntry{data: cert})
}
if len(certEntries) > 0 && hs.clientHello.ocspStapling {
certEntries[0].ocspStaple = hs.cert.OCSPStaple
}
if len(certEntries) > 0 && hs.clientHello.scts {
certEntries[0].sctList = hs.cert.SignedCertificateTimestamps
}
// If hs.delegatedCredential is set (see hs.readClientHello()) then the
// server is using the delegated credential extension. The DC is added as an
// extension to the end-entity certificate, i.e., the last CertificateEntry
// of Certificate.certficate_list. (For details, see
// https://tools.ietf.org/html/draft-ietf-tls-subcerts-02.)
if len(certEntries) > 0 && hs.clientHello.delegatedCredential && hs.delegatedCredential != nil {
certEntries[0].delegatedCredential = hs.delegatedCredential
}
certMsg := &certificateMsg13{certificates: certEntries}
hs.keySchedule.write(certMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
return err
}
sigScheme, err := hs.selectTLS13SignatureScheme()
if err != nil {
c.sendAlert(alertInternalError)
return err
}
sigHash := hashForSignatureScheme(sigScheme)
opts := crypto.SignerOpts(sigHash)
if signatureSchemeIsPSS(sigScheme) {
opts = &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash, Hash: sigHash}
}
toSign := prepareDigitallySigned(sigHash, "TLS 1.3, server CertificateVerify", hs.keySchedule.transcriptHash.Sum(nil))
signature, err := hs.privateKey.(crypto.Signer).Sign(c.config.rand(), toSign[:], opts)
if err != nil {
c.sendAlert(alertInternalError)
return err
}
verifyMsg := &certificateVerifyMsg{
hasSignatureAndHash: true,
signatureAlgorithm: sigScheme,
signature: signature,
}
hs.keySchedule.write(verifyMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, verifyMsg.marshal()); err != nil {
return err
}
return nil
}
func (c *Conn) handleEndOfEarlyData() error {
if c.phase != readingEarlyData || c.vers < VersionTLS13 {
return c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
msg, err := c.readHandshake()
if err != nil {
return err
}
endOfEarlyData, ok := msg.(*endOfEarlyDataMsg)
// No handshake messages are allowed after EOD.
if !ok || c.hand.Len() > 0 {
return c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
c.hs.keySchedule.write(endOfEarlyData.marshal())
c.phase = waitingClientFinished
c.in.exportKey(c.hs.keySchedule.suite, c.hs.hsClientTrafficSecret)
c.in.setKey(c.vers, c.hs.keySchedule.suite, c.hs.hsClientTrafficSecret)
return nil
}
// selectTLS13SignatureScheme chooses the SignatureScheme for the CertificateVerify
// based on the certificate type and client supported schemes. If no overlap is found,
// a fallback is selected.
//
// See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.4.1.2
func (hs *serverHandshakeState) selectTLS13SignatureScheme() (sigScheme SignatureScheme, err error) {
var supportedSchemes []SignatureScheme
signer, ok := hs.privateKey.(crypto.Signer)
if !ok {
return 0, errors.New("tls: private key does not implement crypto.Signer")
}
pk := signer.Public()
if _, ok := pk.(*rsa.PublicKey); ok {
sigScheme = PSSWithSHA256
supportedSchemes = []SignatureScheme{PSSWithSHA256, PSSWithSHA384, PSSWithSHA512}
} else if pk, ok := pk.(*ecdsa.PublicKey); ok {
switch pk.Curve {
case elliptic.P256():
sigScheme = ECDSAWithP256AndSHA256
supportedSchemes = []SignatureScheme{ECDSAWithP256AndSHA256}
case elliptic.P384():
sigScheme = ECDSAWithP384AndSHA384
supportedSchemes = []SignatureScheme{ECDSAWithP384AndSHA384}
case elliptic.P521():
sigScheme = ECDSAWithP521AndSHA512
supportedSchemes = []SignatureScheme{ECDSAWithP521AndSHA512}
default:
return 0, errors.New("tls: unknown ECDSA certificate curve")
}
} else {
return 0, errors.New("tls: unknown certificate key type")
}
for _, ss := range supportedSchemes {
for _, cs := range hs.clientHello.supportedSignatureAlgorithms {
if ss == cs {
return ss, nil
}
}
}
return sigScheme, nil
}
func signatureSchemeIsPSS(s SignatureScheme) bool {
return s == PSSWithSHA256 || s == PSSWithSHA384 || s == PSSWithSHA512
}
// hashForSignatureScheme returns the Hash used by a SignatureScheme which is
// supported by selectTLS13SignatureScheme.
func hashForSignatureScheme(ss SignatureScheme) crypto.Hash {
switch ss {
case PSSWithSHA256, ECDSAWithP256AndSHA256:
return crypto.SHA256
case PSSWithSHA384, ECDSAWithP384AndSHA384:
return crypto.SHA384
case PSSWithSHA512, ECDSAWithP521AndSHA512:
return crypto.SHA512
default:
panic("unsupported SignatureScheme passed to hashForSignatureScheme")
}
}
func hashForSuite(suite *cipherSuite) crypto.Hash {
if suite.flags&suiteSHA384 != 0 {
return crypto.SHA384
}
return crypto.SHA256
}
func prepareDigitallySigned(hash crypto.Hash, context string, data []byte) []byte {
message := bytes.Repeat([]byte{32}, 64)
message = append(message, context...)
message = append(message, 0)
message = append(message, data...)
h := hash.New()
h.Write(message)
return h.Sum(nil)
}
// generateKeyShare generates keypair. Private key is returned as first argument, public key
// is returned in keyShare.data. keyshare.curveID stores ID of the scheme used.
func (c *Conn) generateKeyShare(curveID CurveID) ([]byte, keyShare, error) {
if val, ok := dhKexStrat[curveID]; ok {
return val.generate(c, curveID)
}
return nil, keyShare{}, errors.New("tls: preferredCurves includes unsupported curve")
}
// DH key agreement. ks stores public key, secretKey stores private key used for ephemeral
// key agreement. Function returns shared secret in case of success or empty slice otherwise.
func (c *Conn) deriveDHESecret(ks keyShare, secretKey []byte) []byte {
if val, ok := dhKexStrat[ks.group]; ok {
return val.derive(c, ks, secretKey)
}
return nil
}
// HkdfExpandLabel HKDF expands a label
func HkdfExpandLabel(hash crypto.Hash, secret, hashValue []byte, label string, L int) []byte {
return hkdfExpandLabel(hash, secret, hashValue, label, L)
}
func hkdfExpandLabel(hash crypto.Hash, secret, hashValue []byte, label string, L int) []byte {
prefix := "tls13 "
hkdfLabel := make([]byte, 4+len(prefix)+len(label)+len(hashValue))
hkdfLabel[0] = byte(L >> 8)
hkdfLabel[1] = byte(L)
hkdfLabel[2] = byte(len(prefix) + len(label))
copy(hkdfLabel[3:], prefix)
z := hkdfLabel[3+len(prefix):]
copy(z, label)
z = z[len(label):]
z[0] = byte(len(hashValue))
copy(z[1:], hashValue)
return hkdfExpand(hash, secret, hkdfLabel, L)
}
func hmacOfSum(f crypto.Hash, hash hash.Hash, key []byte) []byte {
h := hmac.New(f.New, key)
h.Write(hash.Sum(nil))
return h.Sum(nil)
}
// Maximum allowed mismatch between the stated age of a ticket
// and the server-observed one. See
// https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.8.2.
const ticketAgeSkewAllowance = 10 * time.Second
// checkPSK tries to resume using a PSK, returning true (and updating the
// early secret in the key schedule) if the PSK was used and false otherwise.
func (hs *serverHandshakeState) checkPSK() (isResumed bool, alert alert) {
if hs.c.config.SessionTicketsDisabled {
return false, alertSuccess
}
foundDHE := false
for _, mode := range hs.clientHello.pskKeyExchangeModes {
if mode == pskDHEKeyExchange {
foundDHE = true
break
}
}
if !foundDHE {
return false, alertSuccess
}
hash := hashForSuite(hs.suite)
hashSize := hash.Size()
for i := range hs.clientHello.psks {
sessionTicket := append([]uint8{}, hs.clientHello.psks[i].identity...)
if hs.c.config.SessionTicketSealer != nil {
var ok bool
sessionTicket, ok = hs.c.config.SessionTicketSealer.Unseal(hs.clientHelloInfo(), sessionTicket)
if !ok {
continue
}
} else {
sessionTicket, _ = hs.c.decryptTicket(sessionTicket)
if sessionTicket == nil {
continue
}
}
s := &sessionState13{}
if s.unmarshal(sessionTicket) != alertSuccess {
continue
}
if s.vers != hs.c.vers {
continue
}
clientAge := time.Duration(hs.clientHello.psks[i].obfTicketAge-s.ageAdd) * time.Millisecond
serverAge := time.Since(time.Unix(int64(s.createdAt), 0))
if clientAge-serverAge > ticketAgeSkewAllowance || clientAge-serverAge < -ticketAgeSkewAllowance {
// XXX: NSS is off spec and sends obfuscated_ticket_age as seconds
clientAge = time.Duration(hs.clientHello.psks[i].obfTicketAge-s.ageAdd) * time.Second
if clientAge-serverAge > ticketAgeSkewAllowance || clientAge-serverAge < -ticketAgeSkewAllowance {
continue
}
}
// This enforces the stricter 0-RTT requirements on all ticket uses.
// The benefit of using PSK+ECDHE without 0-RTT are small enough that
// we can give them up in the edge case of changed suite or ALPN or SNI.
if s.suite != hs.suite.id {
continue
}
if s.alpnProtocol != hs.c.clientProtocol {
continue
}
if s.SNI != hs.c.serverName {
continue
}
hs.keySchedule.setSecret(s.pskSecret)
binderKey := hs.keySchedule.deriveSecret(secretResumptionPskBinder)
binderFinishedKey := hkdfExpandLabel(hash, binderKey, nil, "finished", hashSize)
chHash := hash.New()
chHash.Write(hs.clientHello.rawTruncated)
expectedBinder := hmacOfSum(hash, chHash, binderFinishedKey)
if subtle.ConstantTimeCompare(expectedBinder, hs.clientHello.psks[i].binder) != 1 {
return false, alertDecryptError
}
if i == 0 && hs.clientHello.earlyData {
// This is a ticket intended to be used for 0-RTT
if s.maxEarlyDataLen == 0 {
// But we had not tagged it as such.
return false, alertIllegalParameter
}
if hs.c.config.Accept0RTTData {
hs.c.binder = expectedBinder
hs.c.ticketMaxEarlyData = int64(s.maxEarlyDataLen)
hs.hello13Enc.earlyData = true
}
}
hs.hello.psk = true
hs.hello.pskIdentity = uint16(i)
return true, alertSuccess
}
return false, alertSuccess
}
func (hs *serverHandshakeState) sendSessionTicket13() error {
c := hs.c
if c.config.SessionTicketsDisabled {
return nil
}
foundDHE := false
for _, mode := range hs.clientHello.pskKeyExchangeModes {
if mode == pskDHEKeyExchange {
foundDHE = true
break
}
}
if !foundDHE {
return nil
}
resumptionMasterSecret := hs.keySchedule.deriveSecret(secretResumption)
ageAddBuf := make([]byte, 4)
sessionState := &sessionState13{
vers: c.vers,
suite: hs.suite.id,
createdAt: uint64(time.Now().Unix()),
alpnProtocol: c.clientProtocol,
SNI: c.serverName,
maxEarlyDataLen: c.config.Max0RTTDataSize,
}
hash := hashForSuite(hs.suite)
for i := 0; i < numSessionTickets; i++ {
if _, err := io.ReadFull(c.config.rand(), ageAddBuf); err != nil {
c.sendAlert(alertInternalError)
return err
}
sessionState.ageAdd = uint32(ageAddBuf[0])<<24 | uint32(ageAddBuf[1])<<16 |
uint32(ageAddBuf[2])<<8 | uint32(ageAddBuf[3])
// ticketNonce must be a unique value for this connection.
// Assume there are no more than 255 tickets, otherwise two
// tickets might have the same PSK which could be a problem if
// one of them is compromised.
ticketNonce := []byte{byte(i)}
sessionState.pskSecret = hkdfExpandLabel(hash, resumptionMasterSecret, ticketNonce, "resumption", hash.Size())
ticket := sessionState.marshal()
var err error
if c.config.SessionTicketSealer != nil {
cs := c.ConnectionState()
ticket, err = c.config.SessionTicketSealer.Seal(&cs, ticket)
} else {
ticket, err = c.encryptTicket(ticket)
}
if err != nil {
c.sendAlert(alertInternalError)
return err
}
if ticket == nil {
continue
}
ticketMsg := &newSessionTicketMsg13{
lifetime: 24 * 3600, // TODO(filippo)
maxEarlyDataLength: c.config.Max0RTTDataSize,
withEarlyDataInfo: c.config.Max0RTTDataSize > 0,
ageAdd: sessionState.ageAdd,
nonce: ticketNonce,
ticket: ticket,
}
if _, err := c.writeRecord(recordTypeHandshake, ticketMsg.marshal()); err != nil {
return err
}
}
return nil
}
func (hs *serverHandshakeState) traceErr(err error) {
if err == nil {
return
}
if os.Getenv("TLSDEBUG") == "error" {
if hs != nil && hs.clientHello != nil {
os.Stderr.WriteString(hex.Dump(hs.clientHello.marshal()))
} else if err == io.EOF {
return // don't stack trace on EOF before CH
}
fmt.Fprintf(os.Stderr, "\n%s\n", debug.Stack())
}
if os.Getenv("TLSDEBUG") == "short" {
var pcs [4]uintptr
frames := runtime.CallersFrames(pcs[0:runtime.Callers(3, pcs[:])])
for {
frame, more := frames.Next()
if frame.Function != "crypto/tls.(*halfConn).setErrorLocked" &&
frame.Function != "crypto/tls.(*Conn).sendAlertLocked" &&
frame.Function != "crypto/tls.(*Conn).sendAlert" {
file := frame.File[strings.LastIndex(frame.File, "/")+1:]
log.Printf("%s:%d (%s): %v", file, frame.Line, frame.Function, err)
return
}
if !more {
break
}
}
}
}
func getCertsFromEntries(certEntries []certificateEntry) [][]byte {
certs := make([][]byte, len(certEntries))
for i, cert := range certEntries {
certs[i] = cert.data
}
return certs
}
func (hs *clientHandshakeState) processEncryptedExtensions(ee *encryptedExtensionsMsg) error {
c := hs.c
if ee.alpnProtocol != "" {
c.clientProtocol = ee.alpnProtocol
c.clientProtocolFallback = false
}
if hs.c.config.ReceivedExtensions != nil {
return hs.c.config.ReceivedExtensions(typeEncryptedExtensions, ee.additionalExtensions)
}
return nil
}
func verifyPeerHandshakeSignature(
certVerify *certificateVerifyMsg,
pubKey crypto.PublicKey,
signAlgosKnown []SignatureScheme,
transHash []byte,
contextString string) (error, alert) {
_, sigType, hashFunc, err := pickSignatureAlgorithm(
pubKey,
[]SignatureScheme{certVerify.signatureAlgorithm},
signAlgosKnown,
VersionTLS13)
if err != nil {
return err, alertHandshakeFailure
}
digest := prepareDigitallySigned(hashFunc, contextString, transHash)
err = verifyHandshakeSignature(sigType, pubKey, hashFunc, digest, certVerify.signature)
if err != nil {
return err, alertDecryptError
}
return nil, alertSuccess
}
func (hs *clientHandshakeState) getCertificate13(certReq *certificateRequestMsg13) (*Certificate, error) {
certReq12 := &certificateRequestMsg{
hasSignatureAndHash: true,
supportedSignatureAlgorithms: certReq.supportedSignatureAlgorithms,
certificateAuthorities: certReq.certificateAuthorities,
}
var rsaAvail, ecdsaAvail bool
for _, sigAlg := range certReq.supportedSignatureAlgorithms {
switch signatureFromSignatureScheme(sigAlg) {
case signaturePKCS1v15, signatureRSAPSS:
rsaAvail = true
case signatureECDSA:
ecdsaAvail = true
}
}
if rsaAvail {
certReq12.certificateTypes = append(certReq12.certificateTypes, certTypeRSASign)
}
if ecdsaAvail {
certReq12.certificateTypes = append(certReq12.certificateTypes, certTypeECDSASign)
}
return hs.getCertificate(certReq12)
}
func (hs *clientHandshakeState) sendCertificate13(chainToSend *Certificate, certReq *certificateRequestMsg13) error {
c := hs.c
certEntries := []certificateEntry{}
for _, cert := range chainToSend.Certificate {
certEntries = append(certEntries, certificateEntry{data: cert})
}
certMsg := &certificateMsg13{certificates: certEntries}
hs.keySchedule.write(certMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
return err
}
if len(certEntries) == 0 {
// No client cert available, nothing to sign.
return nil
}
key, ok := chainToSend.PrivateKey.(crypto.Signer)
if !ok {
c.sendAlert(alertInternalError)
return fmt.Errorf("tls: client certificate private key of type %T does not implement crypto.Signer", chainToSend.PrivateKey)
}
signatureAlgorithm, sigType, hashFunc, err := pickSignatureAlgorithm(key.Public(), certReq.supportedSignatureAlgorithms, hs.hello.supportedSignatureAlgorithms, c.vers)
if err != nil {
hs.c.sendAlert(alertHandshakeFailure)
return err
}
digest := prepareDigitallySigned(hashFunc, "TLS 1.3, client CertificateVerify", hs.keySchedule.transcriptHash.Sum(nil))
signOpts := crypto.SignerOpts(hashFunc)
if sigType == signatureRSAPSS {
signOpts = &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash, Hash: hashFunc}
}
signature, err := key.Sign(c.config.rand(), digest, signOpts)
if err != nil {
c.sendAlert(alertInternalError)
return err
}
verifyMsg := &certificateVerifyMsg{
hasSignatureAndHash: true,
signatureAlgorithm: signatureAlgorithm,
signature: signature,
}
hs.keySchedule.write(verifyMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, verifyMsg.marshal()); err != nil {
return err
}
return nil
}
func (hs *clientHandshakeState) doTLS13Handshake() error {
c := hs.c
hash := hashForSuite(hs.suite)
hashSize := hash.Size()
serverHello := hs.serverHello
c.scts = serverHello.scts
// middlebox compatibility mode, send CCS before second flight.
if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
return err
}
// TODO check if keyshare is unacceptable, raise HRR.
clientKS := hs.hello.keyShares[0]
if serverHello.keyShare.group != clientKS.group {
c.sendAlert(alertIllegalParameter)