Commit 37c28759 authored by Tamir Duberstein's avatar Tamir Duberstein Committed by Adam Langley

crypto/tls: check errors from (*Conn).writeRecord

This promotes a connection hang during TLS handshake to a proper error.
This doesn't fully address #14539 because the error reported in that
case is a write-on-socket-not-connected error, which implies that an
earlier error during connection setup is not being checked, but it is
an improvement over the current behaviour.

Updates #14539.

Change-Id: I0571a752d32d5303db48149ab448226868b19495
Reviewed-on: https://go-review.googlesource.com/19990Reviewed-by: default avatarAdam Langley <agl@golang.org>
parent 1012892f
......@@ -694,12 +694,14 @@ func (c *Conn) sendAlertLocked(err alert) error {
c.tmp[0] = alertLevelError
}
c.tmp[1] = byte(err)
c.writeRecord(recordTypeAlert, c.tmp[0:2])
// closeNotify is a special case in that it isn't an error:
if err != alertCloseNotify {
return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
_, writeErr := c.writeRecord(recordTypeAlert, c.tmp[0:2])
if err == alertCloseNotify {
// closeNotify is a special case in that it isn't an error.
return writeErr
}
return nil
return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
}
// sendAlert sends a TLS alert message.
......@@ -713,8 +715,11 @@ func (c *Conn) sendAlert(err alert) error {
// writeRecord writes a TLS record with the given type and payload
// to the connection and updates the record layer state.
// c.out.Mutex <= L.
func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
func (c *Conn) writeRecord(typ recordType, data []byte) (int, error) {
b := c.out.newBlock()
defer c.out.freeBlock(b)
var n int
for len(data) > 0 {
m := len(data)
if m > maxPlaintext {
......@@ -759,34 +764,27 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
if explicitIVIsSeq {
copy(explicitIV, c.out.seq[:])
} else {
if _, err = io.ReadFull(c.config.rand(), explicitIV); err != nil {
break
if _, err := io.ReadFull(c.config.rand(), explicitIV); err != nil {
return n, err
}
}
}
copy(b.data[recordHeaderLen+explicitIVLen:], data)
c.out.encrypt(b, explicitIVLen)
_, err = c.conn.Write(b.data)
if err != nil {
break
if _, err := c.conn.Write(b.data); err != nil {
return n, err
}
n += m
data = data[m:]
}
c.out.freeBlock(b)
if typ == recordTypeChangeCipherSpec {
err = c.out.changeCipherSpec()
if err != nil {
// Cannot call sendAlert directly,
// because we already hold c.out.Mutex.
c.tmp[0] = alertLevelError
c.tmp[1] = byte(err.(alert))
c.writeRecord(recordTypeAlert, c.tmp[0:2])
return n, c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
if err := c.out.changeCipherSpec(); err != nil {
return n, c.sendAlertLocked(err.(alert))
}
}
return
return n, nil
}
// readHandshake reads the next handshake message from
......
......@@ -138,7 +138,9 @@ NextCipherSuite:
}
}
c.writeRecord(recordTypeHandshake, hello.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hello.marshal()); err != nil {
return err
}
msg, err := c.readHandshake()
if err != nil {
......@@ -419,7 +421,9 @@ func (hs *clientHandshakeState) doFullHandshake() error {
certMsg.certificates = chainToSend.Certificate
}
hs.finishedHash.Write(certMsg.marshal())
c.writeRecord(recordTypeHandshake, certMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
return err
}
}
preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, certs[0])
......@@ -429,7 +433,9 @@ func (hs *clientHandshakeState) doFullHandshake() error {
}
if ckx != nil {
hs.finishedHash.Write(ckx.marshal())
c.writeRecord(recordTypeHandshake, ckx.marshal())
if _, err := c.writeRecord(recordTypeHandshake, ckx.marshal()); err != nil {
return err
}
}
if chainToSend != nil {
......@@ -471,7 +477,9 @@ func (hs *clientHandshakeState) doFullHandshake() error {
}
hs.finishedHash.Write(certVerify.marshal())
c.writeRecord(recordTypeHandshake, certVerify.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certVerify.marshal()); err != nil {
return err
}
}
hs.masterSecret = masterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.hello.random, hs.serverHello.random)
......@@ -615,7 +623,9 @@ func (hs *clientHandshakeState) readSessionTicket() error {
func (hs *clientHandshakeState) sendFinished(out []byte) error {
c := hs.c
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
return err
}
if hs.serverHello.nextProtoNeg {
nextProto := new(nextProtoMsg)
proto, fallback := mutualProtocol(c.config.NextProtos, hs.serverHello.nextProtos)
......@@ -624,13 +634,17 @@ func (hs *clientHandshakeState) sendFinished(out []byte) error {
c.clientProtocolFallback = fallback
hs.finishedHash.Write(nextProto.marshal())
c.writeRecord(recordTypeHandshake, nextProto.marshal())
if _, err := c.writeRecord(recordTypeHandshake, nextProto.marshal()); err != nil {
return err
}
}
finished := new(finishedMsg)
finished.verifyData = hs.finishedHash.clientSum(hs.masterSecret)
hs.finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil {
return err
}
copy(out, finished.verifyData)
return nil
}
......
......@@ -12,6 +12,7 @@ import (
"encoding/base64"
"encoding/binary"
"encoding/pem"
"errors"
"fmt"
"io"
"net"
......@@ -725,3 +726,51 @@ func TestServerSelectingUnconfiguredCipherSuite(t *testing.T) {
t.Fatalf("Expected error about unconfigured cipher suite but got %q", err)
}
}
// brokenConn wraps a net.Conn and causes all Writes after a certain number to
// fail with brokenConnErr.
type brokenConn struct {
net.Conn
// breakAfter is the number of successful writes that will be allowed
// before all subsequent writes fail.
breakAfter int
// numWrites is the number of writes that have been done.
numWrites int
}
// brokenConnErr is the error that brokenConn returns once exhausted.
var brokenConnErr = errors.New("too many writes to brokenConn")
func (b *brokenConn) Write(data []byte) (int, error) {
if b.numWrites >= b.breakAfter {
return 0, brokenConnErr
}
b.numWrites++
return b.Conn.Write(data)
}
func TestFailedWrite(t *testing.T) {
// Test that a write error during the handshake is returned.
for _, breakAfter := range []int{0, 1, 2, 3} {
c, s := net.Pipe()
done := make(chan bool)
go func() {
Server(s, testConfig).Handshake()
s.Close()
done <- true
}()
brokenC := &brokenConn{Conn: c, breakAfter: breakAfter}
err := Client(brokenC, testConfig).Handshake()
if err != brokenConnErr {
t.Errorf("#%d: expected error from brokenConn but got %q", breakAfter, err)
}
brokenC.Close()
<-done
}
}
......@@ -322,7 +322,9 @@ func (hs *serverHandshakeState) doResumeHandshake() error {
hs.finishedHash.discardHandshakeBuffer()
hs.finishedHash.Write(hs.clientHello.marshal())
hs.finishedHash.Write(hs.hello.marshal())
c.writeRecord(recordTypeHandshake, hs.hello.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
return err
}
if len(hs.sessionState.certificates) > 0 {
if _, err := hs.processCertsFromClient(hs.sessionState.certificates); err != nil {
......@@ -354,19 +356,25 @@ func (hs *serverHandshakeState) doFullHandshake() error {
}
hs.finishedHash.Write(hs.clientHello.marshal())
hs.finishedHash.Write(hs.hello.marshal())
c.writeRecord(recordTypeHandshake, hs.hello.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
return err
}
certMsg := new(certificateMsg)
certMsg.certificates = hs.cert.Certificate
hs.finishedHash.Write(certMsg.marshal())
c.writeRecord(recordTypeHandshake, certMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
return err
}
if hs.hello.ocspStapling {
certStatus := new(certificateStatusMsg)
certStatus.statusType = statusTypeOCSP
certStatus.response = hs.cert.OCSPStaple
hs.finishedHash.Write(certStatus.marshal())
c.writeRecord(recordTypeHandshake, certStatus.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certStatus.marshal()); err != nil {
return err
}
}
keyAgreement := hs.suite.ka(c.vers)
......@@ -377,7 +385,9 @@ func (hs *serverHandshakeState) doFullHandshake() error {
}
if skx != nil {
hs.finishedHash.Write(skx.marshal())
c.writeRecord(recordTypeHandshake, skx.marshal())
if _, err := c.writeRecord(recordTypeHandshake, skx.marshal()); err != nil {
return err
}
}
if config.ClientAuth >= RequestClientCert {
......@@ -401,12 +411,16 @@ func (hs *serverHandshakeState) doFullHandshake() error {
certReq.certificateAuthorities = config.ClientCAs.Subjects()
}
hs.finishedHash.Write(certReq.marshal())
c.writeRecord(recordTypeHandshake, certReq.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certReq.marshal()); err != nil {
return err
}
}
helloDone := new(serverHelloDoneMsg)
hs.finishedHash.Write(helloDone.marshal())
c.writeRecord(recordTypeHandshake, helloDone.marshal())
if _, err := c.writeRecord(recordTypeHandshake, helloDone.marshal()); err != nil {
return err
}
var pub crypto.PublicKey // public key for client auth, if any
......@@ -632,7 +646,9 @@ func (hs *serverHandshakeState) sendSessionTicket() error {
}
hs.finishedHash.Write(m.marshal())
c.writeRecord(recordTypeHandshake, m.marshal())
if _, err := c.writeRecord(recordTypeHandshake, m.marshal()); err != nil {
return err
}
return nil
}
......@@ -640,12 +656,16 @@ func (hs *serverHandshakeState) sendSessionTicket() error {
func (hs *serverHandshakeState) sendFinished(out []byte) error {
c := hs.c
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
return err
}
finished := new(finishedMsg)
finished.verifyData = hs.finishedHash.serverSum(hs.masterSecret)
hs.finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil {
return err
}
c.cipherSuite = hs.suite.id
copy(out, finished.verifyData)
......
......@@ -80,7 +80,10 @@ func testClientHelloFailure(t *testing.T, serverConfig *Config, m handshakeMessa
cli.writeRecord(recordTypeHandshake, m.marshal())
c.Close()
}()
err := Server(s, serverConfig).Handshake()
hs := serverHandshakeState{
c: Server(s, serverConfig),
}
_, err := hs.readClientHello()
s.Close()
if len(expectedSubStr) == 0 {
if err != nil && err != io.EOF {
......
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