th5/conn_test.go
Filippo Valsorda 318ec0c21a crypto/tls: implement countermeasures against CBC padding oracles
The aim is to make the decrypt() timing profile constant, irrespective of
the CBC padding length or correctness.  The old algorithm, on valid padding,
would only MAC bytes up to the padding length threshold, making CBC
ciphersuites vulnerable to plaintext recovery attacks as presented in the
"Lucky Thirteen" paper.

The new algorithm Write()s to the MAC all supposed payload, performs a
constant time Sum()---which required implementing a constant time Sum() in
crypto/sha1, see the "Lucky Microseconds" paper---and then Write()s the rest
of the data. This is performed whether the padding is good or not.

This should have no explicit secret-dependent timings, but it does NOT
attempt to normalize memory accesses to prevent cache timing leaks.

Updates #13385

Change-Id: I15d91dc3cc6eefc1d44f317f72ff8feb0a9888f7
Reviewed-on: https://go-review.googlesource.com/18130
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2016-10-04 13:21:02 +00:00

244 lines
9.3 KiB
Go

// Copyright 2010 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 tls
import (
"bytes"
"io"
"net"
"testing"
)
func TestRoundUp(t *testing.T) {
if roundUp(0, 16) != 0 ||
roundUp(1, 16) != 16 ||
roundUp(15, 16) != 16 ||
roundUp(16, 16) != 16 ||
roundUp(17, 16) != 32 {
t.Error("roundUp broken")
}
}
var paddingTests = []struct {
in []byte
good bool
expectedLen int
}{
{[]byte{1, 2, 3, 4, 0}, true, 4},
{[]byte{1, 2, 3, 4, 0, 1}, false, 0},
{[]byte{1, 2, 3, 4, 99, 99}, false, 0},
{[]byte{1, 2, 3, 4, 1, 1}, true, 4},
{[]byte{1, 2, 3, 2, 2, 2}, true, 3},
{[]byte{1, 2, 3, 3, 3, 3}, true, 2},
{[]byte{1, 2, 3, 4, 3, 3}, false, 0},
{[]byte{1, 4, 4, 4, 4, 4}, true, 1},
{[]byte{5, 5, 5, 5, 5, 5}, true, 0},
{[]byte{6, 6, 6, 6, 6, 6}, false, 0},
}
func TestRemovePadding(t *testing.T) {
for i, test := range paddingTests {
paddingLen, good := extractPadding(test.in)
expectedGood := byte(255)
if !test.good {
expectedGood = 0
}
if good != expectedGood {
t.Errorf("#%d: wrong validity, want:%d got:%d", i, expectedGood, good)
}
if good == 255 && len(test.in)-paddingLen != test.expectedLen {
t.Errorf("#%d: got %d, want %d", i, len(test.in)-paddingLen, test.expectedLen)
}
}
}
var certExampleCom = `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`
var certWildcardExampleCom = `308201743082011ea003020102021100a7aa6297c9416a4633af8bec2958c607300d06092a864886f70d01010b050030123110300e060355040a130741636d6520436f301e170d3136303831373231343231395a170d3137303831373231343231395a30123110300e060355040a130741636d6520436f305c300d06092a864886f70d0101010500034b003048024100b105afc859a711ee864114e7d2d46c2dcbe392d3506249f6c2285b0eb342cc4bf2d803677c61c0abde443f084745c1a6d62080e5664ef2cc8f50ad8a0ab8870b0203010001a34f304d300e0603551d0f0101ff0404030205a030130603551d25040c300a06082b06010505070301300c0603551d130101ff0402300030180603551d110411300f820d2a2e6578616d706c652e636f6d300d06092a864886f70d01010b0500034100af26088584d266e3f6566360cf862c7fecc441484b098b107439543144a2b93f20781988281e108c6d7656934e56950e1e5f2bcf38796b814ccb729445856c34`
var certFooExampleCom = `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`
var certDoubleWildcardExampleCom = `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`
func TestCertificateSelection(t *testing.T) {
config := Config{
Certificates: []Certificate{
{
Certificate: [][]byte{fromHex(certExampleCom)},
},
{
Certificate: [][]byte{fromHex(certWildcardExampleCom)},
},
{
Certificate: [][]byte{fromHex(certFooExampleCom)},
},
{
Certificate: [][]byte{fromHex(certDoubleWildcardExampleCom)},
},
},
}
config.BuildNameToCertificate()
pointerToIndex := func(c *Certificate) int {
for i := range config.Certificates {
if c == &config.Certificates[i] {
return i
}
}
return -1
}
certificateForName := func(name string) *Certificate {
clientHello := &ClientHelloInfo{
ServerName: name,
}
if cert, err := config.getCertificate(clientHello); err != nil {
t.Errorf("unable to get certificate for name '%s': %s", name, err)
return nil
} else {
return cert
}
}
if n := pointerToIndex(certificateForName("example.com")); n != 0 {
t.Errorf("example.com returned certificate %d, not 0", n)
}
if n := pointerToIndex(certificateForName("bar.example.com")); n != 1 {
t.Errorf("bar.example.com returned certificate %d, not 1", n)
}
if n := pointerToIndex(certificateForName("foo.example.com")); n != 2 {
t.Errorf("foo.example.com returned certificate %d, not 2", n)
}
if n := pointerToIndex(certificateForName("foo.bar.example.com")); n != 3 {
t.Errorf("foo.bar.example.com returned certificate %d, not 3", n)
}
if n := pointerToIndex(certificateForName("foo.bar.baz.example.com")); n != 0 {
t.Errorf("foo.bar.baz.example.com returned certificate %d, not 0", n)
}
}
// Run with multiple crypto configs to test the logic for computing TLS record overheads.
func runDynamicRecordSizingTest(t *testing.T, config *Config) {
clientConn, serverConn := net.Pipe()
serverConfig := config.Clone()
serverConfig.DynamicRecordSizingDisabled = false
tlsConn := Server(serverConn, serverConfig)
recordSizesChan := make(chan []int, 1)
go func() {
// This goroutine performs a TLS handshake over clientConn and
// then reads TLS records until EOF. It writes a slice that
// contains all the record sizes to recordSizesChan.
defer close(recordSizesChan)
defer clientConn.Close()
tlsConn := Client(clientConn, config)
if err := tlsConn.Handshake(); err != nil {
t.Errorf("Error from client handshake: %s", err)
return
}
var recordHeader [recordHeaderLen]byte
var record []byte
var recordSizes []int
for {
n, err := clientConn.Read(recordHeader[:])
if err == io.EOF {
break
}
if err != nil || n != len(recordHeader) {
t.Errorf("Error from client read: %s", err)
return
}
length := int(recordHeader[3])<<8 | int(recordHeader[4])
if len(record) < length {
record = make([]byte, length)
}
n, err = clientConn.Read(record[:length])
if err != nil || n != length {
t.Errorf("Error from client read: %s", err)
return
}
// The last record will be a close_notify alert, which
// we don't wish to record.
if recordType(recordHeader[0]) == recordTypeApplicationData {
recordSizes = append(recordSizes, recordHeaderLen+length)
}
}
recordSizesChan <- recordSizes
}()
if err := tlsConn.Handshake(); err != nil {
t.Fatalf("Error from server handshake: %s", err)
}
// The server writes these plaintexts in order.
plaintext := bytes.Join([][]byte{
bytes.Repeat([]byte("x"), recordSizeBoostThreshold),
bytes.Repeat([]byte("y"), maxPlaintext*2),
bytes.Repeat([]byte("z"), maxPlaintext),
}, nil)
if _, err := tlsConn.Write(plaintext); err != nil {
t.Fatalf("Error from server write: %s", err)
}
if err := tlsConn.Close(); err != nil {
t.Fatalf("Error from server close: %s", err)
}
recordSizes := <-recordSizesChan
if recordSizes == nil {
t.Fatalf("Client encountered an error")
}
// Drop the size of last record, which is likely to be truncated.
recordSizes = recordSizes[:len(recordSizes)-1]
// recordSizes should contain a series of records smaller than
// tcpMSSEstimate followed by some larger than maxPlaintext.
seenLargeRecord := false
for i, size := range recordSizes {
if !seenLargeRecord {
if size > (i+1)*tcpMSSEstimate {
t.Fatalf("Record #%d has size %d, which is too large too soon", i, size)
}
if size >= maxPlaintext {
seenLargeRecord = true
}
} else if size <= maxPlaintext {
t.Fatalf("Record #%d has size %d but should be full sized", i, size)
}
}
if !seenLargeRecord {
t.Fatalf("No large records observed")
}
}
func TestDynamicRecordSizingWithStreamCipher(t *testing.T) {
config := testConfig.Clone()
config.CipherSuites = []uint16{TLS_RSA_WITH_RC4_128_SHA}
runDynamicRecordSizingTest(t, config)
}
func TestDynamicRecordSizingWithCBC(t *testing.T) {
config := testConfig.Clone()
config.CipherSuites = []uint16{TLS_RSA_WITH_AES_256_CBC_SHA}
runDynamicRecordSizingTest(t, config)
}
func TestDynamicRecordSizingWithAEAD(t *testing.T) {
config := testConfig.Clone()
config.CipherSuites = []uint16{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256}
runDynamicRecordSizingTest(t, config)
}