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crypto/tls: disable RC4 by default.

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RC4 is frowned upon[1] at this point and major providers are disabling it
by default[2].

Those who still need RC4 support in crypto/tls can enable it by
specifying the CipherSuites slice in crypto/tls.Config explicitly.

Fixes #10094.

[1] https://tools.ietf.org/html/rfc7465
[2] https://blog.cloudflare.com/killing-rc4-the-long-goodbye/

Change-Id: Ia03a456f7e7a4362b706392b0e3c4cc93ce06f9f
Reviewed-on: https://go-review.googlesource.com/7647
Reviewed-by: Andrew Gerrand <adg@golang.org>
This commit is contained in:
Adam Langley 2015-03-16 17:13:10 -07:00
parent 113bae6283
commit c1da171db7
3 changed files with 41 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
cipher_suites.go
View File

@ -49,6 +49,9 @@ const (
// suiteTLS12 indicates that the cipher suite should only be advertised
// and accepted when using TLS 1.2.
suiteTLS12
// suiteDefaultOff indicates that this cipher suite is not included by
// default.
suiteDefaultOff
)
// A cipherSuite is a specific combination of key agreement, cipher and MAC
@ -75,13 +78,13 @@ var cipherSuites = []*cipherSuite{
{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM, crypto.SHA256},
{TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM, crypto.SHA384},
{TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM, crypto.SHA384},
{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteDefaultOff, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, 0, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil, crypto.SHA256},
{TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil, crypto.SHA256},
{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil, crypto.SHA256},

9
common.go
View File

@ -611,9 +611,12 @@ func defaultCipherSuites() []uint16 {
}
func initDefaultCipherSuites() {
varDefaultCipherSuites = make([]uint16, len(cipherSuites))
for i, suite := range cipherSuites {
varDefaultCipherSuites[i] = suite.id
varDefaultCipherSuites = make([]uint16, 0, len(cipherSuites))
for _, suite := range cipherSuites {
if suite.flags&suiteDefaultOff != 0 {
continue
}
varDefaultCipherSuites = append(varDefaultCipherSuites, suite.id)
}
}

35
handshake_server_test.go
View File

@ -37,6 +37,15 @@ func (zeroSource) Read(b []byte) (n int, err error) {
var testConfig *Config
func allCipherSuites() []uint16 {
ids := make([]uint16, len(cipherSuites))
for i, suite := range cipherSuites {
ids[i] = suite.id
}
return ids
}
func init() {
testConfig = &Config{
Time: func() time.Time { return time.Unix(0, 0) },
@ -45,6 +54,7 @@ func init() {
InsecureSkipVerify: true,
MinVersion: VersionSSL30,
MaxVersion: VersionTLS12,
CipherSuites: allCipherSuites(),
}
testConfig.Certificates[0].Certificate = [][]byte{testRSACertificate}
testConfig.Certificates[0].PrivateKey = testRSAPrivateKey
@ -53,7 +63,7 @@ func init() {
testConfig.BuildNameToCertificate()
}
func testClientHelloFailure(t *testing.T, m handshakeMessage, expectedSubStr string) {
func testClientHelloFailure(t *testing.T, serverConfig *Config, m handshakeMessage, expectedSubStr string) {
// Create in-memory network connection,
// send message to server. Should return
// expected error.
@ -66,7 +76,7 @@ func testClientHelloFailure(t *testing.T, m handshakeMessage, expectedSubStr str
cli.writeRecord(recordTypeHandshake, m.marshal())
c.Close()
}()
err := Server(s, testConfig).Handshake()
err := Server(s, serverConfig).Handshake()
s.Close()
if err == nil || !strings.Contains(err.Error(), expectedSubStr) {
t.Errorf("Got error: %s; expected to match substring '%s'", err, expectedSubStr)
@ -74,14 +84,14 @@ func testClientHelloFailure(t *testing.T, m handshakeMessage, expectedSubStr str
}
func TestSimpleError(t *testing.T) {
testClientHelloFailure(t, &serverHelloDoneMsg{}, "unexpected handshake message")
testClientHelloFailure(t, testConfig, &serverHelloDoneMsg{}, "unexpected handshake message")
}
var badProtocolVersions = []uint16{0x0000, 0x0005, 0x0100, 0x0105, 0x0200, 0x0205}
func TestRejectBadProtocolVersion(t *testing.T) {
for _, v := range badProtocolVersions {
testClientHelloFailure(t, &clientHelloMsg{vers: v}, "unsupported, maximum protocol version")
testClientHelloFailure(t, testConfig, &clientHelloMsg{vers: v}, "unsupported, maximum protocol version")
}
}
@ -91,7 +101,7 @@ func TestNoSuiteOverlap(t *testing.T) {
cipherSuites: []uint16{0xff00},
compressionMethods: []uint8{0},
}
testClientHelloFailure(t, clientHello, "no cipher suite supported by both client and server")
testClientHelloFailure(t, testConfig, clientHello, "no cipher suite supported by both client and server")
}
func TestNoCompressionOverlap(t *testing.T) {
@ -100,7 +110,20 @@ func TestNoCompressionOverlap(t *testing.T) {
cipherSuites: []uint16{TLS_RSA_WITH_RC4_128_SHA},
compressionMethods: []uint8{0xff},
}
testClientHelloFailure(t, clientHello, "client does not support uncompressed connections")
testClientHelloFailure(t, testConfig, clientHello, "client does not support uncompressed connections")
}
func TestNoRC4ByDefault(t *testing.T) {
clientHello := &clientHelloMsg{
vers: 0x0301,
cipherSuites: []uint16{TLS_RSA_WITH_RC4_128_SHA},
compressionMethods: []uint8{0},
}
serverConfig := *testConfig
// Reset the enabled cipher suites to nil in order to test the
// defaults.
serverConfig.CipherSuites = nil
testClientHelloFailure(t, &serverConfig, clientHello, "no cipher suite supported by both client and server")
}
func TestRenegotiationExtension(t *testing.T) {