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restrict TLS cipher suites of the server (#5245)

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This change restircts the supported cipher suites of the minio server.
The server only supports AEAD ciphers (Chacha20Poly1305 and 
AES-GCM)

The supported cipher suites are:
 - tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305
 - tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305
 - tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
 - tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
 - tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
 - tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384

Fixes #5244 and #5291
This commit is contained in:
Andreas Auernhammer 2018-01-13 04:42:11 +01:00 committed by Nitish Tiwari
parent ede504400f
commit dd202a1a5f
2 changed files with 113 additions and 4 deletions
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35
pkg/http/server.go
View file

@ -25,6 +25,7 @@ import (
"time"
humanize "github.com/dustin/go-humanize"
"github.com/minio/minio-go/pkg/set"
)
const (
@ -64,16 +65,19 @@ type Server struct {
// Start - start HTTP server
func (srv *Server) Start() (err error) {
// Take a copy of server fields.
tlsConfig := srv.TLSConfig
var tlsConfig *tls.Config
if srv.TLSConfig != nil {
tlsConfig = srv.TLSConfig.Clone()
}
readTimeout := srv.ReadTimeout
writeTimeout := srv.WriteTimeout
handler := srv.Handler
handler := srv.Handler // if srv.Handler holds non-synced state -> possible data race
addrs := srv.Addrs
addrs := set.CreateStringSet(srv.Addrs...).ToSlice() // copy and remove duplicates
tcpKeepAliveTimeout := srv.TCPKeepAliveTimeout
updateBytesReadFunc := srv.UpdateBytesReadFunc
updateBytesWrittenFunc := srv.UpdateBytesWrittenFunc
errorLogFunc := srv.ErrorLogFunc
errorLogFunc := srv.ErrorLogFunc // if srv.ErrorLogFunc holds non-synced state -> possible data race
// Create new HTTP listener.
var listener *httpListener
@ -118,9 +122,12 @@ func (srv *Server) Start() (err error) {
// Shutdown - shuts down HTTP server.
func (srv *Server) Shutdown() error {
srv.listenerMutex.Lock()
if srv.listener == nil {
srv.listenerMutex.Unlock()
return errors.New("server not initialized")
}
srv.listenerMutex.Unlock()
if atomic.AddUint32(&srv.inShutdown, 1) > 1 {
// shutdown in progress
@ -149,12 +156,32 @@ func (srv *Server) Shutdown() error {
}
}
// Secure Go implementations of modern TLS ciphers
// The following ciphers are excluded because:
// - RC4 ciphers: RC4 is broken
// - 3DES ciphers: Because of the 64 bit blocksize of DES (Sweet32)
// - CBC-SHA256 ciphers: No countermeasures against Lucky13 timing attack
// - CBC-SHA ciphers: Legacy ciphers (SHA-1) and non-constant time
// implementation of CBC.
// (CBC-SHA ciphers can be enabled again if required)
// - RSA key exchange ciphers: Disabled because of dangerous PKCS1-v1.5 RSA
// padding scheme. See Bleichenbacher attacks.
var defaultCipherSuites = []uint16{
tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
}
// NewServer - creates new HTTP server using given arguments.
func NewServer(addrs []string, handler http.Handler, certificate *tls.Certificate) *Server {
var tlsConfig *tls.Config
if certificate != nil {
tlsConfig = &tls.Config{
PreferServerCipherSuites: true,
CipherSuites: defaultCipherSuites,
MinVersion: tls.VersionTLS12,
NextProtos: []string{"http/1.1", "h2"},
}

82
pkg/http/server_test.go
View file

@ -22,6 +22,7 @@ import (
"net/http"
"reflect"
"testing"
"time"
)
func TestNewServer(t *testing.T) {
@ -97,3 +98,84 @@ func TestNewServer(t *testing.T) {
}
}
}
func TestServerTLSCiphers(t *testing.T) {
var unsupportedCipherSuites = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, // No countermeasures against timing attacks
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, // Broken cipher
tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, // Sweet32
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, // No countermeasures against timing attacks
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA, // Broken cipher
// all RSA-PKCS1-v1.5 ciphers are disabled - danger of Bleichenbacher attack variants
tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA, // Sweet32
tls.TLS_RSA_WITH_AES_128_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_RSA_WITH_AES_128_CBC_SHA256, // No countermeasures against timing attacks
tls.TLS_RSA_WITH_AES_256_CBC_SHA, // Go stack contains (some) countermeasures against timing attacks (Lucky13)
tls.TLS_RSA_WITH_RC4_128_SHA, // Broken cipher
tls.TLS_RSA_WITH_AES_128_GCM_SHA256, // Disabled because of RSA-PKCS1-v1.5 - AES-GCM is considered secure.
tls.TLS_RSA_WITH_AES_256_GCM_SHA384, // Disabled because of RSA-PKCS1-v1.5 - AES-GCM is considered secure.
}
certificate, err := getTLSCert()
if err != nil {
t.Fatalf("Unable to parse private/certificate data. %v\n", err)
}
testCases := []struct {
ciphers []uint16
resetServerCiphers bool
expectErr bool
}{
{nil, false, false},
{defaultCipherSuites, false, false},
{unsupportedCipherSuites, false, true},
{nil, true, false},
}
for i, testCase := range testCases {
func() {
addr := "127.0.0.1:" + getNextPort()
server := NewServer([]string{addr},
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello, world")
}),
&certificate)
if testCase.resetServerCiphers {
// Use Go default ciphers.
server.TLSConfig.CipherSuites = nil
}
go func() {
server.Start()
}()
defer server.Shutdown()
client := http.Client{
Transport: &http.Transport{
TLSClientConfig: &tls.Config{
InsecureSkipVerify: true,
CipherSuites: testCase.ciphers,
},
},
}
// There is no guaranteed way to know whether the HTTP server is started successfully.
// The only option is to connect and check. Hence below sleep is used as workaround.
time.Sleep(1 * time.Second)
_, err := client.Get("https://" + addr)
expectErr := (err != nil)
if expectErr != testCase.expectErr {
t.Fatalf("test %v: error: expected: %v, got: %v", i+1, testCase.expectErr, expectErr)
}
}()
}
}