Disable 3DES and other insecure cipher suites

Supported cipher suites:
   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

Closes https://gitlab.com/gitlab-org/gitlab-pages/issues/150.

6 files changed, 99 insertions, 2 deletions

diff --git a/acceptance_test.go b/acceptance_test.go
index 55a83881..f68b31ef 100644
--- a/acceptance_test.go
+++ b/acceptance_test.go
@@ -1057,3 +1057,71 @@ func TestAccessControl(t *testing.T) {
 		})
 	}
 }
+
+func TestAcceptsSupportedCiphers(t *testing.T) {
+	skipUnlessEnabled(t)
+	teardown := RunPagesProcess(t, *pagesBinary, listeners, "")
+	defer teardown()
+
+	ciphers := []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,
+	}
+	client, cleanup := ClientWithCiphers(ciphers)
+	defer cleanup()
+
+	rsp, err := client.Get(httpsListener.URL("/"))
+
+	if rsp != nil {
+		rsp.Body.Close()
+	}
+
+	require.NoError(t, err)
+}
+
+func TestRejectsUnsupportedCiphers(t *testing.T) {
+	skipUnlessEnabled(t)
+	teardown := RunPagesProcess(t, *pagesBinary, listeners, "")
+	defer teardown()
+
+	ciphers := []uint16{
+		tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+		tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+	}
+	client, cleanup := ClientWithCiphers(ciphers)
+	defer cleanup()
+
+	rsp, err := client.Get(httpsListener.URL("/"))
+
+	if rsp != nil {
+		rsp.Body.Close()
+	}
+
+	require.Error(t, err)
+	require.Nil(t, rsp)
+}
+
+func TestEnableInsecureCiphers(t *testing.T) {
+	skipUnlessEnabled(t)
+	teardown := RunPagesProcess(t, *pagesBinary, listeners, "", "-insecure-ciphers")
+	defer teardown()
+
+	ciphers := []uint16{
+		tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+		tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+	}
+	client, cleanup := ClientWithCiphers(ciphers)
+	defer cleanup()
+
+	rsp, err := client.Get(httpsListener.URL("/"))
+
+	if rsp != nil {
+		rsp.Body.Close()
+	}
+
+	require.NoError(t, err)
+}
diff --git a/app.go b/app.go
index c25bcf37..7d7ca9a2 100644
--- a/app.go
+++ b/app.go
@@ -258,7 +258,7 @@ func (a *theApp) Run() {
 		wg.Add(1)
 		go func(fd uintptr) {
 			defer wg.Done()
-			err := listenAndServeTLS(fd, a.RootCertificate, a.RootKey, a.ServeHTTP, a.ServeTLS, a.HTTP2, limiter)
+			err := listenAndServeTLS(fd, a.RootCertificate, a.RootKey, a.ServeHTTP, a.ServeTLS, a.HTTP2, a.InsecureCiphers, limiter)
 			if err != nil {
 				fatal(err)
 			}
diff --git a/app_config.go b/app_config.go
index 9ff26b6b..b2b885f9 100644
--- a/app_config.go
+++ b/app_config.go
@@ -17,6 +17,7 @@ type appConfig struct {
 	ListenMetrics    uintptr
 	ListenAdminUnix  uintptr
 	ListenAdminHTTPS uintptr
+	InsecureCiphers  bool
 
 	HTTP2        bool
 	RedirectHTTP bool
diff --git a/helpers_test.go b/helpers_test.go
index bf61b7a4..2e565300 100644
--- a/helpers_test.go
+++ b/helpers_test.go
@@ -329,6 +329,18 @@ func GetRedirectPageWithCookie(t *testing.T, spec ListenSpec, host, urlsuffix st
 	return TestHTTPSClient.Transport.RoundTrip(req)
 }
 
+func ClientWithCiphers(ciphers []uint16) (*http.Client, func()) {
+	tr := &http.Transport{
+		TLSClientConfig: &tls.Config{
+			RootCAs:      TestCertPool,
+			CipherSuites: ciphers,
+		},
+	}
+	client := &http.Client{Transport: tr}
+
+	return client, tr.CloseIdleConnections
+}
+
 func waitForRoundtrips(t *testing.T, listeners []ListenSpec, timeout time.Duration) {
 	nListening := 0
 	start := time.Now()
diff --git a/main.go b/main.go
index 126ad69e..170e0e7e 100644
--- a/main.go
+++ b/main.go
@@ -51,6 +51,7 @@ var (
 	clientSecret           = flag.String("auth-client-secret", "", "GitLab application Client Secret")
 	redirectURI            = flag.String("auth-redirect-uri", "", "GitLab application redirect URI")
 	maxConns               = flag.Uint("max-conns", 5000, "Limit on the number of concurrent connections to the HTTP, HTTPS or proxy listeners")
+	insecureCiphers        = flag.Bool("insecure-ciphers", false, "Use default list of cipher suites, may contain insecure ones like 3DES and RC4")
 
 	disableCrossOriginRequests = flag.Bool("disable-cross-origin-requests", false, "Disable cross-origin requests")
 
@@ -82,6 +83,7 @@ func configFromFlags() appConfig {
 	config.LogFormat = *logFormat
 	config.LogVerbose = *logVerbose
 	config.MaxConns = int(*maxConns)
+	config.InsecureCiphers = *insecureCiphers
 
 	for _, file := range []struct {
 		contents *[]byte
@@ -194,6 +196,7 @@ func appMain() {
 		"default-config-filename":       flag.DefaultConfigFlagname,
 		"disable-cross-origin-requests": *disableCrossOriginRequests,
 		"domain":                        config.Domain,
+		"insecure-ciphers":              config.InsecureCiphers,
 		"listen-http":                   strings.Join(listenHTTP, ","),
 		"listen-https":                  strings.Join(listenHTTPS, ","),
 		"listen-proxy":                  strings.Join(listenProxy, ","),
diff --git a/server.go b/server.go
index 3a80e797..79268238 100644
--- a/server.go
+++ b/server.go
@@ -25,6 +25,15 @@ type keepAliveSetter interface {
 	SetKeepAlivePeriod(time.Duration) error
 }
 
+var preferredCipherSuites = []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,
+}
+
 func (ln *keepAliveListener) Accept() (net.Conn, error) {
 	conn, err := ln.Listener.Accept()
 	if err != nil {
@@ -65,7 +74,7 @@ func listenAndServe(fd uintptr, handler http.HandlerFunc, useHTTP2 bool, tlsConf
 	return server.Serve(&keepAliveListener{l})
 }
 
-func listenAndServeTLS(fd uintptr, cert, key []byte, handler http.HandlerFunc, tlsHandler tlsHandlerFunc, useHTTP2 bool, limiter *netutil.Limiter) error {
+func listenAndServeTLS(fd uintptr, cert, key []byte, handler http.HandlerFunc, tlsHandler tlsHandlerFunc, useHTTP2 bool, insecureCiphers bool, limiter *netutil.Limiter) error {
 	certificate, err := tls.X509KeyPair(cert, key)
 	if err != nil {
 		return err
@@ -76,5 +85,9 @@ func listenAndServeTLS(fd uintptr, cert, key []byte, handler http.HandlerFunc, t
 	tlsConfig.Certificates = []tls.Certificate{
 		certificate,
 	}
+	if !insecureCiphers {
+		tlsConfig.PreferServerCipherSuites = true
+		tlsConfig.CipherSuites = preferredCipherSuites
+	}
 	return listenAndServe(fd, handler, useHTTP2, tlsConfig, limiter)
 }