Add advanced TLS settings to harden setup. (#7347)

* Hardcoded the most secured TLS options.

pkg/api/http_server.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"context"
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"net/http"
@@ -75,7 +76,32 @@ func (hs *HttpServer) listenAndServeTLS(listenAddr, certfile, keyfile string) er
 		return fmt.Errorf(`Cannot find SSL key_file at %v`, setting.KeyFile)
 	}
 
-	return http.ListenAndServeTLS(listenAddr, setting.CertFile, setting.KeyFile, hs.macaron)
+	tlsCfg := &tls.Config{
+		MinVersion:               tls.VersionTLS12,
+		PreferServerCipherSuites: true,
+		CipherSuites: []uint16{
+			tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+			tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+			tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+			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,
+		},
+	}
+	srv := &http.Server{
+		Addr:         listenAddr,
+		Handler:      hs.macaron,
+		TLSConfig:    tlsCfg,
+		TLSNextProto: make(map[string]func(*http.Server, *tls.Conn, http.Handler), 0),
+	}
+
+	return srv.ListenAndServeTLS(setting.CertFile, setting.KeyFile)
 }
 
 func (hs *HttpServer) newMacaron() *macaron.Macaron {