Make SSL cipher suite configurable (#17440)

9 files changed, 266 insertions, 54 deletions

diff --git a/cmd/web_graceful.go b/cmd/web_graceful.go
index 91ac024ddb..1618208c55 100644
--- a/cmd/web_graceful.go
+++ b/cmd/web_graceful.go
@@ -5,7 +5,6 @@
 package cmd
 
 import (
-	"crypto/tls"
 	"net"
 	"net/http"
 	"net/http/fcgi"
@@ -20,14 +19,6 @@ func runHTTP(network, listenAddr, name string, m http.Handler) error {
 	return graceful.HTTPListenAndServe(network, listenAddr, name, m)
 }
 
-func runHTTPS(network, listenAddr, name, certFile, keyFile string, m http.Handler) error {
-	return graceful.HTTPListenAndServeTLS(network, listenAddr, name, certFile, keyFile, m)
-}
-
-func runHTTPSWithTLSConfig(network, listenAddr, name string, tlsConfig *tls.Config, m http.Handler) error {
-	return graceful.HTTPListenAndServeTLSConfig(network, listenAddr, name, tlsConfig, m)
-}
-
 // NoHTTPRedirector tells our cleanup routine that we will not be using a fallback http redirector
 func NoHTTPRedirector() {
 	graceful.GetManager().InformCleanup()
diff --git a/cmd/web_https.go b/cmd/web_https.go
new file mode 100644
index 0000000000..b939dcab8a
--- /dev/null
+++ b/cmd/web_https.go
@@ -0,0 +1,191 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package cmd
+
+import (
+	"crypto/tls"
+	"net/http"
+	"os"
+	"strings"
+
+	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"github.com/klauspost/cpuid/v2"
+)
+
+var tlsVersionStringMap = map[string]uint16{
+	"":        tls.VersionTLS12, // Default to tls.VersionTLS12
+	"tlsv1.0": tls.VersionTLS10,
+	"tlsv1.1": tls.VersionTLS11,
+	"tlsv1.2": tls.VersionTLS12,
+	"tlsv1.3": tls.VersionTLS13,
+}
+
+func toTLSVersion(version string) uint16 {
+	tlsVersion, ok := tlsVersionStringMap[strings.TrimSpace(strings.ToLower(version))]
+	if !ok {
+		log.Warn("Unknown tls version: %s", version)
+		return 0
+	}
+	return tlsVersion
+}
+
+var curveStringMap = map[string]tls.CurveID{
+	"x25519": tls.X25519,
+	"p256":   tls.CurveP256,
+	"p384":   tls.CurveP384,
+	"p521":   tls.CurveP521,
+}
+
+func toCurvePreferences(preferences []string) []tls.CurveID {
+	ids := make([]tls.CurveID, 0, len(preferences))
+	for _, pref := range preferences {
+		id, ok := curveStringMap[strings.TrimSpace(strings.ToLower(pref))]
+		if !ok {
+			log.Warn("Unknown curve: %s", pref)
+		}
+		if id != 0 {
+			ids = append(ids, id)
+		}
+	}
+	return ids
+}
+
+var cipherStringMap = map[string]uint16{
+	"rsa_with_rc4_128_sha":                      tls.TLS_RSA_WITH_RC4_128_SHA,
+	"rsa_with_3des_ede_cbc_sha":                 tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+	"rsa_with_aes_128_cbc_sha":                  tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+	"rsa_with_aes_256_cbc_sha":                  tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+	"rsa_with_aes_128_cbc_sha256":               tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
+	"rsa_with_aes_128_gcm_sha256":               tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
+	"rsa_with_aes_256_gcm_sha384":               tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
+	"ecdhe_ecdsa_with_rc4_128_sha":              tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+	"ecdhe_ecdsa_with_aes_128_cbc_sha":          tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+	"ecdhe_ecdsa_with_aes_256_cbc_sha":          tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+	"ecdhe_rsa_with_rc4_128_sha":                tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+	"ecdhe_rsa_with_3des_ede_cbc_sha":           tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+	"ecdhe_rsa_with_aes_128_cbc_sha":            tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+	"ecdhe_rsa_with_aes_256_cbc_sha":            tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+	"ecdhe_ecdsa_with_aes_128_cbc_sha256":       tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
+	"ecdhe_rsa_with_aes_128_cbc_sha256":         tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
+	"ecdhe_rsa_with_aes_128_gcm_sha256":         tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+	"ecdhe_ecdsa_with_aes_128_gcm_sha256":       tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+	"ecdhe_rsa_with_aes_256_gcm_sha384":         tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+	"ecdhe_ecdsa_with_aes_256_gcm_sha384":       tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+	"ecdhe_rsa_with_chacha20_poly1305_sha256":   tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
+	"ecdhe_ecdsa_with_chacha20_poly1305_sha256": tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
+	"ecdhe_rsa_with_chacha20_poly1305":          tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
+	"ecdhe_ecdsa_with_chacha20_poly1305":        tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
+	"aes_128_gcm_sha256":                        tls.TLS_AES_128_GCM_SHA256,
+	"aes_256_gcm_sha384":                        tls.TLS_AES_256_GCM_SHA384,
+	"chacha20_poly1305_sha256":                  tls.TLS_CHACHA20_POLY1305_SHA256,
+}
+
+func toTLSCiphers(cipherStrings []string) []uint16 {
+	ciphers := make([]uint16, 0, len(cipherStrings))
+	for _, cipherString := range cipherStrings {
+		cipher, ok := cipherStringMap[strings.TrimSpace(strings.ToLower(cipherString))]
+		if !ok {
+			log.Warn("Unknown cipher: %s", cipherString)
+		}
+		if cipher != 0 {
+			ciphers = append(ciphers, cipher)
+		}
+	}
+
+	return ciphers
+}
+
+// defaultCiphers uses hardware support to check if AES is specifically
+// supported by the CPU.
+//
+// If AES is supported AES ciphers will be preferred over ChaCha based ciphers
+// (This code is directly inspired by the certmagic code.)
+func defaultCiphers() []uint16 {
+	if cpuid.CPU.Supports(cpuid.AESNI) {
+		return defaultCiphersAESfirst
+	}
+	return defaultCiphersChaChaFirst
+}
+
+var (
+	defaultCiphersAES = []uint16{
+		tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+		tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+		tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+		tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+	}
+
+	defaultCiphersChaCha = []uint16{
+		tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
+		tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
+	}
+
+	defaultCiphersAESfirst    = append(defaultCiphersAES, defaultCiphersChaCha...)
+	defaultCiphersChaChaFirst = append(defaultCiphersChaCha, defaultCiphersAES...)
+)
+
+// runHTTPs listens on the provided network address and then calls
+// Serve to handle requests on incoming TLS connections.
+//
+// Filenames containing a certificate and matching private key for the server must
+// be provided. If the certificate is signed by a certificate authority, the
+// certFile should be the concatenation of the server's certificate followed by the
+// CA's certificate.
+func runHTTPS(network, listenAddr, name, certFile, keyFile string, m http.Handler) error {
+	tlsConfig := &tls.Config{}
+	if tlsConfig.NextProtos == nil {
+		tlsConfig.NextProtos = []string{"h2", "http/1.1"}
+	}
+
+	if version := toTLSVersion(setting.SSLMinimumVersion); version != 0 {
+		tlsConfig.MinVersion = version
+	}
+	if version := toTLSVersion(setting.SSLMaximumVersion); version != 0 {
+		tlsConfig.MaxVersion = version
+	}
+
+	// Set curve preferences
+	tlsConfig.CurvePreferences = []tls.CurveID{
+		tls.X25519,
+		tls.CurveP256,
+	}
+	if curves := toCurvePreferences(setting.SSLCurvePreferences); len(curves) > 0 {
+		tlsConfig.CurvePreferences = curves
+	}
+
+	// Set cipher suites
+	tlsConfig.CipherSuites = defaultCiphers()
+	if ciphers := toTLSCiphers(setting.SSLCipherSuites); len(ciphers) > 0 {
+		tlsConfig.CipherSuites = ciphers
+	}
+
+	tlsConfig.Certificates = make([]tls.Certificate, 1)
+
+	certPEMBlock, err := os.ReadFile(certFile)
+	if err != nil {
+		log.Error("Failed to load https cert file %s for %s:%s: %v", certFile, network, listenAddr, err)
+		return err
+	}
+
+	keyPEMBlock, err := os.ReadFile(keyFile)
+	if err != nil {
+		log.Error("Failed to load https key file %s for %s:%s: %v", keyFile, network, listenAddr, err)
+		return err
+	}
+
+	tlsConfig.Certificates[0], err = tls.X509KeyPair(certPEMBlock, keyPEMBlock)
+	if err != nil {
+		log.Error("Failed to create certificate from cert file %s and key file %s for %s:%s: %v", certFile, keyFile, network, listenAddr, err)
+		return err
+	}
+
+	return graceful.HTTPListenAndServeTLSConfig(network, listenAddr, name, tlsConfig, m)
+}
+
+func runHTTPSWithTLSConfig(network, listenAddr, name string, tlsConfig *tls.Config, m http.Handler) error {
+	return graceful.HTTPListenAndServeTLSConfig(network, listenAddr, name, tlsConfig, m)
+}
diff --git a/cmd/web_letsencrypt.go b/cmd/web_letsencrypt.go
index 096db36b24..066208457b 100644
--- a/cmd/web_letsencrypt.go
+++ b/cmd/web_letsencrypt.go
@@ -55,6 +55,23 @@ func runLetsEncrypt(listenAddr, domain, directory, email string, m http.Handler)
 	tlsConfig := magic.TLSConfig()
 	tlsConfig.NextProtos = append(tlsConfig.NextProtos, "h2")
 
+	if version := toTLSVersion(setting.SSLMinimumVersion); version != 0 {
+		tlsConfig.MinVersion = version
+	}
+	if version := toTLSVersion(setting.SSLMaximumVersion); version != 0 {
+		tlsConfig.MaxVersion = version
+	}
+
+	// Set curve preferences
+	if curves := toCurvePreferences(setting.SSLCurvePreferences); len(curves) > 0 {
+		tlsConfig.CurvePreferences = curves
+	}
+
+	// Set cipher suites
+	if ciphers := toTLSCiphers(setting.SSLCipherSuites); len(ciphers) > 0 {
+		tlsConfig.CipherSuites = ciphers
+	}
+
 	if enableHTTPChallenge {
 		go func() {
 			log.Info("Running Let's Encrypt handler on %s", setting.HTTPAddr+":"+setting.PortToRedirect)
diff --git a/custom/conf/app.example.ini b/custom/conf/app.example.ini
index 233e8981cb..16977f609b 100644
--- a/custom/conf/app.example.ini
+++ b/custom/conf/app.example.ini
@@ -51,6 +51,16 @@ RUN_MODE = ; prod
 ;REDIRECT_OTHER_PORT = false
 ;PORT_TO_REDIRECT = 80
 ;;
+;; Minimum and maximum supported TLS versions
+;SSL_MIN_VERSION=TLSv1.2
+;SSL_MAX_VERSION=
+;;
+;; SSL Curve Preferences
+;SSL_CURVE_PREFERENCES=X25519,P256
+;;
+;; SSL Cipher Suites
+;SSL_CIPHER_SUITES=; Will default to "ecdhe_ecdsa_with_aes_256_gcm_sha384,ecdhe_rsa_with_aes_256_gcm_sha384,ecdhe_ecdsa_with_aes_128_gcm_sha256,ecdhe_rsa_with_aes_128_gcm_sha256,ecdhe_ecdsa_with_chacha20_poly1305,ecdhe_rsa_with_chacha20_poly1305" if aes is supported by hardware, otherwise chacha will be first.
+;;
 ;; Timeout for any write to the connection. (Set to 0 to disable all timeouts.)
 ;PER_WRITE_TIMEOUT = 30s
 ;;
diff --git a/docs/content/doc/advanced/config-cheat-sheet.en-us.md b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
index ae4f754170..d7a7023ff5 100644
--- a/docs/content/doc/advanced/config-cheat-sheet.en-us.md
+++ b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
@@ -310,6 +310,42 @@ The following configuration set `Content-Type: application/vnd.android.package-a
 
 - `REDIRECT_OTHER_PORT`: **false**: If true and `PROTOCOL` is https, allows redirecting http requests on `PORT_TO_REDIRECT` to the https port Gitea listens on.
 - `PORT_TO_REDIRECT`: **80**: Port for the http redirection service to listen on. Used when `REDIRECT_OTHER_PORT` is true.
+- `SSL_MIN_VERSION`: **TLSv1.2**: Set the minimum version of ssl support.
+- `SSL_MAX_VERSION`: **\<empty\>**: Set the maximum version of ssl support.
+- `SSL_CURVE_PREFERENCES`: **X25519,P256**: Set the prefered curves,
+- `SSL_CIPHER_SUITES`: **ecdhe_ecdsa_with_aes_256_gcm_sha384,ecdhe_rsa_with_aes_256_gcm_sha384,ecdhe_ecdsa_with_aes_128_gcm_sha256,ecdhe_rsa_with_aes_128_gcm_sha256,ecdhe_ecdsa_with_chacha20_poly1305,ecdhe_rsa_with_chacha20_poly1305**: Set the preferred cipher suites.
+  - If there is not hardware support for AES suites by default the cha cha suites will be preferred over the AES suites
+  - supported suites as of go 1.17 are:
+    - TLS 1.0 - 1.2 cipher suites
+      - "rsa_with_rc4_128_sha"
+      - "rsa_with_3des_ede_cbc_sha"
+      - "rsa_with_aes_128_cbc_sha"
+      - "rsa_with_aes_256_cbc_sha"
+      - "rsa_with_aes_128_cbc_sha256"
+      - "rsa_with_aes_128_gcm_sha256"
+      - "rsa_with_aes_256_gcm_sha384"
+      - "ecdhe_ecdsa_with_rc4_128_sha"
+      - "ecdhe_ecdsa_with_aes_128_cbc_sha"
+      - "ecdhe_ecdsa_with_aes_256_cbc_sha"
+      - "ecdhe_rsa_with_rc4_128_sha"
+      - "ecdhe_rsa_with_3des_ede_cbc_sha"
+      - "ecdhe_rsa_with_aes_128_cbc_sha"
+      - "ecdhe_rsa_with_aes_256_cbc_sha"
+      - "ecdhe_ecdsa_with_aes_128_cbc_sha256"
+      - "ecdhe_rsa_with_aes_128_cbc_sha256"
+      - "ecdhe_rsa_with_aes_128_gcm_sha256"
+      - "ecdhe_ecdsa_with_aes_128_gcm_sha256"
+      - "ecdhe_rsa_with_aes_256_gcm_sha384"
+      - "ecdhe_ecdsa_with_aes_256_gcm_sha384"
+      - "ecdhe_rsa_with_chacha20_poly1305_sha256"
+      - "ecdhe_ecdsa_with_chacha20_poly1305_sha256"
+    - TLS 1.3 cipher suites
+      - "aes_128_gcm_sha256"
+      - "aes_256_gcm_sha384"
+      - "chacha20_poly1305_sha256"
+    - Aliased names
+      - "ecdhe_rsa_with_chacha20_poly1305" is an alias for "ecdhe_rsa_with_chacha20_poly1305_sha256"
+      - "ecdhe_ecdsa_with_chacha20_poly1305" is alias for "ecdhe_ecdsa_with_chacha20_poly1305_sha256"
 - `ENABLE_LETSENCRYPT`: **false**: If enabled you must set `DOMAIN` to valid internet facing domain (ensure DNS is set and port 80 is accessible by letsencrypt validation server).
    By using Lets Encrypt **you must consent** to their [terms of service](https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf).
 - `LETSENCRYPT_ACCEPTTOS`: **false**: This is an explicit check that you accept the terms of service for Let's Encrypt.
diff --git a/go.mod b/go.mod
index a1146372ad..4c156b1957 100644
--- a/go.mod
+++ b/go.mod
@@ -69,7 +69,7 @@ require (
 	github.com/kevinburke/ssh_config v1.1.0 // indirect
 	github.com/keybase/go-crypto v0.0.0-20200123153347-de78d2cb44f4
 	github.com/klauspost/compress v1.13.1
-	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
+	github.com/klauspost/cpuid/v2 v2.0.9
 	github.com/klauspost/pgzip v1.2.5 // indirect
 	github.com/lib/pq v1.10.2
 	github.com/lunny/dingtalk_webhook v0.0.0-20171025031554-e3534c89ef96
diff --git a/modules/graceful/server.go b/modules/graceful/server.go
index f7ec791d85..159a9879df 100644
--- a/modules/graceful/server.go
+++ b/modules/graceful/server.go
@@ -95,48 +95,14 @@ func (srv *Server) ListenAndServe(serve ServeFunction) error {
 	return srv.Serve(serve)
 }
 
-// ListenAndServeTLS listens on the provided network address and then calls
-// Serve to handle requests on incoming TLS connections.
-//
-// Filenames containing a certificate and matching private key for the server must
-// be provided. If the certificate is signed by a certificate authority, the
-// certFile should be the concatenation of the server's certificate followed by the
-// CA's certificate.
-func (srv *Server) ListenAndServeTLS(certFile, keyFile string, serve ServeFunction) error {
-	config := &tls.Config{}
-	if config.NextProtos == nil {
-		config.NextProtos = []string{"h2", "http/1.1"}
-	}
-
-	config.Certificates = make([]tls.Certificate, 1)
-
-	certPEMBlock, err := os.ReadFile(certFile)
-	if err != nil {
-		log.Error("Failed to load https cert file %s for %s:%s: %v", certFile, srv.network, srv.address, err)
-		return err
-	}
-
-	keyPEMBlock, err := os.ReadFile(keyFile)
-	if err != nil {
-		log.Error("Failed to load https key file %s for %s:%s: %v", keyFile, srv.network, srv.address, err)
-		return err
-	}
-
-	config.Certificates[0], err = tls.X509KeyPair(certPEMBlock, keyPEMBlock)
-	if err != nil {
-		log.Error("Failed to create certificate from cert file %s and key file %s for %s:%s: %v", certFile, keyFile, srv.network, srv.address, err)
-		return err
-	}
-
-	return srv.ListenAndServeTLSConfig(config, serve)
-}
-
 // ListenAndServeTLSConfig listens on the provided network address and then calls
 // Serve to handle requests on incoming TLS connections.
 func (srv *Server) ListenAndServeTLSConfig(tlsConfig *tls.Config, serve ServeFunction) error {
 	go srv.awaitShutdown()
 
-	tlsConfig.MinVersion = tls.VersionTLS12
+	if tlsConfig.MinVersion == 0 {
+		tlsConfig.MinVersion = tls.VersionTLS12
+	}
 
 	l, err := GetListener(srv.network, srv.address)
 	if err != nil {
diff --git a/modules/graceful/server_http.go b/modules/graceful/server_http.go
index 4471e379ef..f7b22ceb5e 100644
--- a/modules/graceful/server_http.go
+++ b/modules/graceful/server_http.go
@@ -33,13 +33,6 @@ func HTTPListenAndServe(network, address, name string, handler http.Handler) err
 	return server.ListenAndServe(lHandler)
 }
 
-// HTTPListenAndServeTLS listens on the provided network address and then calls Serve
-// to handle requests on incoming connections.
-func HTTPListenAndServeTLS(network, address, name, certFile, keyFile string, handler http.Handler) error {
-	server, lHandler := newHTTPServer(network, address, name, handler)
-	return server.ListenAndServeTLS(certFile, keyFile, lHandler)
-}
-
 // HTTPListenAndServeTLSConfig listens on the provided network address and then calls Serve
 // to handle requests on incoming connections.
 func HTTPListenAndServeTLSConfig(network, address, name string, tlsConfig *tls.Config, handler http.Handler) error {
diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index c5608c85bc..16ebde1791 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -114,6 +114,10 @@ var (
 	LetsEncryptTOS       bool
 	LetsEncryptDirectory string
 	LetsEncryptEmail     string
+	SSLMinimumVersion    string
+	SSLMaximumVersion    string
+	SSLCurvePreferences  []string
+	SSLCipherSuites      []string
 	GracefulRestartable  bool
 	GracefulHammerTime   time.Duration
 	StartupTimeout       time.Duration
@@ -618,6 +622,10 @@ func NewContext() {
 	}
 	LetsEncryptDirectory = sec.Key("LETSENCRYPT_DIRECTORY").MustString("https")
 	LetsEncryptEmail = sec.Key("LETSENCRYPT_EMAIL").MustString("")
+	SSLMinimumVersion = sec.Key("SSL_MIN_VERSION").MustString("")
+	SSLMaximumVersion = sec.Key("SSL_MAX_VERSION").MustString("")
+	SSLCurvePreferences = sec.Key("SSL_CURVE_PREFERENCES").Strings(",")
+	SSLCipherSuites = sec.Key("SSL_CIPHER_SUITES").Strings(",")
 	Domain = sec.Key("DOMAIN").MustString("localhost")
 	HTTPAddr = sec.Key("HTTP_ADDR").MustString("0.0.0.0")
 	HTTPPort = sec.Key("HTTP_PORT").MustString("3000")