crypto/tls: move defaults into defaults.go

Fixes #65265
Updates #60790

Change-Id: Iaa5f475d614d3ed87f091c93a3f888b7eb3433f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/587296
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Derek Parker <parkerderek86@gmail.com>

auth.go

@@ -242,7 +242,7 @@ func selectSignatureScheme(vers uint16, c *Certificate, peerAlgs []SignatureSche
 	// Pick signature scheme in the peer's preference order, as our
 	// preference order is not configurable.
 	for _, preferredAlg := range peerAlgs {
-		if needFIPS() && !isSupportedSignatureAlgorithm(preferredAlg, fipsSupportedSignatureAlgorithms) {
+		if needFIPS() && !isSupportedSignatureAlgorithm(preferredAlg, defaultSupportedSignatureAlgorithmsFIPS) {
 			continue
 		}
 		if isSupportedSignatureAlgorithm(preferredAlg, supportedAlgs) {

cipher_suites.go

@@ -16,7 +16,6 @@ import (
 	"fmt"
 	"hash"
 	"runtime"
-	"slices"
 
 	"golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/sys/cpu"
@@ -353,30 +352,6 @@ var tdesCiphers = map[uint16]bool{
 	TLS_RSA_WITH_3DES_EDE_CBC_SHA:       true,
 }
 
-func defaultCipherSuites() []uint16 {
-	suites := slices.Clone(cipherSuitesPreferenceOrder)
-	return slices.DeleteFunc(suites, func(c uint16) bool {
-		return disabledCipherSuites[c] ||
-			rsaKexCiphers[c] ||
-			tdesCiphers[c]
-	})
-}
-
-// defaultCipherSuitesTLS13 is also the preference order, since there are no
-// disabled by default TLS 1.3 cipher suites. The same AES vs ChaCha20 logic as
-// cipherSuitesPreferenceOrder applies.
-var defaultCipherSuitesTLS13 = []uint16{
-	TLS_AES_128_GCM_SHA256,
-	TLS_AES_256_GCM_SHA384,
-	TLS_CHACHA20_POLY1305_SHA256,
-}
-
-var defaultCipherSuitesTLS13NoAES = []uint16{
-	TLS_CHACHA20_POLY1305_SHA256,
-	TLS_AES_128_GCM_SHA256,
-	TLS_AES_256_GCM_SHA384,
-}
-
 var (
 	hasGCMAsmAMD64 = cpu.X86.HasAES && cpu.X86.HasPCLMULQDQ
 	hasGCMAsmARM64 = cpu.ARM64.HasAES && cpu.ARM64.HasPMULL

common.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"slices"
 	"strings"
 	"sync"
 	"time"
@@ -199,25 +200,6 @@ const (
 // hash function associated with the Ed25519 signature scheme.
 var directSigning crypto.Hash = 0
 
-// defaultSupportedSignatureAlgorithms contains the signature and hash algorithms that
-// the code advertises as supported in a TLS 1.2+ ClientHello and in a TLS 1.2+
-// CertificateRequest. The two fields are merged to match with TLS 1.3.
-// Note that in TLS 1.2, the ECDSA algorithms are not constrained to P-256, etc.
-var defaultSupportedSignatureAlgorithms = []SignatureScheme{
-	PSSWithSHA256,
-	ECDSAWithP256AndSHA256,
-	Ed25519,
-	PSSWithSHA384,
-	PSSWithSHA512,
-	PKCS1WithSHA256,
-	PKCS1WithSHA384,
-	PKCS1WithSHA512,
-	ECDSAWithP384AndSHA384,
-	ECDSAWithP521AndSHA512,
-	PKCS1WithSHA1,
-	ECDSAWithSHA1,
-}
-
 // helloRetryRequestRandom is set as the Random value of a ServerHello
 // to signal that the message is actually a HelloRetryRequest.
 var helloRetryRequestRandom = []byte{ // See RFC 8446, Section 4.1.3.
@@ -1052,13 +1034,19 @@ func (c *Config) time() time.Time {
 }
 
 func (c *Config) cipherSuites() []uint16 {
+	if c.CipherSuites == nil {
+		if needFIPS() {
+			return defaultCipherSuitesFIPS
+		}
+		return defaultCipherSuites()
+	}
 	if needFIPS() {
-		return fipsCipherSuites(c)
+		cipherSuites := slices.Clone(c.CipherSuites)
+		return slices.DeleteFunc(cipherSuites, func(id uint16) bool {
+			return !slices.Contains(defaultCipherSuitesFIPS, id)
+		})
 	}
-	if c.CipherSuites != nil {
+	return c.CipherSuites
-		return c.CipherSuites
-	}
-	return defaultCipherSuites()
 }
 
 var supportedVersions = []uint16{
@@ -1076,7 +1064,7 @@ const roleServer = false
 func (c *Config) supportedVersions(isClient bool) []uint16 {
 	versions := make([]uint16, 0, len(supportedVersions))
 	for _, v := range supportedVersions {
-		if needFIPS() && (v < fipsMinVersion(c) || v > fipsMaxVersion(c)) {
+		if needFIPS() && !slices.Contains(defaultSupportedVersionsFIPS, v) {
 			continue
 		}
 		if (c == nil || c.MinVersion == 0) && v < VersionTLS12 {
@@ -1115,21 +1103,26 @@ func supportedVersionsFromMax(maxVersion uint16) []uint16 {
 	return versions
 }
 
-var defaultCurvePreferences = []CurveID{x25519Kyber768Draft00, X25519, CurveP256, CurveP384, CurveP521}
-
-var defaultCurvePreferencesWithoutKyber = []CurveID{X25519, CurveP256, CurveP384, CurveP521}
-
 func (c *Config) curvePreferences(version uint16) []CurveID {
-	if needFIPS() {
+	var curvePreferences []CurveID
-		return fipsCurvePreferences(c)
+	if c != nil && len(c.CurvePreferences) != 0 {
-	}
+		curvePreferences = slices.Clone(c.CurvePreferences)
-	if c == nil || len(c.CurvePreferences) == 0 {
+		if needFIPS() {
-		if version < VersionTLS13 || true /*tlskyber.Value() == "0"*/ {
+			return slices.DeleteFunc(curvePreferences, func(c CurveID) bool {
-			return defaultCurvePreferencesWithoutKyber
+				return !slices.Contains(defaultCurvePreferencesFIPS, c)
+			})
 		}
-		return defaultCurvePreferences
+	} else if needFIPS() {
+		curvePreferences = slices.Clone(defaultCurvePreferencesFIPS)
+	} else {
+		curvePreferences = defaultCurvePreferences()
 	}
-	return c.CurvePreferences
+	if version < VersionTLS13 {
+		return slices.DeleteFunc(curvePreferences, func(c CurveID) bool {
+			return c == x25519Kyber768Draft00
+		})
+	}
+	return curvePreferences
 }
 
 func (c *Config) supportsCurve(version uint16, curve CurveID) bool {
@@ -1580,6 +1573,14 @@ func unexpectedMessageError(wanted, got any) error {
 	return fmt.Errorf("tls: received unexpected handshake message of type %T when waiting for %T", got, wanted)
 }
 
+// supportedSignatureAlgorithms returns the supported signature algorithms.
+func supportedSignatureAlgorithms() []SignatureScheme {
+	if !needFIPS() {
+		return defaultSupportedSignatureAlgorithms
+	}
+	return defaultSupportedSignatureAlgorithmsFIPS
+}
+
 func isSupportedSignatureAlgorithm(sigAlg SignatureScheme, supportedSignatureAlgorithms []SignatureScheme) bool {
 	for _, s := range supportedSignatureAlgorithms {
 		if s == sigAlg {

defaults.go

@@ -0,0 +1,106 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package reality
+
+import (
+	"slices"
+)
+
+// Defaults are collected in this file to allow distributions to more easily patch
+// them to apply local policies.
+
+//var tlskyber = godebug.New("tlskyber")
+
+func defaultCurvePreferences() []CurveID {
+	if false {
+		return []CurveID{X25519, CurveP256, CurveP384, CurveP521}
+	}
+	// For now, x25519Kyber768Draft00 must always be followed by X25519.
+	return []CurveID{x25519Kyber768Draft00, X25519, CurveP256, CurveP384, CurveP521}
+}
+
+// defaultSupportedSignatureAlgorithms contains the signature and hash algorithms that
+// the code advertises as supported in a TLS 1.2+ ClientHello and in a TLS 1.2+
+// CertificateRequest. The two fields are merged to match with TLS 1.3.
+// Note that in TLS 1.2, the ECDSA algorithms are not constrained to P-256, etc.
+var defaultSupportedSignatureAlgorithms = []SignatureScheme{
+	PSSWithSHA256,
+	ECDSAWithP256AndSHA256,
+	Ed25519,
+	PSSWithSHA384,
+	PSSWithSHA512,
+	PKCS1WithSHA256,
+	PKCS1WithSHA384,
+	PKCS1WithSHA512,
+	ECDSAWithP384AndSHA384,
+	ECDSAWithP521AndSHA512,
+	PKCS1WithSHA1,
+	ECDSAWithSHA1,
+}
+
+//var tlsrsakex = godebug.New("tlsrsakex")
+//var tls3des = godebug.New("tls3des")
+
+func defaultCipherSuites() []uint16 {
+	suites := slices.Clone(cipherSuitesPreferenceOrder)
+	return slices.DeleteFunc(suites, func(c uint16) bool {
+		return disabledCipherSuites[c] ||
+			rsaKexCiphers[c] ||
+			tdesCiphers[c]
+	})
+}
+
+// defaultCipherSuitesTLS13 is also the preference order, since there are no
+// disabled by default TLS 1.3 cipher suites. The same AES vs ChaCha20 logic as
+// cipherSuitesPreferenceOrder applies.
+var defaultCipherSuitesTLS13 = []uint16{
+	TLS_AES_128_GCM_SHA256,
+	TLS_AES_256_GCM_SHA384,
+	TLS_CHACHA20_POLY1305_SHA256,
+}
+
+var defaultCipherSuitesTLS13NoAES = []uint16{
+	TLS_CHACHA20_POLY1305_SHA256,
+	TLS_AES_128_GCM_SHA256,
+	TLS_AES_256_GCM_SHA384,
+}
+
+var defaultSupportedVersionsFIPS = []uint16{
+	VersionTLS12,
+}
+
+// defaultCurvePreferencesFIPS are the FIPS-allowed curves,
+// in preference order (most preferable first).
+var defaultCurvePreferencesFIPS = []CurveID{CurveP256, CurveP384, CurveP521}
+
+// defaultSupportedSignatureAlgorithmsFIPS currently are a subset of
+// defaultSupportedSignatureAlgorithms without Ed25519 and SHA-1.
+var defaultSupportedSignatureAlgorithmsFIPS = []SignatureScheme{
+	PSSWithSHA256,
+	PSSWithSHA384,
+	PSSWithSHA512,
+	PKCS1WithSHA256,
+	ECDSAWithP256AndSHA256,
+	PKCS1WithSHA384,
+	ECDSAWithP384AndSHA384,
+	PKCS1WithSHA512,
+	ECDSAWithP521AndSHA512,
+}
+
+// defaultCipherSuitesFIPS are the FIPS-allowed cipher suites.
+var defaultCipherSuitesFIPS = []uint16{
+	TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+	TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+	TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+	TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+	TLS_RSA_WITH_AES_128_GCM_SHA256,
+	TLS_RSA_WITH_AES_256_GCM_SHA384,
+}
+
+// defaultCipherSuitesTLS13FIPS are the FIPS-allowed cipher suites for TLS 1.3.
+var defaultCipherSuitesTLS13FIPS = []uint16{
+	TLS_AES_128_GCM_SHA256,
+	TLS_AES_256_GCM_SHA384,
+}

notboring.go

@@ -7,14 +7,3 @@
 package reality
 
 func needFIPS() bool { return false }
-
-func supportedSignatureAlgorithms() []SignatureScheme {
-	return defaultSupportedSignatureAlgorithms
-}
-
-func fipsMinVersion(c *Config) uint16          { panic("fipsMinVersion") }
-func fipsMaxVersion(c *Config) uint16          { panic("fipsMaxVersion") }
-func fipsCurvePreferences(c *Config) []CurveID { panic("fipsCurvePreferences") }
-func fipsCipherSuites(c *Config) []uint16      { panic("fipsCipherSuites") }
-
-var fipsSupportedSignatureAlgorithms []SignatureScheme