crypto/tls: align FIPS-only mode with BoringSSL policy

This enables TLS 1.3, disables P-521, and disables non-ECDHE suites.

Fixes #64717
Updates #62372

Change-Id: I3a65b239ef0198bbdbe5e55e0810e7128f90a091
Reviewed-on: https://go-review.googlesource.com/c/go/+/549975
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>

Author: FiloSottile

src/crypto/internal/boring/aes.go

@@ -228,26 +228,41 @@ func (c *aesCipher) NewGCM(nonceSize, tagSize int) (cipher.AEAD, error) {
 	if tagSize != gcmTagSize {
 		return cipher.NewGCMWithTagSize(&noGCM{c}, tagSize)
 	}
-	return c.newGCM(false)
+	return c.newGCM(0)
 }
 
+const (
+	VersionTLS12 = 0x0303
+	VersionTLS13 = 0x0304
+)
+
 func NewGCMTLS(c cipher.Block) (cipher.AEAD, error) {
-	return c.(*aesCipher).newGCM(true)
+	return c.(*aesCipher).newGCM(VersionTLS12)
+}
+
+func NewGCMTLS13(c cipher.Block) (cipher.AEAD, error) {
+	return c.(*aesCipher).newGCM(VersionTLS13)
 }
 
-func (c *aesCipher) newGCM(tls bool) (cipher.AEAD, error) {
+func (c *aesCipher) newGCM(tlsVersion uint16) (cipher.AEAD, error) {
 	var aead *C.GO_EVP_AEAD
 	switch len(c.key) * 8 {
 	case 128:
-		if tls {
+		switch tlsVersion {
+		case VersionTLS12:
 			aead = C._goboringcrypto_EVP_aead_aes_128_gcm_tls12()
-		} else {
+		case VersionTLS13:
+			aead = C._goboringcrypto_EVP_aead_aes_128_gcm_tls13()
+		default:
 			aead = C._goboringcrypto_EVP_aead_aes_128_gcm()
 		}
 	case 256:
-		if tls {
+		switch tlsVersion {
+		case VersionTLS12:
 			aead = C._goboringcrypto_EVP_aead_aes_256_gcm_tls12()
-		} else {
+		case VersionTLS13:
+			aead = C._goboringcrypto_EVP_aead_aes_256_gcm_tls13()
+		default:
 			aead = C._goboringcrypto_EVP_aead_aes_256_gcm()
 		}
 	default:

src/crypto/internal/boring/notboring.go

@@ -50,6 +50,7 @@ func NewHMAC(h func() hash.Hash, key []byte) hash.Hash { panic("boringcrypto: no
 
 func NewAESCipher(key []byte) (cipher.Block, error) { panic("boringcrypto: not available") }
 func NewGCMTLS(cipher.Block) (cipher.AEAD, error)   { panic("boringcrypto: not available") }
+func NewGCMTLS13(cipher.Block) (cipher.AEAD, error) { panic("boringcrypto: not available") }
 
 type PublicKeyECDSA struct{ _ int }
 type PrivateKeyECDSA struct{ _ int }

src/crypto/tls/boring.go

@@ -6,9 +6,10 @@
 
 package tls
 
-import (
-	"crypto/internal/boring/fipstls"
-)
+import "crypto/internal/boring/fipstls"
+
+// The FIPS-only policies enforced here currently match BoringSSL's
+// ssl_policy_fips_202205.
 
 // needFIPS returns fipstls.Required(); it avoids a new import in common.go.
 func needFIPS() bool {
@@ -17,19 +18,19 @@ func needFIPS() bool {
 
 // fipsMinVersion replaces c.minVersion in FIPS-only mode.
 func fipsMinVersion(c *Config) uint16 {
-	// FIPS requires TLS 1.2.
+	// FIPS requires TLS 1.2 or TLS 1.3.
 	return VersionTLS12
 }
 
 // fipsMaxVersion replaces c.maxVersion in FIPS-only mode.
 func fipsMaxVersion(c *Config) uint16 {
-	// FIPS requires TLS 1.2.
-	return VersionTLS12
+	// FIPS requires TLS 1.2 or TLS 1.3.
+	return VersionTLS13
 }
 
 // default defaultFIPSCurvePreferences is the FIPS-allowed curves,
 // in preference order (most preferable first).
-var defaultFIPSCurvePreferences = []CurveID{CurveP256, CurveP384, CurveP521}
+var defaultFIPSCurvePreferences = []CurveID{CurveP256, CurveP384}
 
 // fipsCurvePreferences replaces c.curvePreferences in FIPS-only mode.
 func fipsCurvePreferences(c *Config) []CurveID {
@@ -54,8 +55,6 @@ var defaultCipherSuitesFIPS = []uint16{
 	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,
 }
 
 // fipsCipherSuites replaces c.cipherSuites in FIPS-only mode.
@@ -75,8 +74,14 @@ func fipsCipherSuites(c *Config) []uint16 {
 	return list
 }
 
+// defaultCipherSuitesTLS13FIPS are the FIPS-allowed cipher suites for TLS 1.3.
+var defaultCipherSuitesTLS13FIPS = []uint16{
+	TLS_AES_128_GCM_SHA256,
+	TLS_AES_256_GCM_SHA384,
+}
+
 // fipsSupportedSignatureAlgorithms currently are a subset of
-// defaultSupportedSignatureAlgorithms without Ed25519 and SHA-1.
+// defaultSupportedSignatureAlgorithms without Ed25519, SHA-1, and P-521.
 var fipsSupportedSignatureAlgorithms = []SignatureScheme{
 	PSSWithSHA256,
 	PSSWithSHA384,
@@ -86,7 +91,6 @@ var fipsSupportedSignatureAlgorithms = []SignatureScheme{
 	PKCS1WithSHA384,
 	ECDSAWithP384AndSHA384,
 	PKCS1WithSHA512,
-	ECDSAWithP521AndSHA512,
 }
 
 // supportedSignatureAlgorithms returns the supported signature algorithms.

src/crypto/tls/boring_test.go

@@ -25,6 +25,31 @@ import (
 	"time"
 )
 
+func allCipherSuitesIncludingTLS13() []uint16 {
+	s := allCipherSuites()
+	for _, suite := range cipherSuitesTLS13 {
+		s = append(s, suite.id)
+	}
+	return s
+}
+
+func isTLS13CipherSuite(id uint16) bool {
+	for _, suite := range cipherSuitesTLS13 {
+		if id == suite.id {
+			return true
+		}
+	}
+	return false
+}
+
+func generateKeyShare(group CurveID) keyShare {
+	key, err := generateECDHEKey(rand.Reader, group)
+	if err != nil {
+		panic(err)
+	}
+	return keyShare{group: group, data: key.PublicKey().Bytes()}
+}
+
 func TestBoringServerProtocolVersion(t *testing.T) {
 	test := func(name string, v uint16, msg string) {
 		t.Run(name, func(t *testing.T) {
@@ -33,8 +58,11 @@ func TestBoringServerProtocolVersion(t *testing.T) {
 			clientHello := &clientHelloMsg{
 				vers:               v,
 				random:             make([]byte, 32),
-				cipherSuites:       allCipherSuites(),
+				cipherSuites:       allCipherSuitesIncludingTLS13(),
 				compressionMethods: []uint8{compressionNone},
+				supportedCurves:    defaultCurvePreferences,
+				keyShares:          []keyShare{generateKeyShare(CurveP256)},
+				supportedPoints:    []uint8{pointFormatUncompressed},
 				supportedVersions:  []uint16{v},
 			}
 			testClientHelloFailure(t, serverConfig, clientHello, msg)
@@ -48,33 +76,33 @@ func TestBoringServerProtocolVersion(t *testing.T) {
 
 	fipstls.Force()
 	defer fipstls.Abandon()
-	test("VersionSSL30", VersionSSL30, "client offered only unsupported versions")
-	test("VersionTLS10", VersionTLS10, "client offered only unsupported versions")
-	test("VersionTLS11", VersionTLS11, "client offered only unsupported versions")
-	test("VersionTLS12", VersionTLS12, "")
-	test("VersionTLS13", VersionTLS13, "client offered only unsupported versions")
+	test("VersionSSL30/fipstls", VersionSSL30, "client offered only unsupported versions")
+	test("VersionTLS10/fipstls", VersionTLS10, "client offered only unsupported versions")
+	test("VersionTLS11/fipstls", VersionTLS11, "client offered only unsupported versions")
+	test("VersionTLS12/fipstls", VersionTLS12, "")
+	test("VersionTLS13/fipstls", VersionTLS13, "")
 }
 
 func isBoringVersion(v uint16) bool {
-	return v == VersionTLS12
+	return v == VersionTLS12 || v == VersionTLS13
 }
 
 func isBoringCipherSuite(id uint16) bool {
 	switch id {
-	case TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+	case TLS_AES_128_GCM_SHA256,
+		TLS_AES_256_GCM_SHA384,
+		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:
+		TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
 		return true
 	}
 	return false
 }
 
 func isBoringCurve(id CurveID) bool {
 	switch id {
-	case CurveP256, CurveP384, CurveP521:
+	case CurveP256, CurveP384:
 		return true
 	}
 	return false
@@ -86,7 +114,7 @@ func isECDSA(id uint16) bool {
 			return suite.flags&suiteECSign == suiteECSign
 		}
 	}
-	panic(fmt.Sprintf("unknown cipher suite %#x", id))
+	return false // TLS 1.3 cipher suites are not tied to the signature algorithm.
 }
 
 func isBoringSignatureScheme(alg SignatureScheme) bool {
@@ -98,7 +126,6 @@ func isBoringSignatureScheme(alg SignatureScheme) bool {
 		PKCS1WithSHA384,
 		ECDSAWithP384AndSHA384,
 		PKCS1WithSHA512,
-		ECDSAWithP521AndSHA512,
 		PSSWithSHA256,
 		PSSWithSHA384,
 		PSSWithSHA512:
@@ -109,10 +136,9 @@ func isBoringSignatureScheme(alg SignatureScheme) bool {
 
 func TestBoringServerCipherSuites(t *testing.T) {
 	serverConfig := testConfig.Clone()
-	serverConfig.CipherSuites = allCipherSuites()
 	serverConfig.Certificates = make([]Certificate, 1)
 
-	for _, id := range allCipherSuites() {
+	for _, id := range allCipherSuitesIncludingTLS13() {
 		if isECDSA(id) {
 			serverConfig.Certificates[0].Certificate = [][]byte{testECDSACertificate}
 			serverConfig.Certificates[0].PrivateKey = testECDSAPrivateKey
@@ -121,14 +147,19 @@ func TestBoringServerCipherSuites(t *testing.T) {
 			serverConfig.Certificates[0].PrivateKey = testRSAPrivateKey
 		}
 		serverConfig.BuildNameToCertificate()
-		t.Run(fmt.Sprintf("suite=%#x", id), func(t *testing.T) {
+		t.Run(fmt.Sprintf("suite=%s", CipherSuiteName(id)), func(t *testing.T) {
 			clientHello := &clientHelloMsg{
 				vers:               VersionTLS12,
 				random:             make([]byte, 32),
 				cipherSuites:       []uint16{id},
 				compressionMethods: []uint8{compressionNone},
 				supportedCurves:    defaultCurvePreferences,
+				keyShares:          []keyShare{generateKeyShare(CurveP256)},
 				supportedPoints:    []uint8{pointFormatUncompressed},
+				supportedVersions:  []uint16{VersionTLS12},
+			}
+			if isTLS13CipherSuite(id) {
+				clientHello.supportedVersions = []uint16{VersionTLS13}
 			}
 
 			testClientHello(t, serverConfig, clientHello)
@@ -160,7 +191,9 @@ func TestBoringServerCurves(t *testing.T) {
 				cipherSuites:       []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
 				compressionMethods: []uint8{compressionNone},
 				supportedCurves:    []CurveID{curveid},
+				keyShares:          []keyShare{generateKeyShare(curveid)},
 				supportedPoints:    []uint8{pointFormatUncompressed},
+				supportedVersions:  []uint16{VersionTLS12},
 			}
 
 			testClientHello(t, serverConfig, clientHello)
@@ -279,7 +312,7 @@ func TestBoringClientHello(t *testing.T) {
 	}
 
 	if !isBoringVersion(hello.vers) {
-		t.Errorf("client vers=%#x, want %#x (TLS 1.2)", hello.vers, VersionTLS12)
+		t.Errorf("client vers=%#x", hello.vers)
 	}
 	for _, v := range hello.supportedVersions {
 		if !isBoringVersion(v) {

src/crypto/tls/cipher_suites.go

@@ -556,7 +556,13 @@ func aeadAESGCMTLS13(key, nonceMask []byte) aead {
 	if err != nil {
 		panic(err)
 	}
-	aead, err := cipher.NewGCM(aes)
+	var aead cipher.AEAD
+	if boring.Enabled {
+		aead, err = boring.NewGCMTLS13(aes)
+	} else {
+		boring.Unreachable()
+		aead, err = cipher.NewGCM(aes)
+	}
 	if err != nil {
 		panic(err)
 	}

src/crypto/tls/handshake_client.go

@@ -139,7 +139,9 @@ func (c *Conn) makeClientHello() (*clientHelloMsg, *ecdh.PrivateKey, error) {
 		if len(hello.supportedVersions) == 1 {
 			hello.cipherSuites = nil
 		}
-		if hasAESGCMHardwareSupport {
+		if needFIPS() {
+			hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13FIPS...)
+		} else if hasAESGCMHardwareSupport {
 			hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13...)
 		} else {
 			hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13NoAES...)

src/crypto/tls/handshake_client_tls13.go

@@ -41,10 +41,6 @@ type clientHandshakeStateTLS13 struct {
 func (hs *clientHandshakeStateTLS13) handshake() error {
 	c := hs.c
 
-	if needFIPS() {
-		return errors.New("tls: internal error: TLS 1.3 reached in FIPS mode")
-	}
-
 	// The server must not select TLS 1.3 in a renegotiation. See RFC 8446,
 	// sections 4.1.2 and 4.1.3.
 	if c.handshakes > 0 {

src/crypto/tls/handshake_server_test.go

@@ -27,6 +27,7 @@ import (
 )
 
 func testClientHello(t *testing.T, serverConfig *Config, m handshakeMessage) {
+	t.Helper()
 	testClientHelloFailure(t, serverConfig, m, "")
 }
 
@@ -52,23 +53,32 @@ func testClientHelloFailure(t *testing.T, serverConfig *Config, m handshakeMessa
 	ctx := context.Background()
 	conn := Server(s, serverConfig)
 	ch, err := conn.readClientHello(ctx)
-	hs := serverHandshakeState{
-		c:           conn,
-		ctx:         ctx,
-		clientHello: ch,
-	}
-	if err == nil {
+	if err == nil && conn.vers == VersionTLS13 {
+		hs := serverHandshakeStateTLS13{
+			c:           conn,
+			ctx:         ctx,
+			clientHello: ch,
+		}
 		err = hs.processClientHello()
-	}
-	if err == nil {
-		err = hs.pickCipherSuite()
+	} else if err == nil {
+		hs := serverHandshakeState{
+			c:           conn,
+			ctx:         ctx,
+			clientHello: ch,
+		}
+		err = hs.processClientHello()
+		if err == nil {
+			err = hs.pickCipherSuite()
+		}
 	}
 	s.Close()
 	if len(expectedSubStr) == 0 {
 		if err != nil && err != io.EOF {
+			t.Helper()
 			t.Errorf("Got error: %s; expected to succeed", err)
 		}
 	} else if err == nil || !strings.Contains(err.Error(), expectedSubStr) {
+		t.Helper()
 		t.Errorf("Got error: %v; expected to match substring '%s'", err, expectedSubStr)
 	}
 }

src/crypto/tls/handshake_server_tls13.go

@@ -45,10 +45,6 @@ type serverHandshakeStateTLS13 struct {
 func (hs *serverHandshakeStateTLS13) handshake() error {
 	c := hs.c
 
-	if needFIPS() {
-		return errors.New("tls: internal error: TLS 1.3 reached in FIPS mode")
-	}
-
 	// For an overview of the TLS 1.3 handshake, see RFC 8446, Section 2.
 	if err := hs.processClientHello(); err != nil {
 		return err
@@ -163,6 +159,9 @@ func (hs *serverHandshakeStateTLS13) processClientHello() error {
 	if !hasAESGCMHardwareSupport || !aesgcmPreferred(hs.clientHello.cipherSuites) {
 		preferenceList = defaultCipherSuitesTLS13NoAES
 	}
+	if needFIPS() {
+		preferenceList = defaultCipherSuitesTLS13FIPS
+	}
 	for _, suiteID := range preferenceList {
 		hs.suite = mutualCipherSuiteTLS13(hs.clientHello.cipherSuites, suiteID)
 		if hs.suite != nil {