[release-branch.go1.25] crypto/tls: check verifiedChains roots when resuming sessions

When resuming TLS sessions, on the server and client verify that the
chains stored in the session state (verifiedChains) are still acceptable
with regards to the Config by checking for the inclusion of the root in
either ClientCAs (server) or RootCAs (client). This prevents resuming
a session with a certificate chain that would be rejected during a full
handshake due to an untrusted root.

Updates #77113
Updates #77356
Updates CVE-2025-68121

Change-Id: I11fe00909ef1961c24ecf80bf5b97f7b1121d359
Reviewed-on: https://go-review.googlesource.com/c/go/+/737700
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Coia Prant <coiaprant@gmail.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/740065
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Nicholas Husin <husin@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Nicholas Husin <nsh@golang.org>

src/cmd/cgo/ast.go

@@ -301,17 +301,12 @@ func (f *File) saveExport(x interface{}, context astContext) {
 			error_(c.Pos(), "export comment has wrong name %q, want %q", name, n.Name.Name)
 		}
 
-		doc := ""
-		for _, c1 := range n.Doc.List {
-			if c1 != c {
-				doc += c1.Text + "\n"
-			}
-		}
-
 		f.ExpFunc = append(f.ExpFunc, &ExpFunc{
 			Func:    n,
 			ExpName: name,
-			Doc:     doc,
+			// Caution: Do not set the Doc field on purpose
+			// to ensure that there are no unintended artifacts
+			// in the binary. See https://go.dev/issue/76697.
 		})
 		break
 	}

src/crypto/tls/common.go

@@ -942,10 +942,6 @@ const maxSessionTicketLifetime = 7 * 24 * time.Hour
 
 // Clone returns a shallow clone of c or nil if c is nil. It is safe to clone a [Config] that is
 // being used concurrently by a TLS client or server.
-//
-// If Config.SessionTicketKey is unpopulated, and Config.SetSessionTicketKeys has not been
-// called, the clone will not share the same auto-rotated session ticket keys as the original
-// Config in order to prevent sessions from being resumed across Configs.
 func (c *Config) Clone() *Config {
 	if c == nil {
 		return nil
@@ -986,8 +982,7 @@ func (c *Config) Clone() *Config {
 		EncryptedClientHelloRejectionVerify: c.EncryptedClientHelloRejectionVerify,
 		EncryptedClientHelloKeys:            c.EncryptedClientHelloKeys,
 		sessionTicketKeys:                   c.sessionTicketKeys,
-		// We explicitly do not copy autoSessionTicketKeys, so that Configs do
-		// not share the same auto-rotated keys.
+		autoSessionTicketKeys:               c.autoSessionTicketKeys,
 	}
 }
 
@@ -1808,3 +1803,31 @@ func fipsAllowChain(chain []*x509.Certificate) bool {
 
 	return true
 }
+
+// anyValidVerifiedChain reports if at least one of the chains in verifiedChains
+// is valid, as indicated by none of the certificates being expired and the root
+// being in opts.Roots (or in the system root pool if opts.Roots is nil). If
+// verifiedChains is empty, it returns false.
+func anyValidVerifiedChain(verifiedChains [][]*x509.Certificate, opts x509.VerifyOptions) bool {
+	for _, chain := range verifiedChains {
+		if len(chain) == 0 {
+			continue
+		}
+		if slices.ContainsFunc(chain, func(cert *x509.Certificate) bool {
+			return opts.CurrentTime.Before(cert.NotBefore) || opts.CurrentTime.After(cert.NotAfter)
+		}) {
+			continue
+		}
+		// Since we already validated the chain, we only care that it is
+		// rooted in a CA in CAs, or in the system pool. On platforms where
+		// we control chain validation (e.g. not Windows or macOS) this is a
+		// simple lookup in the CertPool internal hash map. On other
+		// platforms, this may be more expensive, depending on how they
+		// implement verification of just root certificates.
+		root := chain[len(chain)-1]
+		if _, err := root.Verify(opts); err == nil {
+			return true
+		}
+	}
+	return false
+}

src/crypto/tls/handshake_client.go

@@ -429,9 +429,6 @@ func (c *Conn) loadSession(hello *clientHelloMsg) (
 		return nil, nil, nil, nil
 	}
 
-	// Check that the cached server certificate is not expired, and that it's
-	// valid for the ServerName. This should be ensured by the cache key, but
-	// protect the application from a faulty ClientSessionCache implementation.
 	if c.config.time().After(session.peerCertificates[0].NotAfter) {
 		// Expired certificate, delete the entry.
 		c.config.ClientSessionCache.Put(cacheKey, nil)
@@ -443,6 +440,18 @@ func (c *Conn) loadSession(hello *clientHelloMsg) (
 			return nil, nil, nil, nil
 		}
 		if err := session.peerCertificates[0].VerifyHostname(c.config.ServerName); err != nil {
+			// This should be ensured by the cache key, but protect the
+			// application from a faulty ClientSessionCache implementation.
+			return nil, nil, nil, nil
+		}
+		opts := x509.VerifyOptions{
+			CurrentTime: c.config.time(),
+			Roots:       c.config.RootCAs,
+			KeyUsages:   []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		}
+		if !anyValidVerifiedChain(session.verifiedChains, opts) {
+			// No valid chains, delete the entry.
+			c.config.ClientSessionCache.Put(cacheKey, nil)
 			return nil, nil, nil, nil
 		}
 	}

src/crypto/tls/handshake_server.go

@@ -520,16 +520,16 @@ func (hs *serverHandshakeState) checkForResumption() error {
 	if sessionHasClientCerts && c.config.ClientAuth == NoClientCert {
 		return nil
 	}
-	if sessionHasClientCerts {
-		now := c.config.time()
-		for _, c := range sessionState.peerCertificates {
-			if now.After(c.NotAfter) {
-				return nil
-			}
-		}
+	if sessionHasClientCerts && c.config.time().After(sessionState.peerCertificates[0].NotAfter) {
+		return nil
+	}
+	opts := x509.VerifyOptions{
+		CurrentTime: c.config.time(),
+		Roots:       c.config.ClientCAs,
+		KeyUsages:   []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
 	}
 	if sessionHasClientCerts && c.config.ClientAuth >= VerifyClientCertIfGiven &&
-		len(sessionState.verifiedChains) == 0 {
+		!anyValidVerifiedChain(sessionState.verifiedChains, opts) {
 		return nil
 	}
 

src/crypto/tls/handshake_server_test.go

@@ -2123,7 +2123,7 @@ func TestHandshakeContextHierarchy(t *testing.T) {
 	}
 }
 
-func TestHandshakeChainExpiryResumptionTLS12(t *testing.T) {
+func TestHandshakeChainExpiryResumption(t *testing.T) {
 	t.Run("TLS1.2", func(t *testing.T) {
 		testHandshakeChainExpiryResumption(t, VersionTLS12)
 	})
@@ -2134,7 +2134,8 @@ func TestHandshakeChainExpiryResumptionTLS12(t *testing.T) {
 
 func testHandshakeChainExpiryResumption(t *testing.T, version uint16) {
 	now := time.Now()
-	createChain := func(leafNotAfter, rootNotAfter time.Time) (certDER []byte, root *x509.Certificate) {
+
+	createChain := func(leafNotAfter, rootNotAfter time.Time) (leafDER, expiredLeafDER []byte, root *x509.Certificate) {
 		tmpl := &x509.Certificate{
 			Subject:               pkix.Name{CommonName: "root"},
 			NotBefore:             rootNotAfter.Add(-time.Hour * 24),
@@ -2158,39 +2159,177 @@ func testHandshakeChainExpiryResumption(t *testing.T, version uint16) {
 			NotAfter:  leafNotAfter,
 			KeyUsage:  x509.KeyUsageDigitalSignature,
 		}
-		certDER, err = x509.CreateCertificate(rand.Reader, tmpl, root, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+		leafCertDER, err := x509.CreateCertificate(rand.Reader, tmpl, root, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+		if err != nil {
+			t.Fatalf("CreateCertificate: %v", err)
+		}
+		tmpl.NotBefore, tmpl.NotAfter = leafNotAfter.Add(-time.Hour*24*365), leafNotAfter.Add(-time.Hour*24*364)
+		expiredLeafDERCertDER, err := x509.CreateCertificate(rand.Reader, tmpl, root, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
 		if err != nil {
 			t.Fatalf("CreateCertificate: %v", err)
 		}
 
-		return certDER, root
+		return leafCertDER, expiredLeafDERCertDER, root
+	}
+	testExpiration := func(name string, leafNotAfter, rootNotAfter time.Time) {
+		t.Run(name, func(t *testing.T) {
+			initialLeafDER, expiredLeafDER, initialRoot := createChain(leafNotAfter, rootNotAfter)
+
+			serverConfig := testConfig.Clone()
+			serverConfig.MaxVersion = version
+			serverConfig.Certificates = []Certificate{{
+				Certificate: [][]byte{initialLeafDER, expiredLeafDER},
+				PrivateKey:  testECDSAPrivateKey,
+			}}
+			serverConfig.ClientCAs = x509.NewCertPool()
+			serverConfig.ClientCAs.AddCert(initialRoot)
+			serverConfig.ClientAuth = RequireAndVerifyClientCert
+			serverConfig.Time = func() time.Time {
+				return now
+			}
+			serverConfig.InsecureSkipVerify = false
+			serverConfig.ServerName = "expired-resume.example.com"
+
+			clientConfig := testConfig.Clone()
+			clientConfig.MaxVersion = version
+			clientConfig.Certificates = []Certificate{{
+				Certificate: [][]byte{initialLeafDER, expiredLeafDER},
+				PrivateKey:  testECDSAPrivateKey,
+			}}
+			clientConfig.RootCAs = x509.NewCertPool()
+			clientConfig.RootCAs.AddCert(initialRoot)
+			clientConfig.ServerName = "expired-resume.example.com"
+			clientConfig.ClientSessionCache = NewLRUClientSessionCache(32)
+			clientConfig.InsecureSkipVerify = false
+			clientConfig.ServerName = "expired-resume.example.com"
+			clientConfig.Time = func() time.Time {
+				return now
+			}
+
+			testResume := func(t *testing.T, sc, cc *Config, expectResume bool) {
+				t.Helper()
+				ss, cs, err := testHandshake(t, cc, sc)
+				if err != nil {
+					t.Fatalf("handshake: %v", err)
+				}
+				if cs.DidResume != expectResume {
+					t.Fatalf("DidResume = %v; want %v", cs.DidResume, expectResume)
+				}
+				if ss.DidResume != expectResume {
+					t.Fatalf("DidResume = %v; want %v", cs.DidResume, expectResume)
+				}
+			}
+
+			testResume(t, serverConfig, clientConfig, false)
+			testResume(t, serverConfig, clientConfig, true)
+
+			expiredNow := time.Unix(0, min(leafNotAfter.UnixNano(), rootNotAfter.UnixNano())).Add(time.Minute)
+
+			freshLeafDER, expiredLeafDER, freshRoot := createChain(expiredNow.Add(time.Hour), expiredNow.Add(time.Hour))
+			clientConfig.Certificates = []Certificate{{
+				Certificate: [][]byte{freshLeafDER, expiredLeafDER},
+				PrivateKey:  testECDSAPrivateKey,
+			}}
+			serverConfig.Time = func() time.Time {
+				return expiredNow
+			}
+			serverConfig.ClientCAs = x509.NewCertPool()
+			serverConfig.ClientCAs.AddCert(freshRoot)
+
+			testResume(t, serverConfig, clientConfig, false)
+		})
 	}
 
-	initialLeafDER, initialRoot := createChain(now.Add(time.Hour), now.Add(2*time.Hour))
+	testExpiration("LeafExpiresBeforeRoot", now.Add(2*time.Hour), now.Add(3*time.Hour))
+	testExpiration("LeafExpiresAfterRoot", now.Add(2*time.Hour), now.Add(time.Hour))
+}
+
+func TestHandshakeGetConfigForClientDifferentClientCAs(t *testing.T) {
+	t.Run("TLS1.2", func(t *testing.T) {
+		testHandshakeGetConfigForClientDifferentClientCAs(t, VersionTLS12)
+	})
+	t.Run("TLS1.3", func(t *testing.T) {
+		testHandshakeGetConfigForClientDifferentClientCAs(t, VersionTLS13)
+	})
+}
+
+func testHandshakeGetConfigForClientDifferentClientCAs(t *testing.T, version uint16) {
+	now := time.Now()
+	tmpl := &x509.Certificate{
+		Subject:               pkix.Name{CommonName: "root"},
+		NotBefore:             now.Add(-time.Hour * 24),
+		NotAfter:              now.Add(time.Hour * 24),
+		IsCA:                  true,
+		BasicConstraintsValid: true,
+	}
+	rootDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
+	rootA, err := x509.ParseCertificate(rootDER)
+	if err != nil {
+		t.Fatalf("ParseCertificate: %v", err)
+	}
+	rootDER, err = x509.CreateCertificate(rand.Reader, tmpl, tmpl, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
+	rootB, err := x509.ParseCertificate(rootDER)
+	if err != nil {
+		t.Fatalf("ParseCertificate: %v", err)
+	}
+
+	tmpl = &x509.Certificate{
+		Subject:   pkix.Name{},
+		DNSNames:  []string{"example.com"},
+		NotBefore: now.Add(-time.Hour * 24),
+		NotAfter:  now.Add(time.Hour * 24),
+		KeyUsage:  x509.KeyUsageDigitalSignature,
+	}
+	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, rootA, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
 
 	serverConfig := testConfig.Clone()
 	serverConfig.MaxVersion = version
 	serverConfig.Certificates = []Certificate{{
-		Certificate: [][]byte{initialLeafDER},
+		Certificate: [][]byte{certDER},
 		PrivateKey:  testECDSAPrivateKey,
 	}}
-	serverConfig.ClientCAs = x509.NewCertPool()
-	serverConfig.ClientCAs.AddCert(initialRoot)
-	serverConfig.ClientAuth = RequireAndVerifyClientCert
 	serverConfig.Time = func() time.Time {
 		return now
 	}
+	serverConfig.ClientCAs = x509.NewCertPool()
+	serverConfig.ClientCAs.AddCert(rootA)
+	serverConfig.ClientAuth = RequireAndVerifyClientCert
+	switchConfig := false
+	serverConfig.GetConfigForClient = func(clientHello *ClientHelloInfo) (*Config, error) {
+		if !switchConfig {
+			return nil, nil
+		}
+		cfg := serverConfig.Clone()
+		cfg.ClientCAs = x509.NewCertPool()
+		cfg.ClientCAs.AddCert(rootB)
+		return cfg, nil
+	}
+	serverConfig.InsecureSkipVerify = false
+	serverConfig.ServerName = "example.com"
 
 	clientConfig := testConfig.Clone()
 	clientConfig.MaxVersion = version
 	clientConfig.Certificates = []Certificate{{
-		Certificate: [][]byte{initialLeafDER},
+		Certificate: [][]byte{certDER},
 		PrivateKey:  testECDSAPrivateKey,
 	}}
-	clientConfig.RootCAs = x509.NewCertPool()
-	clientConfig.RootCAs.AddCert(initialRoot)
-	clientConfig.ServerName = "expired-resume.example.com"
 	clientConfig.ClientSessionCache = NewLRUClientSessionCache(32)
+	clientConfig.RootCAs = x509.NewCertPool()
+	clientConfig.RootCAs.AddCert(rootA)
+	clientConfig.Time = func() time.Time {
+		return now
+	}
+	clientConfig.InsecureSkipVerify = false
+	clientConfig.ServerName = "example.com"
 
 	testResume := func(t *testing.T, sc, cc *Config, expectResume bool) {
 		t.Helper()
@@ -2209,16 +2348,112 @@ func testHandshakeChainExpiryResumption(t *testing.T, version uint16) {
 	testResume(t, serverConfig, clientConfig, false)
 	testResume(t, serverConfig, clientConfig, true)
 
-	freshLeafDER, freshRoot := createChain(now.Add(2*time.Hour), now.Add(3*time.Hour))
-	clientConfig.Certificates = []Certificate{{
-		Certificate: [][]byte{freshLeafDER},
+	// Cause GetConfigForClient to return a config cloned from the base config,
+	// but with a different ClientCAs pool. This should cause resumption to fail.
+	switchConfig = true
+
+	testResume(t, serverConfig, clientConfig, false)
+	testResume(t, serverConfig, clientConfig, true)
+}
+
+func TestHandshakeChangeRootCAsResumption(t *testing.T) {
+	t.Run("TLS1.2", func(t *testing.T) {
+		testHandshakeChangeRootCAsResumption(t, VersionTLS12)
+	})
+	t.Run("TLS1.3", func(t *testing.T) {
+		testHandshakeChangeRootCAsResumption(t, VersionTLS13)
+	})
+}
+
+func testHandshakeChangeRootCAsResumption(t *testing.T, version uint16) {
+	now := time.Now()
+	tmpl := &x509.Certificate{
+		Subject:               pkix.Name{CommonName: "root"},
+		NotBefore:             now.Add(-time.Hour * 24),
+		NotAfter:              now.Add(time.Hour * 24),
+		IsCA:                  true,
+		BasicConstraintsValid: true,
+	}
+	rootDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
+	rootA, err := x509.ParseCertificate(rootDER)
+	if err != nil {
+		t.Fatalf("ParseCertificate: %v", err)
+	}
+	rootDER, err = x509.CreateCertificate(rand.Reader, tmpl, tmpl, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
+	rootB, err := x509.ParseCertificate(rootDER)
+	if err != nil {
+		t.Fatalf("ParseCertificate: %v", err)
+	}
+
+	tmpl = &x509.Certificate{
+		Subject:   pkix.Name{},
+		DNSNames:  []string{"example.com"},
+		NotBefore: now.Add(-time.Hour * 24),
+		NotAfter:  now.Add(time.Hour * 24),
+		KeyUsage:  x509.KeyUsageDigitalSignature,
+	}
+	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, rootA, &testECDSAPrivateKey.PublicKey, testECDSAPrivateKey)
+	if err != nil {
+		t.Fatalf("CreateCertificate: %v", err)
+	}
+
+	serverConfig := testConfig.Clone()
+	serverConfig.MaxVersion = version
+	serverConfig.Certificates = []Certificate{{
+		Certificate: [][]byte{certDER},
 		PrivateKey:  testECDSAPrivateKey,
 	}}
 	serverConfig.Time = func() time.Time {
-		return now.Add(1*time.Hour + 30*time.Minute)
+		return now
 	}
 	serverConfig.ClientCAs = x509.NewCertPool()
-	serverConfig.ClientCAs.AddCert(freshRoot)
+	serverConfig.ClientCAs.AddCert(rootA)
+	serverConfig.ClientAuth = RequireAndVerifyClientCert
+	serverConfig.InsecureSkipVerify = false
+	serverConfig.ServerName = "example.com"
+
+	clientConfig := testConfig.Clone()
+	clientConfig.MaxVersion = version
+	clientConfig.Certificates = []Certificate{{
+		Certificate: [][]byte{certDER},
+		PrivateKey:  testECDSAPrivateKey,
+	}}
+	clientConfig.ClientSessionCache = NewLRUClientSessionCache(32)
+	clientConfig.RootCAs = x509.NewCertPool()
+	clientConfig.RootCAs.AddCert(rootA)
+	clientConfig.Time = func() time.Time {
+		return now
+	}
+	clientConfig.InsecureSkipVerify = false
+	clientConfig.ServerName = "example.com"
+
+	testResume := func(t *testing.T, sc, cc *Config, expectResume bool) {
+		t.Helper()
+		ss, cs, err := testHandshake(t, cc, sc)
+		if err != nil {
+			t.Fatalf("handshake: %v", err)
+		}
+		if cs.DidResume != expectResume {
+			t.Fatalf("DidResume = %v; want %v", cs.DidResume, expectResume)
+		}
+		if ss.DidResume != expectResume {
+			t.Fatalf("DidResume = %v; want %v", cs.DidResume, expectResume)
+		}
+	}
 
 	testResume(t, serverConfig, clientConfig, false)
+	testResume(t, serverConfig, clientConfig, true)
+
+	clientConfig = clientConfig.Clone()
+	clientConfig.RootCAs = x509.NewCertPool()
+	clientConfig.RootCAs.AddCert(rootB)
+
+	testResume(t, serverConfig, clientConfig, false)
+	testResume(t, serverConfig, clientConfig, true)
 }

src/crypto/tls/handshake_server_tls13.go

@@ -15,6 +15,7 @@ import (
 	"crypto/internal/hpke"
 	"crypto/rsa"
 	"crypto/tls/internal/fips140tls"
+	"crypto/x509"
 	"errors"
 	"fmt"
 	"hash"
@@ -354,7 +355,6 @@ func (hs *serverHandshakeStateTLS13) checkForResumption() error {
 		return nil
 	}
 
-pskIdentityLoop:
 	for i, identity := range hs.clientHello.pskIdentities {
 		if i >= maxClientPSKIdentities {
 			break
@@ -407,16 +407,16 @@ pskIdentityLoop:
 		if sessionHasClientCerts && c.config.ClientAuth == NoClientCert {
 			continue
 		}
-		if sessionHasClientCerts {
-			now := c.config.time()
-			for _, c := range sessionState.peerCertificates {
-				if now.After(c.NotAfter) {
-					continue pskIdentityLoop
-				}
-			}
+		if sessionHasClientCerts && c.config.time().After(sessionState.peerCertificates[0].NotAfter) {
+			continue
+		}
+		opts := x509.VerifyOptions{
+			CurrentTime: c.config.time(),
+			Roots:       c.config.ClientCAs,
+			KeyUsages:   []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
 		}
 		if sessionHasClientCerts && c.config.ClientAuth >= VerifyClientCertIfGiven &&
-			len(sessionState.verifiedChains) == 0 {
+			!anyValidVerifiedChain(sessionState.verifiedChains, opts) {
 			continue
 		}
 

src/crypto/tls/tls_test.go

@@ -935,8 +935,8 @@ func TestCloneNonFuncFields(t *testing.T) {
 		}
 	}
 	// Set the unexported fields related to session ticket keys, which are copied with Clone().
+	c1.autoSessionTicketKeys = []ticketKey{c1.ticketKeyFromBytes(c1.SessionTicketKey)}
 	c1.sessionTicketKeys = []ticketKey{c1.ticketKeyFromBytes(c1.SessionTicketKey)}
-	// We explicitly don't copy autoSessionTicketKeys in Clone, so don't set it.
 
 	c2 := c1.Clone()
 	if !reflect.DeepEqual(&c1, c2) {
@@ -2347,12 +2347,3 @@ func TestECH(t *testing.T) {
 
 	check()
 }
-
-func TestConfigCloneAutoSessionTicketKeys(t *testing.T) {
-	orig := &Config{}
-	orig.ticketKeys(nil)
-	clone := orig.Clone()
-	if slices.Equal(orig.autoSessionTicketKeys, clone.autoSessionTicketKeys) {
-		t.Fatal("autoSessionTicketKeys slice copied in Clone")
-	}
-}

src/crypto/x509/name_constraints_test.go

@@ -1658,6 +1658,22 @@ var nameConstraintsTests = []nameConstraintsTest{
 		},
 		expectedError: "\"*.example.com\" is not permitted",
 	},
+	// #89: a TLD constraint doesn't exclude unrelated wildcards
+	{
+		roots: []constraintsSpec{
+			{
+				bad: []string{"dns:tld"},
+			},
+		},
+		intermediates: [][]constraintsSpec{
+			{
+				{},
+			},
+		},
+		leaf: leafSpec{
+			sans: []string{"dns:*.example.com"},
+		},
+	},
 }
 
 func makeConstraintsCACert(constraints constraintsSpec, name string, key *ecdsa.PrivateKey, parent *Certificate, parentKey *ecdsa.PrivateKey) (*Certificate, error) {

src/crypto/x509/verify.go

@@ -546,7 +546,7 @@ func matchDomainConstraint(domain, constraint string, excluded bool, reversedDom
 		return false, nil
 	}
 
-	if excluded && wildcardDomain && len(domainLabels) > 1 && len(constraintLabels) > 0 {
+	if excluded && wildcardDomain && len(domainLabels) > 1 && len(constraintLabels) > 1 {
 		domainLabels = domainLabels[:len(domainLabels)-1]
 		constraintLabels = constraintLabels[:len(constraintLabels)-1]
 	}