From d5987bff8ab92b4d96667ca960faeb92b97d5e75 Mon Sep 17 00:00:00 2001 From: Roland Shoemaker Date: Mon, 26 Jan 2026 11:18:45 -0800 Subject: [PATCH] [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 Reviewed-by: Dmitri Shuralyov LUCI-TryBot-Result: Go LUCI Reviewed-by: Coia Prant Reviewed-by: Filippo Valsorda Reviewed-on: https://go-review.googlesource.com/c/go/+/740065 Auto-Submit: Dmitri Shuralyov Reviewed-by: Nicholas Husin Reviewed-by: Damien Neil Reviewed-by: Nicholas Husin --- src/crypto/tls/common.go | 25 ++- src/crypto/tls/handshake_client.go | 7 +- src/crypto/tls/handshake_server.go | 7 +- src/crypto/tls/handshake_server_test.go | 214 +++++++++++++++++++++++ src/crypto/tls/handshake_server_tls13.go | 8 +- 5 files changed, 253 insertions(+), 8 deletions(-) diff --git a/src/crypto/tls/common.go b/src/crypto/tls/common.go index 7208e69334a..074701eb5de 100644 --- a/src/crypto/tls/common.go +++ b/src/crypto/tls/common.go @@ -1804,13 +1804,28 @@ func fipsAllowChain(chain []*x509.Certificate) bool { return true } -// anyUnexpiredChain reports if at least one of verifiedChains is still -// unexpired. If verifiedChains is empty, it returns false. -func anyUnexpiredChain(verifiedChains [][]*x509.Certificate, now time.Time) bool { +// 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 && !slices.ContainsFunc(chain, func(cert *x509.Certificate) bool { - return now.Before(cert.NotBefore) || now.After(cert.NotAfter) // cert is expired + 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 } } diff --git a/src/crypto/tls/handshake_client.go b/src/crypto/tls/handshake_client.go index 3752df09b6d..b1bbff23632 100644 --- a/src/crypto/tls/handshake_client.go +++ b/src/crypto/tls/handshake_client.go @@ -444,7 +444,12 @@ func (c *Conn) loadSession(hello *clientHelloMsg) ( // application from a faulty ClientSessionCache implementation. return nil, nil, nil, nil } - if !anyUnexpiredChain(session.verifiedChains, c.config.time()) { + 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 diff --git a/src/crypto/tls/handshake_server.go b/src/crypto/tls/handshake_server.go index d4d05e54629..2f321f85946 100644 --- a/src/crypto/tls/handshake_server.go +++ b/src/crypto/tls/handshake_server.go @@ -523,8 +523,13 @@ func (hs *serverHandshakeState) checkForResumption() error { 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 && - !anyUnexpiredChain(sessionState.verifiedChains, c.config.time()) { + !anyValidVerifiedChain(sessionState.verifiedChains, opts) { return nil } diff --git a/src/crypto/tls/handshake_server_test.go b/src/crypto/tls/handshake_server_test.go index 406dab48eef..249767b1e46 100644 --- a/src/crypto/tls/handshake_server_test.go +++ b/src/crypto/tls/handshake_server_test.go @@ -2243,3 +2243,217 @@ func testHandshakeChainExpiryResumption(t *testing.T, version uint16) { 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{certDER}, + PrivateKey: testECDSAPrivateKey, + }} + 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{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) + + // 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 + } + serverConfig.ClientCAs = x509.NewCertPool() + 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) +} diff --git a/src/crypto/tls/handshake_server_tls13.go b/src/crypto/tls/handshake_server_tls13.go index 3dba595331d..a4b205908ed 100644 --- a/src/crypto/tls/handshake_server_tls13.go +++ b/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" @@ -409,8 +410,13 @@ func (hs *serverHandshakeStateTLS13) checkForResumption() error { 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 && - !anyUnexpiredChain(sessionState.verifiedChains, c.config.time()) { + !anyValidVerifiedChain(sessionState.verifiedChains, opts) { continue }