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crypto/tls: don't reverify but check certificate expiration on resumption

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We used to inconsistently run certificate verification on the server on
resumption, but not on the client. This made TLS 1.3 resumption pretty
much useless, as it didn't save bytes, CPU, or round-trips.

This requires serializing the verified chains into the session ticket,
so it's a tradeoff making the ticket bigger to save computation (and for
consistency).

The previous behavior also had a "stickyness" issue: if a ticket
contained invalid certificates, they would be used even if the client
had in the meantime configured valid certificates for a full handshake.

We also didn't check expiration on the client side on resumption if
InsecureSkipVerify was set. Again for consistency, we do that now.

Also, we used to run VerifyPeerCertificates on resumption even if
NoClientCerts was set.

Fixes #31641

Change-Id: Icc88269ea4adb544fa81158114aae76f3c91a15f
Reviewed-on: https://go-review.googlesource.com/c/go/+/497895
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
This commit is contained in:
yuhan6665 2023-10-14 09:37:11 -04:00
parent f8cbf5ad3a
commit 84d465d671
5 changed files with 96 additions and 86 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
common.go
View File

@ -618,10 +618,16 @@ type Config struct {
// non-nil error, the handshake is aborted and that error results.
//
// If normal verification fails then the handshake will abort before
// considering this callback. If normal verification is disabled by
// setting InsecureSkipVerify, or (for a server) when ClientAuth is
// RequestClientCert or RequireAnyClientCert, then this callback will
// be considered but the verifiedChains argument will always be nil.
// considering this callback. If normal verification is disabled (on the
// client when InsecureSkipVerify is set, or on a server when ClientAuth is
// RequestClientCert or RequireAnyClientCert), then this callback will be
// considered but the verifiedChains argument will always be nil. When
// ClientAuth is NoClientCert, this callback is not called on the server.
// rawCerts may be empty on the server if ClientAuth is RequestClientCert or
// VerifyClientCertIfGiven.
//
// This callback is not invoked on resumed connections, as certificates are
// not re-verified on resumption.
//
// verifiedChains and its contents should not be modified.
VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error
@ -632,8 +638,9 @@ type Config struct {
// and that error results.
//
// If normal verification fails then the handshake will abort before
// considering this callback. This callback will run for all connections
// regardless of InsecureSkipVerify or ClientAuth settings.
// considering this callback. This callback will run for all connections,
// including resumptions, regardless of InsecureSkipVerify or ClientAuth
// settings.
VerifyConnection func(ConnectionState) error
// RootCAs defines the set of root certificate authorities

13
handshake_client.go
View File

@ -319,18 +319,17 @@ func (c *Conn) loadSession(hello *clientHelloMsg) (
// 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)
return nil, nil, nil, nil
}
if !c.config.InsecureSkipVerify {
if len(session.verifiedChains) == 0 {
// The original connection had InsecureSkipVerify, while this doesn't.
return nil, nil, nil, nil
}
serverCert := session.peerCertificates[0]
if c.config.time().After(serverCert.NotAfter) {
// Expired certificate, delete the entry.
c.config.ClientSessionCache.Put(cacheKey, nil)
return nil, nil, nil, nil
}
if err := serverCert.VerifyHostname(c.config.ServerName); err != nil {
if err := session.peerCertificates[0].VerifyHostname(c.config.ServerName); err != nil {
return nil, nil, nil, nil
}
}

18
handshake_server.go
View File

@ -471,6 +471,13 @@ func (hs *serverHandshakeState) checkForResumption() error {
if sessionHasClientCerts && c.config.ClientAuth == NoClientCert {
return nil
}
if sessionHasClientCerts && c.config.time().After(sessionState.peerCertificates[0].NotAfter) {
return nil
}
if sessionHasClientCerts && c.config.ClientAuth >= VerifyClientCertIfGiven &&
len(sessionState.verifiedChains) == 0 {
return nil
}
// RFC 7627, Section 5.3
if !sessionState.extMasterSecret && hs.clientHello.extendedMasterSecret {
@ -482,6 +489,10 @@ func (hs *serverHandshakeState) checkForResumption() error {
return errors.New("tls: session supported extended_master_secret but client does not")
}
c.peerCertificates = sessionState.peerCertificates
c.ocspResponse = sessionState.ocspResponse
c.scts = sessionState.scts
c.verifiedChains = sessionState.verifiedChains
c.extMasterSecret = sessionState.extMasterSecret
hs.sessionState = sessionState
hs.suite = suite
@ -510,10 +521,6 @@ func (hs *serverHandshakeState) doResumeHandshake() error {
return err
}
if err := c.processCertsFromClient(hs.sessionState.certificate()); err != nil {
return err
}
if c.config.VerifyConnection != nil {
if err := c.config.VerifyConnection(c.connectionStateLocked()); err != nil {
c.sendAlert(alertBadCertificate)
@ -847,8 +854,7 @@ func (hs *serverHandshakeState) sendFinished(out []byte) error {
}
// processCertsFromClient takes a chain of client certificates either from a
// Certificates message or from a sessionState and verifies them. It returns
// the public key of the leaf certificate.
// Certificates message and verifies them.
func (c *Conn) processCertsFromClient(certificate Certificate) error {
certificates := certificate.Certificate
certs := make([]*x509.Certificate, len(certificates))

14
handshake_server_tls13.go
View File

@ -387,6 +387,13 @@ func (hs *serverHandshakeStateTLS13) checkForResumption() error {
if sessionHasClientCerts && c.config.ClientAuth == NoClientCert {
continue
}
if sessionHasClientCerts && c.config.time().After(sessionState.peerCertificates[0].NotAfter) {
continue
}
if sessionHasClientCerts && c.config.ClientAuth >= VerifyClientCertIfGiven &&
len(sessionState.verifiedChains) == 0 {
continue
}
hs.earlySecret = hs.suite.extract(sessionState.secret, nil)
binderKey := hs.suite.deriveSecret(hs.earlySecret, resumptionBinderLabel, nil)
@ -422,9 +429,10 @@ func (hs *serverHandshakeStateTLS13) checkForResumption() error {
}
c.didResume = true
if err := c.processCertsFromClient(sessionState.certificate()); err != nil {
return err
}
c.peerCertificates = sessionState.peerCertificates
c.ocspResponse = sessionState.ocspResponse
c.scts = sessionState.scts
c.verifiedChains = sessionState.verifiedChains
hs.hello.selectedIdentityPresent = true
hs.hello.selectedIdentity = uint16(i)

96
ticket.go
View File

@ -37,16 +37,16 @@ type SessionState struct {
// uint8 ext_master_secret = { 0, 1 };
// uint8 early_data = { 0, 1 };
// CertificateEntry certificate_list<0..2^24-1>;
// CertificateChain verified_chains<0..2^24-1>; /* excluding leaf */
// select (SessionState.early_data) {
// case 0: Empty;
// case 1: opaque alpn<1..2^8-1>;
// };
// select (SessionState.type) {
// case server: /* empty */;
// case server: Empty;
// case client: struct {
// CertificateChain verified_chains<0..2^24-1>; /* excluding leaf */
// select (SessionState.version) {
// case VersionTLS10..VersionTLS12: /* empty */;
// case VersionTLS10..VersionTLS12: Empty;
// case VersionTLS13: struct {
// uint64 use_by;
// uint32 age_add;
@ -87,10 +87,8 @@ type SessionState struct {
activeCertHandles []*activeCert
ocspResponse []byte
scts [][]byte
alpnProtocol string // only set if EarlyData is true
// Client-side fields.
verifiedChains [][]*x509.Certificate
alpnProtocol string // only set if EarlyData is true
// Client-side TLS 1.3-only fields.
useBy uint64 // seconds since UNIX epoch
@ -129,13 +127,11 @@ func (s *SessionState) Bytes() ([]byte, error) {
} else {
b.AddUint8(0)
}
marshalCertificate(&b, s.certificate())
if s.EarlyData {
b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
b.AddBytes([]byte(s.alpnProtocol))
marshalCertificate(&b, Certificate{
Certificate: certificatesToBytesSlice(s.peerCertificates),
OCSPStaple: s.ocspResponse,
SignedCertificateTimestamps: s.scts,
})
}
if s.isClient {
b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
for _, chain := range s.verifiedChains {
b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
@ -152,6 +148,12 @@ func (s *SessionState) Bytes() ([]byte, error) {
})
}
})
if s.EarlyData {
b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
b.AddBytes([]byte(s.alpnProtocol))
})
}
if s.isClient {
if s.version >= VersionTLS13 {
addUint64(&b, s.useBy)
b.AddUint32(s.ageAdd)
@ -160,14 +162,6 @@ func (s *SessionState) Bytes() ([]byte, error) {
return b.Bytes()
}
func (s *SessionState) certificate() Certificate {
return Certificate{
Certificate: certificatesToBytesSlice(s.peerCertificates),
OCSPStaple: s.ocspResponse,
SignedCertificateTimestamps: s.scts,
}
}
func certificatesToBytesSlice(certs []*x509.Certificate) [][]byte {
s := make([][]byte, 0, len(certs))
for _, c := range certs {
@ -221,6 +215,34 @@ func ParseSessionState(data []byte) (*SessionState, error) {
}
ss.ocspResponse = cert.OCSPStaple
ss.scts = cert.SignedCertificateTimestamps
var chainList cryptobyte.String
if !s.ReadUint24LengthPrefixed(&chainList) {
return nil, errors.New("tls: invalid session encoding")
}
for !chainList.Empty() {
var certList cryptobyte.String
if !chainList.ReadUint24LengthPrefixed(&certList) {
return nil, errors.New("tls: invalid session encoding")
}
var chain []*x509.Certificate
if len(ss.peerCertificates) == 0 {
return nil, errors.New("tls: invalid session encoding")
}
chain = append(chain, ss.peerCertificates[0])
for !certList.Empty() {
var cert []byte
if !readUint24LengthPrefixed(&certList, &cert) {
return nil, errors.New("tls: invalid session encoding")
}
c, err := globalCertCache.newCert(cert)
if err != nil {
return nil, err
}
ss.activeCertHandles = append(ss.activeCertHandles, c)
chain = append(chain, c.cert)
}
ss.verifiedChains = append(ss.verifiedChains, chain)
}
if ss.EarlyData {
var alpn []byte
if !readUint8LengthPrefixed(&s, &alpn) {
@ -238,31 +260,6 @@ func ParseSessionState(data []byte) (*SessionState, error) {
if len(ss.peerCertificates) == 0 {
return nil, errors.New("tls: no server certificates in client session")
}
var chainList cryptobyte.String
if !s.ReadUint24LengthPrefixed(&chainList) {
return nil, errors.New("tls: invalid session encoding")
}
for !chainList.Empty() {
var certList cryptobyte.String
if !chainList.ReadUint24LengthPrefixed(&certList) {
return nil, errors.New("tls: invalid session encoding")
}
var chain []*x509.Certificate
chain = append(chain, ss.peerCertificates[0])
for !certList.Empty() {
var cert []byte
if !readUint24LengthPrefixed(&certList, &cert) {
return nil, errors.New("tls: invalid session encoding")
}
c, err := globalCertCache.newCert(cert)
if err != nil {
return nil, err
}
ss.activeCertHandles = append(ss.activeCertHandles, c)
chain = append(chain, c.cert)
}
ss.verifiedChains = append(ss.verifiedChains, chain)
}
if ss.version < VersionTLS13 {
if !s.Empty() {
return nil, errors.New("tls: invalid session encoding")
@ -278,13 +275,6 @@ func ParseSessionState(data []byte) (*SessionState, error) {
// sessionState returns a partially filled-out [SessionState] with information
// from the current connection.
func (c *Conn) sessionState() (*SessionState, error) {
var verifiedChains [][]*x509.Certificate
if c.isClient {
verifiedChains = c.verifiedChains
if len(c.peerCertificates) == 0 {
return nil, errors.New("tls: internal error: empty peer certificates")
}
}
return &SessionState{
version: c.vers,
cipherSuite: c.cipherSuite,
@ -296,7 +286,7 @@ func (c *Conn) sessionState() (*SessionState, error) {
scts: c.scts,
isClient: c.isClient,
extMasterSecret: c.extMasterSecret,
verifiedChains: verifiedChains,
verifiedChains: c.verifiedChains,
}, nil
}