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crypto/tls: replace all usages of BytesOrPanic

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Message marshalling makes use of BytesOrPanic a lot, under the
assumption that it will never panic. This assumption was incorrect, and
specifically crafted handshakes could trigger panics. Rather than just
surgically replacing the usages of BytesOrPanic in paths that could
panic, replace all usages of it with proper error returns in case there
are other ways of triggering panics which we didn't find.

In one specific case, the tree routed by expandLabel, we replace the
usage of BytesOrPanic, but retain a panic. This function already
explicitly panicked elsewhere, and returning an error from it becomes
rather painful because it requires changing a large number of APIs.
The marshalling is unlikely to ever panic, as the inputs are all either
fixed length, or already limited to the sizes required. If it were to
panic, it'd likely only be during development. A close inspection shows
no paths for a user to cause a panic currently.

This patches ends up being rather large, since it requires routing
errors back through functions which previously had no error returns.
Where possible I've tried to use helpers that reduce the verbosity
of frequently repeated stanzas, and to make the diffs as minimal as
possible.

Thanks to Marten Seemann for reporting this issue.

Fixes #58001
Fixes CVE-2022-41724

Change-Id: Ieb55867ef0a3e1e867b33f09421932510cb58851
Reviewed-on: 1679436
Reviewed-by: Julie Qiu <julieqiu@google.com>
TryBot-Result: Security TryBots <security-trybots@go-security-trybots.iam.gserviceaccount.com>
Run-TryBot: Roland Shoemaker <bracewell@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/468125
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
This commit is contained in:
Roland Shoemaker 2022-12-14 09:43:16 -08:00 • committed by Gopher Robot
parent 58e7190673
commit ba1a41d66f
13 changed files with 657 additions and 503 deletions
Download patch file Download diff file Expand all files Collapse all files

74
handshake_client_tls13.go
View file

@ -62,7 +62,10 @@ func (hs *clientHandshakeStateTLS13) handshake() error {
}
hs.transcript = hs.suite.hash.New()
hs.transcript.Write(hs.hello.marshal())
if err := transcriptMsg(hs.hello, hs.transcript); err != nil {
return err
}
if bytes.Equal(hs.serverHello.random, helloRetryRequestRandom) {
if err := hs.sendDummyChangeCipherSpec(); err != nil {
@ -73,7 +76,9 @@ func (hs *clientHandshakeStateTLS13) handshake() error {
}
}
hs.transcript.Write(hs.serverHello.marshal())
if err := transcriptMsg(hs.serverHello, hs.transcript); err != nil {
return err
}
c.buffering = true
if err := hs.processServerHello(); err != nil {
@ -172,8 +177,7 @@ func (hs *clientHandshakeStateTLS13) sendDummyChangeCipherSpec() error {
}
hs.sentDummyCCS = true
_, err := hs.c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
return err
return hs.c.writeChangeCipherRecord()
}
// processHelloRetryRequest handles the HRR in hs.serverHello, modifies and
@ -188,7 +192,9 @@ func (hs *clientHandshakeStateTLS13) processHelloRetryRequest() error {
hs.transcript.Reset()
hs.transcript.Write([]byte{typeMessageHash, 0, 0, uint8(len(chHash))})
hs.transcript.Write(chHash)
hs.transcript.Write(hs.serverHello.marshal())
if err := transcriptMsg(hs.serverHello, hs.transcript); err != nil {
return err
}
// The only HelloRetryRequest extensions we support are key_share and
// cookie, and clients must abort the handshake if the HRR would not result
@ -253,10 +259,18 @@ func (hs *clientHandshakeStateTLS13) processHelloRetryRequest() error {
transcript := hs.suite.hash.New()
transcript.Write([]byte{typeMessageHash, 0, 0, uint8(len(chHash))})
transcript.Write(chHash)
transcript.Write(hs.serverHello.marshal())
transcript.Write(hs.hello.marshalWithoutBinders())
if err := transcriptMsg(hs.serverHello, hs.transcript); err != nil {
return err
}
helloBytes, err := hs.hello.marshalWithoutBinders()
if err != nil {
return err
}
transcript.Write(helloBytes)
pskBinders := [][]byte{hs.suite.finishedHash(hs.binderKey, transcript)}
hs.hello.updateBinders(pskBinders)
if err := hs.hello.updateBinders(pskBinders); err != nil {
return err
}
} else {
// Server selected a cipher suite incompatible with the PSK.
hs.hello.pskIdentities = nil
@ -264,12 +278,12 @@ func (hs *clientHandshakeStateTLS13) processHelloRetryRequest() error {
}
}
hs.transcript.Write(hs.hello.marshal())
if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
if _, err := hs.c.writeHandshakeRecord(hs.hello, hs.transcript); err != nil {
return err
}
msg, err := c.readHandshake()
// serverHelloMsg is not included in the transcript
msg, err := c.readHandshake(nil)
if err != nil {
return err
}
@ -363,6 +377,7 @@ func (hs *clientHandshakeStateTLS13) establishHandshakeKeys() error {
if !hs.usingPSK {
earlySecret = hs.suite.extract(nil, nil)
}
handshakeSecret := hs.suite.extract(sharedKey,
hs.suite.deriveSecret(earlySecret, "derived", nil))
@ -393,7 +408,7 @@ func (hs *clientHandshakeStateTLS13) establishHandshakeKeys() error {
func (hs *clientHandshakeStateTLS13) readServerParameters() error {
c := hs.c
msg, err := c.readHandshake()
msg, err := c.readHandshake(hs.transcript)
if err != nil {
return err
}
@ -403,7 +418,6 @@ func (hs *clientHandshakeStateTLS13) readServerParameters() error {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(encryptedExtensions, msg)
}
hs.transcript.Write(encryptedExtensions.marshal())
if err := checkALPN(hs.hello.alpnProtocols, encryptedExtensions.alpnProtocol); err != nil {
c.sendAlert(alertUnsupportedExtension)
@ -432,18 +446,16 @@ func (hs *clientHandshakeStateTLS13) readServerCertificate() error {
return nil
}
msg, err := c.readHandshake()
msg, err := c.readHandshake(hs.transcript)
if err != nil {
return err
}
certReq, ok := msg.(*certificateRequestMsgTLS13)
if ok {
hs.transcript.Write(certReq.marshal())
hs.certReq = certReq
msg, err = c.readHandshake()
msg, err = c.readHandshake(hs.transcript)
if err != nil {
return err
}
@ -458,7 +470,6 @@ func (hs *clientHandshakeStateTLS13) readServerCertificate() error {
c.sendAlert(alertDecodeError)
return errors.New("tls: received empty certificates message")
}
hs.transcript.Write(certMsg.marshal())
c.scts = certMsg.certificate.SignedCertificateTimestamps
c.ocspResponse = certMsg.certificate.OCSPStaple
@ -467,7 +478,10 @@ func (hs *clientHandshakeStateTLS13) readServerCertificate() error {
return err
}
msg, err = c.readHandshake()
// certificateVerifyMsg is included in the transcript, but not until
// after we verify the handshake signature, since the state before
// this message was sent is used.
msg, err = c.readHandshake(nil)
if err != nil {
return err
}
@ -498,7 +512,9 @@ func (hs *clientHandshakeStateTLS13) readServerCertificate() error {
return errors.New("tls: invalid signature by the server certificate: " + err.Error())
}
hs.transcript.Write(certVerify.marshal())
if err := transcriptMsg(certVerify, hs.transcript); err != nil {
return err
}
return nil
}
@ -506,7 +522,10 @@ func (hs *clientHandshakeStateTLS13) readServerCertificate() error {
func (hs *clientHandshakeStateTLS13) readServerFinished() error {
c := hs.c
msg, err := c.readHandshake()
// finishedMsg is included in the transcript, but not until after we
// check the client version, since the state before this message was
// sent is used during verification.
msg, err := c.readHandshake(nil)
if err != nil {
return err
}
@ -523,7 +542,9 @@ func (hs *clientHandshakeStateTLS13) readServerFinished() error {
return errors.New("tls: invalid server finished hash")
}
hs.transcript.Write(finished.marshal())
if err := transcriptMsg(finished, hs.transcript); err != nil {
return err
}
// Derive secrets that take context through the server Finished.
@ -572,8 +593,7 @@ func (hs *clientHandshakeStateTLS13) sendClientCertificate() error {
certMsg.scts = hs.certReq.scts && len(cert.SignedCertificateTimestamps) > 0
certMsg.ocspStapling = hs.certReq.ocspStapling && len(cert.OCSPStaple) > 0
hs.transcript.Write(certMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
if _, err := hs.c.writeHandshakeRecord(certMsg, hs.transcript); err != nil {
return err
}
@ -610,8 +630,7 @@ func (hs *clientHandshakeStateTLS13) sendClientCertificate() error {
}
certVerifyMsg.signature = sig
hs.transcript.Write(certVerifyMsg.marshal())
if _, err := c.writeRecord(recordTypeHandshake, certVerifyMsg.marshal()); err != nil {
if _, err := hs.c.writeHandshakeRecord(certVerifyMsg, hs.transcript); err != nil {
return err
}
@ -625,8 +644,7 @@ func (hs *clientHandshakeStateTLS13) sendClientFinished() error {
verifyData: hs.suite.finishedHash(c.out.trafficSecret, hs.transcript),
}
hs.transcript.Write(finished.marshal())
if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil {
if _, err := hs.c.writeHandshakeRecord(finished, hs.transcript); err != nil {
return err
}