From: Tero Saarni <tero.saarni@gmail.com>
Date: Wed, 12 Apr 2023 10:07:07 +0000 (+0000)
Subject: crypto/tls: fix PSK binder calculation
X-Git-Tag: go1.21rc1~795
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=2c70690451f1484607a9172a4c24f78ae832dcb0;p=gostls13.git

crypto/tls: fix PSK binder calculation

When server and client have mismatch in curve preference, the server will
send HelloRetryRequest during TLSv1.3 PSK resumption. There was a bug
introduced by Go1.19.6 or later and Go1.20.1 or later, that makes the client
calculate the PSK binder hash incorrectly. Server will reject the TLS
handshake by sending alert: invalid PSK binder.

Fixes #59424

Change-Id: I2ca8948474275740a36d991c057b62a13392dbb9
GitHub-Last-Rev: 1aad9bcf27f563449c1a7ed6d0dd1d247cc65713
GitHub-Pull-Request: golang/go#59425
Reviewed-on: https://go-review.googlesource.com/c/go/+/481955
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Roland Shoemaker <roland@golang.org>
---

diff --git a/src/crypto/tls/handshake_client_test.go b/src/crypto/tls/handshake_client_test.go
index 749c9fc954..22be38faff 100644
--- a/src/crypto/tls/handshake_client_test.go
+++ b/src/crypto/tls/handshake_client_test.go
@@ -1028,6 +1028,27 @@ func testResumption(t *testing.T, version uint16) {
 	deleteTicket()
 	testResumeState("WithoutSessionTicket", false)
 
+	// In TLS 1.3, HelloRetryRequest is sent after incorrect key share.
+	// See https://www.rfc-editor.org/rfc/rfc8446#page-14.
+	if version == VersionTLS13 {
+		deleteTicket()
+		serverConfig = &Config{
+			// Use a different curve than the client to force a HelloRetryRequest.
+			CurvePreferences: []CurveID{CurveP521, CurveP384, CurveP256},
+			MaxVersion:       version,
+			Certificates:     testConfig.Certificates,
+		}
+		testResumeState("InitialHandshake", false)
+		testResumeState("WithHelloRetryRequest", true)
+
+		// Reset serverConfig back.
+		serverConfig = &Config{
+			MaxVersion:   version,
+			CipherSuites: []uint16{TLS_RSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_RC4_128_SHA},
+			Certificates: testConfig.Certificates,
+		}
+	}
+
 	// Session resumption should work when using client certificates
 	deleteTicket()
 	serverConfig.ClientCAs = rootCAs
diff --git a/src/crypto/tls/handshake_client_tls13.go b/src/crypto/tls/handshake_client_tls13.go
index fefba01a06..4a8661085e 100644
--- a/src/crypto/tls/handshake_client_tls13.go
+++ b/src/crypto/tls/handshake_client_tls13.go
@@ -259,7 +259,7 @@ func (hs *clientHandshakeStateTLS13) processHelloRetryRequest() error {
 			transcript := hs.suite.hash.New()
 			transcript.Write([]byte{typeMessageHash, 0, 0, uint8(len(chHash))})
 			transcript.Write(chHash)
-			if err := transcriptMsg(hs.serverHello, hs.transcript); err != nil {
+			if err := transcriptMsg(hs.serverHello, transcript); err != nil {
 				return err
 			}
 			helloBytes, err := hs.hello.marshalWithoutBinders()