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Revert the last change, tolerate the first CCS in TLS 1.3

This commit is contained in:
Daiki Ueno 2020-10-26 06:55:42 +01:00
parent 127b34cee4
commit 97a26627f0
2 changed files with 136 additions and 14 deletions
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145
nss-ccs.patch
View File

@ -1,13 +1,132 @@
Index: nss/lib/ssl/sslsock.c
===================================================================
--- nss.orig/lib/ssl/sslsock.c
+++ nss/lib/ssl/sslsock.c
@@ -86,7 +86,7 @@ static sslOptions ssl_defaults = {
.enableSignedCertTimestamps = PR_FALSE,
.requireDHENamedGroups = PR_FALSE,
.enable0RttData = PR_FALSE,
- .enableTls13CompatMode = PR_FALSE,
+ .enableTls13CompatMode = PR_TRUE,
.enableDtls13VersionCompat = PR_FALSE,
.enableDtlsShortHeader = PR_FALSE,
.enableHelloDowngradeCheck = PR_FALSE,
# HG changeset patch
# User Daiki Ueno <dueno@redhat.com>
# Date 1603691171 -3600
# Mon Oct 26 06:46:11 2020 +0100
# Node ID b03a4fc5b902498414b02640dcb2717dfef9682f
# Parent 6f79a76958129dc09c353c288f115fd9a51ab7d4
Bug 1672703, always tolerate the first CCS in TLS 1.3, r=mt
Summary:
This flips the meaning of the flag for checking excessive CCS
messages, so it only rejects multiple CCS messages while the first CCS
message is always accepted.
Reviewers: mt
Reviewed By: mt
Bug #: 1672703
Differential Revision: https://phabricator.services.mozilla.com/D94603
diff -r 6f79a7695812 -r b03a4fc5b902 gtests/ssl_gtest/ssl_tls13compat_unittest.cc
--- a/gtests/ssl_gtest/ssl_tls13compat_unittest.cc Fri Oct 23 16:14:36 2020 -0700
+++ b/gtests/ssl_gtest/ssl_tls13compat_unittest.cc Mon Oct 26 06:46:11 2020 +0100
@@ -348,8 +348,8 @@
client_->CheckErrorCode(SSL_ERROR_HANDSHAKE_UNEXPECTED_ALERT);
}
-// The server rejects a ChangeCipherSpec if the client advertises an
-// empty session ID.
+// The server accepts a ChangeCipherSpec even if the client advertises
+// an empty session ID.
TEST_F(TlsConnectStreamTls13, ChangeCipherSpecAfterClientHelloEmptySid) {
EnsureTlsSetup();
ConfigureVersion(SSL_LIBRARY_VERSION_TLS_1_3);
@@ -358,9 +358,8 @@
client_->Handshake(); // Send ClientHello
client_->SendDirect(DataBuffer(kCannedCcs, sizeof(kCannedCcs))); // Send CCS
- server_->ExpectSendAlert(kTlsAlertUnexpectedMessage);
- server_->Handshake(); // Consume ClientHello and CCS
- server_->CheckErrorCode(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER);
+ Handshake();
+ CheckConnected();
}
// The server rejects multiple ChangeCipherSpec even if the client
@@ -381,7 +380,7 @@
server_->CheckErrorCode(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER);
}
-// The client rejects a ChangeCipherSpec if it advertises an empty
+// The client accepts a ChangeCipherSpec even if it advertises an empty
// session ID.
TEST_F(TlsConnectStreamTls13, ChangeCipherSpecAfterServerHelloEmptySid) {
EnsureTlsSetup();
@@ -398,9 +397,10 @@
// send ServerHello..CertificateVerify
// Send CCS
server_->SendDirect(DataBuffer(kCannedCcs, sizeof(kCannedCcs)));
- client_->ExpectSendAlert(kTlsAlertUnexpectedMessage);
- client_->Handshake(); // Consume ClientHello and CCS
- client_->CheckErrorCode(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER);
+
+ // No alert is sent from the client. As Finished is dropped, we
+ // can't use Handshake() and CheckConnected().
+ client_->Handshake();
}
// The client rejects multiple ChangeCipherSpec in a row even if the
diff -r 6f79a7695812 -r b03a4fc5b902 lib/ssl/ssl3con.c
--- a/lib/ssl/ssl3con.c Fri Oct 23 16:14:36 2020 -0700
+++ b/lib/ssl/ssl3con.c Mon Oct 26 06:46:11 2020 +0100
@@ -6645,11 +6645,7 @@
/* TLS 1.3: We sent a session ID. The server's should match. */
if (!IS_DTLS(ss) && (sentRealSid || sentFakeSid)) {
- if (sidMatch) {
- ss->ssl3.hs.allowCcs = PR_TRUE;
- return PR_TRUE;
- }
- return PR_FALSE;
+ return sidMatch;
}
/* TLS 1.3 (no SID)/DTLS 1.3: The server shouldn't send a session ID. */
@@ -8696,7 +8692,6 @@
errCode = PORT_GetError();
goto alert_loser;
}
- ss->ssl3.hs.allowCcs = PR_TRUE;
}
/* TLS 1.3 requires that compression include only null. */
@@ -13066,15 +13061,14 @@
ss->ssl3.hs.ws != idle_handshake &&
cText->buf->len == 1 &&
cText->buf->buf[0] == change_cipher_spec_choice) {
- if (ss->ssl3.hs.allowCcs) {
- /* Ignore the first CCS. */
- ss->ssl3.hs.allowCcs = PR_FALSE;
+ if (!ss->ssl3.hs.rejectCcs) {
+ /* Allow only the first CCS. */
+ ss->ssl3.hs.rejectCcs = PR_TRUE;
return SECSuccess;
- }
-
- /* Compatibility mode is not negotiated. */
- alert = unexpected_message;
- PORT_SetError(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER);
+ } else {
+ alert = unexpected_message;
+ PORT_SetError(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER);
+ }
}
if ((IS_DTLS(ss) && !dtls13_AeadLimitReached(spec)) ||
diff -r 6f79a7695812 -r b03a4fc5b902 lib/ssl/sslimpl.h
--- a/lib/ssl/sslimpl.h Fri Oct 23 16:14:36 2020 -0700
+++ b/lib/ssl/sslimpl.h Mon Oct 26 06:46:11 2020 +0100
@@ -710,10 +710,7 @@
* or received. */
PRBool receivedCcs; /* A server received ChangeCipherSpec
* before the handshake started. */
- PRBool allowCcs; /* A server allows ChangeCipherSpec
- * as the middlebox compatibility mode
- * is explicitly indicarted by
- * legacy_session_id in TLS 1.3 ClientHello. */
+ PRBool rejectCcs; /* Excessive ChangeCipherSpecs are rejected. */
PRBool clientCertRequested; /* True if CertificateRequest received. */
PRBool endOfFlight; /* Processed a full flight (DTLS 1.3). */
ssl3KEADef kea_def_mutable; /* Used to hold the writable kea_def

5
nss.spec
View File

@ -44,7 +44,7 @@ rpm.define(string.format("nss_release_tag NSS_%s_RTM",
Summary: Network Security Services
Name: nss
Version: %{nss_version}
Release: 2%{?dist}
Release: 3%{?dist}
License: MPLv2.0
URL: http://www.mozilla.org/projects/security/pki/nss/
Requires: nspr >= %{nspr_version}
@ -904,6 +904,9 @@ update-crypto-policies &> /dev/null || :
%changelog
* Mon Oct 26 2020 Daiki Ueno <dueno@redhat.com> - 3.58.0-3
- Revert the last change, always tolerate the first CCS in TLS 1.3
* Thu Oct 22 2020 Daiki Ueno <dueno@redhat.com> - 3.58.0-2
- Enable TLS 1.3 middlebox compatibility mode by default