diff options
Diffstat (limited to 'backport-CVE-2020-25648-tighten-CSS-handling-in-compatibility-mode.patch')
| -rw-r--r-- | backport-CVE-2020-25648-tighten-CSS-handling-in-compatibility-mode.patch | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/backport-CVE-2020-25648-tighten-CSS-handling-in-compatibility-mode.patch b/backport-CVE-2020-25648-tighten-CSS-handling-in-compatibility-mode.patch new file mode 100644 index 0000000..fc0a5bd --- /dev/null +++ b/backport-CVE-2020-25648-tighten-CSS-handling-in-compatibility-mode.patch @@ -0,0 +1,122 @@ +From e10a362f69191506e73bfa31778da45f4c5df482 Mon Sep 17 00:00:00 2001 +From: Daiki Ueno <dueno@redhat.com> +Date: Mon, 12 Oct 2020 17:42:01 +0000 +Subject: [PATCH] Bug 1641480, TLS 1.3: tighten CCS handling in compatibility + mode, r=mt + +This makes the server reject CCS when the client doesn't indicate the +use of the middlebox compatibility mode with a non-empty +ClientHello.legacy_session_id, or it sends multiple CCS in a row. + +Differential Revision: https://phabricator.services.mozilla.com/D79994 + +--HG-- +extra : moz-landing-system : lando +--- + gtests/ssl_gtest/ssl_tls13compat_unittest.cc | 33 ++++++++++++++++++++ + lib/ssl/ssl3con.c | 18 ++++- + lib/ssl/sslimpl.h | 4 + + 3 files changed, 52 insertions(+), 3 deletions(-) + +diff --git a/nss/gtests/ssl_gtest/ssl_tls13compat_unittest.cc b/nss/gtests/ssl_gtest/ssl_tls13compat_unittest.cc +index 6905ed0c0..dcede798c 100644 +--- a/nss/gtests/ssl_gtest/ssl_tls13compat_unittest.cc ++++ b/nss/gtests/ssl_gtest/ssl_tls13compat_unittest.cc +@@ -348,6 +348,39 @@ TEST_F(TlsConnectStreamTls13, ChangeCipherSpecBeforeClientHelloTwice) { + client_->CheckErrorCode(SSL_ERROR_HANDSHAKE_UNEXPECTED_ALERT); + } + ++// The server rejects a ChangeCipherSpec if the client advertises an ++// empty session ID. ++TEST_F(TlsConnectStreamTls13, ChangeCipherSpecAfterClientHelloEmptySid) { ++ EnsureTlsSetup(); ++ ConfigureVersion(SSL_LIBRARY_VERSION_TLS_1_3); ++ ++ StartConnect(); ++ 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); ++} ++ ++// The server rejects multiple ChangeCipherSpec even if the client ++// indicates compatibility mode with non-empty session ID. ++TEST_F(Tls13CompatTest, ChangeCipherSpecAfterClientHelloTwice) { ++ EnsureTlsSetup(); ++ ConfigureVersion(SSL_LIBRARY_VERSION_TLS_1_3); ++ EnableCompatMode(); ++ ++ StartConnect(); ++ client_->Handshake(); // Send ClientHello ++ // Send CCS twice in a row ++ client_->SendDirect(DataBuffer(kCannedCcs, sizeof(kCannedCcs))); ++ client_->SendDirect(DataBuffer(kCannedCcs, sizeof(kCannedCcs))); ++ ++ server_->ExpectSendAlert(kTlsAlertUnexpectedMessage); ++ server_->Handshake(); // Consume ClientHello and CCS. ++ server_->CheckErrorCode(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER); ++} ++ + // If we negotiate 1.2, we abort. + TEST_F(TlsConnectStreamTls13, ChangeCipherSpecBeforeClientHello12) { + EnsureTlsSetup(); +diff --git a/nss/lib/ssl/ssl3con.c b/nss/lib/ssl/ssl3con.c +index 8be53d357..5f22872f8 100644 +--- a/nss/lib/ssl/ssl3con.c ++++ b/nss/lib/ssl/ssl3con.c +@@ -6645,7 +6645,11 @@ ssl_CheckServerSessionIdCorrectness(sslSocket *ss, SECItem *sidBytes) + + /* TLS 1.3: We sent a session ID. The server's should match. */ + if (!IS_DTLS(ss) && (sentRealSid || sentFakeSid)) { +- return sidMatch; ++ if (sidMatch) { ++ ss->ssl3.hs.allowCcs = PR_TRUE; ++ return PR_TRUE; ++ } ++ return PR_FALSE; + } + + /* TLS 1.3 (no SID)/DTLS 1.3: The server shouldn't send a session ID. */ +@@ -8692,6 +8696,7 @@ ssl3_HandleClientHello(sslSocket *ss, PRUint8 *b, PRUint32 length) + errCode = PORT_GetError(); + goto alert_loser; + } ++ ss->ssl3.hs.allowCcs = PR_TRUE; + } + + /* TLS 1.3 requires that compression include only null. */ +@@ -13061,8 +13066,15 @@ ssl3_HandleRecord(sslSocket *ss, SSL3Ciphertext *cText) + ss->ssl3.hs.ws != idle_handshake && + cText->buf->len == 1 && + cText->buf->buf[0] == change_cipher_spec_choice) { +- /* Ignore the CCS. */ +- return SECSuccess; ++ if (ss->ssl3.hs.allowCcs) { ++ /* Ignore the first CCS. */ ++ ss->ssl3.hs.allowCcs = PR_FALSE; ++ return SECSuccess; ++ } ++ ++ /* Compatibility mode is not negotiated. */ ++ alert = unexpected_message; ++ PORT_SetError(SSL_ERROR_RX_MALFORMED_CHANGE_CIPHER); + } + + if (IS_DTLS(ss) || +diff --git a/nss/lib/ssl/sslimpl.h b/nss/lib/ssl/sslimpl.h +index b0e44a088..44c43a0e6 100644 +--- a/nss/lib/ssl/sslimpl.h ++++ b/nss/lib/ssl/sslimpl.h +@@ -710,6 +710,10 @@ typedef struct SSL3HandshakeStateStr { + * 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 clientCertRequested; /* True if CertificateRequest received. */ + ssl3KEADef kea_def_mutable; /* Used to hold the writable kea_def + * we use for TLS 1.3 */ |