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Backport fix for handling DTLS application_data before handshake

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This commit is contained in:
Daiki Ueno 2018-06-06 11:18:51 +02:00
parent b8c5640659
commit b1121a2732
2 changed files with 159 additions and 4 deletions
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152
nss-dtls-discard-app-data-before-handshake.patch Normal file
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@ -0,0 +1,152 @@
# HG changeset patch
# User Martin Thomson <martin.thomson@gmail.com>
# Date 1523260140 -36000
# Mon Apr 09 17:49:00 2018 +1000
# Node ID 350b7210e90758de454feb4339379ef7f6b9b470
# Parent 5db9e969c74a2a02c4b1d918792827014d1a9d5e
Bug 1452549 - Discard application data that arrives before DTLS handshake completes, r=ekr
diff --git a/gtests/ssl_gtest/ssl_drop_unittest.cc b/gtests/ssl_gtest/ssl_drop_unittest.cc
--- a/gtests/ssl_gtest/ssl_drop_unittest.cc
+++ b/gtests/ssl_gtest/ssl_drop_unittest.cc
@@ -884,6 +884,45 @@ TEST_P(TlsConnectDatagram12Plus, MissAWi
SendReceive();
}
+// This filter replaces the first record it sees with junk application data.
+class TlsReplaceFirstRecordWithJunk : public TlsRecordFilter {
+ public:
+ TlsReplaceFirstRecordWithJunk(const std::shared_ptr<TlsAgent>& a)
+ : TlsRecordFilter(a), replaced_(false) {}
+
+ protected:
+ PacketFilter::Action FilterRecord(const TlsRecordHeader& header,
+ const DataBuffer& record, size_t* offset,
+ DataBuffer* output) override {
+ if (replaced_) {
+ return KEEP;
+ }
+ replaced_ = true;
+ TlsRecordHeader out_header(header.variant(), header.version(),
+ kTlsApplicationDataType,
+ header.sequence_number());
+
+ static const uint8_t junk[] = {1, 2, 3, 4};
+ *offset = out_header.Write(output, *offset, DataBuffer(junk, sizeof(junk)));
+ return CHANGE;
+ }
+
+ private:
+ bool replaced_;
+};
+
+// DTLS needs to discard application_data that it receives prior to handshake
+// completion, not generate an error.
+TEST_P(TlsConnectDatagram, ReplaceFirstServerRecordWithApplicationData) {
+ MakeTlsFilter<TlsReplaceFirstRecordWithJunk>(server_);
+ Connect();
+}
+
+TEST_P(TlsConnectDatagram, ReplaceFirstClientRecordWithApplicationData) {
+ MakeTlsFilter<TlsReplaceFirstRecordWithJunk>(client_);
+ Connect();
+}
+
INSTANTIATE_TEST_CASE_P(Datagram12Plus, TlsConnectDatagram12Plus,
TlsConnectTestBase::kTlsV12Plus);
INSTANTIATE_TEST_CASE_P(DatagramPre13, TlsConnectDatagramPre13,
diff --git a/lib/ssl/ssl3con.c b/lib/ssl/ssl3con.c
--- a/lib/ssl/ssl3con.c
+++ b/lib/ssl/ssl3con.c
@@ -12216,23 +12216,33 @@ ssl3_HandleRecord(sslSocket *ss, SSL3Cip
}
}
-#ifdef UNSAFE_FUZZER_MODE
+ /* Most record types aside from protected TLS 1.3 records carry the content
+ * type in the first octet. TLS 1.3 will override this value later. */
rType = cText->hdr[0];
- rv = Null_Cipher(NULL, plaintext->buf, (int *)&plaintext->len,
- plaintext->space, cText->buf->buf, cText->buf->len);
+ /* Encrypted application data records could arrive before the handshake
+ * completes in DTLS 1.3. These can look like valid TLS 1.2 application_data
+ * records in epoch 0, which is never valid. Pretend they didn't decrypt. */
+ if (spec->epoch == 0 && rType == content_application_data) {
+ PORT_SetError(SSL_ERROR_RX_UNEXPECTED_APPLICATION_DATA);
+ alert = unexpected_message;
+ rv = SECFailure;
+ } else {
+#ifdef UNSAFE_FUZZER_MODE
+ rv = Null_Cipher(NULL, plaintext->buf, (int *)&plaintext->len,
+ plaintext->space, cText->buf->buf, cText->buf->len);
#else
- /* IMPORTANT: Unprotect functions MUST NOT send alerts
- * because we still hold the spec read lock. Instead, if they
- * return SECFailure, they set *alert to the alert to be sent. */
- if (spec->version < SSL_LIBRARY_VERSION_TLS_1_3 ||
- spec->cipherDef->calg == ssl_calg_null) {
- /* Unencrypted TLS 1.3 records use the pre-TLS 1.3 format. */
- rType = cText->hdr[0];
- rv = ssl3_UnprotectRecord(ss, spec, cText, plaintext, &alert);
- } else {
- rv = tls13_UnprotectRecord(ss, spec, cText, plaintext, &rType, &alert);
- }
+ /* IMPORTANT: Unprotect functions MUST NOT send alerts
+ * because we still hold the spec read lock. Instead, if they
+ * return SECFailure, they set *alert to the alert to be sent. */
+ if (spec->version < SSL_LIBRARY_VERSION_TLS_1_3 ||
+ spec->epoch == 0) {
+ rv = ssl3_UnprotectRecord(ss, spec, cText, plaintext, &alert);
+ } else {
+ rv = tls13_UnprotectRecord(ss, spec, cText, plaintext, &rType,
+ &alert);
+ }
#endif
+ }
if (rv != SECSuccess) {
ssl_ReleaseSpecReadLock(ss); /***************************/
@@ -12242,10 +12252,10 @@ ssl3_HandleRecord(sslSocket *ss, SSL3Cip
/* Ensure that we don't process this data again. */
plaintext->len = 0;
- /* Ignore a CCS if the alternative handshake is negotiated. Note that
- * this will fail if the server fails to negotiate the alternative
- * handshake type in a 0-RTT session that is resumed from a session that
- * did negotiate it. We don't care about that corner case right now. */
+ /* Ignore a CCS if compatibility mode is negotiated. Note that this
+ * will fail if the server fails to negotiate compatibility mode in a
+ * 0-RTT session that is resumed from a session that did negotiate it.
+ * We don't care about that corner case right now. */
if (ss->version >= SSL_LIBRARY_VERSION_TLS_1_3 &&
cText->hdr[0] == content_change_cipher_spec &&
ss->ssl3.hs.ws != idle_handshake &&
@@ -12254,19 +12264,20 @@ ssl3_HandleRecord(sslSocket *ss, SSL3Cip
/* Ignore the CCS. */
return SECSuccess;
}
+
if (IS_DTLS(ss) ||
(ss->sec.isServer &&
ss->ssl3.hs.zeroRttIgnore == ssl_0rtt_ignore_trial)) {
/* Silently drop the packet */
return SECSuccess;
- } else {
- int errCode = PORT_GetError();
- SSL3_SendAlert(ss, alert_fatal, alert);
- /* Reset the error code in case SSL3_SendAlert called
- * PORT_SetError(). */
- PORT_SetError(errCode);
- return SECFailure;
- }
+ }
+
+ int errCode = PORT_GetError();
+ SSL3_SendAlert(ss, alert_fatal, alert);
+ /* Reset the error code in case SSL3_SendAlert called
+ * PORT_SetError(). */
+ PORT_SetError(errCode);
+ return SECFailure;
}
/* SECSuccess */

11
nss.spec
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@ -9,7 +9,7 @@ Name: nss
Version: 3.37.3
# for Rawhide, please always use release >= 2
# for Fedora release branches, please use release < 2 (1.0, 1.1, ...)
Release: 1.0%{?dist}
Release: 1.1%{?dist}
License: MPLv2.0
URL: http://www.mozilla.org/projects/security/pki/nss/
Group: System Environment/Libraries
@ -91,6 +91,8 @@ Patch59: nss-check-policy-file.patch
Patch62: nss-skip-util-gtest.patch
# Upstream: https://bugzilla.mozilla.org/show_bug.cgi?id=1458518
Patch63: nss-moz1458518.patch
# Upstream: https://bugzilla.mozilla.org/show_bug.cgi?id=1452549
Patch64: nss-dtls-discard-app-data-before-handshake.patch
%description
Network Security Services (NSS) is a set of libraries designed to
@ -174,6 +176,7 @@ pushd nss
%patch59 -p1 -b .check_policy_file
%patch62 -p1 -b .skip_util_gtest
%patch63 -p1 -b .moz1458518
%patch64 -p1 -b .dtls-discard-app-data
popd
#########################################################
@ -379,9 +382,6 @@ export USE_64
%endif
%endif
# These tests currently fail intermittently
export GTESTFILTER='-GenericDatagram/TlsConnectGeneric.AlertBeforeServerHello:DatagramDrop13/TlsDropDatagram13.DropServerFirstRecordOnce'
export NSS_BLTEST_NOT_AVAILABLE=1
# needed for the fips mangling test
@ -750,6 +750,9 @@ done
%changelog
* Wed Jun 6 2018 Daiki Ueno <dueno@redhat.com> - 3.37.3-1.1
- Backport fix for handling DTLS application_data before handshake
* Tue Jun 5 2018 Daiki Ueno <dueno@redhat.com> - 3.37.3-1.0
- Update to NSS 3.37.3