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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "sslerr.h"
#include "tls_connect.h"
#include "tls_filter.h"
#include "tls_parser.h"
/*
* The tests in this file test that the TLS state machine is robust against
* attacks that alter the order of handshake messages.
*
* See <https://www.smacktls.com/smack.pdf> for a description of the problems
* that this sort of attack can enable.
*/
namespace nss_test {
class TlsHandshakeSkipFilter : public TlsRecordFilter {
public:
// A TLS record filter that skips handshake messages of the identified type.
TlsHandshakeSkipFilter(const std::shared_ptr<TlsAgent>& a,
uint8_t handshake_type)
: TlsRecordFilter(a), handshake_type_(handshake_type), skipped_(false) {}
protected:
// Takes a record; if it is a handshake record, it removes the first handshake
// message that is of handshake_type_ type.
virtual PacketFilter::Action FilterRecord(
const TlsRecordHeader& record_header, const DataBuffer& input,
DataBuffer* output) {
if (record_header.content_type() != ssl_ct_handshake) {
return KEEP;
}
size_t output_offset = 0U;
output->Allocate(input.len());
TlsParser parser(input);
while (parser.remaining()) {
size_t start = parser.consumed();
TlsHandshakeFilter::HandshakeHeader header;
DataBuffer ignored;
bool complete = false;
if (!header.Parse(&parser, record_header, DataBuffer(), &ignored,
&complete)) {
ADD_FAILURE() << "Error parsing handshake header";
return KEEP;
}
if (!complete) {
ADD_FAILURE() << "Don't want to deal with fragmented input";
return KEEP;
}
if (skipped_ || header.handshake_type() != handshake_type_) {
size_t entire_length = parser.consumed() - start;
output->Write(output_offset, input.data() + start, entire_length);
// DTLS sequence numbers need to be rewritten
if (skipped_ && header.is_dtls()) {
output->data()[start + 5] -= 1;
}
output_offset += entire_length;
} else {
std::cerr << "Dropping handshake: "
<< static_cast<unsigned>(handshake_type_) << std::endl;
// We only need to report that the output contains changed data if we
// drop a handshake message. But once we've skipped one message, we
// have to modify all subsequent handshake messages so that they include
// the correct DTLS sequence numbers.
skipped_ = true;
}
}
output->Truncate(output_offset);
return skipped_ ? CHANGE : KEEP;
}
private:
// The type of handshake message to drop.
uint8_t handshake_type_;
// Whether this filter has ever skipped a handshake message. Track this so
// that sequence numbers on DTLS handshake messages can be rewritten in
// subsequent calls.
bool skipped_;
};
class TlsSkipTest : public TlsConnectTestBase,
public ::testing::WithParamInterface<
std::tuple<SSLProtocolVariant, uint16_t>> {
protected:
TlsSkipTest()
: TlsConnectTestBase(std::get<0>(GetParam()), std::get<1>(GetParam())) {}
void SetUp() override {
TlsConnectTestBase::SetUp();
EnsureTlsSetup();
}
void ServerSkipTest(std::shared_ptr<PacketFilter> filter,
uint8_t alert = kTlsAlertUnexpectedMessage) {
server_->SetFilter(filter);
ConnectExpectAlert(client_, alert);
}
};
class Tls13SkipTest : public TlsConnectTestBase,
public ::testing::WithParamInterface<SSLProtocolVariant> {
protected:
Tls13SkipTest()
: TlsConnectTestBase(GetParam(), SSL_LIBRARY_VERSION_TLS_1_3) {}
void SetUp() override {
TlsConnectTestBase::SetUp();
EnsureTlsSetup();
}
void ServerSkipTest(std::shared_ptr<TlsRecordFilter> filter, int32_t error) {
filter->EnableDecryption();
server_->SetFilter(filter);
ExpectAlert(client_, kTlsAlertUnexpectedMessage);
ConnectExpectFail();
client_->CheckErrorCode(error);
server_->CheckErrorCode(SSL_ERROR_HANDSHAKE_UNEXPECTED_ALERT);
}
void ClientSkipTest(std::shared_ptr<TlsRecordFilter> filter, int32_t error) {
filter->EnableDecryption();
client_->SetFilter(filter);
server_->ExpectSendAlert(kTlsAlertUnexpectedMessage);
ConnectExpectFailOneSide(TlsAgent::SERVER);
server_->CheckErrorCode(error);
ASSERT_EQ(TlsAgent::STATE_CONNECTED, client_->state());
client_->Handshake(); // Make sure to consume the alert the server sends.
}
};
TEST_P(TlsSkipTest, SkipCertificateRsa) {
EnableOnlyStaticRsaCiphers();
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_HELLO_DONE);
}
TEST_P(TlsSkipTest, SkipCertificateDhe) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_SERVER_KEY_EXCH);
}
TEST_P(TlsSkipTest, SkipCertificateEcdhe) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_SERVER_KEY_EXCH);
}
TEST_P(TlsSkipTest, SkipCertificateEcdsa) {
Reset(TlsAgent::kServerEcdsa256);
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_SERVER_KEY_EXCH);
}
TEST_P(TlsSkipTest, SkipServerKeyExchange) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeServerKeyExchange));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_HELLO_DONE);
}
TEST_P(TlsSkipTest, SkipServerKeyExchangeEcdsa) {
Reset(TlsAgent::kServerEcdsa256);
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeServerKeyExchange));
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_HELLO_DONE);
}
TEST_P(TlsSkipTest, SkipCertAndKeyExch) {
auto chain = std::make_shared<ChainedPacketFilter>(
ChainedPacketFilterInit{std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate),
std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeServerKeyExchange)});
ServerSkipTest(chain);
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_HELLO_DONE);
}
TEST_P(TlsSkipTest, SkipCertAndKeyExchEcdsa) {
Reset(TlsAgent::kServerEcdsa256);
auto chain = std::make_shared<ChainedPacketFilter>();
chain->Add(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate));
chain->Add(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeServerKeyExchange));
ServerSkipTest(chain);
client_->CheckErrorCode(SSL_ERROR_RX_UNEXPECTED_HELLO_DONE);
}
TEST_P(Tls13SkipTest, SkipEncryptedExtensions) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeEncryptedExtensions),
SSL_ERROR_RX_UNEXPECTED_CERTIFICATE);
}
TEST_P(Tls13SkipTest, SkipServerCertificate) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificate),
SSL_ERROR_RX_UNEXPECTED_CERT_VERIFY);
}
TEST_P(Tls13SkipTest, SkipServerCertificateVerify) {
ServerSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
server_, kTlsHandshakeCertificateVerify),
SSL_ERROR_RX_UNEXPECTED_FINISHED);
}
TEST_P(Tls13SkipTest, SkipClientCertificate) {
client_->SetupClientAuth();
server_->RequestClientAuth(true);
client_->ExpectReceiveAlert(kTlsAlertUnexpectedMessage);
ClientSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
client_, kTlsHandshakeCertificate),
SSL_ERROR_RX_UNEXPECTED_CERT_VERIFY);
}
TEST_P(Tls13SkipTest, SkipClientCertificateVerify) {
client_->SetupClientAuth();
server_->RequestClientAuth(true);
client_->ExpectReceiveAlert(kTlsAlertUnexpectedMessage);
ClientSkipTest(std::make_shared<TlsHandshakeSkipFilter>(
client_, kTlsHandshakeCertificateVerify),
SSL_ERROR_RX_UNEXPECTED_FINISHED);
}
INSTANTIATE_TEST_CASE_P(
SkipTls10, TlsSkipTest,
::testing::Combine(TlsConnectTestBase::kTlsVariantsStream,
TlsConnectTestBase::kTlsV10));
INSTANTIATE_TEST_CASE_P(SkipVariants, TlsSkipTest,
::testing::Combine(TlsConnectTestBase::kTlsVariantsAll,
TlsConnectTestBase::kTlsV11V12));
INSTANTIATE_TEST_CASE_P(Skip13Variants, Tls13SkipTest,
TlsConnectTestBase::kTlsVariantsAll);
} // namespace nss_test
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