quic/core/tls_client_handshaker.cc

// Copyright (c) 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/third_party/quiche/src/quic/core/tls_client_handshaker.h"

#include <cstring>
#include <string>

#include "third_party/boringssl/src/include/openssl/ssl.h"
#include "net/third_party/quiche/src/quic/core/crypto/quic_encrypter.h"
#include "net/third_party/quiche/src/quic/core/crypto/transport_parameters.h"
#include "net/third_party/quiche/src/quic/core/quic_session.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_text_utils.h"

namespace quic {

TlsClientHandshaker::ProofVerifierCallbackImpl::ProofVerifierCallbackImpl(
    TlsClientHandshaker* parent)
    : parent_(parent) {}

TlsClientHandshaker::ProofVerifierCallbackImpl::~ProofVerifierCallbackImpl() {}

void TlsClientHandshaker::ProofVerifierCallbackImpl::Run(
    bool ok,
    const std::string& error_details,
    std::unique_ptr<ProofVerifyDetails>* details) {
  if (parent_ == nullptr) {
    return;
  }

  parent_->verify_details_ = std::move(*details);
  parent_->verify_result_ = ok ? ssl_verify_ok : ssl_verify_invalid;
  parent_->state_ = STATE_HANDSHAKE_RUNNING;
  parent_->proof_verify_callback_ = nullptr;
  parent_->AdvanceHandshake();
}

void TlsClientHandshaker::ProofVerifierCallbackImpl::Cancel() {
  parent_ = nullptr;
}

TlsClientHandshaker::TlsClientHandshaker(
    QuicCryptoStream* stream,
    QuicSession* session,
    const QuicServerId& server_id,
    ProofVerifier* proof_verifier,
    SSL_CTX* ssl_ctx,
    std::unique_ptr<ProofVerifyContext> verify_context,
    const std::string& user_agent_id)
    : TlsHandshaker(stream, session, ssl_ctx),
      server_id_(server_id),
      proof_verifier_(proof_verifier),
      verify_context_(std::move(verify_context)),
      user_agent_id_(user_agent_id),
      crypto_negotiated_params_(new QuicCryptoNegotiatedParameters) {}

TlsClientHandshaker::~TlsClientHandshaker() {
  if (proof_verify_callback_) {
    proof_verify_callback_->Cancel();
  }
}

// static
bssl::UniquePtr<SSL_CTX> TlsClientHandshaker::CreateSslCtx() {
  return TlsHandshaker::CreateSslCtx();
}

bool TlsClientHandshaker::CryptoConnect() {
  CrypterPair crypters;
  CryptoUtils::CreateTlsInitialCrypters(
      Perspective::IS_CLIENT, session()->connection()->transport_version(),
      session()->connection_id(), &crypters);
  session()->connection()->SetEncrypter(ENCRYPTION_INITIAL,
                                        std::move(crypters.encrypter));
  session()->connection()->InstallDecrypter(ENCRYPTION_INITIAL,
                                            std::move(crypters.decrypter));
  state_ = STATE_HANDSHAKE_RUNNING;
  // Configure certificate verification.
  // TODO(nharper): This only verifies certs on initial connection, not on
  // resumption. Chromium has this callback be a no-op and verifies the
  // certificate after the connection is complete. We need to re-verify on
  // resumption in case of expiration or revocation/distrust.
  SSL_set_custom_verify(ssl(), SSL_VERIFY_PEER, &VerifyCallback);

  // Configure the SSL to be a client.
  SSL_set_connect_state(ssl());
  if (SSL_set_tlsext_host_name(ssl(), server_id_.host().c_str()) != 1) {
    return false;
  }

  std::string alpn_string =
      AlpnForVersion(session()->supported_versions().front());
  if (alpn_string.length() > std::numeric_limits<uint8_t>::max()) {
    QUIC_BUG << "ALPN too long: '" << alpn_string << "'";
    CloseConnection(QUIC_HANDSHAKE_FAILED, "ALPN too long");
    return false;
  }
  const uint8_t alpn_length = alpn_string.length();
  // SSL_set_alpn_protos expects a sequence of one-byte-length-prefixed strings
  // so we copy alpn_string to a new buffer that has the length in alpn[0].
  uint8_t alpn[std::numeric_limits<uint8_t>::max() + 1];
  alpn[0] = alpn_length;
  memcpy(reinterpret_cast<char*>(alpn + 1), alpn_string.data(), alpn_length);
  if (SSL_set_alpn_protos(ssl(), alpn,
                          static_cast<unsigned>(alpn_length) + 1) != 0) {
    QUIC_BUG << "Failed to set ALPN: '" << alpn_string << "'";
    CloseConnection(QUIC_HANDSHAKE_FAILED, "Failed to set ALPN");
    return false;
  }
  QUIC_DLOG(INFO) << "Client using ALPN: '" << alpn_string << "'";

  // Set the Transport Parameters to send in the ClientHello
  if (!SetTransportParameters()) {
    CloseConnection(QUIC_HANDSHAKE_FAILED,
                    "Failed to set Transport Parameters");
    return false;
  }

  // Start the handshake.
  AdvanceHandshake();
  return session()->connection()->connected();
}

bool TlsClientHandshaker::SetTransportParameters() {
  TransportParameters params;
  params.perspective = Perspective::IS_CLIENT;
  params.version =
      CreateQuicVersionLabel(session()->supported_versions().front());

  if (!session()->config()->FillTransportParameters(&params)) {
    return false;
  }
  params.google_quic_params->SetStringPiece(kUAID, user_agent_id_);

  std::vector<uint8_t> param_bytes;
  return SerializeTransportParameters(params, &param_bytes) &&
         SSL_set_quic_transport_params(ssl(), param_bytes.data(),
                                       param_bytes.size()) == 1;
}

bool TlsClientHandshaker::ProcessTransportParameters(
    std::string* error_details) {
  TransportParameters params;
  const uint8_t* param_bytes;
  size_t param_bytes_len;
  SSL_get_peer_quic_transport_params(ssl(), &param_bytes, &param_bytes_len);
  if (param_bytes_len == 0 ||
      !ParseTransportParameters(param_bytes, param_bytes_len,
                                Perspective::IS_SERVER, &params)) {
    *error_details = "Unable to parse Transport Parameters";
    return false;
  }

  if (params.version !=
      CreateQuicVersionLabel(session()->connection()->version())) {
    *error_details = "Version mismatch detected";
    return false;
  }
  if (CryptoUtils::ValidateServerHelloVersions(
          params.supported_versions,
          session()->connection()->server_supported_versions(),
          error_details) != QUIC_NO_ERROR ||
      session()->config()->ProcessTransportParameters(
          params, SERVER, error_details) != QUIC_NO_ERROR) {
    DCHECK(!error_details->empty());
    return false;
  }

  session()->OnConfigNegotiated();
  return true;
}

int TlsClientHandshaker::num_sent_client_hellos() const {
  // TODO(nharper): Return a sensible value here.
  return 0;
}

int TlsClientHandshaker::num_scup_messages_received() const {
  // SCUP messages aren't sent or received when using the TLS handshake.
  return 0;
}

bool TlsClientHandshaker::WasChannelIDSent() const {
  // Channel ID is not used with TLS in QUIC.
  return false;
}

bool TlsClientHandshaker::WasChannelIDSourceCallbackRun() const {
  // Channel ID is not used with TLS in QUIC.
  return false;
}

std::string TlsClientHandshaker::chlo_hash() const {
  return "";
}

bool TlsClientHandshaker::encryption_established() const {
  return encryption_established_;
}

bool TlsClientHandshaker::handshake_confirmed() const {
  return handshake_confirmed_;
}

const QuicCryptoNegotiatedParameters&
TlsClientHandshaker::crypto_negotiated_params() const {
  return *crypto_negotiated_params_;
}

CryptoMessageParser* TlsClientHandshaker::crypto_message_parser() {
  return TlsHandshaker::crypto_message_parser();
}

void TlsClientHandshaker::AdvanceHandshake() {
  if (state_ == STATE_CONNECTION_CLOSED) {
    QUIC_LOG(INFO)
        << "TlsClientHandshaker received message after connection closed";
    return;
  }
  if (state_ == STATE_IDLE) {
    CloseConnection(QUIC_HANDSHAKE_FAILED, "TLS handshake failed");
    return;
  }
  if (state_ == STATE_HANDSHAKE_COMPLETE) {
    // TODO(nharper): Handle post-handshake messages.
    return;
  }

  QUIC_LOG(INFO) << "TlsClientHandshaker: continuing handshake";
  int rv = SSL_do_handshake(ssl());
  if (rv == 1) {
    FinishHandshake();
    return;
  }
  int ssl_error = SSL_get_error(ssl(), rv);
  bool should_close = true;
  switch (state_) {
    case STATE_HANDSHAKE_RUNNING:
      should_close = ssl_error != SSL_ERROR_WANT_READ;
      break;
    case STATE_CERT_VERIFY_PENDING:
      should_close = ssl_error != SSL_ERROR_WANT_CERTIFICATE_VERIFY;
      break;
    default:
      should_close = true;
  }
  if (should_close && state_ != STATE_CONNECTION_CLOSED) {
    // TODO(nharper): Surface error details from the error queue when ssl_error
    // is SSL_ERROR_SSL.
    QUIC_LOG(WARNING) << "SSL_do_handshake failed; closing connection";
    CloseConnection(QUIC_HANDSHAKE_FAILED, "TLS handshake failed");
  }
}

void TlsClientHandshaker::CloseConnection(QuicErrorCode error,
                                          const std::string& reason_phrase) {
  DCHECK(!reason_phrase.empty());
  state_ = STATE_CONNECTION_CLOSED;
  stream()->CloseConnectionWithDetails(error, reason_phrase);
}

void TlsClientHandshaker::FinishHandshake() {
  QUIC_LOG(INFO) << "Client: handshake finished";
  state_ = STATE_HANDSHAKE_COMPLETE;

  std::string error_details;
  if (!ProcessTransportParameters(&error_details)) {
    DCHECK(!error_details.empty());
    CloseConnection(QUIC_HANDSHAKE_FAILED, error_details);
    return;
  }

  const uint8_t* alpn_data = nullptr;
  unsigned alpn_length = 0;
  SSL_get0_alpn_selected(ssl(), &alpn_data, &alpn_length);
  // TODO(b/130164908) Act on ALPN.
  if (alpn_length != 0) {
    std::string received_alpn_string(reinterpret_cast<const char*>(alpn_data),
                                     alpn_length);
    std::string sent_alpn_string =
        AlpnForVersion(session()->supported_versions().front());
    if (received_alpn_string != sent_alpn_string) {
      QUIC_LOG(ERROR) << "Client: received mismatched ALPN '"
                      << received_alpn_string << "', expected '"
                      << sent_alpn_string << "'";
      CloseConnection(QUIC_HANDSHAKE_FAILED, "Mismatched ALPN");
      return;
    }
    QUIC_DLOG(INFO) << "Client: server selected ALPN: '" << received_alpn_string
                    << "'";
  } else {
    QUIC_DLOG(INFO) << "Client: server did not select ALPN";
  }

  session()->connection()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  session()->NeuterUnencryptedData();
  encryption_established_ = true;
  handshake_confirmed_ = true;
}

// static
TlsClientHandshaker* TlsClientHandshaker::HandshakerFromSsl(SSL* ssl) {
  return static_cast<TlsClientHandshaker*>(
      TlsHandshaker::HandshakerFromSsl(ssl));
}

// static
enum ssl_verify_result_t TlsClientHandshaker::VerifyCallback(
    SSL* ssl,
    uint8_t* out_alert) {
  return HandshakerFromSsl(ssl)->VerifyCert(out_alert);
}

enum ssl_verify_result_t TlsClientHandshaker::VerifyCert(uint8_t* out_alert) {
  if (verify_result_ != ssl_verify_retry ||
      state_ == STATE_CERT_VERIFY_PENDING) {
    enum ssl_verify_result_t result = verify_result_;
    verify_result_ = ssl_verify_retry;
    return result;
  }
  const STACK_OF(CRYPTO_BUFFER)* cert_chain = SSL_get0_peer_certificates(ssl());
  if (cert_chain == nullptr) {
    *out_alert = SSL_AD_INTERNAL_ERROR;
    return ssl_verify_invalid;
  }
  // TODO(nharper): Pass the CRYPTO_BUFFERs into the QUIC stack to avoid copies.
  std::vector<std::string> certs;
  for (CRYPTO_BUFFER* cert : cert_chain) {
    certs.push_back(
        std::string(reinterpret_cast<const char*>(CRYPTO_BUFFER_data(cert)),
                    CRYPTO_BUFFER_len(cert)));
  }

  ProofVerifierCallbackImpl* proof_verify_callback =
      new ProofVerifierCallbackImpl(this);

  QuicAsyncStatus verify_result = proof_verifier_->VerifyCertChain(
      server_id_.host(), certs, verify_context_.get(),
      &cert_verify_error_details_, &verify_details_,
      std::unique_ptr<ProofVerifierCallback>(proof_verify_callback));
  switch (verify_result) {
    case QUIC_SUCCESS:
      return ssl_verify_ok;
    case QUIC_PENDING:
      proof_verify_callback_ = proof_verify_callback;
      state_ = STATE_CERT_VERIFY_PENDING;
      return ssl_verify_retry;
    case QUIC_FAILURE:
    default:
      QUIC_LOG(INFO) << "Cert chain verification failed: "
                     << cert_verify_error_details_;
      return ssl_verify_invalid;
  }
}

}  // namespace quic