remoting/protocol/ssl_hmac_channel_authenticator.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/protocol/ssl_hmac_channel_authenticator.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/callback_helpers.h"
  10 #include "base/logging.h"
  11 #include "crypto/secure_util.h"
  12 #include "net/base/host_port_pair.h"
  13 #include "net/base/io_buffer.h"
  14 #include "net/base/net_errors.h"
  15 #include "net/cert/cert_status_flags.h"
  16 #include "net/cert/cert_verifier.h"
  17 #include "net/cert/x509_certificate.h"
  18 #include "net/http/transport_security_state.h"
  19 #include "net/socket/client_socket_factory.h"
  20 #include "net/socket/client_socket_handle.h"
  21 #include "net/socket/ssl_client_socket.h"
  22 #include "net/socket/ssl_client_socket_openssl.h"
  23 #include "net/socket/ssl_server_socket.h"
  24 #include "net/ssl/ssl_config_service.h"
  25 #include "remoting/base/rsa_key_pair.h"
  26 #include "remoting/protocol/auth_util.h"
  27
  28 namespace remoting {
  29 namespace protocol {
  30
  31 namespace {
  32
  33 // A CertVerifier which rejects every certificate.
  34 class FailingCertVerifier : public net::CertVerifier {
  35  public:
  36   FailingCertVerifier() {}
  37   ~FailingCertVerifier() override {}
  38
  39   int Verify(net::X509Certificate* cert,
  40              const std::string& hostname,
  41              const std::string& ocsp_response,
  42              int flags,
  43              net::CRLSet* crl_set,
  44              net::CertVerifyResult* verify_result,
  45              const net::CompletionCallback& callback,
  46              scoped_ptr<Request>* out_req,
  47              const net::BoundNetLog& net_log) override {
  48     verify_result->verified_cert = cert;
  49     verify_result->cert_status = net::CERT_STATUS_INVALID;
  50     return net::ERR_CERT_INVALID;
  51   }
  52 };
  53
  54 }  // namespace
  55
  56 // static
  57 scoped_ptr<SslHmacChannelAuthenticator>
  58 SslHmacChannelAuthenticator::CreateForClient(
  59       const std::string& remote_cert,
  60       const std::string& auth_key) {
  61   scoped_ptr<SslHmacChannelAuthenticator> result(
  62       new SslHmacChannelAuthenticator(auth_key));
  63   result->remote_cert_ = remote_cert;
  64   return result.Pass();
  65 }
  66
  67 scoped_ptr<SslHmacChannelAuthenticator>
  68 SslHmacChannelAuthenticator::CreateForHost(
  69     const std::string& local_cert,
  70     scoped_refptr<RsaKeyPair> key_pair,
  71     const std::string& auth_key) {
  72   scoped_ptr<SslHmacChannelAuthenticator> result(
  73       new SslHmacChannelAuthenticator(auth_key));
  74   result->local_cert_ = local_cert;
  75   result->local_key_pair_ = key_pair;
  76   return result.Pass();
  77 }
  78
  79 SslHmacChannelAuthenticator::SslHmacChannelAuthenticator(
  80     const std::string& auth_key)
  81     : auth_key_(auth_key) {
  82 }
  83
  84 SslHmacChannelAuthenticator::~SslHmacChannelAuthenticator() {
  85 }
  86
  87 void SslHmacChannelAuthenticator::SecureAndAuthenticate(
  88     scoped_ptr<net::StreamSocket> socket, const DoneCallback& done_callback) {
  89   DCHECK(CalledOnValidThread());
  90   DCHECK(socket->IsConnected());
  91
  92   done_callback_ = done_callback;
  93
  94   int result;
  95   if (is_ssl_server()) {
  96 #if defined(OS_NACL)
  97     // Client plugin doesn't use server SSL sockets, and so SSLServerSocket
  98     // implementation is not compiled for NaCl as part of net_nacl.
  99     NOTREACHED();
 100     result = net::ERR_FAILED;
 101 #else
 102     scoped_refptr<net::X509Certificate> cert =
 103         net::X509Certificate::CreateFromBytes(
 104             local_cert_.data(), local_cert_.length());
 105     if (!cert.get()) {
 106       LOG(ERROR) << "Failed to parse X509Certificate";
 107       NotifyError(net::ERR_FAILED);
 108       return;
 109     }
 110
 111     net::SSLConfig ssl_config;
 112     ssl_config.require_ecdhe = true;
 113
 114     scoped_ptr<net::SSLServerSocket> server_socket =
 115         net::CreateSSLServerSocket(socket.Pass(),
 116                                    cert.get(),
 117                                    local_key_pair_->private_key(),
 118                                    ssl_config);
 119     net::SSLServerSocket* raw_server_socket = server_socket.get();
 120     socket_ = server_socket.Pass();
 121     result = raw_server_socket->Handshake(
 122         base::Bind(&SslHmacChannelAuthenticator::OnConnected,
 123                    base::Unretained(this)));
 124 #endif
 125   } else {
 126     transport_security_state_.reset(new net::TransportSecurityState);
 127     cert_verifier_.reset(new FailingCertVerifier);
 128
 129     net::SSLConfig::CertAndStatus cert_and_status;
 130     cert_and_status.cert_status = net::CERT_STATUS_AUTHORITY_INVALID;
 131     cert_and_status.der_cert = remote_cert_;
 132
 133     net::SSLConfig ssl_config;
 134     // Certificate verification and revocation checking are not needed
 135     // because we use self-signed certs. Disable it so that the SSL
 136     // layer doesn't try to initialize OCSP (OCSP works only on the IO
 137     // thread).
 138     ssl_config.cert_io_enabled = false;
 139     ssl_config.rev_checking_enabled = false;
 140     ssl_config.allowed_bad_certs.push_back(cert_and_status);
 141
 142     net::HostPortPair host_and_port(kSslFakeHostName, 0);
 143     net::SSLClientSocketContext context;
 144     context.transport_security_state = transport_security_state_.get();
 145     context.cert_verifier = cert_verifier_.get();
 146     scoped_ptr<net::ClientSocketHandle> socket_handle(
 147         new net::ClientSocketHandle);
 148     socket_handle->SetSocket(socket.Pass());
 149
 150 #if defined(OS_NACL)
 151     // net_nacl doesn't include ClientSocketFactory.
 152     socket_.reset(new net::SSLClientSocketOpenSSL(
 153         socket_handle.Pass(), host_and_port, ssl_config, context));
 154 #else
 155     socket_ =
 156         net::ClientSocketFactory::GetDefaultFactory()->CreateSSLClientSocket(
 157             socket_handle.Pass(), host_and_port, ssl_config, context);
 158 #endif
 159
 160     result = socket_->Connect(
 161         base::Bind(&SslHmacChannelAuthenticator::OnConnected,
 162                    base::Unretained(this)));
 163   }
 164
 165   if (result == net::ERR_IO_PENDING)
 166     return;
 167
 168   OnConnected(result);
 169 }
 170
 171 bool SslHmacChannelAuthenticator::is_ssl_server() {
 172   return local_key_pair_.get() != nullptr;
 173 }
 174
 175 void SslHmacChannelAuthenticator::OnConnected(int result) {
 176   if (result != net::OK) {
 177     LOG(WARNING) << "Failed to establish SSL connection";
 178     NotifyError(result);
 179     return;
 180   }
 181
 182   // Generate authentication digest to write to the socket.
 183   std::string auth_bytes = GetAuthBytes(
 184       socket_.get(), is_ssl_server() ?
 185       kHostAuthSslExporterLabel : kClientAuthSslExporterLabel, auth_key_);
 186   if (auth_bytes.empty()) {
 187     NotifyError(net::ERR_FAILED);
 188     return;
 189   }
 190
 191   // Allocate a buffer to write the digest.
 192   auth_write_buf_ = new net::DrainableIOBuffer(
 193       new net::StringIOBuffer(auth_bytes), auth_bytes.size());
 194
 195   // Read an incoming token.
 196   auth_read_buf_ = new net::GrowableIOBuffer();
 197   auth_read_buf_->SetCapacity(kAuthDigestLength);
 198
 199   // If WriteAuthenticationBytes() results in |done_callback_| being
 200   // called then we must not do anything else because this object may
 201   // be destroyed at that point.
 202   bool callback_called = false;
 203   WriteAuthenticationBytes(&callback_called);
 204   if (!callback_called)
 205     ReadAuthenticationBytes();
 206 }
 207
 208 void SslHmacChannelAuthenticator::WriteAuthenticationBytes(
 209     bool* callback_called) {
 210   while (true) {
 211     int result = socket_->Write(
 212         auth_write_buf_.get(),
 213         auth_write_buf_->BytesRemaining(),
 214         base::Bind(&SslHmacChannelAuthenticator::OnAuthBytesWritten,
 215                    base::Unretained(this)));
 216     if (result == net::ERR_IO_PENDING)
 217       break;
 218     if (!HandleAuthBytesWritten(result, callback_called))
 219       break;
 220   }
 221 }
 222
 223 void SslHmacChannelAuthenticator::OnAuthBytesWritten(int result) {
 224   DCHECK(CalledOnValidThread());
 225
 226   if (HandleAuthBytesWritten(result, nullptr))
 227     WriteAuthenticationBytes(nullptr);
 228 }
 229
 230 bool SslHmacChannelAuthenticator::HandleAuthBytesWritten(
 231     int result, bool* callback_called) {
 232   if (result <= 0) {
 233     LOG(ERROR) << "Error writing authentication: " << result;
 234     if (callback_called)
 235       *callback_called = false;
 236     NotifyError(result);
 237     return false;
 238   }
 239
 240   auth_write_buf_->DidConsume(result);
 241   if (auth_write_buf_->BytesRemaining() > 0)
 242     return true;
 243
 244   auth_write_buf_ = nullptr;
 245   CheckDone(callback_called);
 246   return false;
 247 }
 248
 249 void SslHmacChannelAuthenticator::ReadAuthenticationBytes() {
 250   while (true) {
 251     int result =
 252         socket_->Read(auth_read_buf_.get(),
 253                       auth_read_buf_->RemainingCapacity(),
 254                       base::Bind(&SslHmacChannelAuthenticator::OnAuthBytesRead,
 255                                  base::Unretained(this)));
 256     if (result == net::ERR_IO_PENDING)
 257       break;
 258     if (!HandleAuthBytesRead(result))
 259       break;
 260   }
 261 }
 262
 263 void SslHmacChannelAuthenticator::OnAuthBytesRead(int result) {
 264   DCHECK(CalledOnValidThread());
 265
 266   if (HandleAuthBytesRead(result))
 267     ReadAuthenticationBytes();
 268 }
 269
 270 bool SslHmacChannelAuthenticator::HandleAuthBytesRead(int read_result) {
 271   if (read_result <= 0) {
 272     NotifyError(read_result);
 273     return false;
 274   }
 275
 276   auth_read_buf_->set_offset(auth_read_buf_->offset() + read_result);
 277   if (auth_read_buf_->RemainingCapacity() > 0)
 278     return true;
 279
 280   if (!VerifyAuthBytes(std::string(
 281           auth_read_buf_->StartOfBuffer(),
 282           auth_read_buf_->StartOfBuffer() + kAuthDigestLength))) {
 283     LOG(WARNING) << "Mismatched authentication";
 284     NotifyError(net::ERR_FAILED);
 285     return false;
 286   }
 287
 288   auth_read_buf_ = nullptr;
 289   CheckDone(nullptr);
 290   return false;
 291 }
 292
 293 bool SslHmacChannelAuthenticator::VerifyAuthBytes(
 294     const std::string& received_auth_bytes) {
 295   DCHECK(received_auth_bytes.length() == kAuthDigestLength);
 296
 297   // Compute expected auth bytes.
 298   std::string auth_bytes = GetAuthBytes(
 299       socket_.get(), is_ssl_server() ?
 300       kClientAuthSslExporterLabel : kHostAuthSslExporterLabel, auth_key_);
 301   if (auth_bytes.empty())
 302     return false;
 303
 304   return crypto::SecureMemEqual(received_auth_bytes.data(),
 305                                 &(auth_bytes[0]), kAuthDigestLength);
 306 }
 307
 308 void SslHmacChannelAuthenticator::CheckDone(bool* callback_called) {
 309   if (auth_write_buf_.get() == nullptr && auth_read_buf_.get() == nullptr) {
 310     DCHECK(socket_.get() != nullptr);
 311     if (callback_called)
 312       *callback_called = true;
 313
 314     base::ResetAndReturn(&done_callback_).Run(net::OK, socket_.Pass());
 315   }
 316 }
 317
 318 void SslHmacChannelAuthenticator::NotifyError(int error) {
 319   base::ResetAndReturn(&done_callback_).Run(error, nullptr);
 320 }
 321
 322 }  // namespace protocol
 323 }  // namespace remoting