gio/gunixconnection.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright © 2009 Codethink Limited
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License as published
   7  * by the Free Software Foundation; either version 2 of the licence or (at
   8  * your option) any later version.
   9  *
  10  * See the included COPYING file for more information.
  11  *
  12  * Authors: Ryan Lortie <desrt@desrt.ca>
  13  */
  14
  15 #include "config.h"
  16 #include "gunixconnection.h"
  17 #include "gunixcredentialsmessage.h"
  18 #include "glibintl.h"
  19
  20 /**
  21  * SECTION: gunixconnection
  22  * @title: GUnixConnection
  23  * @short_description: A UNIX domain GSocketConnection
  24  * @include: gio/gunixconnection.h
  25  * @see_also: #GSocketConnection.
  26  *
  27  * This is the subclass of #GSocketConnection that is created
  28  * for UNIX domain sockets.
  29  *
  30  * It contains functions to do some of the UNIX socket specific
  31  * functionality like passing file descriptors.
  32  *
  33  * Note that <filename>&lt;gio/gunixconnection.h&gt;</filename> belongs to
  34  * the UNIX-specific GIO interfaces, thus you have to use the
  35  * <filename>gio-unix-2.0.pc</filename> pkg-config file when using it.
  36  *
  37  * Since: 2.22
  38  */
  39
  40 #include <gio/gsocketcontrolmessage.h>
  41 #include <gio/gunixfdmessage.h>
  42 #include <gio/gsocket.h>
  43 #include <unistd.h>
  44
  45 #ifdef __linux__
  46 /* for getsockopt() and setsockopt() */
  47 #include <sys/types.h>          /* See NOTES */
  48 #include <sys/socket.h>
  49 #include <errno.h>
  50 #include <string.h>
  51 #endif
  52
  53
  54 G_DEFINE_TYPE_WITH_CODE (GUnixConnection, g_unix_connection,
  55                          G_TYPE_SOCKET_CONNECTION,
  56   g_socket_connection_factory_register_type (g_define_type_id,
  57                                              G_SOCKET_FAMILY_UNIX,
  58                                              G_SOCKET_TYPE_STREAM,
  59                                              G_SOCKET_PROTOCOL_DEFAULT);
  60                          );
  61
  62 /**
  63  * g_unix_connection_send_fd:
  64  * @connection: a #GUnixConnection
  65  * @fd: a file descriptor
  66  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
  67  * @error: (allow-none): #GError for error reporting, or %NULL to ignore.
  68  *
  69  * Passes a file descriptor to the recieving side of the
  70  * connection. The recieving end has to call g_unix_connection_receive_fd()
  71  * to accept the file descriptor.
  72  *
  73  * As well as sending the fd this also writes a single byte to the
  74  * stream, as this is required for fd passing to work on some
  75  * implementations.
  76  *
  77  * Returns: a %TRUE on success, %NULL on error.
  78  *
  79  * Since: 2.22
  80  */
  81 gboolean
  82 g_unix_connection_send_fd (GUnixConnection  *connection,
  83                            gint              fd,
  84                            GCancellable     *cancellable,
  85                            GError          **error)
  86 {
  87   GSocketControlMessage *scm;
  88   GSocket *socket;
  89
  90   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);
  91   g_return_val_if_fail (fd >= 0, FALSE);
  92
  93   scm = g_unix_fd_message_new ();
  94
  95   if (!g_unix_fd_message_append_fd (G_UNIX_FD_MESSAGE (scm), fd, error))
  96     {
  97       g_object_unref (scm);
  98       return FALSE;
  99     }
 100
 101   g_object_get (connection, "socket", &socket, NULL);
 102   if (g_socket_send_message (socket, NULL, NULL, 0, &scm, 1, 0, cancellable, error) != 1)
 103     /* XXX could it 'fail' with zero? */
 104     {
 105       g_object_unref (socket);
 106       g_object_unref (scm);
 107
 108       return FALSE;
 109     }
 110
 111   g_object_unref (socket);
 112   g_object_unref (scm);
 113
 114   return TRUE;
 115 }
 116
 117 /**
 118  * g_unix_connection_receive_fd:
 119  * @connection: a #GUnixConnection
 120  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
 121  * @error: (allow-none): #GError for error reporting, or %NULL to ignore
 122  *
 123  * Receives a file descriptor from the sending end of the connection.
 124  * The sending end has to call g_unix_connection_send_fd() for this
 125  * to work.
 126  *
 127  * As well as reading the fd this also reads a single byte from the
 128  * stream, as this is required for fd passing to work on some
 129  * implementations.
 130  *
 131  * Returns: a file descriptor on success, -1 on error.
 132  *
 133  * Since: 2.22
 134  **/
 135 gint
 136 g_unix_connection_receive_fd (GUnixConnection  *connection,
 137                               GCancellable     *cancellable,
 138                               GError          **error)
 139 {
 140   GSocketControlMessage **scms;
 141   gint *fds, nfd, fd, nscm;
 142   GUnixFDMessage *fdmsg;
 143   GSocket *socket;
 144
 145   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), -1);
 146
 147   g_object_get (connection, "socket", &socket, NULL);
 148   if (g_socket_receive_message (socket, NULL, NULL, 0,
 149                                 &scms, &nscm, NULL, cancellable, error) != 1)
 150     /* XXX it _could_ 'fail' with zero. */
 151     {
 152       g_object_unref (socket);
 153
 154       return -1;
 155     }
 156
 157   g_object_unref (socket);
 158
 159   if (nscm != 1)
 160     {
 161       gint i;
 162
 163       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 164                    _("Expecting 1 control message, got %d"), nscm);
 165
 166       for (i = 0; i < nscm; i++)
 167         g_object_unref (scms[i]);
 168
 169       g_free (scms);
 170
 171       return -1;
 172     }
 173
 174   if (!G_IS_UNIX_FD_MESSAGE (scms[0]))
 175     {
 176       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 177                            _("Unexpected type of ancillary data"));
 178       g_object_unref (scms[0]);
 179       g_free (scms);
 180
 181       return -1;
 182     }
 183
 184   fdmsg = G_UNIX_FD_MESSAGE (scms[0]);
 185   g_free (scms);
 186
 187   fds = g_unix_fd_message_steal_fds (fdmsg, &nfd);
 188   g_object_unref (fdmsg);
 189
 190   if (nfd != 1)
 191     {
 192       gint i;
 193
 194       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 195                    _("Expecting one fd, but got %d\n"), nfd);
 196
 197       for (i = 0; i < nfd; i++)
 198         close (fds[i]);
 199
 200       g_free (fds);
 201
 202       return -1;
 203     }
 204
 205   fd = *fds;
 206   g_free (fds);
 207
 208   if (fd < 0)
 209     {
 210       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 211                            _("Received invalid fd"));
 212       fd = -1;
 213     }
 214
 215   return fd;
 216 }
 217
 218 static void
 219 g_unix_connection_init (GUnixConnection *connection)
 220 {
 221 }
 222
 223 static void
 224 g_unix_connection_class_init (GUnixConnectionClass *class)
 225 {
 226 }
 227
 228 /* TODO: Other stuff we might want to add are:
 229 void                    g_unix_connection_send_fd_async                 (GUnixConnection      *connection,
 230                                                                          gint                  fd,
 231                                                                          gboolean              close,
 232                                                                          gint                  io_priority,
 233                                                                          GAsyncReadyCallback   callback,
 234                                                                          gpointer              user_data);
 235 gboolean                g_unix_connection_send_fd_finish                (GUnixConnection      *connection,
 236                                                                          GError              **error);
 237
 238 gboolean                g_unix_connection_send_fds                      (GUnixConnection      *connection,
 239                                                                          gint                 *fds,
 240                                                                          gint                  nfds,
 241                                                                          GError              **error);
 242 void                    g_unix_connection_send_fds_async                (GUnixConnection      *connection,
 243                                                                          gint                 *fds,
 244                                                                          gint                  nfds,
 245                                                                          gint                  io_priority,
 246                                                                          GAsyncReadyCallback   callback,
 247                                                                          gpointer              user_data);
 248 gboolean                g_unix_connection_send_fds_finish               (GUnixConnection      *connection,
 249                                                                          GError              **error);
 250
 251 void                    g_unix_connection_receive_fd_async              (GUnixConnection      *connection,
 252                                                                          gint                  io_priority,
 253                                                                          GAsyncReadyCallback   callback,
 254                                                                          gpointer              user_data);
 255 gint                    g_unix_connection_receive_fd_finish             (GUnixConnection      *connection,
 256                                                                          GError              **error);
 257
 258
 259 gboolean                g_unix_connection_send_credentials              (GUnixConnection      *connection,
 260                                                                          GError              **error);
 261 void                    g_unix_connection_send_credentials_async        (GUnixConnection      *connection,
 262                                                                          gint                  io_priority,
 263                                                                          GAsyncReadyCallback   callback,
 264                                                                          gpointer              user_data);
 265 gboolean                g_unix_connection_send_credentials_finish       (GUnixConnection      *connection,
 266                                                                          GError              **error);
 267
 268 gboolean                g_unix_connection_send_fake_credentials         (GUnixConnection      *connection,
 269                                                                          guint64               pid,
 270                                                                          guint64               uid,
 271                                                                          guint64               gid,
 272                                                                          GError              **error);
 273 void                    g_unix_connection_send_fake_credentials_async   (GUnixConnection      *connection,
 274                                                                          guint64               pid,
 275                                                                          guint64               uid,
 276                                                                          guint64               gid,
 277                                                                          gint                  io_priority,
 278                                                                          GAsyncReadyCallback   callback,
 279                                                                          gpointer              user_data);
 280 gboolean                g_unix_connection_send_fake_credentials_finish  (GUnixConnection      *connection,
 281                                                                          GError              **error);
 282
 283 gboolean                g_unix_connection_receive_credentials           (GUnixConnection      *connection,
 284                                                                          guint64              *pid,
 285                                                                          guint64              *uid,
 286                                                                          guint64              *gid,
 287                                                                          GError              **error);
 288 void                    g_unix_connection_receive_credentials_async     (GUnixConnection      *connection,
 289                                                                          gint                  io_priority,
 290                                                                          GAsyncReadyCallback   callback,
 291                                                                          gpointer              user_data);
 292 gboolean                g_unix_connection_receive_credentials_finish    (GUnixConnection      *connection,
 293                                                                          guint64              *pid,
 294                                                                          guint64              *uid,
 295                                                                          guint64              *gid,
 296                                                                          GError              **error);
 297
 298 gboolean                g_unix_connection_create_pair                   (GUnixConnection     **one,
 299                                                                          GUnixConnection     **two,
 300                                                                          GError              **error);
 301 */
 302
 303
 304 /**
 305  * g_unix_connection_send_credentials:
 306  * @connection: A #GUnixConnection.
 307  * @cancellable: A #GCancellable or %NULL.
 308  * @error: Return location for error or %NULL.
 309  *
 310  * Passes the credentials of the current user the receiving side
 311  * of the connection. The recieving end has to call
 312  * g_unix_connection_receive_credentials() (or similar) to accept the
 313  * credentials.
 314  *
 315  * As well as sending the credentials this also writes a single NUL
 316  * byte to the stream, as this is required for credentials passing to
 317  * work on some implementations.
 318  *
 319  * Other ways to exchange credentials with a foreign peer includes the
 320  * #GUnixCredentialsMessage type and g_socket_get_credentials() function.
 321  *
 322  * Note that this function only works on Linux, currently.
 323  *
 324  * Returns: %TRUE on success, %FALSE if @error is set.
 325  *
 326  * Since: 2.26
 327  */
 328 gboolean
 329 g_unix_connection_send_credentials (GUnixConnection      *connection,
 330                                     GCancellable         *cancellable,
 331                                     GError              **error)
 332 {
 333   GCredentials *credentials;
 334   GSocketControlMessage *scm;
 335   GSocket *socket;
 336   gboolean ret;
 337   GOutputVector vector;
 338   guchar nul_byte[1] = {'\0'};
 339
 340   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);
 341   g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 342
 343   ret = FALSE;
 344
 345   credentials = g_credentials_new ();
 346
 347   vector.buffer = &nul_byte;
 348   vector.size = 1;
 349   scm = g_unix_credentials_message_new_with_credentials (credentials);
 350   g_object_get (connection, "socket", &socket, NULL);
 351   if (g_socket_send_message (socket,
 352                              NULL, /* address */
 353                              &vector,
 354                              1,
 355                              &scm,
 356                              1,
 357                              G_SOCKET_MSG_NONE,
 358                              cancellable,
 359                              error) != 1)
 360     {
 361       g_prefix_error (error, _("Error sending credentials: "));
 362       goto out;
 363     }
 364
 365   ret = TRUE;
 366
 367  out:
 368   g_object_unref (socket);
 369   g_object_unref (scm);
 370   g_object_unref (credentials);
 371   return ret;
 372 }
 373
 374 /**
 375  * g_unix_connection_receive_credentials:
 376  * @connection: A #GUnixConnection.
 377  * @cancellable: A #GCancellable or %NULL.
 378  * @error: Return location for error or %NULL.
 379  *
 380  * Receives credentials from the sending end of the connection.  The
 381  * sending end has to call g_unix_connection_send_credentials() (or
 382  * similar) for this to work.
 383  *
 384  * As well as reading the credentials this also reads (and discards) a
 385  * single byte from the stream, as this is required for credentials
 386  * passing to work on some implementations.
 387  *
 388  * Other ways to exchange credentials with a foreign peer includes the
 389  * #GUnixCredentialsMessage type and g_socket_get_credentials() function.
 390  *
 391  * Returns: Received credentials on success (free with
 392  * g_object_unref()), %NULL if @error is set.
 393  *
 394  * Since: 2.26
 395  */
 396 GCredentials *
 397 g_unix_connection_receive_credentials (GUnixConnection      *connection,
 398                                        GCancellable         *cancellable,
 399                                        GError              **error)
 400 {
 401   GCredentials *ret;
 402   GSocketControlMessage **scms;
 403   gint nscm;
 404   GSocket *socket;
 405   gint n;
 406   volatile GType credentials_message_gtype;
 407   gssize num_bytes_read;
 408 #ifdef __linux__
 409   gboolean turn_off_so_passcreds;
 410 #endif
 411
 412   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), NULL);
 413   g_return_val_if_fail (error == NULL || *error == NULL, NULL);
 414
 415   ret = NULL;
 416   scms = NULL;
 417
 418   g_object_get (connection, "socket", &socket, NULL);
 419
 420   /* On Linux, we need to turn on SO_PASSCRED if it isn't enabled
 421    * already. We also need to turn it off when we're done.  See
 422    * #617483 for more discussion.
 423    */
 424 #ifdef __linux__
 425   {
 426     gint opt_val;
 427     socklen_t opt_len;
 428
 429     turn_off_so_passcreds = FALSE;
 430     opt_val = 0;
 431     opt_len = sizeof (gint);
 432     if (getsockopt (g_socket_get_fd (socket),
 433                     SOL_SOCKET,
 434                     SO_PASSCRED,
 435                     &opt_val,
 436                     &opt_len) != 0)
 437       {
 438         g_set_error (error,
 439                      G_IO_ERROR,
 440                      g_io_error_from_errno (errno),
 441                      _("Error checking if SO_PASSCRED is enabled for socket: %s"),
 442                      strerror (errno));
 443         goto out;
 444       }
 445     if (opt_len != sizeof (gint))
 446       {
 447         g_set_error (error,
 448                      G_IO_ERROR,
 449                      G_IO_ERROR_FAILED,
 450                      _("Unexpected option length while checking if SO_PASSCRED is enabled for socket. "
 451                        "Expected %d bytes, got %d"),
 452                      (gint) sizeof (gint), (gint) opt_len);
 453         goto out;
 454       }
 455     if (opt_val == 0)
 456       {
 457         opt_val = 1;
 458         if (setsockopt (g_socket_get_fd (socket),
 459                         SOL_SOCKET,
 460                         SO_PASSCRED,
 461                         &opt_val,
 462                         sizeof opt_val) != 0)
 463           {
 464             g_set_error (error,
 465                          G_IO_ERROR,
 466                          g_io_error_from_errno (errno),
 467                          _("Error enabling SO_PASSCRED: %s"),
 468                          strerror (errno));
 469             goto out;
 470           }
 471         turn_off_so_passcreds = TRUE;
 472       }
 473   }
 474 #endif
 475
 476   /* ensure the type of GUnixCredentialsMessage has been registered with the type system */
 477   credentials_message_gtype = G_TYPE_UNIX_CREDENTIALS_MESSAGE;
 478   num_bytes_read = g_socket_receive_message (socket,
 479                                              NULL, /* GSocketAddress **address */
 480                                              NULL,
 481                                              0,
 482                                              &scms,
 483                                              &nscm,
 484                                              NULL,
 485                                              cancellable,
 486                                              error);
 487   if (num_bytes_read != 1)
 488     {
 489       /* Handle situation where g_socket_receive_message() returns
 490        * 0 bytes and not setting @error
 491        */
 492       if (num_bytes_read == 0 && error != NULL && *error == NULL)
 493         {
 494           g_set_error_literal (error,
 495                                G_IO_ERROR,
 496                                G_IO_ERROR_FAILED,
 497                                _("Expecting to read a single byte for receiving credentials but read zero bytes"));
 498         }
 499       goto out;
 500     }
 501
 502   if (nscm != 1)
 503     {
 504       g_set_error (error,
 505                    G_IO_ERROR,
 506                    G_IO_ERROR_FAILED,
 507                    _("Expecting 1 control message, got %d"),
 508                    nscm);
 509       goto out;
 510     }
 511
 512   if (!G_IS_UNIX_CREDENTIALS_MESSAGE (scms[0]))
 513     {
 514       g_set_error_literal (error,
 515                            G_IO_ERROR,
 516                            G_IO_ERROR_FAILED,
 517                            _("Unexpected type of ancillary data"));
 518       goto out;
 519     }
 520
 521   ret = g_unix_credentials_message_get_credentials (G_UNIX_CREDENTIALS_MESSAGE (scms[0]));
 522   g_object_ref (ret);
 523
 524  out:
 525
 526 #ifdef __linux__
 527   if (turn_off_so_passcreds)
 528     {
 529       gint opt_val;
 530       opt_val = 0;
 531       if (setsockopt (g_socket_get_fd (socket),
 532                       SOL_SOCKET,
 533                       SO_PASSCRED,
 534                       &opt_val,
 535                       sizeof opt_val) != 0)
 536         {
 537           g_set_error (error,
 538                        G_IO_ERROR,
 539                        g_io_error_from_errno (errno),
 540                        _("Error while disabling SO_PASSCRED: %s"),
 541                        strerror (errno));
 542           goto out;
 543         }
 544     }
 545 #endif
 546
 547   if (scms != NULL)
 548     {
 549       for (n = 0; n < nscm; n++)
 550         g_object_unref (scms[n]);
 551       g_free (scms);
 552     }
 553   g_object_unref (socket);
 554   return ret;
 555 }