src/greeter.c

   1 /*
   2  * Copyright (C) 2010-2011 Robert Ancell.
   3  * Author: Robert Ancell <robert.ancell@canonical.com>
   4  *
   5  * This program is free software: you can redistribute it and/or modify it under
   6  * the terms of the GNU General Public License as published by the Free Software
   7  * Foundation, either version 3 of the License, or (at your option) any later
   8  * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
   9  * license.
  10  */
  11
  12 #include <config.h>
  13
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <errno.h>
  17 #include <fcntl.h>
  18 #include <gcrypt.h>
  19
  20 #include "greeter.h"
  21 #include "configuration.h"
  22 #include "shared-data-manager.h"
  23
  24 enum {
  25     PROP_0,
  26     PROP_ACTIVE_USERNAME,
  27 };
  28
  29 enum {
  30     CONNECTED,
  31     CREATE_SESSION,
  32     START_SESSION,
  33     LAST_SIGNAL
  34 };
  35 static guint signals[LAST_SIGNAL] = { 0 };
  36
  37 struct GreeterPrivate
  38 {
  39     /* PAM service to authenticate with */
  40     gchar *pam_service;
  41     gchar *autologin_pam_service;
  42
  43     /* Buffer for data read from greeter */
  44     guint8 *read_buffer;
  45     gsize n_read;
  46     gboolean use_secure_memory;
  47
  48     /* Hints for the greeter */
  49     GHashTable *hints;
  50
  51     /* Default session to use */
  52     gchar *default_session;
  53
  54     /* Sequence number of current PAM session */
  55     guint32 authentication_sequence_number;
  56
  57     /* Remote session name */
  58     gchar *remote_session;
  59
  60     /* Currently selected user */
  61     gchar *active_username;
  62
  63     /* PAM session being constructed by the greeter */
  64     Session *authentication_session;
  65
  66     /* TRUE if a the greeter can handle a reset; else we will just kill it instead */
  67     gboolean resettable;
  68
  69     /* TRUE if a user has been authenticated and the session requested to start */
  70     gboolean start_session;
  71
  72     /* TRUE if can log into guest accounts */
  73     gboolean allow_guest;
  74
  75     /* TRUE if logging into guest session */
  76     gboolean guest_account_authenticated;
  77
  78     /* Communication channels to communicate with */
  79     int to_greeter_input;
  80     int from_greeter_output;
  81     GIOChannel *to_greeter_channel;
  82     GIOChannel *from_greeter_channel;
  83     guint from_greeter_watch;
  84 };
  85
  86 G_DEFINE_TYPE (Greeter, greeter, SESSION_TYPE);
  87
  88 /* Messages from the greeter to the server */
  89 typedef enum
  90 {
  91     GREETER_MESSAGE_CONNECT = 0,
  92     GREETER_MESSAGE_AUTHENTICATE,
  93     GREETER_MESSAGE_AUTHENTICATE_AS_GUEST,
  94     GREETER_MESSAGE_CONTINUE_AUTHENTICATION,
  95     GREETER_MESSAGE_START_SESSION,
  96     GREETER_MESSAGE_CANCEL_AUTHENTICATION,
  97     GREETER_MESSAGE_SET_LANGUAGE,
  98     GREETER_MESSAGE_AUTHENTICATE_REMOTE,
  99     GREETER_MESSAGE_ENSURE_SHARED_DIR,
 100 } GreeterMessage;
 101
 102 /* Messages from the server to the greeter */
 103 typedef enum
 104 {
 105     SERVER_MESSAGE_CONNECTED = 0,
 106     SERVER_MESSAGE_PROMPT_AUTHENTICATION,
 107     SERVER_MESSAGE_END_AUTHENTICATION,
 108     SERVER_MESSAGE_SESSION_RESULT,
 109     SERVER_MESSAGE_SHARED_DIR_RESULT,
 110     SERVER_MESSAGE_IDLE,
 111     SERVER_MESSAGE_RESET,
 112 } ServerMessage;
 113
 114 static gboolean read_cb (GIOChannel *source, GIOCondition condition, gpointer data);
 115
 116 Greeter *
 117 greeter_new (void)
 118 {
 119     return g_object_new (GREETER_TYPE, NULL);
 120 }
 121
 122 void
 123 greeter_set_pam_services (Greeter *greeter, const gchar *pam_service, const gchar *autologin_pam_service)
 124 {
 125     g_free (greeter->priv->pam_service);
 126     greeter->priv->pam_service = g_strdup (pam_service);
 127     g_free (greeter->priv->autologin_pam_service);
 128     greeter->priv->autologin_pam_service = g_strdup (autologin_pam_service);
 129 }
 130
 131 void
 132 greeter_set_allow_guest (Greeter *greeter, gboolean allow_guest)
 133 {
 134     greeter->priv->allow_guest = allow_guest;
 135 }
 136
 137 void
 138 greeter_clear_hints (Greeter *greeter)
 139 {
 140     g_hash_table_remove_all (greeter->priv->hints);
 141 }
 142
 143 void
 144 greeter_set_hint (Greeter *greeter, const gchar *name, const gchar *value)
 145 {
 146     g_hash_table_insert (greeter->priv->hints, g_strdup (name), g_strdup (value));
 147 }
 148
 149 static void *
 150 secure_malloc (Greeter *greeter, size_t n)
 151 {
 152     if (greeter->priv->use_secure_memory)
 153         return gcry_malloc_secure (n);
 154     else
 155         return g_malloc (n);
 156 }
 157
 158 static void *
 159 secure_realloc (Greeter *greeter, void *ptr, size_t n)
 160 {
 161     if (greeter->priv->use_secure_memory)
 162         return gcry_realloc (ptr, n);
 163     else
 164         return g_realloc (ptr, n);
 165 }
 166
 167 static void
 168 secure_free (Greeter *greeter, void *ptr)
 169 {
 170     if (greeter->priv->use_secure_memory)
 171         return gcry_free (ptr);
 172     else
 173         return g_free (ptr);
 174 }
 175
 176 static guint32
 177 int_length (void)
 178 {
 179     return 4;
 180 }
 181
 182 #define HEADER_SIZE (sizeof (guint32) * 2)
 183 #define MAX_MESSAGE_LENGTH 1024
 184
 185 static void
 186 write_message (Greeter *greeter, guint8 *message, gsize message_length)
 187 {
 188     gchar *data;
 189     gsize data_length;
 190     GError *error = NULL;
 191
 192     data = (gchar *) message;
 193     data_length = message_length;
 194     while (data_length > 0)
 195     {
 196         GIOStatus status;
 197         gsize n_written;
 198
 199         status = g_io_channel_write_chars (greeter->priv->to_greeter_channel, data, data_length, &n_written, &error);
 200         if (error)
 201             l_warning (greeter, "Error writing to greeter: %s", error->message);
 202         g_clear_error (&error);
 203         if (status != G_IO_STATUS_NORMAL)
 204             return;
 205         data_length -= n_written;
 206         data += n_written;
 207     }
 208
 209     g_io_channel_flush (greeter->priv->to_greeter_channel, &error);
 210     if (error)
 211         l_warning (greeter, "Failed to flush data to greeter: %s", error->message);
 212     g_clear_error (&error);
 213 }
 214
 215 static void
 216 write_int (guint8 *buffer, gint buffer_length, guint32 value, gsize *offset)
 217 {
 218     if (*offset + 4 >= buffer_length)
 219         return;
 220     buffer[*offset] = value >> 24;
 221     buffer[*offset+1] = (value >> 16) & 0xFF;
 222     buffer[*offset+2] = (value >> 8) & 0xFF;
 223     buffer[*offset+3] = value & 0xFF;
 224     *offset += 4;
 225 }
 226
 227 static void
 228 write_string (guint8 *buffer, gint buffer_length, const gchar *value, gsize *offset)
 229 {
 230     gint length;
 231
 232     if (value)
 233         length = strlen (value);
 234     else
 235         length = 0;
 236     write_int (buffer, buffer_length, length, offset);
 237     if (*offset + length >= buffer_length)
 238         return;
 239     if (length > 0)
 240     {
 241         memcpy (buffer + *offset, value, length);
 242         *offset += length;
 243     }
 244 }
 245
 246 static void
 247 write_header (guint8 *buffer, gint buffer_length, guint32 id, guint32 length, gsize *offset)
 248 {
 249     write_int (buffer, buffer_length, id, offset);
 250     write_int (buffer, buffer_length, length, offset);
 251 }
 252
 253 static guint32
 254 string_length (const gchar *value)
 255 {
 256     if (value == NULL)
 257         return int_length ();
 258     else
 259         return int_length () + strlen (value);
 260 }
 261
 262 static void
 263 handle_connect (Greeter *greeter, const gchar *version, gboolean resettable)
 264 {
 265     guint8 message[MAX_MESSAGE_LENGTH];
 266     gsize offset = 0;
 267     guint32 length;
 268     GHashTableIter iter;
 269     gpointer key, value;
 270
 271     l_debug (greeter, "Greeter connected version=%s resettable=%s", version, resettable ? "true" : "false");
 272
 273     greeter->priv->resettable = resettable;
 274
 275     length = string_length (VERSION);
 276     g_hash_table_iter_init (&iter, greeter->priv->hints);
 277     while (g_hash_table_iter_next (&iter, &key, &value))
 278         length += string_length (key) + string_length (value);
 279
 280     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_CONNECTED, length, &offset);
 281     write_string (message, MAX_MESSAGE_LENGTH, VERSION, &offset);
 282     g_hash_table_iter_init (&iter, greeter->priv->hints);
 283     while (g_hash_table_iter_next (&iter, &key, &value))
 284     {
 285         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 286         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 287     }
 288     write_message (greeter, message, offset);
 289
 290     g_signal_emit (greeter, signals[CONNECTED], 0);
 291 }
 292
 293 static void
 294 pam_messages_cb (Session *session, Greeter *greeter)
 295 {
 296     int i;
 297     guint32 size;
 298     guint8 message[MAX_MESSAGE_LENGTH];
 299     const struct pam_message *messages;
 300     int messages_length;
 301     gsize offset = 0;
 302     int n_prompts = 0;
 303
 304     messages = session_get_messages (session);
 305     messages_length = session_get_messages_length (session);
 306
 307     /* Respond to d-bus query with messages */
 308     l_debug (greeter, "Prompt greeter with %d message(s)", messages_length);
 309     size = int_length () + string_length (session_get_username (session)) + int_length ();
 310     for (i = 0; i < messages_length; i++)
 311         size += int_length () + string_length (messages[i].msg);
 312
 313     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_PROMPT_AUTHENTICATION, size, &offset);
 314     write_int (message, MAX_MESSAGE_LENGTH, greeter->priv->authentication_sequence_number, &offset);
 315     write_string (message, MAX_MESSAGE_LENGTH, session_get_username (session), &offset);
 316     write_int (message, MAX_MESSAGE_LENGTH, messages_length, &offset);
 317     for (i = 0; i < messages_length; i++)
 318     {
 319         write_int (message, MAX_MESSAGE_LENGTH, messages[i].msg_style, &offset);
 320         write_string (message, MAX_MESSAGE_LENGTH, messages[i].msg, &offset);
 321
 322         if (messages[i].msg_style == PAM_PROMPT_ECHO_OFF || messages[i].msg_style == PAM_PROMPT_ECHO_ON)
 323             n_prompts++;
 324     }
 325     write_message (greeter, message, offset);
 326
 327     /* Continue immediately if nothing to respond with */
 328     // FIXME: Should probably give the greeter a chance to ack the message
 329     if (n_prompts == 0)
 330     {
 331         struct pam_response *response;
 332         response = calloc (messages_length, sizeof (struct pam_response));
 333         session_respond (greeter->priv->authentication_session, response);
 334         free (response);
 335     }
 336 }
 337
 338 static void
 339 send_end_authentication (Greeter *greeter, guint32 sequence_number, const gchar *username, int result)
 340 {
 341     guint8 message[MAX_MESSAGE_LENGTH];
 342     gsize offset = 0;
 343
 344     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_END_AUTHENTICATION, int_length () + string_length (username) + int_length (), &offset);
 345     write_int (message, MAX_MESSAGE_LENGTH, sequence_number, &offset);
 346     write_string (message, MAX_MESSAGE_LENGTH, username, &offset);
 347     write_int (message, MAX_MESSAGE_LENGTH, result, &offset);
 348     write_message (greeter, message, offset);
 349 }
 350
 351 void
 352 greeter_idle (Greeter *greeter)
 353 {
 354     guint8 message[MAX_MESSAGE_LENGTH];
 355     gsize offset = 0;
 356
 357     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_IDLE, 0, &offset);
 358     write_message (greeter, message, offset);
 359 }
 360
 361 void
 362 greeter_reset (Greeter *greeter)
 363 {
 364     guint8 message[MAX_MESSAGE_LENGTH];
 365     gsize offset = 0;
 366     guint32 length = 0;
 367     GHashTableIter iter;
 368     gpointer key, value;
 369
 370     g_hash_table_iter_init (&iter, greeter->priv->hints);
 371     while (g_hash_table_iter_next (&iter, &key, &value))
 372         length += string_length (key) + string_length (value);
 373
 374     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_RESET, length, &offset);
 375     g_hash_table_iter_init (&iter, greeter->priv->hints);
 376     while (g_hash_table_iter_next (&iter, &key, &value))
 377     {
 378         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 379         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 380     }
 381     write_message (greeter, message, offset);
 382 }
 383
 384 static void
 385 authentication_complete_cb (Session *session, Greeter *greeter)
 386 {
 387     int result;
 388
 389     l_debug (greeter, "Authenticate result for user %s: %s", session_get_username (session), session_get_authentication_result_string (session));
 390
 391     result = session_get_authentication_result (session);
 392     if (session_get_is_authenticated (session))
 393     {
 394         if (session_get_user (session))
 395             l_debug (greeter, "User %s authorized", session_get_username (session));
 396         else
 397         {
 398             l_debug (greeter, "User %s authorized, but no account of that name exists", session_get_username (session));
 399             result = PAM_USER_UNKNOWN;
 400         }
 401     }
 402
 403     send_end_authentication (greeter, greeter->priv->authentication_sequence_number, session_get_username (session), result);
 404 }
 405
 406 static void
 407 reset_session (Greeter *greeter)
 408 {
 409     g_free (greeter->priv->remote_session);
 410     greeter->priv->remote_session = NULL;
 411     if (greeter->priv->authentication_session)
 412     {
 413         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 414         session_stop (greeter->priv->authentication_session);
 415         g_object_unref (greeter->priv->authentication_session);
 416         greeter->priv->authentication_session = NULL;
 417     }
 418
 419     greeter->priv->guest_account_authenticated = FALSE;
 420 }
 421
 422 static void
 423 handle_login (Greeter *greeter, guint32 sequence_number, const gchar *username)
 424 {
 425     const gchar *autologin_username, *service;
 426     gboolean is_interactive;
 427
 428     if (username[0] == '\0')
 429     {
 430         l_debug (greeter, "Greeter start authentication");
 431         username = NULL;
 432     }
 433     else
 434         l_debug (greeter, "Greeter start authentication for %s", username);
 435
 436     reset_session (greeter);
 437
 438     if (greeter->priv->active_username)
 439         g_free (greeter->priv->active_username);
 440     greeter->priv->active_username = g_strdup (username);
 441     g_object_notify (G_OBJECT (greeter), GREETER_PROPERTY_ACTIVE_USERNAME);
 442
 443     greeter->priv->authentication_sequence_number = sequence_number;
 444     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 445     if (!greeter->priv->authentication_session)
 446     {
 447         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 448         return;
 449     }
 450
 451     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 452     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 453
 454     /* Use non-interactive service for autologin user */
 455     autologin_username = g_hash_table_lookup (greeter->priv->hints, "autologin-user");
 456     if (autologin_username != NULL && g_strcmp0 (username, autologin_username) == 0)
 457     {
 458         service = greeter->priv->autologin_pam_service;
 459         is_interactive = FALSE;
 460     }
 461     else
 462     {
 463         service = greeter->priv->pam_service;
 464         is_interactive = TRUE;
 465     }
 466
 467     /* Run the session process */
 468     session_set_pam_service (greeter->priv->authentication_session, service);
 469     session_set_username (greeter->priv->authentication_session, username);
 470     session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 471     session_set_is_interactive (greeter->priv->authentication_session, is_interactive);
 472     session_start (greeter->priv->authentication_session);
 473 }
 474
 475 static void
 476 handle_login_as_guest (Greeter *greeter, guint32 sequence_number)
 477 {
 478     l_debug (greeter, "Greeter start authentication for guest account");
 479
 480     reset_session (greeter);
 481
 482     if (!greeter->priv->allow_guest)
 483     {
 484         l_debug (greeter, "Guest account is disabled");
 485         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 486         return;
 487     }
 488
 489     greeter->priv->guest_account_authenticated = TRUE;
 490     send_end_authentication (greeter, sequence_number, "", PAM_SUCCESS);
 491 }
 492
 493 static gchar *
 494 get_remote_session_service (const gchar *session_name)
 495 {
 496     GKeyFile *session_desktop_file;
 497     gboolean result;
 498     const gchar *c;
 499     gchar *remote_sessions_dir, *filename, *path, *service = NULL;
 500     GError *error = NULL;
 501
 502     /* Validate session name doesn't contain directory separators */
 503     for (c = session_name; *c; c++)
 504     {
 505         if (*c == '/')
 506             return NULL;
 507     }
 508
 509     /* Load the session file */
 510     session_desktop_file = g_key_file_new ();
 511     filename = g_strdup_printf ("%s.desktop", session_name);
 512     remote_sessions_dir = config_get_string (config_get_instance (), "LightDM", "remote-sessions-directory");
 513     path = g_build_filename (remote_sessions_dir, filename, NULL);
 514     g_free (remote_sessions_dir);
 515     g_free (filename);
 516     result = g_key_file_load_from_file (session_desktop_file, path, G_KEY_FILE_NONE, &error);
 517     if (error)
 518         g_debug ("Failed to load session file %s: %s", path, error->message);
 519     g_free (path);
 520     g_clear_error (&error);
 521     if (result)
 522         service = g_key_file_get_string (session_desktop_file, G_KEY_FILE_DESKTOP_GROUP, "X-LightDM-PAM-Service", NULL);
 523     g_key_file_free (session_desktop_file);
 524
 525     return service;
 526 }
 527
 528 static void
 529 handle_login_remote (Greeter *greeter, const gchar *session_name, const gchar *username, guint32 sequence_number)
 530 {
 531     gchar *service;
 532
 533     if (username[0] == '\0')
 534     {
 535         l_debug (greeter, "Greeter start authentication for remote session %s", session_name);
 536         username = NULL;
 537     }
 538     else
 539         l_debug (greeter, "Greeter start authentication for remote session %s as user %s", session_name, username);
 540
 541     reset_session (greeter);
 542
 543     service = get_remote_session_service (session_name);
 544     if (!service)
 545     {
 546         send_end_authentication (greeter, sequence_number, "", PAM_SYSTEM_ERR);
 547         return;
 548     }
 549
 550     greeter->priv->authentication_sequence_number = sequence_number;
 551     greeter->priv->remote_session = g_strdup (session_name);
 552     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 553     if (greeter->priv->authentication_session)
 554     {
 555         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 556         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 557
 558         /* Run the session process */
 559         session_set_pam_service (greeter->priv->authentication_session, service);
 560         session_set_username (greeter->priv->authentication_session, username);
 561         session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 562         session_set_is_interactive (greeter->priv->authentication_session, TRUE);
 563         session_set_is_guest (greeter->priv->authentication_session, TRUE);
 564         session_start (greeter->priv->authentication_session);
 565     }
 566
 567     g_free (service);
 568
 569     if (!greeter->priv->authentication_session)
 570     {
 571         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 572         return;
 573     }
 574 }
 575
 576 static void
 577 handle_continue_authentication (Greeter *greeter, gchar **secrets)
 578 {
 579     int messages_length;
 580     const struct pam_message *messages;
 581     struct pam_response *response;
 582     int i, j, n_prompts = 0;
 583
 584     /* Not in authentication */
 585     if (greeter->priv->authentication_session == NULL)
 586         return;
 587
 588     messages_length = session_get_messages_length (greeter->priv->authentication_session);
 589     messages = session_get_messages (greeter->priv->authentication_session);
 590
 591     /* Check correct number of responses */
 592     for (i = 0; i < messages_length; i++)
 593     {
 594         int msg_style = messages[i].msg_style;
 595         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 596             n_prompts++;
 597     }
 598     if (g_strv_length (secrets) != n_prompts)
 599     {
 600         session_respond_error (greeter->priv->authentication_session, PAM_CONV_ERR);
 601         return;
 602     }
 603
 604     l_debug (greeter, "Continue authentication");
 605
 606     /* Build response */
 607     response = calloc (messages_length, sizeof (struct pam_response));
 608     for (i = 0, j = 0; i < messages_length; i++)
 609     {
 610         int msg_style = messages[i].msg_style;
 611         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 612         {
 613             size_t secret_length = strlen (secrets[j]) + 1;
 614             response[i].resp = secure_malloc (greeter, secret_length);
 615             memcpy (response[i].resp, secrets[j], secret_length); // FIXME: Need to convert from UTF-8
 616             j++;
 617         }
 618     }
 619
 620     session_respond (greeter->priv->authentication_session, response);
 621
 622     for (i = 0; i < messages_length; i++)
 623         secure_free (greeter, response[i].resp);
 624     free (response);
 625 }
 626
 627 static void
 628 handle_cancel_authentication (Greeter *greeter)
 629 {
 630     /* Not in authentication */
 631     if (greeter->priv->authentication_session == NULL)
 632         return;
 633
 634     l_debug (greeter, "Cancel authentication");
 635     reset_session (greeter);
 636 }
 637
 638 static void
 639 handle_start_session (Greeter *greeter, const gchar *session)
 640 {
 641     gboolean result;
 642     guint8 message[MAX_MESSAGE_LENGTH];
 643     gsize offset = 0;
 644     SessionType session_type = SESSION_TYPE_LOCAL;
 645
 646     if (strcmp (session, "") == 0)
 647         session = NULL;
 648
 649     /* Use session type chosen in remote session */
 650     if (greeter->priv->remote_session)
 651     {
 652         session_type = SESSION_TYPE_REMOTE;
 653         session = greeter->priv->remote_session;
 654     }
 655
 656     if (greeter->priv->guest_account_authenticated || session_get_is_authenticated (greeter->priv->authentication_session))
 657     {
 658         if (session)
 659             l_debug (greeter, "Greeter requests session %s", session);
 660         else
 661             l_debug (greeter, "Greeter requests default session");
 662         greeter->priv->start_session = TRUE;
 663         g_signal_emit (greeter, signals[START_SESSION], 0, session_type, session, &result);
 664     }
 665     else
 666     {
 667         l_debug (greeter, "Ignoring start session request, user is not authorized");
 668         result = FALSE;
 669     }
 670
 671     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SESSION_RESULT, int_length (), &offset);
 672     write_int (message, MAX_MESSAGE_LENGTH, result ? 0 : 1, &offset);
 673     write_message (greeter, message, offset);
 674 }
 675
 676 static void
 677 handle_set_language (Greeter *greeter, const gchar *language)
 678 {
 679     User *user;
 680
 681     if (!greeter->priv->guest_account_authenticated && !session_get_is_authenticated (greeter->priv->authentication_session))
 682     {
 683         l_debug (greeter, "Ignoring set language request, user is not authorized");
 684         return;
 685     }
 686
 687     // FIXME: Could use this
 688     if (greeter->priv->guest_account_authenticated)
 689     {
 690         l_debug (greeter, "Ignoring set language request for guest user");
 691         return;
 692     }
 693
 694     l_debug (greeter, "Greeter sets language %s", language);
 695     user = session_get_user (greeter->priv->authentication_session);
 696     user_set_language (user, language);
 697 }
 698
 699 static void
 700 handle_ensure_shared_dir (Greeter *greeter, const gchar *username)
 701 {
 702     gchar *dir;
 703     guint8 message[MAX_MESSAGE_LENGTH];
 704     gsize offset = 0;
 705
 706     l_debug (greeter, "Greeter requests data directory for user %s", username);
 707
 708     dir = shared_data_manager_ensure_user_dir (shared_data_manager_get_instance (), username);
 709
 710     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SHARED_DIR_RESULT, string_length (dir), &offset);
 711     write_string (message, MAX_MESSAGE_LENGTH, dir, &offset);
 712     write_message (greeter, message, offset);
 713
 714     g_free (dir);
 715 }
 716
 717 static guint32
 718 read_int (Greeter *greeter, gsize *offset)
 719 {
 720     guint32 value;
 721     guint8 *buffer;
 722     if (greeter->priv->n_read - *offset < sizeof (guint32))
 723     {
 724         l_warning (greeter, "Not enough space for int, need %zu, got %zu", sizeof (guint32), greeter->priv->n_read - *offset);
 725         return 0;
 726     }
 727     buffer = greeter->priv->read_buffer + *offset;
 728     value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
 729     *offset += int_length ();
 730     return value;
 731 }
 732
 733 static int
 734 get_message_length (Greeter *greeter)
 735 {
 736     gsize offset;
 737     int payload_length;
 738
 739     offset = int_length ();
 740     payload_length = read_int (greeter, &offset);
 741
 742     if (HEADER_SIZE + payload_length < HEADER_SIZE)
 743     {
 744         l_warning (greeter, "Payload length of %u octets too long", payload_length);
 745         return HEADER_SIZE;
 746     }
 747
 748     return HEADER_SIZE + payload_length;
 749 }
 750
 751 static gchar *
 752 read_string_full (Greeter *greeter, gsize *offset, void* (*alloc_fn)(size_t n))
 753 {
 754     guint32 length;
 755     gchar *value;
 756
 757     length = read_int (greeter, offset);
 758     if (greeter->priv->n_read - *offset < length)
 759     {
 760         l_warning (greeter, "Not enough space for string, need %u, got %zu", length, greeter->priv->n_read - *offset);
 761         return g_strdup ("");
 762     }
 763
 764     value = (*alloc_fn) (sizeof (gchar) * (length + 1));
 765     memcpy (value, greeter->priv->read_buffer + *offset, length);
 766     value[length] = '\0';
 767     *offset += length;
 768
 769     return value;
 770 }
 771
 772 static gchar *
 773 read_string (Greeter *greeter, gsize *offset)
 774 {
 775     return read_string_full (greeter, offset, g_malloc);
 776 }
 777
 778 static gchar *
 779 read_secret (Greeter *greeter, gsize *offset)
 780 {
 781     if (greeter->priv->use_secure_memory)
 782         return read_string_full (greeter, offset, gcry_malloc_secure);
 783     else
 784         return read_string_full (greeter, offset, g_malloc);
 785 }
 786
 787 static gboolean
 788 read_cb (GIOChannel *source, GIOCondition condition, gpointer data)
 789 {
 790     Greeter *greeter = data;
 791     gsize n_to_read, n_read, offset;
 792     GIOStatus status;
 793     int id, length, i;
 794     guint32 sequence_number, n_secrets, max_secrets;
 795     gchar *version, *username, *session_name, *language;
 796     gchar **secrets;
 797     gboolean resettable = FALSE;
 798     GError *error = NULL;
 799
 800     if (condition == G_IO_HUP)
 801     {
 802         l_debug (greeter, "Greeter closed communication channel");
 803         greeter->priv->from_greeter_watch = 0;
 804         return FALSE;
 805     }
 806
 807     n_to_read = HEADER_SIZE;
 808     if (greeter->priv->n_read >= HEADER_SIZE)
 809     {
 810         n_to_read = get_message_length (greeter);
 811         if (n_to_read <= HEADER_SIZE)
 812         {
 813             greeter->priv->from_greeter_watch = 0;
 814             return FALSE;
 815         }
 816     }
 817
 818     status = g_io_channel_read_chars (greeter->priv->from_greeter_channel,
 819                                       (gchar *) greeter->priv->read_buffer + greeter->priv->n_read,
 820                                       n_to_read - greeter->priv->n_read,
 821                                       &n_read,
 822                                       &error);
 823     if (error)
 824         l_warning (greeter, "Error reading from greeter: %s", error->message);
 825     g_clear_error (&error);
 826     if (status != G_IO_STATUS_NORMAL)
 827         return TRUE;
 828
 829     greeter->priv->n_read += n_read;
 830     if (greeter->priv->n_read != n_to_read)
 831         return TRUE;
 832
 833     /* If have header, rerun for content */
 834     if (greeter->priv->n_read == HEADER_SIZE)
 835     {
 836         n_to_read = get_message_length (greeter);
 837         if (n_to_read > HEADER_SIZE)
 838         {
 839             greeter->priv->read_buffer = secure_realloc (greeter, greeter->priv->read_buffer, n_to_read);
 840             read_cb (source, condition, greeter);
 841             return TRUE;
 842         }
 843     }
 844
 845     offset = 0;
 846     id = read_int (greeter, &offset);
 847     length = HEADER_SIZE + read_int (greeter, &offset);
 848     switch (id)
 849     {
 850     case GREETER_MESSAGE_CONNECT:
 851         version = read_string (greeter, &offset);
 852         if (offset < length)
 853             resettable = read_int (greeter, &offset) != 0;
 854         handle_connect (greeter, version, resettable);
 855         g_free (version);
 856         break;
 857     case GREETER_MESSAGE_AUTHENTICATE:
 858         sequence_number = read_int (greeter, &offset);
 859         username = read_string (greeter, &offset);
 860         handle_login (greeter, sequence_number, username);
 861         g_free (username);
 862         break;
 863     case GREETER_MESSAGE_AUTHENTICATE_AS_GUEST:
 864         sequence_number = read_int (greeter, &offset);
 865         handle_login_as_guest (greeter, sequence_number);
 866         break;
 867     case GREETER_MESSAGE_AUTHENTICATE_REMOTE:
 868         sequence_number = read_int (greeter, &offset);
 869         session_name = read_string (greeter, &offset);
 870         username = read_string (greeter, &offset);
 871         handle_login_remote (greeter, session_name, username, sequence_number);
 872         break;
 873     case GREETER_MESSAGE_CONTINUE_AUTHENTICATION:
 874         n_secrets = read_int (greeter, &offset);
 875         max_secrets = (G_MAXUINT32 - 1) / sizeof (gchar *);
 876         if (n_secrets > max_secrets)
 877         {
 878             l_warning (greeter, "Array length of %u elements too long", n_secrets);
 879             greeter->priv->from_greeter_watch = 0;
 880             return FALSE;
 881         }
 882         secrets = g_malloc (sizeof (gchar *) * (n_secrets + 1));
 883         for (i = 0; i < n_secrets; i++)
 884             secrets[i] = read_secret (greeter, &offset);
 885         secrets[i] = NULL;
 886         handle_continue_authentication (greeter, secrets);
 887         for (i = 0; i < n_secrets; i++)
 888             secure_free (greeter, secrets[i]);
 889         g_free (secrets);
 890         break;
 891     case GREETER_MESSAGE_CANCEL_AUTHENTICATION:
 892         handle_cancel_authentication (greeter);
 893         break;
 894     case GREETER_MESSAGE_START_SESSION:
 895         session_name = read_string (greeter, &offset);
 896         handle_start_session (greeter, session_name);
 897         g_free (session_name);
 898         break;
 899     case GREETER_MESSAGE_SET_LANGUAGE:
 900         language = read_string (greeter, &offset);
 901         handle_set_language (greeter, language);
 902         g_free (language);
 903         break;
 904     case GREETER_MESSAGE_ENSURE_SHARED_DIR:
 905         username = read_string (greeter, &offset);
 906         handle_ensure_shared_dir (greeter, username);
 907         g_free (username);
 908         break;
 909     default:
 910         l_warning (greeter, "Unknown message from greeter: %d", id);
 911         break;
 912     }
 913
 914     greeter->priv->n_read = 0;
 915
 916     return TRUE;
 917 }
 918
 919 gboolean
 920 greeter_get_guest_authenticated (Greeter *greeter)
 921 {
 922     g_return_val_if_fail (greeter != NULL, FALSE);
 923     return greeter->priv->guest_account_authenticated;
 924 }
 925
 926 Session *
 927 greeter_get_authentication_session (Greeter *greeter)
 928 {
 929     g_return_val_if_fail (greeter != NULL, NULL);
 930     return greeter->priv->authentication_session;
 931 }
 932
 933 gboolean
 934 greeter_get_resettable (Greeter *greeter)
 935 {
 936     g_return_val_if_fail (greeter != NULL, FALSE);
 937     return greeter->priv->resettable;
 938 }
 939
 940 gboolean
 941 greeter_get_start_session (Greeter *greeter)
 942 {
 943     g_return_val_if_fail (greeter != NULL, FALSE);
 944     return greeter->priv->start_session;
 945 }
 946
 947 const gchar *
 948 greeter_get_active_username (Greeter *greeter)
 949 {
 950     g_return_val_if_fail (greeter != NULL, NULL);
 951     return greeter->priv->active_username;
 952 }
 953
 954 static gboolean
 955 greeter_start (Session *session)
 956 {
 957     Greeter *greeter = GREETER (session);
 958     int to_greeter_pipe[2], from_greeter_pipe[2];
 959     int to_greeter_output, from_greeter_input;
 960     gboolean result = FALSE;
 961     gchar *value;
 962     GError *error = NULL;
 963
 964     /* Create a pipe to talk with the greeter */
 965     if (pipe (to_greeter_pipe) != 0 || pipe (from_greeter_pipe) != 0)
 966     {
 967         g_warning ("Failed to create pipes: %s", strerror (errno));
 968         return FALSE;
 969     }
 970     to_greeter_output = to_greeter_pipe[0];
 971     greeter->priv->to_greeter_input = to_greeter_pipe[1];
 972     greeter->priv->to_greeter_channel = g_io_channel_unix_new (greeter->priv->to_greeter_input);
 973     g_io_channel_set_encoding (greeter->priv->to_greeter_channel, NULL, &error);
 974     if (error)
 975         g_warning ("Failed to set encoding on to greeter channel to binary: %s\n", error->message);
 976     g_clear_error (&error);
 977     greeter->priv->from_greeter_output = from_greeter_pipe[0];
 978     from_greeter_input = from_greeter_pipe[1];
 979     greeter->priv->from_greeter_channel = g_io_channel_unix_new (greeter->priv->from_greeter_output);
 980     g_io_channel_set_encoding (greeter->priv->from_greeter_channel, NULL, &error);
 981     if (error)
 982         g_warning ("Failed to set encoding on from greeter channel to binary: %s\n", error->message);
 983     g_clear_error (&error);
 984     g_io_channel_set_buffered (greeter->priv->from_greeter_channel, FALSE);
 985     greeter->priv->from_greeter_watch = g_io_add_watch (greeter->priv->from_greeter_channel, G_IO_IN | G_IO_HUP, read_cb, greeter);
 986
 987     /* Let the greeter session know how to communicate with the daemon */
 988     value = g_strdup_printf ("%d", from_greeter_input);
 989     session_set_env (SESSION (greeter), "LIGHTDM_TO_SERVER_FD", value);
 990     g_free (value);
 991     value = g_strdup_printf ("%d", to_greeter_output);
 992     session_set_env (SESSION (greeter), "LIGHTDM_FROM_SERVER_FD", value);
 993     g_free (value);
 994
 995     /* Don't allow the daemon end of the pipes to be accessed in child processes */
 996     fcntl (greeter->priv->to_greeter_input, F_SETFD, FD_CLOEXEC);
 997     fcntl (greeter->priv->from_greeter_output, F_SETFD, FD_CLOEXEC);
 998
 999     result = SESSION_CLASS (greeter_parent_class)->start (session);
1000
1001     /* Close the session ends of the pipe */
1002     close (to_greeter_output);
1003     close (from_greeter_input);
1004
1005     return result;
1006 }
1007
1008 static Session *
1009 greeter_real_create_session (Greeter *greeter)
1010 {
1011     return NULL;
1012 }
1013
1014 static gboolean
1015 greeter_real_start_session (Greeter *greeter, SessionType type, const gchar *session)
1016 {
1017     return FALSE;
1018 }
1019
1020 static void
1021 greeter_stop (Session *session)
1022 {
1023     Greeter *greeter = GREETER (session);
1024
1025     /* Stop any events occurring after we've stopped */
1026     if (greeter->priv->authentication_session)
1027         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
1028
1029     SESSION_CLASS (greeter_parent_class)->stop (session);
1030 }
1031
1032 static void
1033 greeter_init (Greeter *greeter)
1034 {
1035     greeter->priv = G_TYPE_INSTANCE_GET_PRIVATE (greeter, GREETER_TYPE, GreeterPrivate);
1036     greeter->priv->read_buffer = secure_malloc (greeter, HEADER_SIZE);
1037     greeter->priv->hints = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
1038     greeter->priv->use_secure_memory = config_get_boolean (config_get_instance (), "LightDM", "lock-memory");
1039     greeter->priv->to_greeter_input = -1;
1040     greeter->priv->from_greeter_output = -1;
1041 }
1042
1043 static void
1044 greeter_finalize (GObject *object)
1045 {
1046     Greeter *self;
1047
1048     self = GREETER (object);
1049
1050     g_free (self->priv->pam_service);
1051     g_free (self->priv->autologin_pam_service);
1052     secure_free (self, self->priv->read_buffer);
1053     g_hash_table_unref (self->priv->hints);
1054     g_free (self->priv->remote_session);
1055     g_free (self->priv->active_username);
1056     if (self->priv->authentication_session)
1057     {
1058         g_signal_handlers_disconnect_matched (self->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, self);
1059         g_object_unref (self->priv->authentication_session);
1060     }
1061     close (self->priv->to_greeter_input);
1062     close (self->priv->from_greeter_output);
1063     if (self->priv->to_greeter_channel)
1064         g_io_channel_unref (self->priv->to_greeter_channel);
1065     if (self->priv->from_greeter_channel)
1066         g_io_channel_unref (self->priv->from_greeter_channel);
1067     if (self->priv->from_greeter_watch)
1068         g_source_remove (self->priv->from_greeter_watch);
1069
1070     G_OBJECT_CLASS (greeter_parent_class)->finalize (object);
1071 }
1072
1073 static void
1074 greeter_set_property (GObject      *object,
1075                       guint         prop_id,
1076                       const GValue *value,
1077                       GParamSpec   *pspec)
1078 {
1079     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1080 }
1081
1082 static void
1083 greeter_get_property (GObject    *object,
1084                       guint       prop_id,
1085                       GValue     *value,
1086                       GParamSpec *pspec)
1087 {
1088     Greeter *greeter = GREETER (object);
1089
1090     switch (prop_id) {
1091     case PROP_ACTIVE_USERNAME:
1092         g_value_set_string (value, greeter_get_active_username (greeter));
1093         break;
1094     default:
1095         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1096         break;
1097     }
1098 }
1099
1100 static void
1101 greeter_class_init (GreeterClass *klass)
1102 {
1103     SessionClass *session_class = SESSION_CLASS (klass);
1104     GObjectClass *object_class = G_OBJECT_CLASS (klass);
1105
1106     klass->create_session = greeter_real_create_session;
1107     klass->start_session = greeter_real_start_session;
1108     session_class->start = greeter_start;
1109     session_class->stop = greeter_stop;
1110     object_class->finalize = greeter_finalize;
1111     object_class->get_property = greeter_get_property;
1112     object_class->set_property = greeter_set_property;
1113
1114     signals[CONNECTED] =
1115         g_signal_new (GREETER_SIGNAL_CONNECTED,
1116                       G_TYPE_FROM_CLASS (klass),
1117                       G_SIGNAL_RUN_LAST,
1118                       G_STRUCT_OFFSET (GreeterClass, connected),
1119                       NULL, NULL,
1120                       NULL,
1121                       G_TYPE_NONE, 0);
1122
1123     signals[CREATE_SESSION] =
1124         g_signal_new (GREETER_SIGNAL_CREATE_SESSION,
1125                       G_TYPE_FROM_CLASS (klass),
1126                       G_SIGNAL_RUN_LAST,
1127                       G_STRUCT_OFFSET (GreeterClass, create_session),
1128                       g_signal_accumulator_first_wins,
1129                       NULL,
1130                       NULL,
1131                       SESSION_TYPE, 0);
1132
1133     signals[START_SESSION] =
1134         g_signal_new (GREETER_SIGNAL_START_SESSION,
1135                       G_TYPE_FROM_CLASS (klass),
1136                       G_SIGNAL_RUN_LAST,
1137                       G_STRUCT_OFFSET (GreeterClass, start_session),
1138                       g_signal_accumulator_true_handled,
1139                       NULL,
1140                       NULL,
1141                       G_TYPE_BOOLEAN, 2, G_TYPE_INT, G_TYPE_STRING);
1142
1143     g_object_class_install_property (object_class,
1144                                      PROP_ACTIVE_USERNAME,
1145                                      g_param_spec_string (GREETER_PROPERTY_ACTIVE_USERNAME,
1146                                                           GREETER_PROPERTY_ACTIVE_USERNAME,
1147                                                           "Active username",
1148                                                           NULL,
1149                                                           G_PARAM_READABLE));
1150
1151     g_type_class_add_private (klass, sizeof (GreeterPrivate));
1152 }