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_clear_object (&greeter->priv->authentication_session);
 416     }
 417
 418     greeter->priv->guest_account_authenticated = FALSE;
 419 }
 420
 421 static void
 422 handle_login (Greeter *greeter, guint32 sequence_number, const gchar *username)
 423 {
 424     const gchar *autologin_username, *service;
 425     gboolean is_interactive;
 426
 427     if (username[0] == '\0')
 428     {
 429         l_debug (greeter, "Greeter start authentication");
 430         username = NULL;
 431     }
 432     else
 433         l_debug (greeter, "Greeter start authentication for %s", username);
 434
 435     reset_session (greeter);
 436
 437     if (greeter->priv->active_username)
 438         g_free (greeter->priv->active_username);
 439     greeter->priv->active_username = g_strdup (username);
 440     g_object_notify (G_OBJECT (greeter), GREETER_PROPERTY_ACTIVE_USERNAME);
 441
 442     greeter->priv->authentication_sequence_number = sequence_number;
 443     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 444     if (!greeter->priv->authentication_session)
 445     {
 446         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 447         return;
 448     }
 449
 450     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 451     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 452
 453     /* Use non-interactive service for autologin user */
 454     autologin_username = g_hash_table_lookup (greeter->priv->hints, "autologin-user");
 455     if (autologin_username != NULL && g_strcmp0 (username, autologin_username) == 0)
 456     {
 457         service = greeter->priv->autologin_pam_service;
 458         is_interactive = FALSE;
 459     }
 460     else
 461     {
 462         service = greeter->priv->pam_service;
 463         is_interactive = TRUE;
 464     }
 465
 466     /* Run the session process */
 467     session_set_pam_service (greeter->priv->authentication_session, service);
 468     session_set_username (greeter->priv->authentication_session, username);
 469     session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 470     session_set_is_interactive (greeter->priv->authentication_session, is_interactive);
 471     session_start (greeter->priv->authentication_session);
 472 }
 473
 474 static void
 475 handle_login_as_guest (Greeter *greeter, guint32 sequence_number)
 476 {
 477     l_debug (greeter, "Greeter start authentication for guest account");
 478
 479     reset_session (greeter);
 480
 481     if (!greeter->priv->allow_guest)
 482     {
 483         l_debug (greeter, "Guest account is disabled");
 484         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 485         return;
 486     }
 487
 488     greeter->priv->guest_account_authenticated = TRUE;
 489     send_end_authentication (greeter, sequence_number, "", PAM_SUCCESS);
 490 }
 491
 492 static gchar *
 493 get_remote_session_service (const gchar *session_name)
 494 {
 495     GKeyFile *session_desktop_file;
 496     gboolean result;
 497     const gchar *c;
 498     gchar *remote_sessions_dir, *filename, *path, *service = NULL;
 499     GError *error = NULL;
 500
 501     /* Validate session name doesn't contain directory separators */
 502     for (c = session_name; *c; c++)
 503     {
 504         if (*c == '/')
 505             return NULL;
 506     }
 507
 508     /* Load the session file */
 509     session_desktop_file = g_key_file_new ();
 510     filename = g_strdup_printf ("%s.desktop", session_name);
 511     remote_sessions_dir = config_get_string (config_get_instance (), "LightDM", "remote-sessions-directory");
 512     path = g_build_filename (remote_sessions_dir, filename, NULL);
 513     g_free (remote_sessions_dir);
 514     g_free (filename);
 515     result = g_key_file_load_from_file (session_desktop_file, path, G_KEY_FILE_NONE, &error);
 516     if (error)
 517         g_debug ("Failed to load session file %s: %s", path, error->message);
 518     g_free (path);
 519     g_clear_error (&error);
 520     if (result)
 521         service = g_key_file_get_string (session_desktop_file, G_KEY_FILE_DESKTOP_GROUP, "X-LightDM-PAM-Service", NULL);
 522     g_key_file_free (session_desktop_file);
 523
 524     return service;
 525 }
 526
 527 static void
 528 handle_login_remote (Greeter *greeter, const gchar *session_name, const gchar *username, guint32 sequence_number)
 529 {
 530     gchar *service;
 531
 532     if (username[0] == '\0')
 533     {
 534         l_debug (greeter, "Greeter start authentication for remote session %s", session_name);
 535         username = NULL;
 536     }
 537     else
 538         l_debug (greeter, "Greeter start authentication for remote session %s as user %s", session_name, username);
 539
 540     reset_session (greeter);
 541
 542     service = get_remote_session_service (session_name);
 543     if (!service)
 544     {
 545         send_end_authentication (greeter, sequence_number, "", PAM_SYSTEM_ERR);
 546         return;
 547     }
 548
 549     greeter->priv->authentication_sequence_number = sequence_number;
 550     greeter->priv->remote_session = g_strdup (session_name);
 551     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 552     if (greeter->priv->authentication_session)
 553     {
 554         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 555         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 556
 557         /* Run the session process */
 558         session_set_pam_service (greeter->priv->authentication_session, service);
 559         session_set_username (greeter->priv->authentication_session, username);
 560         session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 561         session_set_is_interactive (greeter->priv->authentication_session, TRUE);
 562         session_set_is_guest (greeter->priv->authentication_session, TRUE);
 563         session_start (greeter->priv->authentication_session);
 564     }
 565
 566     g_free (service);
 567
 568     if (!greeter->priv->authentication_session)
 569     {
 570         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 571         return;
 572     }
 573 }
 574
 575 static void
 576 handle_continue_authentication (Greeter *greeter, gchar **secrets)
 577 {
 578     int messages_length;
 579     const struct pam_message *messages;
 580     struct pam_response *response;
 581     int i, j, n_prompts = 0;
 582
 583     /* Not in authentication */
 584     if (greeter->priv->authentication_session == NULL)
 585         return;
 586
 587     messages_length = session_get_messages_length (greeter->priv->authentication_session);
 588     messages = session_get_messages (greeter->priv->authentication_session);
 589
 590     /* Check correct number of responses */
 591     for (i = 0; i < messages_length; i++)
 592     {
 593         int msg_style = messages[i].msg_style;
 594         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 595             n_prompts++;
 596     }
 597     if (g_strv_length (secrets) != n_prompts)
 598     {
 599         session_respond_error (greeter->priv->authentication_session, PAM_CONV_ERR);
 600         return;
 601     }
 602
 603     l_debug (greeter, "Continue authentication");
 604
 605     /* Build response */
 606     response = calloc (messages_length, sizeof (struct pam_response));
 607     for (i = 0, j = 0; i < messages_length; i++)
 608     {
 609         int msg_style = messages[i].msg_style;
 610         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 611         {
 612             size_t secret_length = strlen (secrets[j]) + 1;
 613             response[i].resp = secure_malloc (greeter, secret_length);
 614             memcpy (response[i].resp, secrets[j], secret_length); // FIXME: Need to convert from UTF-8
 615             j++;
 616         }
 617     }
 618
 619     session_respond (greeter->priv->authentication_session, response);
 620
 621     for (i = 0; i < messages_length; i++)
 622         secure_free (greeter, response[i].resp);
 623     free (response);
 624 }
 625
 626 static void
 627 handle_cancel_authentication (Greeter *greeter)
 628 {
 629     /* Not in authentication */
 630     if (greeter->priv->authentication_session == NULL)
 631         return;
 632
 633     l_debug (greeter, "Cancel authentication");
 634     reset_session (greeter);
 635 }
 636
 637 static void
 638 handle_start_session (Greeter *greeter, const gchar *session)
 639 {
 640     gboolean result;
 641     guint8 message[MAX_MESSAGE_LENGTH];
 642     gsize offset = 0;
 643     SessionType session_type = SESSION_TYPE_LOCAL;
 644
 645     if (strcmp (session, "") == 0)
 646         session = NULL;
 647
 648     /* Use session type chosen in remote session */
 649     if (greeter->priv->remote_session)
 650     {
 651         session_type = SESSION_TYPE_REMOTE;
 652         session = greeter->priv->remote_session;
 653     }
 654
 655     if (greeter->priv->guest_account_authenticated || session_get_is_authenticated (greeter->priv->authentication_session))
 656     {
 657         if (session)
 658             l_debug (greeter, "Greeter requests session %s", session);
 659         else
 660             l_debug (greeter, "Greeter requests default session");
 661         greeter->priv->start_session = TRUE;
 662         g_signal_emit (greeter, signals[START_SESSION], 0, session_type, session, &result);
 663     }
 664     else
 665     {
 666         l_debug (greeter, "Ignoring start session request, user is not authorized");
 667         result = FALSE;
 668     }
 669
 670     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SESSION_RESULT, int_length (), &offset);
 671     write_int (message, MAX_MESSAGE_LENGTH, result ? 0 : 1, &offset);
 672     write_message (greeter, message, offset);
 673 }
 674
 675 static void
 676 handle_set_language (Greeter *greeter, const gchar *language)
 677 {
 678     User *user;
 679
 680     if (!greeter->priv->guest_account_authenticated && !session_get_is_authenticated (greeter->priv->authentication_session))
 681     {
 682         l_debug (greeter, "Ignoring set language request, user is not authorized");
 683         return;
 684     }
 685
 686     // FIXME: Could use this
 687     if (greeter->priv->guest_account_authenticated)
 688     {
 689         l_debug (greeter, "Ignoring set language request for guest user");
 690         return;
 691     }
 692
 693     l_debug (greeter, "Greeter sets language %s", language);
 694     user = session_get_user (greeter->priv->authentication_session);
 695     user_set_language (user, language);
 696 }
 697
 698 static void
 699 handle_ensure_shared_dir (Greeter *greeter, const gchar *username)
 700 {
 701     gchar *dir;
 702     guint8 message[MAX_MESSAGE_LENGTH];
 703     gsize offset = 0;
 704
 705     l_debug (greeter, "Greeter requests data directory for user %s", username);
 706
 707     dir = shared_data_manager_ensure_user_dir (shared_data_manager_get_instance (), username);
 708
 709     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SHARED_DIR_RESULT, string_length (dir), &offset);
 710     write_string (message, MAX_MESSAGE_LENGTH, dir, &offset);
 711     write_message (greeter, message, offset);
 712
 713     g_free (dir);
 714 }
 715
 716 static guint32
 717 read_int (Greeter *greeter, gsize *offset)
 718 {
 719     guint32 value;
 720     guint8 *buffer;
 721     if (greeter->priv->n_read - *offset < sizeof (guint32))
 722     {
 723         l_warning (greeter, "Not enough space for int, need %zu, got %zu", sizeof (guint32), greeter->priv->n_read - *offset);
 724         return 0;
 725     }
 726     buffer = greeter->priv->read_buffer + *offset;
 727     value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
 728     *offset += int_length ();
 729     return value;
 730 }
 731
 732 static int
 733 get_message_length (Greeter *greeter)
 734 {
 735     gsize offset;
 736     int payload_length;
 737
 738     offset = int_length ();
 739     payload_length = read_int (greeter, &offset);
 740
 741     if (HEADER_SIZE + payload_length < HEADER_SIZE)
 742     {
 743         l_warning (greeter, "Payload length of %u octets too long", payload_length);
 744         return HEADER_SIZE;
 745     }
 746
 747     return HEADER_SIZE + payload_length;
 748 }
 749
 750 static gchar *
 751 read_string_full (Greeter *greeter, gsize *offset, void* (*alloc_fn)(size_t n))
 752 {
 753     guint32 length;
 754     gchar *value;
 755
 756     length = read_int (greeter, offset);
 757     if (greeter->priv->n_read - *offset < length)
 758     {
 759         l_warning (greeter, "Not enough space for string, need %u, got %zu", length, greeter->priv->n_read - *offset);
 760         return g_strdup ("");
 761     }
 762
 763     value = (*alloc_fn) (sizeof (gchar) * (length + 1));
 764     memcpy (value, greeter->priv->read_buffer + *offset, length);
 765     value[length] = '\0';
 766     *offset += length;
 767
 768     return value;
 769 }
 770
 771 static gchar *
 772 read_string (Greeter *greeter, gsize *offset)
 773 {
 774     return read_string_full (greeter, offset, g_malloc);
 775 }
 776
 777 static gchar *
 778 read_secret (Greeter *greeter, gsize *offset)
 779 {
 780     if (greeter->priv->use_secure_memory)
 781         return read_string_full (greeter, offset, gcry_malloc_secure);
 782     else
 783         return read_string_full (greeter, offset, g_malloc);
 784 }
 785
 786 static gboolean
 787 read_cb (GIOChannel *source, GIOCondition condition, gpointer data)
 788 {
 789     Greeter *greeter = data;
 790     gsize n_to_read, n_read, offset;
 791     GIOStatus status;
 792     int id, length, i;
 793     guint32 sequence_number, n_secrets, max_secrets;
 794     gchar *version, *username, *session_name, *language;
 795     gchar **secrets;
 796     gboolean resettable = FALSE;
 797     GError *error = NULL;
 798
 799     if (condition == G_IO_HUP)
 800     {
 801         l_debug (greeter, "Greeter closed communication channel");
 802         greeter->priv->from_greeter_watch = 0;
 803         return FALSE;
 804     }
 805
 806     n_to_read = HEADER_SIZE;
 807     if (greeter->priv->n_read >= HEADER_SIZE)
 808     {
 809         n_to_read = get_message_length (greeter);
 810         if (n_to_read <= HEADER_SIZE)
 811         {
 812             greeter->priv->from_greeter_watch = 0;
 813             return FALSE;
 814         }
 815     }
 816
 817     status = g_io_channel_read_chars (greeter->priv->from_greeter_channel,
 818                                       (gchar *) greeter->priv->read_buffer + greeter->priv->n_read,
 819                                       n_to_read - greeter->priv->n_read,
 820                                       &n_read,
 821                                       &error);
 822     if (error)
 823         l_warning (greeter, "Error reading from greeter: %s", error->message);
 824     g_clear_error (&error);
 825     if (status != G_IO_STATUS_NORMAL)
 826         return TRUE;
 827
 828     greeter->priv->n_read += n_read;
 829     if (greeter->priv->n_read != n_to_read)
 830         return TRUE;
 831
 832     /* If have header, rerun for content */
 833     if (greeter->priv->n_read == HEADER_SIZE)
 834     {
 835         n_to_read = get_message_length (greeter);
 836         if (n_to_read > HEADER_SIZE)
 837         {
 838             greeter->priv->read_buffer = secure_realloc (greeter, greeter->priv->read_buffer, n_to_read);
 839             read_cb (source, condition, greeter);
 840             return TRUE;
 841         }
 842     }
 843
 844     offset = 0;
 845     id = read_int (greeter, &offset);
 846     length = HEADER_SIZE + read_int (greeter, &offset);
 847     switch (id)
 848     {
 849     case GREETER_MESSAGE_CONNECT:
 850         version = read_string (greeter, &offset);
 851         if (offset < length)
 852             resettable = read_int (greeter, &offset) != 0;
 853         handle_connect (greeter, version, resettable);
 854         g_free (version);
 855         break;
 856     case GREETER_MESSAGE_AUTHENTICATE:
 857         sequence_number = read_int (greeter, &offset);
 858         username = read_string (greeter, &offset);
 859         handle_login (greeter, sequence_number, username);
 860         g_free (username);
 861         break;
 862     case GREETER_MESSAGE_AUTHENTICATE_AS_GUEST:
 863         sequence_number = read_int (greeter, &offset);
 864         handle_login_as_guest (greeter, sequence_number);
 865         break;
 866     case GREETER_MESSAGE_AUTHENTICATE_REMOTE:
 867         sequence_number = read_int (greeter, &offset);
 868         session_name = read_string (greeter, &offset);
 869         username = read_string (greeter, &offset);
 870         handle_login_remote (greeter, session_name, username, sequence_number);
 871         break;
 872     case GREETER_MESSAGE_CONTINUE_AUTHENTICATION:
 873         n_secrets = read_int (greeter, &offset);
 874         max_secrets = (G_MAXUINT32 - 1) / sizeof (gchar *);
 875         if (n_secrets > max_secrets)
 876         {
 877             l_warning (greeter, "Array length of %u elements too long", n_secrets);
 878             greeter->priv->from_greeter_watch = 0;
 879             return FALSE;
 880         }
 881         secrets = g_malloc (sizeof (gchar *) * (n_secrets + 1));
 882         for (i = 0; i < n_secrets; i++)
 883             secrets[i] = read_secret (greeter, &offset);
 884         secrets[i] = NULL;
 885         handle_continue_authentication (greeter, secrets);
 886         for (i = 0; i < n_secrets; i++)
 887             secure_free (greeter, secrets[i]);
 888         g_free (secrets);
 889         break;
 890     case GREETER_MESSAGE_CANCEL_AUTHENTICATION:
 891         handle_cancel_authentication (greeter);
 892         break;
 893     case GREETER_MESSAGE_START_SESSION:
 894         session_name = read_string (greeter, &offset);
 895         handle_start_session (greeter, session_name);
 896         g_free (session_name);
 897         break;
 898     case GREETER_MESSAGE_SET_LANGUAGE:
 899         language = read_string (greeter, &offset);
 900         handle_set_language (greeter, language);
 901         g_free (language);
 902         break;
 903     case GREETER_MESSAGE_ENSURE_SHARED_DIR:
 904         username = read_string (greeter, &offset);
 905         handle_ensure_shared_dir (greeter, username);
 906         g_free (username);
 907         break;
 908     default:
 909         l_warning (greeter, "Unknown message from greeter: %d", id);
 910         break;
 911     }
 912
 913     greeter->priv->n_read = 0;
 914
 915     return TRUE;
 916 }
 917
 918 gboolean
 919 greeter_get_guest_authenticated (Greeter *greeter)
 920 {
 921     g_return_val_if_fail (greeter != NULL, FALSE);
 922     return greeter->priv->guest_account_authenticated;
 923 }
 924
 925 Session *
 926 greeter_get_authentication_session (Greeter *greeter)
 927 {
 928     g_return_val_if_fail (greeter != NULL, NULL);
 929     return greeter->priv->authentication_session;
 930 }
 931
 932 gboolean
 933 greeter_get_resettable (Greeter *greeter)
 934 {
 935     g_return_val_if_fail (greeter != NULL, FALSE);
 936     return greeter->priv->resettable;
 937 }
 938
 939 gboolean
 940 greeter_get_start_session (Greeter *greeter)
 941 {
 942     g_return_val_if_fail (greeter != NULL, FALSE);
 943     return greeter->priv->start_session;
 944 }
 945
 946 const gchar *
 947 greeter_get_active_username (Greeter *greeter)
 948 {
 949     g_return_val_if_fail (greeter != NULL, NULL);
 950     return greeter->priv->active_username;
 951 }
 952
 953 static gboolean
 954 greeter_start (Session *session)
 955 {
 956     Greeter *greeter = GREETER (session);
 957     int to_greeter_pipe[2], from_greeter_pipe[2];
 958     int to_greeter_output, from_greeter_input;
 959     gboolean result = FALSE;
 960     gchar *value;
 961     GError *error = NULL;
 962
 963     /* Create a pipe to talk with the greeter */
 964     if (pipe (to_greeter_pipe) != 0 || pipe (from_greeter_pipe) != 0)
 965     {
 966         g_warning ("Failed to create pipes: %s", strerror (errno));
 967         return FALSE;
 968     }
 969     to_greeter_output = to_greeter_pipe[0];
 970     greeter->priv->to_greeter_input = to_greeter_pipe[1];
 971     greeter->priv->to_greeter_channel = g_io_channel_unix_new (greeter->priv->to_greeter_input);
 972     g_io_channel_set_encoding (greeter->priv->to_greeter_channel, NULL, &error);
 973     if (error)
 974         g_warning ("Failed to set encoding on to greeter channel to binary: %s\n", error->message);
 975     g_clear_error (&error);
 976     greeter->priv->from_greeter_output = from_greeter_pipe[0];
 977     from_greeter_input = from_greeter_pipe[1];
 978     greeter->priv->from_greeter_channel = g_io_channel_unix_new (greeter->priv->from_greeter_output);
 979     g_io_channel_set_encoding (greeter->priv->from_greeter_channel, NULL, &error);
 980     if (error)
 981         g_warning ("Failed to set encoding on from greeter channel to binary: %s\n", error->message);
 982     g_clear_error (&error);
 983     g_io_channel_set_buffered (greeter->priv->from_greeter_channel, FALSE);
 984     greeter->priv->from_greeter_watch = g_io_add_watch (greeter->priv->from_greeter_channel, G_IO_IN | G_IO_HUP, read_cb, greeter);
 985
 986     /* Let the greeter session know how to communicate with the daemon */
 987     value = g_strdup_printf ("%d", from_greeter_input);
 988     session_set_env (SESSION (greeter), "LIGHTDM_TO_SERVER_FD", value);
 989     g_free (value);
 990     value = g_strdup_printf ("%d", to_greeter_output);
 991     session_set_env (SESSION (greeter), "LIGHTDM_FROM_SERVER_FD", value);
 992     g_free (value);
 993
 994     /* Don't allow the daemon end of the pipes to be accessed in child processes */
 995     fcntl (greeter->priv->to_greeter_input, F_SETFD, FD_CLOEXEC);
 996     fcntl (greeter->priv->from_greeter_output, F_SETFD, FD_CLOEXEC);
 997
 998     result = SESSION_CLASS (greeter_parent_class)->start (session);
 999
1000     /* Close the session ends of the pipe */
1001     close (to_greeter_output);
1002     close (from_greeter_input);
1003
1004     return result;
1005 }
1006
1007 static Session *
1008 greeter_real_create_session (Greeter *greeter)
1009 {
1010     return NULL;
1011 }
1012
1013 static gboolean
1014 greeter_real_start_session (Greeter *greeter, SessionType type, const gchar *session)
1015 {
1016     return FALSE;
1017 }
1018
1019 static void
1020 greeter_stop (Session *session)
1021 {
1022     Greeter *greeter = GREETER (session);
1023
1024     /* Stop any events occurring after we've stopped */
1025     if (greeter->priv->authentication_session)
1026         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
1027
1028     SESSION_CLASS (greeter_parent_class)->stop (session);
1029 }
1030
1031 static void
1032 greeter_init (Greeter *greeter)
1033 {
1034     greeter->priv = G_TYPE_INSTANCE_GET_PRIVATE (greeter, GREETER_TYPE, GreeterPrivate);
1035     greeter->priv->read_buffer = secure_malloc (greeter, HEADER_SIZE);
1036     greeter->priv->hints = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
1037     greeter->priv->use_secure_memory = config_get_boolean (config_get_instance (), "LightDM", "lock-memory");
1038     greeter->priv->to_greeter_input = -1;
1039     greeter->priv->from_greeter_output = -1;
1040 }
1041
1042 static void
1043 greeter_finalize (GObject *object)
1044 {
1045     Greeter *self = GREETER (object);
1046
1047     g_free (self->priv->pam_service);
1048     g_free (self->priv->autologin_pam_service);
1049     secure_free (self, self->priv->read_buffer);
1050     g_hash_table_unref (self->priv->hints);
1051     g_free (self->priv->remote_session);
1052     g_free (self->priv->active_username);
1053     if (self->priv->authentication_session)
1054     {
1055         g_signal_handlers_disconnect_matched (self->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, self);
1056         g_object_unref (self->priv->authentication_session);
1057     }
1058     close (self->priv->to_greeter_input);
1059     close (self->priv->from_greeter_output);
1060     if (self->priv->to_greeter_channel)
1061         g_io_channel_unref (self->priv->to_greeter_channel);
1062     if (self->priv->from_greeter_channel)
1063         g_io_channel_unref (self->priv->from_greeter_channel);
1064     if (self->priv->from_greeter_watch)
1065         g_source_remove (self->priv->from_greeter_watch);
1066
1067     G_OBJECT_CLASS (greeter_parent_class)->finalize (object);
1068 }
1069
1070 static void
1071 greeter_set_property (GObject      *object,
1072                       guint         prop_id,
1073                       const GValue *value,
1074                       GParamSpec   *pspec)
1075 {
1076     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1077 }
1078
1079 static void
1080 greeter_get_property (GObject    *object,
1081                       guint       prop_id,
1082                       GValue     *value,
1083                       GParamSpec *pspec)
1084 {
1085     Greeter *greeter = GREETER (object);
1086
1087     switch (prop_id) {
1088     case PROP_ACTIVE_USERNAME:
1089         g_value_set_string (value, greeter_get_active_username (greeter));
1090         break;
1091     default:
1092         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1093         break;
1094     }
1095 }
1096
1097 static void
1098 greeter_class_init (GreeterClass *klass)
1099 {
1100     SessionClass *session_class = SESSION_CLASS (klass);
1101     GObjectClass *object_class = G_OBJECT_CLASS (klass);
1102
1103     klass->create_session = greeter_real_create_session;
1104     klass->start_session = greeter_real_start_session;
1105     session_class->start = greeter_start;
1106     session_class->stop = greeter_stop;
1107     object_class->finalize = greeter_finalize;
1108     object_class->get_property = greeter_get_property;
1109     object_class->set_property = greeter_set_property;
1110
1111     signals[CONNECTED] =
1112         g_signal_new (GREETER_SIGNAL_CONNECTED,
1113                       G_TYPE_FROM_CLASS (klass),
1114                       G_SIGNAL_RUN_LAST,
1115                       G_STRUCT_OFFSET (GreeterClass, connected),
1116                       NULL, NULL,
1117                       NULL,
1118                       G_TYPE_NONE, 0);
1119
1120     signals[CREATE_SESSION] =
1121         g_signal_new (GREETER_SIGNAL_CREATE_SESSION,
1122                       G_TYPE_FROM_CLASS (klass),
1123                       G_SIGNAL_RUN_LAST,
1124                       G_STRUCT_OFFSET (GreeterClass, create_session),
1125                       g_signal_accumulator_first_wins,
1126                       NULL,
1127                       NULL,
1128                       SESSION_TYPE, 0);
1129
1130     signals[START_SESSION] =
1131         g_signal_new (GREETER_SIGNAL_START_SESSION,
1132                       G_TYPE_FROM_CLASS (klass),
1133                       G_SIGNAL_RUN_LAST,
1134                       G_STRUCT_OFFSET (GreeterClass, start_session),
1135                       g_signal_accumulator_true_handled,
1136                       NULL,
1137                       NULL,
1138                       G_TYPE_BOOLEAN, 2, G_TYPE_INT, G_TYPE_STRING);
1139
1140     g_object_class_install_property (object_class,
1141                                      PROP_ACTIVE_USERNAME,
1142                                      g_param_spec_string (GREETER_PROPERTY_ACTIVE_USERNAME,
1143                                                           GREETER_PROPERTY_ACTIVE_USERNAME,
1144                                                           "Active username",
1145                                                           NULL,
1146                                                           G_PARAM_READABLE));
1147
1148     g_type_class_add_private (klass, sizeof (GreeterPrivate));
1149 }