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