src/greeter.c

   1 /*
   2  * Copyright (C) 2010-2016 Canonical Ltd.
   3  *
   4  * This program is free software: you can redistribute it and/or modify it under
   5  * the terms of the GNU General Public License as published by the Free Software
   6  * Foundation, either version 3 of the License, or (at your option) any later
   7  * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
   8  * license.
   9  */
  10
  11 #include <config.h>
  12
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <gcrypt.h>
  16
  17 #include "greeter.h"
  18 #include "configuration.h"
  19 #include "shared-data-manager.h"
  20
  21 enum {
  22     PROP_0,
  23     PROP_ACTIVE_USERNAME,
  24 };
  25
  26 enum {
  27     CONNECTED,
  28     DISCONNECTED,
  29     CREATE_SESSION,
  30     START_SESSION,
  31     LAST_SIGNAL
  32 };
  33 static guint signals[LAST_SIGNAL] = { 0 };
  34
  35 struct GreeterPrivate
  36 {
  37     /* PAM service to authenticate with */
  38     gchar *pam_service;
  39     gchar *autologin_pam_service;
  40
  41     /* Buffer for data read from greeter */
  42     guint8 *read_buffer;
  43     gsize n_read;
  44     gboolean use_secure_memory;
  45
  46     /* Hints for the greeter */
  47     GHashTable *hints;
  48
  49     /* Default session to use */
  50     gchar *default_session;
  51
  52     /* Sequence number of current PAM session */
  53     guint32 authentication_sequence_number;
  54
  55     /* Remote session name */
  56     gchar *remote_session;
  57
  58     /* Currently selected user */
  59     gchar *active_username;
  60
  61     /* PAM session being constructed by the greeter */
  62     Session *authentication_session;
  63
  64     /* TRUE if a the greeter can handle a reset; else we will just kill it instead */
  65     gboolean resettable;
  66
  67     /* TRUE if a user has been authenticated and the session requested to start */
  68     gboolean start_session;
  69
  70     /* TRUE if can log into guest accounts */
  71     gboolean allow_guest;
  72
  73     /* TRUE if logging into guest session */
  74     gboolean guest_account_authenticated;
  75
  76     /* Communication channels to communicate with */
  77     int to_greeter_input;
  78     int from_greeter_output;
  79     GIOChannel *to_greeter_channel;
  80     GIOChannel *from_greeter_channel;
  81     guint from_greeter_watch;
  82 };
  83
  84 G_DEFINE_TYPE (Greeter, greeter, G_TYPE_OBJECT);
  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 } GreeterMessage;
  99
 100 /* Messages from the server to the greeter */
 101 typedef enum
 102 {
 103     SERVER_MESSAGE_CONNECTED = 0,
 104     SERVER_MESSAGE_PROMPT_AUTHENTICATION,
 105     SERVER_MESSAGE_END_AUTHENTICATION,
 106     SERVER_MESSAGE_SESSION_RESULT,
 107     SERVER_MESSAGE_SHARED_DIR_RESULT,
 108     SERVER_MESSAGE_IDLE,
 109     SERVER_MESSAGE_RESET,
 110 } ServerMessage;
 111
 112 static gboolean read_cb (GIOChannel *source, GIOCondition condition, gpointer data);
 113
 114 Greeter *
 115 greeter_new (void)
 116 {
 117     return g_object_new (GREETER_TYPE, NULL);
 118 }
 119
 120 void
 121 greeter_set_file_descriptors (Greeter *greeter, int to_greeter_fd, int from_greeter_fd)
 122 {
 123     GError *error = NULL;
 124
 125     g_return_if_fail (greeter != NULL);
 126     g_return_if_fail (greeter->priv->to_greeter_input < 0);
 127     g_return_if_fail (greeter->priv->from_greeter_output < 0);
 128
 129     greeter->priv->to_greeter_input = to_greeter_fd;
 130     greeter->priv->to_greeter_channel = g_io_channel_unix_new (greeter->priv->to_greeter_input);
 131     g_io_channel_set_encoding (greeter->priv->to_greeter_channel, NULL, &error);
 132     if (error)
 133         g_warning ("Failed to set encoding on to greeter channel to binary: %s\n", error->message);
 134     g_clear_error (&error);
 135     greeter->priv->from_greeter_output = from_greeter_fd;
 136     greeter->priv->from_greeter_channel = g_io_channel_unix_new (greeter->priv->from_greeter_output);
 137     g_io_channel_set_encoding (greeter->priv->from_greeter_channel, NULL, &error);
 138     if (error)
 139         g_warning ("Failed to set encoding on from greeter channel to binary: %s\n", error->message);
 140     g_clear_error (&error);
 141     g_io_channel_set_buffered (greeter->priv->from_greeter_channel, FALSE);
 142     greeter->priv->from_greeter_watch = g_io_add_watch (greeter->priv->from_greeter_channel, G_IO_IN | G_IO_HUP, read_cb, greeter);
 143 }
 144
 145 void
 146 greeter_stop (Greeter *greeter)
 147 {
 148     /* Stop any events occurring after we've stopped */
 149     if (greeter->priv->authentication_session)
 150         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 151 }
 152
 153 void
 154 greeter_set_pam_services (Greeter *greeter, const gchar *pam_service, const gchar *autologin_pam_service)
 155 {
 156     g_return_if_fail (greeter != NULL);
 157     g_free (greeter->priv->pam_service);
 158     greeter->priv->pam_service = g_strdup (pam_service);
 159     g_free (greeter->priv->autologin_pam_service);
 160     greeter->priv->autologin_pam_service = g_strdup (autologin_pam_service);
 161 }
 162
 163 void
 164 greeter_set_allow_guest (Greeter *greeter, gboolean allow_guest)
 165 {
 166     g_return_if_fail (greeter != NULL);
 167     greeter->priv->allow_guest = allow_guest;
 168 }
 169
 170 void
 171 greeter_clear_hints (Greeter *greeter)
 172 {
 173     g_return_if_fail (greeter != NULL);
 174     g_hash_table_remove_all (greeter->priv->hints);
 175 }
 176
 177 void
 178 greeter_set_hint (Greeter *greeter, const gchar *name, const gchar *value)
 179 {
 180     g_return_if_fail (greeter != NULL);
 181     g_hash_table_insert (greeter->priv->hints, g_strdup (name), g_strdup (value));
 182 }
 183
 184 static void *
 185 secure_malloc (Greeter *greeter, size_t n)
 186 {
 187     if (greeter->priv->use_secure_memory)
 188         return gcry_malloc_secure (n);
 189     else
 190         return g_malloc (n);
 191 }
 192
 193 static void *
 194 secure_realloc (Greeter *greeter, void *ptr, size_t n)
 195 {
 196     if (greeter->priv->use_secure_memory)
 197         return gcry_realloc (ptr, n);
 198     else
 199         return g_realloc (ptr, n);
 200 }
 201
 202 static void
 203 secure_free (Greeter *greeter, void *ptr)
 204 {
 205     if (greeter->priv->use_secure_memory)
 206         return gcry_free (ptr);
 207     else
 208         return g_free (ptr);
 209 }
 210
 211 static guint32
 212 int_length (void)
 213 {
 214     return 4;
 215 }
 216
 217 #define HEADER_SIZE (sizeof (guint32) * 2)
 218 #define MAX_MESSAGE_LENGTH 1024
 219
 220 static void
 221 write_message (Greeter *greeter, guint8 *message, gsize message_length)
 222 {
 223     gchar *data;
 224     gsize data_length;
 225     GError *error = NULL;
 226
 227     data = (gchar *) message;
 228     data_length = message_length;
 229     while (data_length > 0)
 230     {
 231         GIOStatus status;
 232         gsize n_written;
 233
 234         status = g_io_channel_write_chars (greeter->priv->to_greeter_channel, data, data_length, &n_written, &error);
 235         if (error)
 236             g_warning ("Error writing to greeter: %s", error->message);
 237         g_clear_error (&error);
 238         if (status != G_IO_STATUS_NORMAL)
 239             return;
 240         data_length -= n_written;
 241         data += n_written;
 242     }
 243
 244     g_io_channel_flush (greeter->priv->to_greeter_channel, &error);
 245     if (error)
 246         g_warning ("Failed to flush data to greeter: %s", error->message);
 247     g_clear_error (&error);
 248 }
 249
 250 static void
 251 write_int (guint8 *buffer, gint buffer_length, guint32 value, gsize *offset)
 252 {
 253     if (*offset + 4 >= buffer_length)
 254         return;
 255     buffer[*offset] = value >> 24;
 256     buffer[*offset+1] = (value >> 16) & 0xFF;
 257     buffer[*offset+2] = (value >> 8) & 0xFF;
 258     buffer[*offset+3] = value & 0xFF;
 259     *offset += 4;
 260 }
 261
 262 static void
 263 write_string (guint8 *buffer, gint buffer_length, const gchar *value, gsize *offset)
 264 {
 265     gint length;
 266
 267     if (value)
 268         length = strlen (value);
 269     else
 270         length = 0;
 271     write_int (buffer, buffer_length, length, offset);
 272     if (*offset + length >= buffer_length)
 273         return;
 274     if (length > 0)
 275     {
 276         memcpy (buffer + *offset, value, length);
 277         *offset += length;
 278     }
 279 }
 280
 281 static void
 282 write_header (guint8 *buffer, gint buffer_length, guint32 id, guint32 length, gsize *offset)
 283 {
 284     write_int (buffer, buffer_length, id, offset);
 285     write_int (buffer, buffer_length, length, offset);
 286 }
 287
 288 static guint32
 289 string_length (const gchar *value)
 290 {
 291     if (value == NULL)
 292         return int_length ();
 293     else
 294         return int_length () + strlen (value);
 295 }
 296
 297 static void
 298 handle_connect (Greeter *greeter, const gchar *version, gboolean resettable)
 299 {
 300     guint8 message[MAX_MESSAGE_LENGTH];
 301     gsize offset = 0;
 302     guint32 length;
 303     GHashTableIter iter;
 304     gpointer key, value;
 305
 306     g_debug ("Greeter connected version=%s resettable=%s", version, resettable ? "true" : "false");
 307
 308     greeter->priv->resettable = resettable;
 309
 310     length = string_length (VERSION);
 311     g_hash_table_iter_init (&iter, greeter->priv->hints);
 312     while (g_hash_table_iter_next (&iter, &key, &value))
 313         length += string_length (key) + string_length (value);
 314
 315     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_CONNECTED, length, &offset);
 316     write_string (message, MAX_MESSAGE_LENGTH, VERSION, &offset);
 317     g_hash_table_iter_init (&iter, greeter->priv->hints);
 318     while (g_hash_table_iter_next (&iter, &key, &value))
 319     {
 320         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 321         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 322     }
 323     write_message (greeter, message, offset);
 324
 325     g_signal_emit (greeter, signals[CONNECTED], 0);
 326 }
 327
 328 static void
 329 pam_messages_cb (Session *session, Greeter *greeter)
 330 {
 331     int i;
 332     guint32 size;
 333     guint8 message[MAX_MESSAGE_LENGTH];
 334     const struct pam_message *messages;
 335     int messages_length;
 336     gsize offset = 0;
 337     int n_prompts = 0;
 338
 339     messages = session_get_messages (session);
 340     messages_length = session_get_messages_length (session);
 341
 342     /* Respond to d-bus query with messages */
 343     g_debug ("Prompt greeter with %d message(s)", messages_length);
 344     size = int_length () + string_length (session_get_username (session)) + int_length ();
 345     for (i = 0; i < messages_length; i++)
 346         size += int_length () + string_length (messages[i].msg);
 347
 348     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_PROMPT_AUTHENTICATION, size, &offset);
 349     write_int (message, MAX_MESSAGE_LENGTH, greeter->priv->authentication_sequence_number, &offset);
 350     write_string (message, MAX_MESSAGE_LENGTH, session_get_username (session), &offset);
 351     write_int (message, MAX_MESSAGE_LENGTH, messages_length, &offset);
 352     for (i = 0; i < messages_length; i++)
 353     {
 354         write_int (message, MAX_MESSAGE_LENGTH, messages[i].msg_style, &offset);
 355         write_string (message, MAX_MESSAGE_LENGTH, messages[i].msg, &offset);
 356
 357         if (messages[i].msg_style == PAM_PROMPT_ECHO_OFF || messages[i].msg_style == PAM_PROMPT_ECHO_ON)
 358             n_prompts++;
 359     }
 360     write_message (greeter, message, offset);
 361
 362     /* Continue immediately if nothing to respond with */
 363     // FIXME: Should probably give the greeter a chance to ack the message
 364     if (n_prompts == 0)
 365     {
 366         struct pam_response *response;
 367         response = calloc (messages_length, sizeof (struct pam_response));
 368         session_respond (greeter->priv->authentication_session, response);
 369         free (response);
 370     }
 371 }
 372
 373 static void
 374 send_end_authentication (Greeter *greeter, guint32 sequence_number, const gchar *username, int result)
 375 {
 376     guint8 message[MAX_MESSAGE_LENGTH];
 377     gsize offset = 0;
 378
 379     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_END_AUTHENTICATION, int_length () + string_length (username) + int_length (), &offset);
 380     write_int (message, MAX_MESSAGE_LENGTH, sequence_number, &offset);
 381     write_string (message, MAX_MESSAGE_LENGTH, username, &offset);
 382     write_int (message, MAX_MESSAGE_LENGTH, result, &offset);
 383     write_message (greeter, message, offset);
 384 }
 385
 386 void
 387 greeter_idle (Greeter *greeter)
 388 {
 389     guint8 message[MAX_MESSAGE_LENGTH];
 390     gsize offset = 0;
 391
 392     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_IDLE, 0, &offset);
 393     write_message (greeter, message, offset);
 394 }
 395
 396 void
 397 greeter_reset (Greeter *greeter)
 398 {
 399     guint8 message[MAX_MESSAGE_LENGTH];
 400     gsize offset = 0;
 401     guint32 length = 0;
 402     GHashTableIter iter;
 403     gpointer key, value;
 404
 405     g_return_if_fail (greeter != NULL);
 406
 407     g_hash_table_iter_init (&iter, greeter->priv->hints);
 408     while (g_hash_table_iter_next (&iter, &key, &value))
 409         length += string_length (key) + string_length (value);
 410
 411     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_RESET, length, &offset);
 412     g_hash_table_iter_init (&iter, greeter->priv->hints);
 413     while (g_hash_table_iter_next (&iter, &key, &value))
 414     {
 415         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 416         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 417     }
 418     write_message (greeter, message, offset);
 419 }
 420
 421 static void
 422 authentication_complete_cb (Session *session, Greeter *greeter)
 423 {
 424     int result;
 425
 426     g_debug ("Authenticate result for user %s: %s", session_get_username (session), session_get_authentication_result_string (session));
 427
 428     result = session_get_authentication_result (session);
 429     if (session_get_is_authenticated (session))
 430     {
 431         if (session_get_user (session))
 432             g_debug ("User %s authorized", session_get_username (session));
 433         else
 434         {
 435             g_debug ("User %s authorized, but no account of that name exists", session_get_username (session));
 436             result = PAM_USER_UNKNOWN;
 437         }
 438     }
 439
 440     send_end_authentication (greeter, greeter->priv->authentication_sequence_number, session_get_username (session), result);
 441 }
 442
 443 static void
 444 reset_session (Greeter *greeter)
 445 {
 446     g_free (greeter->priv->remote_session);
 447     greeter->priv->remote_session = NULL;
 448     if (greeter->priv->authentication_session)
 449     {
 450         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 451         session_stop (greeter->priv->authentication_session);
 452         g_clear_object (&greeter->priv->authentication_session);
 453     }
 454
 455     greeter->priv->guest_account_authenticated = FALSE;
 456 }
 457
 458 static void
 459 handle_login (Greeter *greeter, guint32 sequence_number, const gchar *username)
 460 {
 461     const gchar *autologin_username, *service;
 462     gboolean is_interactive;
 463
 464     if (username[0] == '\0')
 465     {
 466         g_debug ("Greeter start authentication");
 467         username = NULL;
 468     }
 469     else
 470         g_debug ("Greeter start authentication for %s", username);
 471
 472     reset_session (greeter);
 473
 474     if (greeter->priv->active_username)
 475         g_free (greeter->priv->active_username);
 476     greeter->priv->active_username = g_strdup (username);
 477     g_object_notify (G_OBJECT (greeter), GREETER_PROPERTY_ACTIVE_USERNAME);
 478
 479     greeter->priv->authentication_sequence_number = sequence_number;
 480     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 481     if (!greeter->priv->authentication_session)
 482     {
 483         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 484         return;
 485     }
 486
 487     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 488     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 489
 490     /* Use non-interactive service for autologin user */
 491     autologin_username = g_hash_table_lookup (greeter->priv->hints, "autologin-user");
 492     if (autologin_username != NULL && g_strcmp0 (username, autologin_username) == 0)
 493     {
 494         service = greeter->priv->autologin_pam_service;
 495         is_interactive = FALSE;
 496     }
 497     else
 498     {
 499         service = greeter->priv->pam_service;
 500         is_interactive = TRUE;
 501     }
 502
 503     /* Run the session process */
 504     session_set_pam_service (greeter->priv->authentication_session, service);
 505     session_set_username (greeter->priv->authentication_session, username);
 506     session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 507     session_set_is_interactive (greeter->priv->authentication_session, is_interactive);
 508     session_start (greeter->priv->authentication_session);
 509 }
 510
 511 static void
 512 handle_login_as_guest (Greeter *greeter, guint32 sequence_number)
 513 {
 514     g_debug ("Greeter start authentication for guest account");
 515
 516     reset_session (greeter);
 517
 518     if (!greeter->priv->allow_guest)
 519     {
 520         g_debug ("Guest account is disabled");
 521         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 522         return;
 523     }
 524
 525     greeter->priv->guest_account_authenticated = TRUE;
 526     send_end_authentication (greeter, sequence_number, "", PAM_SUCCESS);
 527 }
 528
 529 static gchar *
 530 get_remote_session_service (const gchar *session_name)
 531 {
 532     GKeyFile *session_desktop_file;
 533     gboolean result;
 534     const gchar *c;
 535     gchar *remote_sessions_dir, *filename, *path, *service = NULL;
 536     GError *error = NULL;
 537
 538     /* Validate session name doesn't contain directory separators */
 539     for (c = session_name; *c; c++)
 540     {
 541         if (*c == '/')
 542             return NULL;
 543     }
 544
 545     /* Load the session file */
 546     session_desktop_file = g_key_file_new ();
 547     filename = g_strdup_printf ("%s.desktop", session_name);
 548     remote_sessions_dir = config_get_string (config_get_instance (), "LightDM", "remote-sessions-directory");
 549     path = g_build_filename (remote_sessions_dir, filename, NULL);
 550     g_free (remote_sessions_dir);
 551     g_free (filename);
 552     result = g_key_file_load_from_file (session_desktop_file, path, G_KEY_FILE_NONE, &error);
 553     if (error)
 554         g_debug ("Failed to load session file %s: %s", path, error->message);
 555     g_free (path);
 556     g_clear_error (&error);
 557     if (result)
 558         service = g_key_file_get_string (session_desktop_file, G_KEY_FILE_DESKTOP_GROUP, "X-LightDM-PAM-Service", NULL);
 559     g_key_file_free (session_desktop_file);
 560
 561     return service;
 562 }
 563
 564 static void
 565 handle_login_remote (Greeter *greeter, const gchar *session_name, const gchar *username, guint32 sequence_number)
 566 {
 567     gchar *service;
 568
 569     if (username[0] == '\0')
 570     {
 571         g_debug ("Greeter start authentication for remote session %s", session_name);
 572         username = NULL;
 573     }
 574     else
 575         g_debug ("Greeter start authentication for remote session %s as user %s", session_name, username);
 576
 577     reset_session (greeter);
 578
 579     service = get_remote_session_service (session_name);
 580     if (!service)
 581     {
 582         send_end_authentication (greeter, sequence_number, "", PAM_SYSTEM_ERR);
 583         return;
 584     }
 585
 586     greeter->priv->authentication_sequence_number = sequence_number;
 587     greeter->priv->remote_session = g_strdup (session_name);
 588     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 589     if (greeter->priv->authentication_session)
 590     {
 591         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 592         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 593
 594         /* Run the session process */
 595         session_set_pam_service (greeter->priv->authentication_session, service);
 596         session_set_username (greeter->priv->authentication_session, username);
 597         session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 598         session_set_is_interactive (greeter->priv->authentication_session, TRUE);
 599         session_set_is_guest (greeter->priv->authentication_session, TRUE);
 600         session_start (greeter->priv->authentication_session);
 601     }
 602
 603     g_free (service);
 604
 605     if (!greeter->priv->authentication_session)
 606     {
 607         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 608         return;
 609     }
 610 }
 611
 612 static void
 613 handle_continue_authentication (Greeter *greeter, gchar **secrets)
 614 {
 615     int messages_length;
 616     const struct pam_message *messages;
 617     struct pam_response *response;
 618     int i, j, n_prompts = 0;
 619
 620     /* Not in authentication */
 621     if (greeter->priv->authentication_session == NULL)
 622         return;
 623
 624     messages_length = session_get_messages_length (greeter->priv->authentication_session);
 625     messages = session_get_messages (greeter->priv->authentication_session);
 626
 627     /* Check correct number of responses */
 628     for (i = 0; i < messages_length; i++)
 629     {
 630         int msg_style = messages[i].msg_style;
 631         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 632             n_prompts++;
 633     }
 634     if (g_strv_length (secrets) != n_prompts)
 635     {
 636         session_respond_error (greeter->priv->authentication_session, PAM_CONV_ERR);
 637         return;
 638     }
 639
 640     g_debug ("Continue authentication");
 641
 642     /* Build response */
 643     response = calloc (messages_length, sizeof (struct pam_response));
 644     for (i = 0, j = 0; i < messages_length; i++)
 645     {
 646         int msg_style = messages[i].msg_style;
 647         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 648         {
 649             size_t secret_length = strlen (secrets[j]) + 1;
 650             response[i].resp = secure_malloc (greeter, secret_length);
 651             memcpy (response[i].resp, secrets[j], secret_length); // FIXME: Need to convert from UTF-8
 652             j++;
 653         }
 654     }
 655
 656     session_respond (greeter->priv->authentication_session, response);
 657
 658     for (i = 0; i < messages_length; i++)
 659         secure_free (greeter, response[i].resp);
 660     free (response);
 661 }
 662
 663 static void
 664 handle_cancel_authentication (Greeter *greeter)
 665 {
 666     /* Not in authentication */
 667     if (greeter->priv->authentication_session == NULL)
 668         return;
 669
 670     g_debug ("Cancel authentication");
 671     reset_session (greeter);
 672 }
 673
 674 static void
 675 handle_start_session (Greeter *greeter, const gchar *session)
 676 {
 677     gboolean result;
 678     guint8 message[MAX_MESSAGE_LENGTH];
 679     gsize offset = 0;
 680     SessionType session_type = SESSION_TYPE_LOCAL;
 681
 682     if (strcmp (session, "") == 0)
 683         session = NULL;
 684
 685     /* Use session type chosen in remote session */
 686     if (greeter->priv->remote_session)
 687     {
 688         session_type = SESSION_TYPE_REMOTE;
 689         session = greeter->priv->remote_session;
 690     }
 691
 692     if (greeter->priv->guest_account_authenticated || session_get_is_authenticated (greeter->priv->authentication_session))
 693     {
 694         if (session)
 695             g_debug ("Greeter requests session %s", session);
 696         else
 697             g_debug ("Greeter requests default session");
 698         greeter->priv->start_session = TRUE;
 699         g_signal_emit (greeter, signals[START_SESSION], 0, session_type, session, &result);
 700     }
 701     else
 702     {
 703         g_debug ("Ignoring start session request, user is not authorized");
 704         result = FALSE;
 705     }
 706
 707     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SESSION_RESULT, int_length (), &offset);
 708     write_int (message, MAX_MESSAGE_LENGTH, result ? 0 : 1, &offset);
 709     write_message (greeter, message, offset);
 710 }
 711
 712 static void
 713 handle_set_language (Greeter *greeter, const gchar *language)
 714 {
 715     User *user;
 716
 717     if (!greeter->priv->guest_account_authenticated && !session_get_is_authenticated (greeter->priv->authentication_session))
 718     {
 719         g_debug ("Ignoring set language request, user is not authorized");
 720         return;
 721     }
 722
 723     // FIXME: Could use this
 724     if (greeter->priv->guest_account_authenticated)
 725     {
 726         g_debug ("Ignoring set language request for guest user");
 727         return;
 728     }
 729
 730     g_debug ("Greeter sets language %s", language);
 731     user = session_get_user (greeter->priv->authentication_session);
 732     user_set_language (user, language);
 733 }
 734
 735 static void
 736 handle_ensure_shared_dir (Greeter *greeter, const gchar *username)
 737 {
 738     gchar *dir;
 739     guint8 message[MAX_MESSAGE_LENGTH];
 740     gsize offset = 0;
 741
 742     g_debug ("Greeter requests data directory for user %s", username);
 743
 744     dir = shared_data_manager_ensure_user_dir (shared_data_manager_get_instance (), username);
 745
 746     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SHARED_DIR_RESULT, string_length (dir), &offset);
 747     write_string (message, MAX_MESSAGE_LENGTH, dir, &offset);
 748     write_message (greeter, message, offset);
 749
 750     g_free (dir);
 751 }
 752
 753 static guint32
 754 read_int (Greeter *greeter, gsize *offset)
 755 {
 756     guint32 value;
 757     guint8 *buffer;
 758     if (greeter->priv->n_read - *offset < sizeof (guint32))
 759     {
 760         g_warning ("Not enough space for int, need %zu, got %zu", sizeof (guint32), greeter->priv->n_read - *offset);
 761         return 0;
 762     }
 763     buffer = greeter->priv->read_buffer + *offset;
 764     value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
 765     *offset += int_length ();
 766     return value;
 767 }
 768
 769 static int
 770 get_message_length (Greeter *greeter)
 771 {
 772     gsize offset;
 773     int payload_length;
 774
 775     offset = int_length ();
 776     payload_length = read_int (greeter, &offset);
 777
 778     if (HEADER_SIZE + payload_length < HEADER_SIZE)
 779     {
 780         g_warning ("Payload length of %u octets too long", payload_length);
 781         return HEADER_SIZE;
 782     }
 783
 784     return HEADER_SIZE + payload_length;
 785 }
 786
 787 static gchar *
 788 read_string_full (Greeter *greeter, gsize *offset, void* (*alloc_fn)(size_t n))
 789 {
 790     guint32 length;
 791     gchar *value;
 792
 793     length = read_int (greeter, offset);
 794     if (greeter->priv->n_read - *offset < length)
 795     {
 796         g_warning ("Not enough space for string, need %u, got %zu", length, greeter->priv->n_read - *offset);
 797         return g_strdup ("");
 798     }
 799
 800     value = (*alloc_fn) (sizeof (gchar) * (length + 1));
 801     memcpy (value, greeter->priv->read_buffer + *offset, length);
 802     value[length] = '\0';
 803     *offset += length;
 804
 805     return value;
 806 }
 807
 808 static gchar *
 809 read_string (Greeter *greeter, gsize *offset)
 810 {
 811     return read_string_full (greeter, offset, g_malloc);
 812 }
 813
 814 static gchar *
 815 read_secret (Greeter *greeter, gsize *offset)
 816 {
 817     if (greeter->priv->use_secure_memory)
 818         return read_string_full (greeter, offset, gcry_malloc_secure);
 819     else
 820         return read_string_full (greeter, offset, g_malloc);
 821 }
 822
 823 static gboolean
 824 read_cb (GIOChannel *source, GIOCondition condition, gpointer data)
 825 {
 826     Greeter *greeter = data;
 827     gsize n_to_read, n_read, offset;
 828     GIOStatus status;
 829     int id, length, i;
 830     guint32 sequence_number, n_secrets, max_secrets;
 831     gchar *version, *username, *session_name, *language;
 832     gchar **secrets;
 833     gboolean resettable = FALSE;
 834     GError *error = NULL;
 835
 836     if (condition == G_IO_HUP)
 837     {
 838         g_debug ("Greeter closed communication channel");
 839         greeter->priv->from_greeter_watch = 0;
 840         g_signal_emit (greeter, signals[DISCONNECTED], 0);
 841         return FALSE;
 842     }
 843
 844     n_to_read = HEADER_SIZE;
 845     if (greeter->priv->n_read >= HEADER_SIZE)
 846     {
 847         n_to_read = get_message_length (greeter);
 848         if (n_to_read <= HEADER_SIZE)
 849         {
 850             greeter->priv->from_greeter_watch = 0;
 851             return FALSE;
 852         }
 853     }
 854
 855     status = g_io_channel_read_chars (greeter->priv->from_greeter_channel,
 856                                       (gchar *) greeter->priv->read_buffer + greeter->priv->n_read,
 857                                       n_to_read - greeter->priv->n_read,
 858                                       &n_read,
 859                                       &error);
 860     if (error)
 861         g_warning ("Error reading from greeter: %s", error->message);
 862     g_clear_error (&error);
 863     if (status == G_IO_STATUS_EOF)
 864     {
 865         g_debug ("Greeter closed communication channel");
 866         greeter->priv->from_greeter_watch = 0;
 867         g_signal_emit (greeter, signals[DISCONNECTED], 0);
 868         return FALSE;
 869     }
 870     else if (status != G_IO_STATUS_NORMAL)
 871         return TRUE;
 872
 873     greeter->priv->n_read += n_read;
 874     if (greeter->priv->n_read != n_to_read)
 875         return TRUE;
 876
 877     /* If have header, rerun for content */
 878     if (greeter->priv->n_read == HEADER_SIZE)
 879     {
 880         n_to_read = get_message_length (greeter);
 881         if (n_to_read > HEADER_SIZE)
 882         {
 883             greeter->priv->read_buffer = secure_realloc (greeter, greeter->priv->read_buffer, n_to_read);
 884             read_cb (source, condition, greeter);
 885             return TRUE;
 886         }
 887     }
 888
 889     offset = 0;
 890     id = read_int (greeter, &offset);
 891     length = HEADER_SIZE + read_int (greeter, &offset);
 892     switch (id)
 893     {
 894     case GREETER_MESSAGE_CONNECT:
 895         version = read_string (greeter, &offset);
 896         if (offset < length)
 897             resettable = read_int (greeter, &offset) != 0;
 898         handle_connect (greeter, version, resettable);
 899         g_free (version);
 900         break;
 901     case GREETER_MESSAGE_AUTHENTICATE:
 902         sequence_number = read_int (greeter, &offset);
 903         username = read_string (greeter, &offset);
 904         handle_login (greeter, sequence_number, username);
 905         g_free (username);
 906         break;
 907     case GREETER_MESSAGE_AUTHENTICATE_AS_GUEST:
 908         sequence_number = read_int (greeter, &offset);
 909         handle_login_as_guest (greeter, sequence_number);
 910         break;
 911     case GREETER_MESSAGE_AUTHENTICATE_REMOTE:
 912         sequence_number = read_int (greeter, &offset);
 913         session_name = read_string (greeter, &offset);
 914         username = read_string (greeter, &offset);
 915         handle_login_remote (greeter, session_name, username, sequence_number);
 916         break;
 917     case GREETER_MESSAGE_CONTINUE_AUTHENTICATION:
 918         n_secrets = read_int (greeter, &offset);
 919         max_secrets = (G_MAXUINT32 - 1) / sizeof (gchar *);
 920         if (n_secrets > max_secrets)
 921         {
 922             g_warning ("Array length of %u elements too long", n_secrets);
 923             greeter->priv->from_greeter_watch = 0;
 924             return FALSE;
 925         }
 926         secrets = g_malloc (sizeof (gchar *) * (n_secrets + 1));
 927         for (i = 0; i < n_secrets; i++)
 928             secrets[i] = read_secret (greeter, &offset);
 929         secrets[i] = NULL;
 930         handle_continue_authentication (greeter, secrets);
 931         for (i = 0; i < n_secrets; i++)
 932             secure_free (greeter, secrets[i]);
 933         g_free (secrets);
 934         break;
 935     case GREETER_MESSAGE_CANCEL_AUTHENTICATION:
 936         handle_cancel_authentication (greeter);
 937         break;
 938     case GREETER_MESSAGE_START_SESSION:
 939         session_name = read_string (greeter, &offset);
 940         handle_start_session (greeter, session_name);
 941         g_free (session_name);
 942         break;
 943     case GREETER_MESSAGE_SET_LANGUAGE:
 944         language = read_string (greeter, &offset);
 945         handle_set_language (greeter, language);
 946         g_free (language);
 947         break;
 948     case GREETER_MESSAGE_ENSURE_SHARED_DIR:
 949         username = read_string (greeter, &offset);
 950         handle_ensure_shared_dir (greeter, username);
 951         g_free (username);
 952         break;
 953     default:
 954         g_warning ("Unknown message from greeter: %d", id);
 955         break;
 956     }
 957
 958     greeter->priv->n_read = 0;
 959
 960     return TRUE;
 961 }
 962
 963 gboolean
 964 greeter_get_guest_authenticated (Greeter *greeter)
 965 {
 966     g_return_val_if_fail (greeter != NULL, FALSE);
 967     return greeter->priv->guest_account_authenticated;
 968 }
 969
 970 Session *
 971 greeter_get_authentication_session (Greeter *greeter)
 972 {
 973     g_return_val_if_fail (greeter != NULL, NULL);
 974     return greeter->priv->authentication_session;
 975 }
 976
 977 gboolean
 978 greeter_get_resettable (Greeter *greeter)
 979 {
 980     g_return_val_if_fail (greeter != NULL, FALSE);
 981     return greeter->priv->resettable;
 982 }
 983
 984 gboolean
 985 greeter_get_start_session (Greeter *greeter)
 986 {
 987     g_return_val_if_fail (greeter != NULL, FALSE);
 988     return greeter->priv->start_session;
 989 }
 990
 991 const gchar *
 992 greeter_get_active_username (Greeter *greeter)
 993 {
 994     g_return_val_if_fail (greeter != NULL, NULL);
 995     return greeter->priv->active_username;
 996 }
 997
 998 static Session *
 999 greeter_real_create_session (Greeter *greeter)
1000 {
1001     return NULL;
1002 }
1003
1004 static gboolean
1005 greeter_real_start_session (Greeter *greeter, SessionType type, const gchar *session)
1006 {
1007     return FALSE;
1008 }
1009
1010 static void
1011 greeter_init (Greeter *greeter)
1012 {
1013     greeter->priv = G_TYPE_INSTANCE_GET_PRIVATE (greeter, GREETER_TYPE, GreeterPrivate);
1014     greeter->priv->read_buffer = secure_malloc (greeter, HEADER_SIZE);
1015     greeter->priv->hints = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
1016     greeter->priv->use_secure_memory = config_get_boolean (config_get_instance (), "LightDM", "lock-memory");
1017     greeter->priv->to_greeter_input = -1;
1018     greeter->priv->from_greeter_output = -1;
1019 }
1020
1021 static void
1022 greeter_finalize (GObject *object)
1023 {
1024     Greeter *self = GREETER (object);
1025
1026     g_free (self->priv->pam_service);
1027     g_free (self->priv->autologin_pam_service);
1028     secure_free (self, self->priv->read_buffer);
1029     g_hash_table_unref (self->priv->hints);
1030     g_free (self->priv->remote_session);
1031     g_free (self->priv->active_username);
1032     if (self->priv->authentication_session)
1033     {
1034         g_signal_handlers_disconnect_matched (self->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, self);
1035         g_object_unref (self->priv->authentication_session);
1036     }
1037     close (self->priv->to_greeter_input);
1038     close (self->priv->from_greeter_output);
1039     if (self->priv->to_greeter_channel)
1040         g_io_channel_unref (self->priv->to_greeter_channel);
1041     if (self->priv->from_greeter_channel)
1042         g_io_channel_unref (self->priv->from_greeter_channel);
1043     if (self->priv->from_greeter_watch)
1044         g_source_remove (self->priv->from_greeter_watch);
1045
1046     G_OBJECT_CLASS (greeter_parent_class)->finalize (object);
1047 }
1048
1049 static void
1050 greeter_set_property (GObject      *object,
1051                       guint         prop_id,
1052                       const GValue *value,
1053                       GParamSpec   *pspec)
1054 {
1055     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1056 }
1057
1058 static void
1059 greeter_get_property (GObject    *object,
1060                       guint       prop_id,
1061                       GValue     *value,
1062                       GParamSpec *pspec)
1063 {
1064     Greeter *greeter = GREETER (object);
1065
1066     switch (prop_id) {
1067     case PROP_ACTIVE_USERNAME:
1068         g_value_set_string (value, greeter_get_active_username (greeter));
1069         break;
1070     default:
1071         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1072         break;
1073     }
1074 }
1075
1076 static void
1077 greeter_class_init (GreeterClass *klass)
1078 {
1079     GObjectClass *object_class = G_OBJECT_CLASS (klass);
1080
1081     klass->create_session = greeter_real_create_session;
1082     klass->start_session = greeter_real_start_session;
1083     object_class->finalize = greeter_finalize;
1084     object_class->get_property = greeter_get_property;
1085     object_class->set_property = greeter_set_property;
1086
1087     signals[CONNECTED] =
1088         g_signal_new (GREETER_SIGNAL_CONNECTED,
1089                       G_TYPE_FROM_CLASS (klass),
1090                       G_SIGNAL_RUN_LAST,
1091                       G_STRUCT_OFFSET (GreeterClass, connected),
1092                       NULL, NULL,
1093                       NULL,
1094                       G_TYPE_NONE, 0);
1095
1096     signals[DISCONNECTED] =
1097         g_signal_new (GREETER_SIGNAL_DISCONNECTED,
1098                       G_TYPE_FROM_CLASS (klass),
1099                       G_SIGNAL_RUN_LAST,
1100                       G_STRUCT_OFFSET (GreeterClass, disconnected),
1101                       NULL, NULL,
1102                       NULL,
1103                       G_TYPE_NONE, 0);
1104
1105     signals[CREATE_SESSION] =
1106         g_signal_new (GREETER_SIGNAL_CREATE_SESSION,
1107                       G_TYPE_FROM_CLASS (klass),
1108                       G_SIGNAL_RUN_LAST,
1109                       G_STRUCT_OFFSET (GreeterClass, create_session),
1110                       g_signal_accumulator_first_wins,
1111                       NULL,
1112                       NULL,
1113                       SESSION_TYPE, 0);
1114
1115     signals[START_SESSION] =
1116         g_signal_new (GREETER_SIGNAL_START_SESSION,
1117                       G_TYPE_FROM_CLASS (klass),
1118                       G_SIGNAL_RUN_LAST,
1119                       G_STRUCT_OFFSET (GreeterClass, start_session),
1120                       g_signal_accumulator_true_handled,
1121                       NULL,
1122                       NULL,
1123                       G_TYPE_BOOLEAN, 2, G_TYPE_INT, G_TYPE_STRING);
1124
1125     g_object_class_install_property (object_class,
1126                                      PROP_ACTIVE_USERNAME,
1127                                      g_param_spec_string (GREETER_PROPERTY_ACTIVE_USERNAME,
1128                                                           GREETER_PROPERTY_ACTIVE_USERNAME,
1129                                                           "Active username",
1130                                                           NULL,
1131                                                           G_PARAM_READABLE));
1132
1133     g_type_class_add_private (klass, sizeof (GreeterPrivate));
1134 }