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