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
 331 greeter_idle (Greeter *greeter)
 332 {
 333     guint8 message[MAX_MESSAGE_LENGTH];
 334     gsize offset = 0;
 335
 336     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_IDLE, 0, &offset);
 337     write_message (greeter, message, offset);
 338 }
 339
 340 void
 341 greeter_reset (Greeter *greeter)
 342 {
 343     guint8 message[MAX_MESSAGE_LENGTH];
 344     gsize offset = 0;
 345     guint32 length = 0;
 346     GHashTableIter iter;
 347     gpointer key, value;
 348
 349     g_hash_table_iter_init (&iter, greeter->priv->hints);
 350     while (g_hash_table_iter_next (&iter, &key, &value))
 351         length += string_length (key) + string_length (value);
 352
 353     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_RESET, length, &offset);
 354     g_hash_table_iter_init (&iter, greeter->priv->hints);
 355     while (g_hash_table_iter_next (&iter, &key, &value))
 356     {
 357         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 358         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 359     }
 360     write_message (greeter, message, offset);
 361 }
 362
 363 static void
 364 authentication_complete_cb (Session *session, Greeter *greeter)
 365 {
 366     int result;
 367
 368     l_debug (greeter, "Authenticate result for user %s: %s", session_get_username (session), session_get_authentication_result_string (session));
 369
 370     result = session_get_authentication_result (session);
 371     if (session_get_is_authenticated (session))
 372     {
 373         if (session_get_user (session))
 374             l_debug (greeter, "User %s authorized", session_get_username (session));
 375         else
 376         {
 377             l_debug (greeter, "User %s authorized, but no account of that name exists", session_get_username (session));
 378             result = PAM_USER_UNKNOWN;
 379         }
 380     }
 381
 382     send_end_authentication (greeter, greeter->priv->authentication_sequence_number, session_get_username (session), result);
 383 }
 384
 385 static void
 386 reset_session (Greeter *greeter)
 387 {
 388     g_free (greeter->priv->remote_session);
 389     greeter->priv->remote_session = NULL;
 390     if (greeter->priv->authentication_session)
 391     {
 392         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 393         session_stop (greeter->priv->authentication_session);
 394         g_object_unref (greeter->priv->authentication_session);
 395         greeter->priv->authentication_session = NULL;
 396     }
 397
 398     greeter->priv->guest_account_authenticated = FALSE;
 399 }
 400
 401 static void
 402 handle_login (Greeter *greeter, guint32 sequence_number, const gchar *username)
 403 {
 404     const gchar *autologin_username, *service;
 405     gboolean is_interactive;
 406
 407     if (username[0] == '\0')
 408     {
 409         l_debug (greeter, "Greeter start authentication");
 410         username = NULL;
 411     }
 412     else
 413         l_debug (greeter, "Greeter start authentication for %s", username);
 414
 415     reset_session (greeter);
 416
 417     if (greeter->priv->active_username)
 418         g_free (greeter->priv->active_username);
 419     greeter->priv->active_username = g_strdup (username);
 420     g_object_notify (G_OBJECT (greeter), "active-username");
 421
 422     greeter->priv->authentication_sequence_number = sequence_number;
 423     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 424     if (!greeter->priv->authentication_session)
 425     {
 426         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 427         return;
 428     }
 429
 430     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), "got-messages", G_CALLBACK (pam_messages_cb), greeter);
 431     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), "authentication-complete", G_CALLBACK (authentication_complete_cb), greeter);
 432
 433     /* Use non-interactive service for autologin user */
 434     autologin_username = g_hash_table_lookup (greeter->priv->hints, "autologin-user");
 435     if (autologin_username != NULL && g_strcmp0 (username, autologin_username) == 0)
 436     {
 437         service = greeter->priv->autologin_pam_service;
 438         is_interactive = FALSE;
 439     }
 440     else
 441     {
 442         service = greeter->priv->pam_service;
 443         is_interactive = TRUE;
 444     }
 445
 446     /* Run the session process */
 447     session_set_pam_service (greeter->priv->authentication_session, service);
 448     session_set_username (greeter->priv->authentication_session, username);
 449     session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 450     session_set_is_interactive (greeter->priv->authentication_session, is_interactive);
 451     session_start (greeter->priv->authentication_session);
 452 }
 453
 454 static void
 455 handle_login_as_guest (Greeter *greeter, guint32 sequence_number)
 456 {
 457     l_debug (greeter, "Greeter start authentication for guest account");
 458
 459     reset_session (greeter);
 460
 461     if (!greeter->priv->allow_guest)
 462     {
 463         l_debug (greeter, "Guest account is disabled");
 464         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 465         return;
 466     }
 467
 468     greeter->priv->guest_account_authenticated = TRUE;
 469     send_end_authentication (greeter, sequence_number, "", PAM_SUCCESS);
 470 }
 471
 472 static gchar *
 473 get_remote_session_service (const gchar *session_name)
 474 {
 475     GKeyFile *session_desktop_file;
 476     gboolean result;
 477     const gchar *c;
 478     gchar *remote_sessions_dir, *filename, *path, *service = NULL;
 479     GError *error = NULL;
 480
 481     /* Validate session name doesn't contain directory separators */
 482     for (c = session_name; *c; c++)
 483     {
 484         if (*c == '/')
 485             return NULL;
 486     }
 487
 488     /* Load the session file */
 489     session_desktop_file = g_key_file_new ();
 490     filename = g_strdup_printf ("%s.desktop", session_name);
 491     remote_sessions_dir = config_get_string (config_get_instance (), "LightDM", "remote-sessions-directory");
 492     path = g_build_filename (remote_sessions_dir, filename, NULL);
 493     g_free (remote_sessions_dir);
 494     g_free (filename);
 495     result = g_key_file_load_from_file (session_desktop_file, path, G_KEY_FILE_NONE, &error);
 496     if (error)
 497         g_debug ("Failed to load session file %s: %s", path, error->message);
 498     g_free (path);
 499     g_clear_error (&error);
 500     if (result)
 501         service = g_key_file_get_string (session_desktop_file, G_KEY_FILE_DESKTOP_GROUP, "X-LightDM-PAM-Service", NULL);
 502     g_key_file_free (session_desktop_file);
 503
 504     return service;
 505 }
 506
 507 static void
 508 handle_login_remote (Greeter *greeter, const gchar *session_name, const gchar *username, guint32 sequence_number)
 509 {
 510     gchar *service;
 511
 512     if (username[0] == '\0')
 513     {
 514         l_debug (greeter, "Greeter start authentication for remote session %s", session_name);
 515         username = NULL;
 516     }
 517     else
 518         l_debug (greeter, "Greeter start authentication for remote session %s as user %s", session_name, username);
 519
 520     reset_session (greeter);
 521
 522     service = get_remote_session_service (session_name);
 523     if (!service)
 524     {
 525         send_end_authentication (greeter, sequence_number, "", PAM_SYSTEM_ERR);
 526         return;
 527     }
 528
 529     greeter->priv->authentication_sequence_number = sequence_number;
 530     greeter->priv->remote_session = g_strdup (session_name);
 531     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 532     if (greeter->priv->authentication_session)
 533     {
 534         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), "got-messages", G_CALLBACK (pam_messages_cb), greeter);
 535         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), "authentication-complete", G_CALLBACK (authentication_complete_cb), greeter);
 536
 537         /* Run the session process */
 538         session_set_pam_service (greeter->priv->authentication_session, service);
 539         session_set_username (greeter->priv->authentication_session, username);
 540         session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 541         session_set_is_interactive (greeter->priv->authentication_session, TRUE);
 542         session_set_is_guest (greeter->priv->authentication_session, TRUE);
 543         session_start (greeter->priv->authentication_session);
 544     }
 545
 546     g_free (service);
 547
 548     if (!greeter->priv->authentication_session)
 549     {
 550         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 551         return;
 552     }
 553 }
 554
 555 static void
 556 handle_continue_authentication (Greeter *greeter, gchar **secrets)
 557 {
 558     int messages_length;
 559     const struct pam_message *messages;
 560     struct pam_response *response;
 561     int i, j, n_prompts = 0;
 562
 563     /* Not in authentication */
 564     if (greeter->priv->authentication_session == NULL)
 565         return;
 566
 567     messages_length = session_get_messages_length (greeter->priv->authentication_session);
 568     messages = session_get_messages (greeter->priv->authentication_session);
 569
 570     /* Check correct number of responses */
 571     for (i = 0; i < messages_length; i++)
 572     {
 573         int msg_style = messages[i].msg_style;
 574         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 575             n_prompts++;
 576     }
 577     if (g_strv_length (secrets) != n_prompts)
 578     {
 579         session_respond_error (greeter->priv->authentication_session, PAM_CONV_ERR);
 580         return;
 581     }
 582
 583     l_debug (greeter, "Continue authentication");
 584
 585     /* Build response */
 586     response = calloc (messages_length, sizeof (struct pam_response));
 587     for (i = 0, j = 0; i < messages_length; i++)
 588     {
 589         int msg_style = messages[i].msg_style;
 590         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 591         {
 592             size_t secret_length = strlen (secrets[j]) + 1;
 593             response[i].resp = secure_malloc (greeter, secret_length);
 594             memcpy (response[i].resp, secrets[j], secret_length); // FIXME: Need to convert from UTF-8
 595             j++;
 596         }
 597     }
 598
 599     session_respond (greeter->priv->authentication_session, response);
 600
 601     for (i = 0; i < messages_length; i++)
 602         secure_free (greeter, response[i].resp);
 603     free (response);
 604 }
 605
 606 static void
 607 handle_cancel_authentication (Greeter *greeter)
 608 {
 609     /* Not in authentication */
 610     if (greeter->priv->authentication_session == NULL)
 611         return;
 612
 613     l_debug (greeter, "Cancel authentication");
 614     reset_session (greeter);
 615 }
 616
 617 static void
 618 handle_start_session (Greeter *greeter, const gchar *session)
 619 {
 620     gboolean result;
 621     guint8 message[MAX_MESSAGE_LENGTH];
 622     gsize offset = 0;
 623     SessionType session_type = SESSION_TYPE_LOCAL;
 624
 625     if (strcmp (session, "") == 0)
 626         session = NULL;
 627
 628     /* Use session type chosen in remote session */
 629     if (greeter->priv->remote_session)
 630     {
 631         session_type = SESSION_TYPE_REMOTE;
 632         session = greeter->priv->remote_session;
 633     }
 634
 635     if (greeter->priv->guest_account_authenticated || session_get_is_authenticated (greeter->priv->authentication_session))
 636     {
 637         if (session)
 638             l_debug (greeter, "Greeter requests session %s", session);
 639         else
 640             l_debug (greeter, "Greeter requests default session");
 641         greeter->priv->start_session = TRUE;
 642         g_signal_emit (greeter, signals[START_SESSION], 0, session_type, session, &result);
 643     }
 644     else
 645     {
 646         l_debug (greeter, "Ignoring start session request, user is not authorized");
 647         result = FALSE;
 648     }
 649
 650     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SESSION_RESULT, int_length (), &offset);
 651     write_int (message, MAX_MESSAGE_LENGTH, result ? 0 : 1, &offset);
 652     write_message (greeter, message, offset);
 653 }
 654
 655 static void
 656 handle_set_language (Greeter *greeter, const gchar *language)
 657 {
 658     User *user;
 659
 660     if (!greeter->priv->guest_account_authenticated && !session_get_is_authenticated (greeter->priv->authentication_session))
 661     {
 662         l_debug (greeter, "Ignoring set language request, user is not authorized");
 663         return;
 664     }
 665
 666     // FIXME: Could use this
 667     if (greeter->priv->guest_account_authenticated)
 668     {
 669         l_debug (greeter, "Ignoring set language request for guest user");
 670         return;
 671     }
 672
 673     l_debug (greeter, "Greeter sets language %s", language);
 674     user = session_get_user (greeter->priv->authentication_session);
 675     user_set_language (user, language);
 676 }
 677
 678 static void
 679 handle_ensure_shared_dir (Greeter *greeter, const gchar *username)
 680 {
 681     gchar *dir;
 682     guint8 message[MAX_MESSAGE_LENGTH];
 683     gsize offset = 0;
 684
 685     l_debug (greeter, "Greeter requests data directory for user %s", username);
 686
 687     dir = shared_data_manager_ensure_user_dir (shared_data_manager_get_instance (), username);
 688
 689     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SHARED_DIR_RESULT, string_length (dir), &offset);
 690     write_string (message, MAX_MESSAGE_LENGTH, dir, &offset);
 691     write_message (greeter, message, offset);
 692
 693     g_free (dir);
 694 }
 695
 696 static guint32
 697 read_int (Greeter *greeter, gsize *offset)
 698 {
 699     guint32 value;
 700     guint8 *buffer;
 701     if (greeter->priv->n_read - *offset < sizeof (guint32))
 702     {
 703         l_warning (greeter, "Not enough space for int, need %zu, got %zu", sizeof (guint32), greeter->priv->n_read - *offset);
 704         return 0;
 705     }
 706     buffer = greeter->priv->read_buffer + *offset;
 707     value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
 708     *offset += int_length ();
 709     return value;
 710 }
 711
 712 static int
 713 get_message_length (Greeter *greeter)
 714 {
 715     gsize offset;
 716     int payload_length;
 717
 718     offset = int_length ();
 719     payload_length = read_int (greeter, &offset);
 720
 721     if (HEADER_SIZE + payload_length < HEADER_SIZE)
 722     {
 723         l_warning (greeter, "Payload length of %u octets too long", payload_length);
 724         return HEADER_SIZE;
 725     }
 726
 727     return HEADER_SIZE + payload_length;
 728 }
 729
 730 static gchar *
 731 read_string_full (Greeter *greeter, gsize *offset, void* (*alloc_fn)(size_t n))
 732 {
 733     guint32 length;
 734     gchar *value;
 735
 736     length = read_int (greeter, offset);
 737     if (greeter->priv->n_read - *offset < length)
 738     {
 739         l_warning (greeter, "Not enough space for string, need %u, got %zu", length, greeter->priv->n_read - *offset);
 740         return g_strdup ("");
 741     }
 742
 743     value = (*alloc_fn) (sizeof (gchar) * (length + 1));
 744     memcpy (value, greeter->priv->read_buffer + *offset, length);
 745     value[length] = '\0';
 746     *offset += length;
 747
 748     return value;
 749 }
 750
 751 static gchar *
 752 read_string (Greeter *greeter, gsize *offset)
 753 {
 754     return read_string_full (greeter, offset, g_malloc);
 755 }
 756
 757 static gchar *
 758 read_secret (Greeter *greeter, gsize *offset)
 759 {
 760     if (greeter->priv->use_secure_memory)
 761         return read_string_full (greeter, offset, gcry_malloc_secure);
 762     else
 763         return read_string_full (greeter, offset, g_malloc);
 764 }
 765
 766 static gboolean
 767 read_cb (GIOChannel *source, GIOCondition condition, gpointer data)
 768 {
 769     Greeter *greeter = data;
 770     gsize n_to_read, n_read, offset;
 771     GIOStatus status;
 772     int id, i;
 773     guint32 sequence_number, n_secrets, max_secrets;
 774     gchar *version, *username, *session_name, *language;
 775     gchar **secrets;
 776     GError *error = NULL;
 777
 778     if (condition == G_IO_HUP)
 779     {
 780         l_debug (greeter, "Greeter closed communication channel");
 781         greeter->priv->from_greeter_watch = 0;
 782         return FALSE;
 783     }
 784
 785     n_to_read = HEADER_SIZE;
 786     if (greeter->priv->n_read >= HEADER_SIZE)
 787     {
 788         n_to_read = get_message_length (greeter);
 789         if (n_to_read <= HEADER_SIZE)
 790         {
 791             greeter->priv->from_greeter_watch = 0;
 792             return FALSE;
 793         }
 794     }
 795
 796     status = g_io_channel_read_chars (greeter->priv->from_greeter_channel,
 797                                       (gchar *) greeter->priv->read_buffer + greeter->priv->n_read,
 798                                       n_to_read - greeter->priv->n_read,
 799                                       &n_read,
 800                                       &error);
 801     if (error)
 802         l_warning (greeter, "Error reading from greeter: %s", error->message);
 803     g_clear_error (&error);
 804     if (status != G_IO_STATUS_NORMAL)
 805         return TRUE;
 806
 807     greeter->priv->n_read += n_read;
 808     if (greeter->priv->n_read != n_to_read)
 809         return TRUE;
 810
 811     /* If have header, rerun for content */
 812     if (greeter->priv->n_read == HEADER_SIZE)
 813     {
 814         n_to_read = get_message_length (greeter);
 815         if (n_to_read > HEADER_SIZE)
 816         {
 817             greeter->priv->read_buffer = secure_realloc (greeter, greeter->priv->read_buffer, n_to_read);
 818             read_cb (source, condition, greeter);
 819             return TRUE;
 820         }
 821     }
 822
 823     offset = 0;
 824     id = read_int (greeter, &offset);
 825     read_int (greeter, &offset);
 826     switch (id)
 827     {
 828     case GREETER_MESSAGE_CONNECT:
 829         version = read_string (greeter, &offset);
 830         handle_connect (greeter, version);
 831         g_free (version);
 832         break;
 833     case GREETER_MESSAGE_AUTHENTICATE:
 834         sequence_number = read_int (greeter, &offset);
 835         username = read_string (greeter, &offset);
 836         handle_login (greeter, sequence_number, username);
 837         g_free (username);
 838         break;
 839     case GREETER_MESSAGE_AUTHENTICATE_AS_GUEST:
 840         sequence_number = read_int (greeter, &offset);
 841         handle_login_as_guest (greeter, sequence_number);
 842         break;
 843     case GREETER_MESSAGE_AUTHENTICATE_REMOTE:
 844         sequence_number = read_int (greeter, &offset);
 845         session_name = read_string (greeter, &offset);
 846         username = read_string (greeter, &offset);
 847         handle_login_remote (greeter, session_name, username, sequence_number);
 848         break;
 849     case GREETER_MESSAGE_CONTINUE_AUTHENTICATION:
 850         n_secrets = read_int (greeter, &offset);
 851         max_secrets = (G_MAXUINT32 - 1) / sizeof (gchar *);
 852         if (n_secrets > max_secrets)
 853         {
 854             l_warning (greeter, "Array length of %u elements too long", n_secrets);
 855             greeter->priv->from_greeter_watch = 0;
 856             return FALSE;
 857         }
 858         secrets = g_malloc (sizeof (gchar *) * (n_secrets + 1));
 859         for (i = 0; i < n_secrets; i++)
 860             secrets[i] = read_secret (greeter, &offset);
 861         secrets[i] = NULL;
 862         handle_continue_authentication (greeter, secrets);
 863         for (i = 0; i < n_secrets; i++)
 864             secure_free (greeter, secrets[i]);
 865         g_free (secrets);
 866         break;
 867     case GREETER_MESSAGE_CANCEL_AUTHENTICATION:
 868         handle_cancel_authentication (greeter);
 869         break;
 870     case GREETER_MESSAGE_START_SESSION:
 871         session_name = read_string (greeter, &offset);
 872         handle_start_session (greeter, session_name);
 873         g_free (session_name);
 874         break;
 875     case GREETER_MESSAGE_SET_LANGUAGE:
 876         language = read_string (greeter, &offset);
 877         handle_set_language (greeter, language);
 878         g_free (language);
 879         break;
 880     case GREETER_MESSAGE_ENSURE_SHARED_DIR:
 881         username = read_string (greeter, &offset);
 882         handle_ensure_shared_dir (greeter, username);
 883         g_free (username);
 884         break;
 885     case GREETER_MESSAGE_SET_RESETTABLE:
 886         greeter->priv->resettable = read_int (greeter, &offset) != 0;
 887         break;
 888     default:
 889         l_warning (greeter, "Unknown message from greeter: %d", id);
 890         break;
 891     }
 892
 893     greeter->priv->n_read = 0;
 894
 895     return TRUE;
 896 }
 897
 898 gboolean
 899 greeter_get_guest_authenticated (Greeter *greeter)
 900 {
 901     g_return_val_if_fail (greeter != NULL, FALSE);
 902     return greeter->priv->guest_account_authenticated;
 903 }
 904
 905 Session *
 906 greeter_get_authentication_session (Greeter *greeter)
 907 {
 908     g_return_val_if_fail (greeter != NULL, NULL);
 909     return greeter->priv->authentication_session;
 910 }
 911
 912 gboolean
 913 greeter_get_resettable (Greeter *greeter)
 914 {
 915     g_return_val_if_fail (greeter != NULL, FALSE);
 916     return greeter->priv->resettable;
 917 }
 918
 919 gboolean
 920 greeter_get_start_session (Greeter *greeter)
 921 {
 922     g_return_val_if_fail (greeter != NULL, FALSE);
 923     return greeter->priv->start_session;
 924 }
 925
 926 const gchar *
 927 greeter_get_active_username (Greeter *greeter)
 928 {
 929     g_return_val_if_fail (greeter != NULL, NULL);
 930     return greeter->priv->active_username;
 931 }
 932
 933 static gboolean
 934 greeter_start (Session *session)
 935 {
 936     Greeter *greeter = GREETER (session);
 937     int to_greeter_pipe[2], from_greeter_pipe[2];
 938     gboolean result = FALSE;
 939     gchar *value;
 940
 941     /* Create a pipe to talk with the greeter */
 942     if (pipe (to_greeter_pipe) != 0 || pipe (from_greeter_pipe) != 0)
 943     {
 944         g_warning ("Failed to create pipes: %s", strerror (errno));
 945         return FALSE;
 946     }
 947     greeter->priv->to_greeter_channel = g_io_channel_unix_new (to_greeter_pipe[1]);
 948     g_io_channel_set_encoding (greeter->priv->to_greeter_channel, NULL, NULL);
 949     greeter->priv->from_greeter_channel = g_io_channel_unix_new (from_greeter_pipe[0]);
 950     g_io_channel_set_encoding (greeter->priv->from_greeter_channel, NULL, NULL);
 951     g_io_channel_set_buffered (greeter->priv->from_greeter_channel, FALSE);
 952     greeter->priv->from_greeter_watch = g_io_add_watch (greeter->priv->from_greeter_channel, G_IO_IN | G_IO_HUP, read_cb, greeter);
 953
 954     /* Let the greeter session know how to communicate with the daemon */
 955     value = g_strdup_printf ("%d", from_greeter_pipe[1]);
 956     session_set_env (SESSION (greeter), "LIGHTDM_TO_SERVER_FD", value);
 957     g_free (value);
 958     value = g_strdup_printf ("%d", to_greeter_pipe[0]);
 959     session_set_env (SESSION (greeter), "LIGHTDM_FROM_SERVER_FD", value);
 960     g_free (value);
 961
 962     /* Don't allow the daemon end of the pipes to be accessed in child processes */
 963     fcntl (to_greeter_pipe[1], F_SETFD, FD_CLOEXEC);
 964     fcntl (from_greeter_pipe[0], F_SETFD, FD_CLOEXEC);
 965
 966     result = SESSION_CLASS (greeter_parent_class)->start (session);
 967
 968     /* Close the session ends of the pipe */
 969     close (to_greeter_pipe[0]);
 970     close (from_greeter_pipe[1]);
 971
 972     return result;
 973 }
 974
 975 static Session *
 976 greeter_real_create_session (Greeter *greeter)
 977 {
 978     return NULL;
 979 }
 980
 981 static gboolean
 982 greeter_real_start_session (Greeter *greeter, SessionType type, const gchar *session)
 983 {
 984     return FALSE;
 985 }
 986
 987 static void
 988 greeter_stop (Session *session)
 989 {
 990     Greeter *greeter = GREETER (session);
 991
 992     /* Stop any events occurring after we've stopped */
 993     if (greeter->priv->authentication_session)
 994         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 995
 996     SESSION_CLASS (greeter_parent_class)->stop (session);
 997 }
 998
 999 static void
1000 greeter_init (Greeter *greeter)
1001 {
1002     greeter->priv = G_TYPE_INSTANCE_GET_PRIVATE (greeter, GREETER_TYPE, GreeterPrivate);
1003     greeter->priv->read_buffer = secure_malloc (greeter, HEADER_SIZE);
1004     greeter->priv->hints = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
1005     greeter->priv->use_secure_memory = config_get_boolean (config_get_instance (), "LightDM", "lock-memory");
1006 }
1007
1008 static void
1009 greeter_finalize (GObject *object)
1010 {
1011     Greeter *self;
1012
1013     self = GREETER (object);
1014
1015     g_free (self->priv->pam_service);
1016     g_free (self->priv->autologin_pam_service);
1017     secure_free (self, self->priv->read_buffer);
1018     g_hash_table_unref (self->priv->hints);
1019     g_free (self->priv->remote_session);
1020     g_free (self->priv->active_username);
1021     if (self->priv->authentication_session)
1022     {
1023         g_signal_handlers_disconnect_matched (self->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, self);
1024         g_object_unref (self->priv->authentication_session);
1025     }
1026     if (self->priv->to_greeter_channel)
1027         g_io_channel_unref (self->priv->to_greeter_channel);
1028     if (self->priv->from_greeter_channel)
1029         g_io_channel_unref (self->priv->from_greeter_channel);
1030     if (self->priv->from_greeter_watch)
1031         g_source_remove (self->priv->from_greeter_watch);
1032
1033     G_OBJECT_CLASS (greeter_parent_class)->finalize (object);
1034 }
1035
1036 static void
1037 greeter_set_property (GObject      *object,
1038                       guint         prop_id,
1039                       const GValue *value,
1040                       GParamSpec   *pspec)
1041 {
1042     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1043 }
1044
1045 static void
1046 greeter_get_property (GObject    *object,
1047                       guint       prop_id,
1048                       GValue     *value,
1049                       GParamSpec *pspec)
1050 {
1051     Greeter *greeter = GREETER (object);
1052
1053     switch (prop_id) {
1054     case PROP_ACTIVE_USERNAME:
1055         g_value_set_string (value, greeter_get_active_username (greeter));
1056         break;
1057     default:
1058         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1059         break;
1060     }
1061 }
1062
1063 static void
1064 greeter_class_init (GreeterClass *klass)
1065 {
1066     SessionClass *session_class = SESSION_CLASS (klass);
1067     GObjectClass *object_class = G_OBJECT_CLASS (klass);
1068
1069     klass->create_session = greeter_real_create_session;
1070     klass->start_session = greeter_real_start_session;
1071     session_class->start = greeter_start;
1072     session_class->stop = greeter_stop;
1073     object_class->finalize = greeter_finalize;
1074     object_class->get_property = greeter_get_property;
1075     object_class->set_property = greeter_set_property;
1076
1077     signals[CONNECTED] =
1078         g_signal_new ("connected",
1079                       G_TYPE_FROM_CLASS (klass),
1080                       G_SIGNAL_RUN_LAST,
1081                       G_STRUCT_OFFSET (GreeterClass, connected),
1082                       NULL, NULL,
1083                       NULL,
1084                       G_TYPE_NONE, 0);
1085
1086     signals[CREATE_SESSION] =
1087         g_signal_new ("create-session",
1088                       G_TYPE_FROM_CLASS (klass),
1089                       G_SIGNAL_RUN_LAST,
1090                       G_STRUCT_OFFSET (GreeterClass, create_session),
1091                       g_signal_accumulator_first_wins,
1092                       NULL,
1093                       NULL,
1094                       SESSION_TYPE, 0);
1095
1096     signals[START_SESSION] =
1097         g_signal_new ("start-session",
1098                       G_TYPE_FROM_CLASS (klass),
1099                       G_SIGNAL_RUN_LAST,
1100                       G_STRUCT_OFFSET (GreeterClass, start_session),
1101                       g_signal_accumulator_true_handled,
1102                       NULL,
1103                       NULL,
1104                       G_TYPE_BOOLEAN, 2, G_TYPE_INT, G_TYPE_STRING);
1105
1106     g_object_class_install_property (object_class,
1107                                      PROP_ACTIVE_USERNAME,
1108                                      g_param_spec_string ("active-username",
1109                                                           "active-username",
1110                                                           "Active username",
1111                                                           NULL,
1112                                                           G_PARAM_READABLE));
1113
1114     g_type_class_add_private (klass, sizeof (GreeterPrivate));
1115 }