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 <errno.h>
  16 #include <fcntl.h>
  17 #include <gcrypt.h>
  18
  19 #include "greeter.h"
  20 #include "configuration.h"
  21 #include "shared-data-manager.h"
  22
  23 enum {
  24     PROP_0,
  25     PROP_ACTIVE_USERNAME,
  26 };
  27
  28 enum {
  29     CONNECTED,
  30     CREATE_SESSION,
  31     START_SESSION,
  32     LAST_SIGNAL
  33 };
  34 static guint signals[LAST_SIGNAL] = { 0 };
  35
  36 struct GreeterPrivate
  37 {
  38     /* PAM service to authenticate with */
  39     gchar *pam_service;
  40     gchar *autologin_pam_service;
  41
  42     /* Buffer for data read from greeter */
  43     guint8 *read_buffer;
  44     gsize n_read;
  45     gboolean use_secure_memory;
  46
  47     /* Hints for the greeter */
  48     GHashTable *hints;
  49
  50     /* Default session to use */
  51     gchar *default_session;
  52
  53     /* Sequence number of current PAM session */
  54     guint32 authentication_sequence_number;
  55
  56     /* Remote session name */
  57     gchar *remote_session;
  58
  59     /* Currently selected user */
  60     gchar *active_username;
  61
  62     /* PAM session being constructed by the greeter */
  63     Session *authentication_session;
  64
  65     /* TRUE if a the greeter can handle a reset; else we will just kill it instead */
  66     gboolean resettable;
  67
  68     /* TRUE if a user has been authenticated and the session requested to start */
  69     gboolean start_session;
  70
  71     /* TRUE if can log into guest accounts */
  72     gboolean allow_guest;
  73
  74     /* TRUE if logging into guest session */
  75     gboolean guest_account_authenticated;
  76
  77     /* Communication channels to communicate with */
  78     int to_greeter_input;
  79     int from_greeter_output;
  80     GIOChannel *to_greeter_channel;
  81     GIOChannel *from_greeter_channel;
  82     guint from_greeter_watch;
  83 };
  84
  85 G_DEFINE_TYPE (Greeter, greeter, G_TYPE_OBJECT);
  86
  87 /* Messages from the greeter to the server */
  88 typedef enum
  89 {
  90     GREETER_MESSAGE_CONNECT = 0,
  91     GREETER_MESSAGE_AUTHENTICATE,
  92     GREETER_MESSAGE_AUTHENTICATE_AS_GUEST,
  93     GREETER_MESSAGE_CONTINUE_AUTHENTICATION,
  94     GREETER_MESSAGE_START_SESSION,
  95     GREETER_MESSAGE_CANCEL_AUTHENTICATION,
  96     GREETER_MESSAGE_SET_LANGUAGE,
  97     GREETER_MESSAGE_AUTHENTICATE_REMOTE,
  98     GREETER_MESSAGE_ENSURE_SHARED_DIR,
  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 gboolean
 122 greeter_start (Greeter *greeter, gboolean (*setup_child_cb)(Greeter *greeter, int input_fd, int output_fd, gpointer user_data), gpointer user_data)
 123 {
 124     int to_greeter_pipe[2], from_greeter_pipe[2];
 125     int to_greeter_output, from_greeter_input;
 126     gboolean result;
 127     GError *error = NULL;
 128
 129     /* Create a pipe to talk with the greeter */
 130     if (pipe (to_greeter_pipe) != 0 || pipe (from_greeter_pipe) != 0)
 131     {
 132         g_warning ("Failed to create pipes: %s", strerror (errno));
 133         return FALSE;
 134     }
 135     to_greeter_output = to_greeter_pipe[0];
 136     greeter->priv->to_greeter_input = to_greeter_pipe[1];
 137     greeter->priv->to_greeter_channel = g_io_channel_unix_new (greeter->priv->to_greeter_input);
 138     g_io_channel_set_encoding (greeter->priv->to_greeter_channel, NULL, &error);
 139     if (error)
 140         g_warning ("Failed to set encoding on to greeter channel to binary: %s\n", error->message);
 141     g_clear_error (&error);
 142     greeter->priv->from_greeter_output = from_greeter_pipe[0];
 143     from_greeter_input = from_greeter_pipe[1];
 144     greeter->priv->from_greeter_channel = g_io_channel_unix_new (greeter->priv->from_greeter_output);
 145     g_io_channel_set_encoding (greeter->priv->from_greeter_channel, NULL, &error);
 146     if (error)
 147         g_warning ("Failed to set encoding on from greeter channel to binary: %s\n", error->message);
 148     g_clear_error (&error);
 149     g_io_channel_set_buffered (greeter->priv->from_greeter_channel, FALSE);
 150     greeter->priv->from_greeter_watch = g_io_add_watch (greeter->priv->from_greeter_channel, G_IO_IN | G_IO_HUP, read_cb, greeter);
 151
 152     /* Don't allow the daemon end of the pipes to be accessed in child processes */
 153     fcntl (greeter->priv->to_greeter_input, F_SETFD, FD_CLOEXEC);
 154     fcntl (greeter->priv->from_greeter_output, F_SETFD, FD_CLOEXEC);
 155
 156     result = setup_child_cb (greeter, from_greeter_input, to_greeter_output, user_data);
 157
 158     /* Close the session ends of the pipe */
 159     close (from_greeter_input);
 160     close (to_greeter_output);
 161
 162     return result;
 163 }
 164
 165 void
 166 greeter_stop (Greeter *greeter)
 167 {
 168     /* Stop any events occurring after we've stopped */
 169     if (greeter->priv->authentication_session)
 170         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 171 }
 172
 173 void
 174 greeter_set_pam_services (Greeter *greeter, const gchar *pam_service, const gchar *autologin_pam_service)
 175 {
 176     g_return_if_fail (greeter != NULL);
 177     g_free (greeter->priv->pam_service);
 178     greeter->priv->pam_service = g_strdup (pam_service);
 179     g_free (greeter->priv->autologin_pam_service);
 180     greeter->priv->autologin_pam_service = g_strdup (autologin_pam_service);
 181 }
 182
 183 void
 184 greeter_set_allow_guest (Greeter *greeter, gboolean allow_guest)
 185 {
 186     g_return_if_fail (greeter != NULL);
 187     greeter->priv->allow_guest = allow_guest;
 188 }
 189
 190 void
 191 greeter_clear_hints (Greeter *greeter)
 192 {
 193     g_return_if_fail (greeter != NULL);
 194     g_hash_table_remove_all (greeter->priv->hints);
 195 }
 196
 197 void
 198 greeter_set_hint (Greeter *greeter, const gchar *name, const gchar *value)
 199 {
 200     g_return_if_fail (greeter != NULL);
 201     g_hash_table_insert (greeter->priv->hints, g_strdup (name), g_strdup (value));
 202 }
 203
 204 static void *
 205 secure_malloc (Greeter *greeter, size_t n)
 206 {
 207     if (greeter->priv->use_secure_memory)
 208         return gcry_malloc_secure (n);
 209     else
 210         return g_malloc (n);
 211 }
 212
 213 static void *
 214 secure_realloc (Greeter *greeter, void *ptr, size_t n)
 215 {
 216     if (greeter->priv->use_secure_memory)
 217         return gcry_realloc (ptr, n);
 218     else
 219         return g_realloc (ptr, n);
 220 }
 221
 222 static void
 223 secure_free (Greeter *greeter, void *ptr)
 224 {
 225     if (greeter->priv->use_secure_memory)
 226         return gcry_free (ptr);
 227     else
 228         return g_free (ptr);
 229 }
 230
 231 static guint32
 232 int_length (void)
 233 {
 234     return 4;
 235 }
 236
 237 #define HEADER_SIZE (sizeof (guint32) * 2)
 238 #define MAX_MESSAGE_LENGTH 1024
 239
 240 static void
 241 write_message (Greeter *greeter, guint8 *message, gsize message_length)
 242 {
 243     gchar *data;
 244     gsize data_length;
 245     GError *error = NULL;
 246
 247     data = (gchar *) message;
 248     data_length = message_length;
 249     while (data_length > 0)
 250     {
 251         GIOStatus status;
 252         gsize n_written;
 253
 254         status = g_io_channel_write_chars (greeter->priv->to_greeter_channel, data, data_length, &n_written, &error);
 255         if (error)
 256             g_warning ("Error writing to greeter: %s", error->message);
 257         g_clear_error (&error);
 258         if (status != G_IO_STATUS_NORMAL)
 259             return;
 260         data_length -= n_written;
 261         data += n_written;
 262     }
 263
 264     g_io_channel_flush (greeter->priv->to_greeter_channel, &error);
 265     if (error)
 266         g_warning ("Failed to flush data to greeter: %s", error->message);
 267     g_clear_error (&error);
 268 }
 269
 270 static void
 271 write_int (guint8 *buffer, gint buffer_length, guint32 value, gsize *offset)
 272 {
 273     if (*offset + 4 >= buffer_length)
 274         return;
 275     buffer[*offset] = value >> 24;
 276     buffer[*offset+1] = (value >> 16) & 0xFF;
 277     buffer[*offset+2] = (value >> 8) & 0xFF;
 278     buffer[*offset+3] = value & 0xFF;
 279     *offset += 4;
 280 }
 281
 282 static void
 283 write_string (guint8 *buffer, gint buffer_length, const gchar *value, gsize *offset)
 284 {
 285     gint length;
 286
 287     if (value)
 288         length = strlen (value);
 289     else
 290         length = 0;
 291     write_int (buffer, buffer_length, length, offset);
 292     if (*offset + length >= buffer_length)
 293         return;
 294     if (length > 0)
 295     {
 296         memcpy (buffer + *offset, value, length);
 297         *offset += length;
 298     }
 299 }
 300
 301 static void
 302 write_header (guint8 *buffer, gint buffer_length, guint32 id, guint32 length, gsize *offset)
 303 {
 304     write_int (buffer, buffer_length, id, offset);
 305     write_int (buffer, buffer_length, length, offset);
 306 }
 307
 308 static guint32
 309 string_length (const gchar *value)
 310 {
 311     if (value == NULL)
 312         return int_length ();
 313     else
 314         return int_length () + strlen (value);
 315 }
 316
 317 static void
 318 handle_connect (Greeter *greeter, const gchar *version, gboolean resettable)
 319 {
 320     guint8 message[MAX_MESSAGE_LENGTH];
 321     gsize offset = 0;
 322     guint32 length;
 323     GHashTableIter iter;
 324     gpointer key, value;
 325
 326     g_debug ("Greeter connected version=%s resettable=%s", version, resettable ? "true" : "false");
 327
 328     greeter->priv->resettable = resettable;
 329
 330     length = string_length (VERSION);
 331     g_hash_table_iter_init (&iter, greeter->priv->hints);
 332     while (g_hash_table_iter_next (&iter, &key, &value))
 333         length += string_length (key) + string_length (value);
 334
 335     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_CONNECTED, length, &offset);
 336     write_string (message, MAX_MESSAGE_LENGTH, VERSION, &offset);
 337     g_hash_table_iter_init (&iter, greeter->priv->hints);
 338     while (g_hash_table_iter_next (&iter, &key, &value))
 339     {
 340         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 341         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 342     }
 343     write_message (greeter, message, offset);
 344
 345     g_signal_emit (greeter, signals[CONNECTED], 0);
 346 }
 347
 348 static void
 349 pam_messages_cb (Session *session, Greeter *greeter)
 350 {
 351     int i;
 352     guint32 size;
 353     guint8 message[MAX_MESSAGE_LENGTH];
 354     const struct pam_message *messages;
 355     int messages_length;
 356     gsize offset = 0;
 357     int n_prompts = 0;
 358
 359     messages = session_get_messages (session);
 360     messages_length = session_get_messages_length (session);
 361
 362     /* Respond to d-bus query with messages */
 363     g_debug ("Prompt greeter with %d message(s)", messages_length);
 364     size = int_length () + string_length (session_get_username (session)) + int_length ();
 365     for (i = 0; i < messages_length; i++)
 366         size += int_length () + string_length (messages[i].msg);
 367
 368     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_PROMPT_AUTHENTICATION, size, &offset);
 369     write_int (message, MAX_MESSAGE_LENGTH, greeter->priv->authentication_sequence_number, &offset);
 370     write_string (message, MAX_MESSAGE_LENGTH, session_get_username (session), &offset);
 371     write_int (message, MAX_MESSAGE_LENGTH, messages_length, &offset);
 372     for (i = 0; i < messages_length; i++)
 373     {
 374         write_int (message, MAX_MESSAGE_LENGTH, messages[i].msg_style, &offset);
 375         write_string (message, MAX_MESSAGE_LENGTH, messages[i].msg, &offset);
 376
 377         if (messages[i].msg_style == PAM_PROMPT_ECHO_OFF || messages[i].msg_style == PAM_PROMPT_ECHO_ON)
 378             n_prompts++;
 379     }
 380     write_message (greeter, message, offset);
 381
 382     /* Continue immediately if nothing to respond with */
 383     // FIXME: Should probably give the greeter a chance to ack the message
 384     if (n_prompts == 0)
 385     {
 386         struct pam_response *response;
 387         response = calloc (messages_length, sizeof (struct pam_response));
 388         session_respond (greeter->priv->authentication_session, response);
 389         free (response);
 390     }
 391 }
 392
 393 static void
 394 send_end_authentication (Greeter *greeter, guint32 sequence_number, const gchar *username, int result)
 395 {
 396     guint8 message[MAX_MESSAGE_LENGTH];
 397     gsize offset = 0;
 398
 399     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_END_AUTHENTICATION, int_length () + string_length (username) + int_length (), &offset);
 400     write_int (message, MAX_MESSAGE_LENGTH, sequence_number, &offset);
 401     write_string (message, MAX_MESSAGE_LENGTH, username, &offset);
 402     write_int (message, MAX_MESSAGE_LENGTH, result, &offset);
 403     write_message (greeter, message, offset);
 404 }
 405
 406 void
 407 greeter_idle (Greeter *greeter)
 408 {
 409     guint8 message[MAX_MESSAGE_LENGTH];
 410     gsize offset = 0;
 411
 412     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_IDLE, 0, &offset);
 413     write_message (greeter, message, offset);
 414 }
 415
 416 void
 417 greeter_reset (Greeter *greeter)
 418 {
 419     guint8 message[MAX_MESSAGE_LENGTH];
 420     gsize offset = 0;
 421     guint32 length = 0;
 422     GHashTableIter iter;
 423     gpointer key, value;
 424
 425     g_return_if_fail (greeter != NULL);
 426
 427     g_hash_table_iter_init (&iter, greeter->priv->hints);
 428     while (g_hash_table_iter_next (&iter, &key, &value))
 429         length += string_length (key) + string_length (value);
 430
 431     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_RESET, length, &offset);
 432     g_hash_table_iter_init (&iter, greeter->priv->hints);
 433     while (g_hash_table_iter_next (&iter, &key, &value))
 434     {
 435         write_string (message, MAX_MESSAGE_LENGTH, key, &offset);
 436         write_string (message, MAX_MESSAGE_LENGTH, value, &offset);
 437     }
 438     write_message (greeter, message, offset);
 439 }
 440
 441 static void
 442 authentication_complete_cb (Session *session, Greeter *greeter)
 443 {
 444     int result;
 445
 446     g_debug ("Authenticate result for user %s: %s", session_get_username (session), session_get_authentication_result_string (session));
 447
 448     result = session_get_authentication_result (session);
 449     if (session_get_is_authenticated (session))
 450     {
 451         if (session_get_user (session))
 452             g_debug ("User %s authorized", session_get_username (session));
 453         else
 454         {
 455             g_debug ("User %s authorized, but no account of that name exists", session_get_username (session));
 456             result = PAM_USER_UNKNOWN;
 457         }
 458     }
 459
 460     send_end_authentication (greeter, greeter->priv->authentication_sequence_number, session_get_username (session), result);
 461 }
 462
 463 static void
 464 reset_session (Greeter *greeter)
 465 {
 466     g_free (greeter->priv->remote_session);
 467     greeter->priv->remote_session = NULL;
 468     if (greeter->priv->authentication_session)
 469     {
 470         g_signal_handlers_disconnect_matched (greeter->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, greeter);
 471         session_stop (greeter->priv->authentication_session);
 472         g_clear_object (&greeter->priv->authentication_session);
 473     }
 474
 475     greeter->priv->guest_account_authenticated = FALSE;
 476 }
 477
 478 static void
 479 handle_login (Greeter *greeter, guint32 sequence_number, const gchar *username)
 480 {
 481     const gchar *autologin_username, *service;
 482     gboolean is_interactive;
 483
 484     if (username[0] == '\0')
 485     {
 486         g_debug ("Greeter start authentication");
 487         username = NULL;
 488     }
 489     else
 490         g_debug ("Greeter start authentication for %s", username);
 491
 492     reset_session (greeter);
 493
 494     if (greeter->priv->active_username)
 495         g_free (greeter->priv->active_username);
 496     greeter->priv->active_username = g_strdup (username);
 497     g_object_notify (G_OBJECT (greeter), GREETER_PROPERTY_ACTIVE_USERNAME);
 498
 499     greeter->priv->authentication_sequence_number = sequence_number;
 500     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 501     if (!greeter->priv->authentication_session)
 502     {
 503         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 504         return;
 505     }
 506
 507     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 508     g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 509
 510     /* Use non-interactive service for autologin user */
 511     autologin_username = g_hash_table_lookup (greeter->priv->hints, "autologin-user");
 512     if (autologin_username != NULL && g_strcmp0 (username, autologin_username) == 0)
 513     {
 514         service = greeter->priv->autologin_pam_service;
 515         is_interactive = FALSE;
 516     }
 517     else
 518     {
 519         service = greeter->priv->pam_service;
 520         is_interactive = TRUE;
 521     }
 522
 523     /* Run the session process */
 524     session_set_pam_service (greeter->priv->authentication_session, service);
 525     session_set_username (greeter->priv->authentication_session, username);
 526     session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 527     session_set_is_interactive (greeter->priv->authentication_session, is_interactive);
 528     session_start (greeter->priv->authentication_session);
 529 }
 530
 531 static void
 532 handle_login_as_guest (Greeter *greeter, guint32 sequence_number)
 533 {
 534     g_debug ("Greeter start authentication for guest account");
 535
 536     reset_session (greeter);
 537
 538     if (!greeter->priv->allow_guest)
 539     {
 540         g_debug ("Guest account is disabled");
 541         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 542         return;
 543     }
 544
 545     greeter->priv->guest_account_authenticated = TRUE;
 546     send_end_authentication (greeter, sequence_number, "", PAM_SUCCESS);
 547 }
 548
 549 static gchar *
 550 get_remote_session_service (const gchar *session_name)
 551 {
 552     GKeyFile *session_desktop_file;
 553     gboolean result;
 554     const gchar *c;
 555     gchar *remote_sessions_dir, *filename, *path, *service = NULL;
 556     GError *error = NULL;
 557
 558     /* Validate session name doesn't contain directory separators */
 559     for (c = session_name; *c; c++)
 560     {
 561         if (*c == '/')
 562             return NULL;
 563     }
 564
 565     /* Load the session file */
 566     session_desktop_file = g_key_file_new ();
 567     filename = g_strdup_printf ("%s.desktop", session_name);
 568     remote_sessions_dir = config_get_string (config_get_instance (), "LightDM", "remote-sessions-directory");
 569     path = g_build_filename (remote_sessions_dir, filename, NULL);
 570     g_free (remote_sessions_dir);
 571     g_free (filename);
 572     result = g_key_file_load_from_file (session_desktop_file, path, G_KEY_FILE_NONE, &error);
 573     if (error)
 574         g_debug ("Failed to load session file %s: %s", path, error->message);
 575     g_free (path);
 576     g_clear_error (&error);
 577     if (result)
 578         service = g_key_file_get_string (session_desktop_file, G_KEY_FILE_DESKTOP_GROUP, "X-LightDM-PAM-Service", NULL);
 579     g_key_file_free (session_desktop_file);
 580
 581     return service;
 582 }
 583
 584 static void
 585 handle_login_remote (Greeter *greeter, const gchar *session_name, const gchar *username, guint32 sequence_number)
 586 {
 587     gchar *service;
 588
 589     if (username[0] == '\0')
 590     {
 591         g_debug ("Greeter start authentication for remote session %s", session_name);
 592         username = NULL;
 593     }
 594     else
 595         g_debug ("Greeter start authentication for remote session %s as user %s", session_name, username);
 596
 597     reset_session (greeter);
 598
 599     service = get_remote_session_service (session_name);
 600     if (!service)
 601     {
 602         send_end_authentication (greeter, sequence_number, "", PAM_SYSTEM_ERR);
 603         return;
 604     }
 605
 606     greeter->priv->authentication_sequence_number = sequence_number;
 607     greeter->priv->remote_session = g_strdup (session_name);
 608     g_signal_emit (greeter, signals[CREATE_SESSION], 0, &greeter->priv->authentication_session);
 609     if (greeter->priv->authentication_session)
 610     {
 611         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_GOT_MESSAGES, G_CALLBACK (pam_messages_cb), greeter);
 612         g_signal_connect (G_OBJECT (greeter->priv->authentication_session), SESSION_SIGNAL_AUTHENTICATION_COMPLETE, G_CALLBACK (authentication_complete_cb), greeter);
 613
 614         /* Run the session process */
 615         session_set_pam_service (greeter->priv->authentication_session, service);
 616         session_set_username (greeter->priv->authentication_session, username);
 617         session_set_do_authenticate (greeter->priv->authentication_session, TRUE);
 618         session_set_is_interactive (greeter->priv->authentication_session, TRUE);
 619         session_set_is_guest (greeter->priv->authentication_session, TRUE);
 620         session_start (greeter->priv->authentication_session);
 621     }
 622
 623     g_free (service);
 624
 625     if (!greeter->priv->authentication_session)
 626     {
 627         send_end_authentication (greeter, sequence_number, "", PAM_USER_UNKNOWN);
 628         return;
 629     }
 630 }
 631
 632 static void
 633 handle_continue_authentication (Greeter *greeter, gchar **secrets)
 634 {
 635     int messages_length;
 636     const struct pam_message *messages;
 637     struct pam_response *response;
 638     int i, j, n_prompts = 0;
 639
 640     /* Not in authentication */
 641     if (greeter->priv->authentication_session == NULL)
 642         return;
 643
 644     messages_length = session_get_messages_length (greeter->priv->authentication_session);
 645     messages = session_get_messages (greeter->priv->authentication_session);
 646
 647     /* Check correct number of responses */
 648     for (i = 0; i < messages_length; i++)
 649     {
 650         int msg_style = messages[i].msg_style;
 651         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 652             n_prompts++;
 653     }
 654     if (g_strv_length (secrets) != n_prompts)
 655     {
 656         session_respond_error (greeter->priv->authentication_session, PAM_CONV_ERR);
 657         return;
 658     }
 659
 660     g_debug ("Continue authentication");
 661
 662     /* Build response */
 663     response = calloc (messages_length, sizeof (struct pam_response));
 664     for (i = 0, j = 0; i < messages_length; i++)
 665     {
 666         int msg_style = messages[i].msg_style;
 667         if (msg_style == PAM_PROMPT_ECHO_OFF || msg_style == PAM_PROMPT_ECHO_ON)
 668         {
 669             size_t secret_length = strlen (secrets[j]) + 1;
 670             response[i].resp = secure_malloc (greeter, secret_length);
 671             memcpy (response[i].resp, secrets[j], secret_length); // FIXME: Need to convert from UTF-8
 672             j++;
 673         }
 674     }
 675
 676     session_respond (greeter->priv->authentication_session, response);
 677
 678     for (i = 0; i < messages_length; i++)
 679         secure_free (greeter, response[i].resp);
 680     free (response);
 681 }
 682
 683 static void
 684 handle_cancel_authentication (Greeter *greeter)
 685 {
 686     /* Not in authentication */
 687     if (greeter->priv->authentication_session == NULL)
 688         return;
 689
 690     g_debug ("Cancel authentication");
 691     reset_session (greeter);
 692 }
 693
 694 static void
 695 handle_start_session (Greeter *greeter, const gchar *session)
 696 {
 697     gboolean result;
 698     guint8 message[MAX_MESSAGE_LENGTH];
 699     gsize offset = 0;
 700     SessionType session_type = SESSION_TYPE_LOCAL;
 701
 702     if (strcmp (session, "") == 0)
 703         session = NULL;
 704
 705     /* Use session type chosen in remote session */
 706     if (greeter->priv->remote_session)
 707     {
 708         session_type = SESSION_TYPE_REMOTE;
 709         session = greeter->priv->remote_session;
 710     }
 711
 712     if (greeter->priv->guest_account_authenticated || session_get_is_authenticated (greeter->priv->authentication_session))
 713     {
 714         if (session)
 715             g_debug ("Greeter requests session %s", session);
 716         else
 717             g_debug ("Greeter requests default session");
 718         greeter->priv->start_session = TRUE;
 719         g_signal_emit (greeter, signals[START_SESSION], 0, session_type, session, &result);
 720     }
 721     else
 722     {
 723         g_debug ("Ignoring start session request, user is not authorized");
 724         result = FALSE;
 725     }
 726
 727     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SESSION_RESULT, int_length (), &offset);
 728     write_int (message, MAX_MESSAGE_LENGTH, result ? 0 : 1, &offset);
 729     write_message (greeter, message, offset);
 730 }
 731
 732 static void
 733 handle_set_language (Greeter *greeter, const gchar *language)
 734 {
 735     User *user;
 736
 737     if (!greeter->priv->guest_account_authenticated && !session_get_is_authenticated (greeter->priv->authentication_session))
 738     {
 739         g_debug ("Ignoring set language request, user is not authorized");
 740         return;
 741     }
 742
 743     // FIXME: Could use this
 744     if (greeter->priv->guest_account_authenticated)
 745     {
 746         g_debug ("Ignoring set language request for guest user");
 747         return;
 748     }
 749
 750     g_debug ("Greeter sets language %s", language);
 751     user = session_get_user (greeter->priv->authentication_session);
 752     user_set_language (user, language);
 753 }
 754
 755 static void
 756 handle_ensure_shared_dir (Greeter *greeter, const gchar *username)
 757 {
 758     gchar *dir;
 759     guint8 message[MAX_MESSAGE_LENGTH];
 760     gsize offset = 0;
 761
 762     g_debug ("Greeter requests data directory for user %s", username);
 763
 764     dir = shared_data_manager_ensure_user_dir (shared_data_manager_get_instance (), username);
 765
 766     write_header (message, MAX_MESSAGE_LENGTH, SERVER_MESSAGE_SHARED_DIR_RESULT, string_length (dir), &offset);
 767     write_string (message, MAX_MESSAGE_LENGTH, dir, &offset);
 768     write_message (greeter, message, offset);
 769
 770     g_free (dir);
 771 }
 772
 773 static guint32
 774 read_int (Greeter *greeter, gsize *offset)
 775 {
 776     guint32 value;
 777     guint8 *buffer;
 778     if (greeter->priv->n_read - *offset < sizeof (guint32))
 779     {
 780         g_warning ("Not enough space for int, need %zu, got %zu", sizeof (guint32), greeter->priv->n_read - *offset);
 781         return 0;
 782     }
 783     buffer = greeter->priv->read_buffer + *offset;
 784     value = buffer[0] << 24 | buffer[1] << 16 | buffer[2] << 8 | buffer[3];
 785     *offset += int_length ();
 786     return value;
 787 }
 788
 789 static int
 790 get_message_length (Greeter *greeter)
 791 {
 792     gsize offset;
 793     int payload_length;
 794
 795     offset = int_length ();
 796     payload_length = read_int (greeter, &offset);
 797
 798     if (HEADER_SIZE + payload_length < HEADER_SIZE)
 799     {
 800         g_warning ("Payload length of %u octets too long", payload_length);
 801         return HEADER_SIZE;
 802     }
 803
 804     return HEADER_SIZE + payload_length;
 805 }
 806
 807 static gchar *
 808 read_string_full (Greeter *greeter, gsize *offset, void* (*alloc_fn)(size_t n))
 809 {
 810     guint32 length;
 811     gchar *value;
 812
 813     length = read_int (greeter, offset);
 814     if (greeter->priv->n_read - *offset < length)
 815     {
 816         g_warning ("Not enough space for string, need %u, got %zu", length, greeter->priv->n_read - *offset);
 817         return g_strdup ("");
 818     }
 819
 820     value = (*alloc_fn) (sizeof (gchar) * (length + 1));
 821     memcpy (value, greeter->priv->read_buffer + *offset, length);
 822     value[length] = '\0';
 823     *offset += length;
 824
 825     return value;
 826 }
 827
 828 static gchar *
 829 read_string (Greeter *greeter, gsize *offset)
 830 {
 831     return read_string_full (greeter, offset, g_malloc);
 832 }
 833
 834 static gchar *
 835 read_secret (Greeter *greeter, gsize *offset)
 836 {
 837     if (greeter->priv->use_secure_memory)
 838         return read_string_full (greeter, offset, gcry_malloc_secure);
 839     else
 840         return read_string_full (greeter, offset, g_malloc);
 841 }
 842
 843 static gboolean
 844 read_cb (GIOChannel *source, GIOCondition condition, gpointer data)
 845 {
 846     Greeter *greeter = data;
 847     gsize n_to_read, n_read, offset;
 848     GIOStatus status;
 849     int id, length, i;
 850     guint32 sequence_number, n_secrets, max_secrets;
 851     gchar *version, *username, *session_name, *language;
 852     gchar **secrets;
 853     gboolean resettable = FALSE;
 854     GError *error = NULL;
 855
 856     if (condition == G_IO_HUP)
 857     {
 858         g_debug ("Greeter closed communication channel");
 859         greeter->priv->from_greeter_watch = 0;
 860         return FALSE;
 861     }
 862
 863     n_to_read = HEADER_SIZE;
 864     if (greeter->priv->n_read >= HEADER_SIZE)
 865     {
 866         n_to_read = get_message_length (greeter);
 867         if (n_to_read <= HEADER_SIZE)
 868         {
 869             greeter->priv->from_greeter_watch = 0;
 870             return FALSE;
 871         }
 872     }
 873
 874     status = g_io_channel_read_chars (greeter->priv->from_greeter_channel,
 875                                       (gchar *) greeter->priv->read_buffer + greeter->priv->n_read,
 876                                       n_to_read - greeter->priv->n_read,
 877                                       &n_read,
 878                                       &error);
 879     if (error)
 880         g_warning ("Error reading from greeter: %s", error->message);
 881     g_clear_error (&error);
 882     if (status != G_IO_STATUS_NORMAL)
 883         return TRUE;
 884
 885     greeter->priv->n_read += n_read;
 886     if (greeter->priv->n_read != n_to_read)
 887         return TRUE;
 888
 889     /* If have header, rerun for content */
 890     if (greeter->priv->n_read == HEADER_SIZE)
 891     {
 892         n_to_read = get_message_length (greeter);
 893         if (n_to_read > HEADER_SIZE)
 894         {
 895             greeter->priv->read_buffer = secure_realloc (greeter, greeter->priv->read_buffer, n_to_read);
 896             read_cb (source, condition, greeter);
 897             return TRUE;
 898         }
 899     }
 900
 901     offset = 0;
 902     id = read_int (greeter, &offset);
 903     length = HEADER_SIZE + read_int (greeter, &offset);
 904     switch (id)
 905     {
 906     case GREETER_MESSAGE_CONNECT:
 907         version = read_string (greeter, &offset);
 908         if (offset < length)
 909             resettable = read_int (greeter, &offset) != 0;
 910         handle_connect (greeter, version, resettable);
 911         g_free (version);
 912         break;
 913     case GREETER_MESSAGE_AUTHENTICATE:
 914         sequence_number = read_int (greeter, &offset);
 915         username = read_string (greeter, &offset);
 916         handle_login (greeter, sequence_number, username);
 917         g_free (username);
 918         break;
 919     case GREETER_MESSAGE_AUTHENTICATE_AS_GUEST:
 920         sequence_number = read_int (greeter, &offset);
 921         handle_login_as_guest (greeter, sequence_number);
 922         break;
 923     case GREETER_MESSAGE_AUTHENTICATE_REMOTE:
 924         sequence_number = read_int (greeter, &offset);
 925         session_name = read_string (greeter, &offset);
 926         username = read_string (greeter, &offset);
 927         handle_login_remote (greeter, session_name, username, sequence_number);
 928         break;
 929     case GREETER_MESSAGE_CONTINUE_AUTHENTICATION:
 930         n_secrets = read_int (greeter, &offset);
 931         max_secrets = (G_MAXUINT32 - 1) / sizeof (gchar *);
 932         if (n_secrets > max_secrets)
 933         {
 934             g_warning ("Array length of %u elements too long", n_secrets);
 935             greeter->priv->from_greeter_watch = 0;
 936             return FALSE;
 937         }
 938         secrets = g_malloc (sizeof (gchar *) * (n_secrets + 1));
 939         for (i = 0; i < n_secrets; i++)
 940             secrets[i] = read_secret (greeter, &offset);
 941         secrets[i] = NULL;
 942         handle_continue_authentication (greeter, secrets);
 943         for (i = 0; i < n_secrets; i++)
 944             secure_free (greeter, secrets[i]);
 945         g_free (secrets);
 946         break;
 947     case GREETER_MESSAGE_CANCEL_AUTHENTICATION:
 948         handle_cancel_authentication (greeter);
 949         break;
 950     case GREETER_MESSAGE_START_SESSION:
 951         session_name = read_string (greeter, &offset);
 952         handle_start_session (greeter, session_name);
 953         g_free (session_name);
 954         break;
 955     case GREETER_MESSAGE_SET_LANGUAGE:
 956         language = read_string (greeter, &offset);
 957         handle_set_language (greeter, language);
 958         g_free (language);
 959         break;
 960     case GREETER_MESSAGE_ENSURE_SHARED_DIR:
 961         username = read_string (greeter, &offset);
 962         handle_ensure_shared_dir (greeter, username);
 963         g_free (username);
 964         break;
 965     default:
 966         g_warning ("Unknown message from greeter: %d", id);
 967         break;
 968     }
 969
 970     greeter->priv->n_read = 0;
 971
 972     return TRUE;
 973 }
 974
 975 gboolean
 976 greeter_get_guest_authenticated (Greeter *greeter)
 977 {
 978     g_return_val_if_fail (greeter != NULL, FALSE);
 979     return greeter->priv->guest_account_authenticated;
 980 }
 981
 982 Session *
 983 greeter_get_authentication_session (Greeter *greeter)
 984 {
 985     g_return_val_if_fail (greeter != NULL, NULL);
 986     return greeter->priv->authentication_session;
 987 }
 988
 989 gboolean
 990 greeter_get_resettable (Greeter *greeter)
 991 {
 992     g_return_val_if_fail (greeter != NULL, FALSE);
 993     return greeter->priv->resettable;
 994 }
 995
 996 gboolean
 997 greeter_get_start_session (Greeter *greeter)
 998 {
 999     g_return_val_if_fail (greeter != NULL, FALSE);
1000     return greeter->priv->start_session;
1001 }
1002
1003 const gchar *
1004 greeter_get_active_username (Greeter *greeter)
1005 {
1006     g_return_val_if_fail (greeter != NULL, NULL);
1007     return greeter->priv->active_username;
1008 }
1009
1010 static Session *
1011 greeter_real_create_session (Greeter *greeter)
1012 {
1013     return NULL;
1014 }
1015
1016 static gboolean
1017 greeter_real_start_session (Greeter *greeter, SessionType type, const gchar *session)
1018 {
1019     return FALSE;
1020 }
1021
1022 static void
1023 greeter_init (Greeter *greeter)
1024 {
1025     greeter->priv = G_TYPE_INSTANCE_GET_PRIVATE (greeter, GREETER_TYPE, GreeterPrivate);
1026     greeter->priv->read_buffer = secure_malloc (greeter, HEADER_SIZE);
1027     greeter->priv->hints = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
1028     greeter->priv->use_secure_memory = config_get_boolean (config_get_instance (), "LightDM", "lock-memory");
1029     greeter->priv->to_greeter_input = -1;
1030     greeter->priv->from_greeter_output = -1;
1031 }
1032
1033 static void
1034 greeter_finalize (GObject *object)
1035 {
1036     Greeter *self = GREETER (object);
1037
1038     g_free (self->priv->pam_service);
1039     g_free (self->priv->autologin_pam_service);
1040     secure_free (self, self->priv->read_buffer);
1041     g_hash_table_unref (self->priv->hints);
1042     g_free (self->priv->remote_session);
1043     g_free (self->priv->active_username);
1044     if (self->priv->authentication_session)
1045     {
1046         g_signal_handlers_disconnect_matched (self->priv->authentication_session, G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL, self);
1047         g_object_unref (self->priv->authentication_session);
1048     }
1049     close (self->priv->to_greeter_input);
1050     close (self->priv->from_greeter_output);
1051     if (self->priv->to_greeter_channel)
1052         g_io_channel_unref (self->priv->to_greeter_channel);
1053     if (self->priv->from_greeter_channel)
1054         g_io_channel_unref (self->priv->from_greeter_channel);
1055     if (self->priv->from_greeter_watch)
1056         g_source_remove (self->priv->from_greeter_watch);
1057
1058     G_OBJECT_CLASS (greeter_parent_class)->finalize (object);
1059 }
1060
1061 static void
1062 greeter_set_property (GObject      *object,
1063                       guint         prop_id,
1064                       const GValue *value,
1065                       GParamSpec   *pspec)
1066 {
1067     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1068 }
1069
1070 static void
1071 greeter_get_property (GObject    *object,
1072                       guint       prop_id,
1073                       GValue     *value,
1074                       GParamSpec *pspec)
1075 {
1076     Greeter *greeter = GREETER (object);
1077
1078     switch (prop_id) {
1079     case PROP_ACTIVE_USERNAME:
1080         g_value_set_string (value, greeter_get_active_username (greeter));
1081         break;
1082     default:
1083         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
1084         break;
1085     }
1086 }
1087
1088 static void
1089 greeter_class_init (GreeterClass *klass)
1090 {
1091     GObjectClass *object_class = G_OBJECT_CLASS (klass);
1092
1093     klass->create_session = greeter_real_create_session;
1094     klass->start_session = greeter_real_start_session;
1095     object_class->finalize = greeter_finalize;
1096     object_class->get_property = greeter_get_property;
1097     object_class->set_property = greeter_set_property;
1098
1099     signals[CONNECTED] =
1100         g_signal_new (GREETER_SIGNAL_CONNECTED,
1101                       G_TYPE_FROM_CLASS (klass),
1102                       G_SIGNAL_RUN_LAST,
1103                       G_STRUCT_OFFSET (GreeterClass, connected),
1104                       NULL, NULL,
1105                       NULL,
1106                       G_TYPE_NONE, 0);
1107
1108     signals[CREATE_SESSION] =
1109         g_signal_new (GREETER_SIGNAL_CREATE_SESSION,
1110                       G_TYPE_FROM_CLASS (klass),
1111                       G_SIGNAL_RUN_LAST,
1112                       G_STRUCT_OFFSET (GreeterClass, create_session),
1113                       g_signal_accumulator_first_wins,
1114                       NULL,
1115                       NULL,
1116                       SESSION_TYPE, 0);
1117
1118     signals[START_SESSION] =
1119         g_signal_new (GREETER_SIGNAL_START_SESSION,
1120                       G_TYPE_FROM_CLASS (klass),
1121                       G_SIGNAL_RUN_LAST,
1122                       G_STRUCT_OFFSET (GreeterClass, start_session),
1123                       g_signal_accumulator_true_handled,
1124                       NULL,
1125                       NULL,
1126                       G_TYPE_BOOLEAN, 2, G_TYPE_INT, G_TYPE_STRING);
1127
1128     g_object_class_install_property (object_class,
1129                                      PROP_ACTIVE_USERNAME,
1130                                      g_param_spec_string (GREETER_PROPERTY_ACTIVE_USERNAME,
1131                                                           GREETER_PROPERTY_ACTIVE_USERNAME,
1132                                                           "Active username",
1133                                                           NULL,
1134                                                           G_PARAM_READABLE));
1135
1136     g_type_class_add_private (klass, sizeof (GreeterPrivate));
1137 }