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