15 #include <security/pam_appl.h>
24 #include "configuration.h"
25 #include "session-child.h"
27 #include "console-kit.h"
30 #include "privileges.h"
31 #include "x-authority.h"
32 #include "configuration.h"
34 /* Child process being run */
35 static GPid child_pid = 0;
37 /* Pipe to communicate with daemon */
38 static int from_daemon_output = 0;
39 static int to_daemon_input = 0;
41 static gboolean is_interactive;
42 static gboolean do_authenticate;
43 static gboolean authentication_complete = FALSE;
44 static pam_handle_t *pam_handle;
46 /* Maximum length of a string to pass between daemon and session */
47 #define MAX_STRING_LENGTH 65535
50 write_data (const void *buf, size_t count)
52 if (write (to_daemon_input, buf, count) != count)
53 g_printerr ("Error writing to daemon: %s\n", strerror (errno));
57 write_string (const char *value)
61 length = value ? strlen (value) : -1;
62 write_data (&length, sizeof (length));
64 write_data (value, sizeof (char) * length);
68 read_data (void *buf, size_t count)
72 n_read = read (from_daemon_output, buf, count);
74 g_printerr ("Error reading from daemon: %s\n", strerror (errno));
80 read_string_full (void* (*alloc_fn)(size_t n))
85 if (read_data (&length, sizeof (length)) <= 0)
89 if (length > MAX_STRING_LENGTH)
91 g_printerr ("Invalid string length %d from daemon\n", length);
95 value = (*alloc_fn) (sizeof (char) * (length + 1));
96 read_data (value, length);
105 return read_string_full (g_malloc);
109 pam_conv_cb (int msg_length, const struct pam_message **msg, struct pam_response **resp, void *app_data)
112 gboolean auth_complete = FALSE;
113 struct pam_response *response;
114 gchar *username = NULL;
116 /* FIXME: We don't support communication after pam_authenticate completes */
117 if (authentication_complete)
120 /* Cancel authentication if requiring input */
123 for (i = 0; i < msg_length; i++)
125 if (msg[i]->msg_style == PAM_PROMPT_ECHO_ON || msg[i]->msg_style == PAM_PROMPT_ECHO_OFF)
127 g_printerr ("Stopping PAM conversation, interaction requested but not supported\n");
132 /* Ignore informational messages */
136 /* Check if we changed user */
137 pam_get_item (pam_handle, PAM_USER, (const void **) &username);
139 /* Notify the daemon */
140 write_string (username);
141 write_data (&auth_complete, sizeof (auth_complete));
142 write_data (&msg_length, sizeof (msg_length));
143 for (i = 0; i < msg_length; i++)
145 const struct pam_message *m = msg[i];
146 write_data (&m->msg_style, sizeof (m->msg_style));
147 write_string (m->msg);
151 read_data (&error, sizeof (error));
152 if (error != PAM_SUCCESS)
154 response = calloc (msg_length, sizeof (struct pam_response));
155 for (i = 0; i < msg_length; i++)
157 struct pam_response *r = &response[i];
158 // callers of this function inside pam will expect to be able to call
159 // free() on the strings we give back. So alloc with malloc.
160 r->resp = read_string_full (malloc);
161 read_data (&r->resp_retcode, sizeof (r->resp_retcode));
169 signal_cb (int signum)
171 /* Pass on signal to child, otherwise just quit */
173 kill (child_pid, signum);
181 gchar *x_authority_name;
182 guint16 x_authority_family;
183 guint8 *x_authority_address;
184 gsize x_authority_address_length;
185 gchar *x_authority_number;
186 guint8 *x_authority_data;
187 gsize x_authority_data_length;
189 x_authority_name = read_string ();
190 if (!x_authority_name)
193 read_data (&x_authority_family, sizeof (x_authority_family));
194 read_data (&x_authority_address_length, sizeof (x_authority_address_length));
195 x_authority_address = g_malloc (x_authority_address_length);
196 read_data (x_authority_address, x_authority_address_length);
197 x_authority_number = read_string ();
198 read_data (&x_authority_data_length, sizeof (x_authority_data_length));
199 x_authority_data = g_malloc (x_authority_data_length);
200 read_data (x_authority_data, x_authority_data_length);
202 return x_authority_new (x_authority_family, x_authority_address, x_authority_address_length, x_authority_number, x_authority_name, x_authority_data, x_authority_data_length);
205 /* GNU provides this but we can't rely on that so let's make our own version */
207 updwtmpx (const gchar *wtmp_file, struct utmpx *ut)
211 memset (&u, 0, sizeof (u));
212 u.ut_type = ut->ut_type;
213 u.ut_pid = ut->ut_pid;
215 strncpy (u.ut_line, ut->ut_line, sizeof (u.ut_line));
217 strncpy (u.ut_id, ut->ut_id, sizeof (u.ut_id));
219 strncpy (u.ut_user, ut->ut_user, sizeof (u.ut_user));
221 strncpy (u.ut_host, ut->ut_host, sizeof (u.ut_host));
222 u.ut_tv.tv_sec = ut->ut_tv.tv_sec;
223 u.ut_tv.tv_usec = ut->ut_tv.tv_usec;
225 updwtmp (wtmp_file, &u);
230 audit_event (int type, const gchar *username, uid_t uid, const gchar *remote_host_name, const gchar *tty, gboolean success)
233 const char *op = NULL;
235 auditfd = audit_open ();
237 g_printerr ("Error opening audit socket: %s\n", strerror (errno));
241 if (type == AUDIT_USER_LOGIN)
243 else if (type == AUDIT_USER_LOGOUT)
245 result = success == TRUE ? 1 : 0;
247 if (audit_log_acct_message (auditfd, type, NULL, op, username, uid, remote_host_name, NULL, tty, result) <= 0)
248 g_printerr ("Error writing audit message: %s\n", strerror (errno));
255 session_child_run (int argc, char **argv)
257 struct pam_conv conversation = { pam_conv_cb, NULL };
258 int i, version, fd, result;
259 gboolean auth_complete = TRUE;
262 LogMode log_mode = LOG_MODE_BACKUP_AND_TRUNCATE;
265 gchar **command_argv;
266 GVariantBuilder ck_parameters;
268 int authentication_result;
269 gchar *authentication_result_string;
273 gchar *remote_host_name;
275 XAuthority *x_authority = NULL;
276 gchar *x_authority_filename;
277 GDBusConnection *bus;
278 const gchar *login1_session_id = NULL;
279 gchar *console_kit_cookie = NULL;
280 const gchar *locale_value;
282 static const gchar * const locale_var_names[] = {
301 const gchar *home_directory;
302 GError *error = NULL;
304 #if !defined(GLIB_VERSION_2_36)
308 if (config_get_boolean (config_get_instance (), "LightDM", "lock-memory"))
310 /* Protect memory from being paged to disk, as we deal with passwords */
311 mlockall (MCL_CURRENT | MCL_FUTURE);
314 /* Make input non-blocking */
315 fd = open ("/dev/null", O_RDONLY);
316 dup2 (fd, STDIN_FILENO);
320 fd = open ("/dev/null", O_WRONLY);
321 dup2 (fd, STDOUT_FILENO);
324 /* Get the pipe from the daemon */
327 g_printerr ("Usage: lightdm --session-child INPUTFD OUTPUTFD\n");
330 from_daemon_output = atoi (argv[2]);
331 to_daemon_input = atoi (argv[3]);
332 if (from_daemon_output == 0 || to_daemon_input == 0)
334 g_printerr ("Invalid file descriptors %s %s\n", argv[2], argv[3]);
338 /* Don't let these pipes leak to the command we will run */
339 fcntl (from_daemon_output, F_SETFD, FD_CLOEXEC);
340 fcntl (to_daemon_input, F_SETFD, FD_CLOEXEC);
342 /* Read a version number so we can handle upgrades (i.e. a newer version of session child is run for an old daemon */
343 read_data (&version, sizeof (version));
345 service = read_string ();
346 username = read_string ();
347 read_data (&do_authenticate, sizeof (do_authenticate));
348 read_data (&is_interactive, sizeof (is_interactive));
349 read_string (); /* Used to be class, now we just use the environment variable */
350 tty = read_string ();
351 remote_host_name = read_string ();
352 xdisplay = read_string ();
353 x_authority = read_xauth ();
356 result = pam_start (service, username, &conversation, &pam_handle);
357 if (result != PAM_SUCCESS)
359 g_printerr ("Failed to start PAM: %s", pam_strerror (NULL, result));
365 pam_set_item (pam_handle, PAM_XDISPLAY, xdisplay);
367 pam_set_item (pam_handle, PAM_TTY, xdisplay);
370 pam_set_item (pam_handle, PAM_TTY, tty);
375 struct pam_xauth_data value;
377 value.name = (char *) x_authority_get_authorization_name (x_authority);
378 value.namelen = strlen (x_authority_get_authorization_name (x_authority));
379 value.data = (char *) x_authority_get_authorization_data (x_authority);
380 value.datalen = x_authority_get_authorization_data_length (x_authority);
381 pam_set_item (pam_handle, PAM_XAUTHDATA, &value);
388 const gchar *new_username;
390 authentication_result = pam_authenticate (pam_handle, 0);
392 /* See what user we ended up as */
393 if (pam_get_item (pam_handle, PAM_USER, (const void **) &new_username) != PAM_SUCCESS)
395 pam_end (pam_handle, 0);
399 username = g_strdup (new_username);
401 /* Write record to btmp database */
402 if (authentication_result == PAM_AUTH_ERR)
407 memset (&ut, 0, sizeof (ut));
408 ut.ut_type = USER_PROCESS;
409 ut.ut_pid = getpid ();
411 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
412 if (tty && g_str_has_prefix (tty, "/dev/"))
413 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
414 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
416 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
417 else if (remote_host_name)
418 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
419 gettimeofday (&tv, NULL);
420 ut.ut_tv.tv_sec = tv.tv_sec;
421 ut.ut_tv.tv_usec = tv.tv_usec;
423 updwtmpx ("/var/log/btmp", &ut);
426 audit_event (AUDIT_USER_LOGIN, username, -1, remote_host_name, tty, FALSE);
430 /* Check account is valid */
431 if (authentication_result == PAM_SUCCESS)
432 authentication_result = pam_acct_mgmt (pam_handle, 0);
433 if (authentication_result == PAM_NEW_AUTHTOK_REQD)
434 authentication_result = pam_chauthtok (pam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
437 authentication_result = PAM_SUCCESS;
438 authentication_complete = TRUE;
440 if (authentication_result == PAM_SUCCESS)
442 /* Fail authentication if user doesn't actually exist */
443 user = accounts_get_user_by_name (username);
446 g_printerr ("Failed to get information on user %s: %s\n", username, strerror (errno));
447 authentication_result = PAM_USER_UNKNOWN;
451 /* Set POSIX variables */
452 pam_putenv (pam_handle, "PATH=/usr/local/bin:/usr/bin:/bin");
453 pam_putenv (pam_handle, g_strdup_printf ("USER=%s", username));
454 pam_putenv (pam_handle, g_strdup_printf ("LOGNAME=%s", username));
455 pam_putenv (pam_handle, g_strdup_printf ("HOME=%s", user_get_home_directory (user)));
456 pam_putenv (pam_handle, g_strdup_printf ("SHELL=%s", user_get_shell (user)));
458 /* Let the greeter and user session inherit the system default locale */
459 for (i = 0; locale_var_names[i] != NULL; i++)
461 if ((locale_value = g_getenv (locale_var_names[i])) != NULL)
463 locale_var = g_strdup_printf ("%s=%s", locale_var_names[i], locale_value);
464 pam_putenv (pam_handle, locale_var);
471 authentication_result_string = g_strdup (pam_strerror (pam_handle, authentication_result));
473 /* Report authentication result */
474 write_string (username);
475 write_data (&auth_complete, sizeof (auth_complete));
476 write_data (&authentication_result, sizeof (authentication_result));
477 write_string (authentication_result_string);
479 /* Check we got a valid user */
482 g_printerr ("No user selected during authentication\n");
483 pam_end (pam_handle, 0);
487 /* Stop if we didn't authenticated */
488 if (authentication_result != PAM_SUCCESS)
490 pam_end (pam_handle, 0);
494 /* Get the command to run (blocks) */
495 log_filename = read_string ();
497 read_data (&log_mode, sizeof (log_mode));
501 tty = read_string ();
503 x_authority_filename = read_string ();
507 xdisplay = read_string ();
509 g_object_unref (x_authority);
510 x_authority = read_xauth ();
512 read_data (&env_length, sizeof (env_length));
513 for (i = 0; i < env_length; i++)
514 pam_putenv (pam_handle, read_string ());
515 read_data (&command_argc, sizeof (command_argc));
516 command_argv = g_malloc (sizeof (gchar *) * (command_argc + 1));
517 for (i = 0; i < command_argc; i++)
518 command_argv[i] = read_string ();
519 command_argv[i] = NULL;
521 /* If nothing to run just refresh credentials because we successfully authenticated */
522 if (command_argc == 0)
524 pam_setcred (pam_handle, PAM_REINITIALIZE_CRED);
525 pam_end (pam_handle, 0);
529 /* Redirect stderr to a log file */
532 if (g_path_is_absolute (log_filename))
534 fd = log_file_open (log_filename, log_mode);
535 dup2 (fd, STDERR_FILENO);
537 g_free (log_filename);
543 fd = open ("/dev/null", O_WRONLY);
544 dup2 (fd, STDERR_FILENO);
548 /* Set group membership - these can be overriden in pam_setcred */
551 if (initgroups (username, user_get_gid (user)) < 0)
553 g_printerr ("Failed to initialize supplementary groups for %s: %s\n", username, strerror (errno));
554 _exit (EXIT_FAILURE);
558 /* Set credentials */
559 result = pam_setcred (pam_handle, PAM_ESTABLISH_CRED);
560 if (result != PAM_SUCCESS)
562 g_printerr ("Failed to establish PAM credentials: %s\n", pam_strerror (pam_handle, result));
563 pam_end (pam_handle, 0);
567 /* Open the session */
568 result = pam_open_session (pam_handle, 0);
569 if (result != PAM_SUCCESS)
571 g_printerr ("Failed to open PAM session: %s\n", pam_strerror (pam_handle, result));
572 pam_end (pam_handle, 0);
576 /* Open a connection to the system bus for ConsoleKit - we must keep it open or CK will close the session */
577 bus = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, &error);
579 g_printerr ("Unable to contact system bus: %s", error->message);
582 pam_end (pam_handle, 0);
586 /* Check what logind session we are, or fallback to ConsoleKit */
587 login1_session_id = pam_getenv (pam_handle, "XDG_SESSION_ID");
588 if (login1_session_id)
590 write_string (login1_session_id);
596 g_variant_builder_init (&ck_parameters, G_VARIANT_TYPE ("(a(sv))"));
597 g_variant_builder_open (&ck_parameters, G_VARIANT_TYPE ("a(sv)"));
598 g_variant_builder_add (&ck_parameters, "(sv)", "unix-user", g_variant_new_int32 (user_get_uid (user)));
599 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") == 0)
600 g_variant_builder_add (&ck_parameters, "(sv)", "session-type", g_variant_new_string ("LoginWindow"));
603 g_variant_builder_add (&ck_parameters, "(sv)", "x11-display", g_variant_new_string (xdisplay));
605 g_variant_builder_add (&ck_parameters, "(sv)", "x11-display-device", g_variant_new_string (tty));
607 if (remote_host_name)
609 g_variant_builder_add (&ck_parameters, "(sv)", "is-local", g_variant_new_boolean (FALSE));
610 g_variant_builder_add (&ck_parameters, "(sv)", "remote-host-name", g_variant_new_string (remote_host_name));
613 g_variant_builder_add (&ck_parameters, "(sv)", "is-local", g_variant_new_boolean (TRUE));
614 console_kit_cookie = ck_open_session (&ck_parameters);
617 write_string (console_kit_cookie);
618 if (console_kit_cookie)
622 value = g_strdup_printf ("XDG_SESSION_COOKIE=%s", console_kit_cookie);
623 pam_putenv (pam_handle, value);
626 runtime_dir = ck_get_xdg_runtime_dir (console_kit_cookie);
630 value = g_strdup_printf ("XDG_RUNTIME_DIR=%s", runtime_dir);
631 pam_putenv (pam_handle, value);
633 g_free (runtime_dir);
638 /* Write X authority */
641 gboolean drop_privileges, result;
643 GError *error = NULL;
645 drop_privileges = geteuid () == 0;
647 privileges_drop (user_get_uid (user), user_get_gid (user));
648 result = x_authority_write (x_authority, XAUTH_WRITE_MODE_REPLACE, x_authority_filename, &error);
650 privileges_reclaim ();
653 g_printerr ("Error writing X authority: %s\n", error->message);
654 g_clear_error (&error);
657 pam_end (pam_handle, 0);
661 value = g_strdup_printf ("XAUTHORITY=%s", x_authority_filename);
662 pam_putenv (pam_handle, value);
666 /* Catch terminate signal and pass it to the child */
667 signal (SIGTERM, signal_cb);
669 /* Run the command as the authenticated user */
670 uid = user_get_uid (user);
671 gid = user_get_gid (user);
672 home_directory = user_get_home_directory (user);
676 /* Make this process its own session */
680 /* Change to this user */
683 if (setgid (gid) != 0)
686 if (setuid (uid) != 0)
690 /* Change working directory */
691 /* NOTE: This must be done after the permissions are changed because NFS filesystems can
692 * be setup so the local root user accesses the NFS files as 'nobody'. If the home directories
693 * are not system readable then the chdir can fail */
694 if (chdir (home_directory) != 0)
699 fd = log_file_open (log_filename, log_mode);
702 dup2 (fd, STDERR_FILENO);
707 /* Run the command */
708 execve (command_argv[0], command_argv, pam_getenvlist (pam_handle));
709 _exit (EXIT_FAILURE);
712 /* Bail out if failed to fork */
715 g_printerr ("Failed to fork session child process: %s\n", strerror (errno));
716 return_code = EXIT_FAILURE;
719 /* Wait for the command to complete (blocks) */
723 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") != 0)
728 memset (&ut, 0, sizeof (ut));
729 ut.ut_type = USER_PROCESS;
730 ut.ut_pid = child_pid;
732 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
733 if (tty && g_str_has_prefix (tty, "/dev/"))
734 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
735 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
737 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
738 else if (remote_host_name)
739 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
740 gettimeofday (&tv, NULL);
741 ut.ut_tv.tv_sec = tv.tv_sec;
742 ut.ut_tv.tv_usec = tv.tv_usec;
744 /* Write records to utmp/wtmp databases */
746 if (!pututxline (&ut))
747 g_printerr ("Failed to write utmpx: %s\n", strerror (errno));
749 updwtmpx ("/var/log/wtmp", &ut);
752 audit_event (AUDIT_USER_LOGIN, username, uid, remote_host_name, tty, TRUE);
756 waitpid (child_pid, &return_code, 0);
760 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") != 0)
765 memset (&ut, 0, sizeof (ut));
766 ut.ut_type = DEAD_PROCESS;
767 ut.ut_pid = child_pid;
769 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
770 if (tty && g_str_has_prefix (tty, "/dev/"))
771 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
772 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
774 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
775 else if (remote_host_name)
776 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
777 gettimeofday (&tv, NULL);
778 ut.ut_tv.tv_sec = tv.tv_sec;
779 ut.ut_tv.tv_usec = tv.tv_usec;
781 /* Write records to utmp/wtmp databases */
783 if (!pututxline (&ut))
784 g_printerr ("Failed to write utmpx: %s\n", strerror (errno));
786 updwtmpx ("/var/log/wtmp", &ut);
789 audit_event (AUDIT_USER_LOGOUT, username, uid, remote_host_name, tty, TRUE);
794 /* Remove X authority */
797 gboolean drop_privileges, result;
798 GError *error = NULL;
800 drop_privileges = geteuid () == 0;
802 privileges_drop (user_get_uid (user), user_get_gid (user));
803 result = x_authority_write (x_authority, XAUTH_WRITE_MODE_REMOVE, x_authority_filename, &error);
805 privileges_reclaim ();
808 g_printerr ("Error removing X authority: %s\n", error->message);
809 g_clear_error (&error);
811 _exit (EXIT_FAILURE);
814 /* Close the Console Kit session */
815 if (console_kit_cookie)
816 ck_close_session (console_kit_cookie);
818 /* Close the session */
819 pam_close_session (pam_handle, 0);
821 /* Remove credentials */
822 pam_setcred (pam_handle, PAM_DELETE_CRED);
824 pam_end (pam_handle, 0);
827 /* Return result of session process to the daemon */