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[] = {
295 const gchar *home_directory;
296 GError *error = NULL;
298 #if !defined(GLIB_VERSION_2_36)
302 if (config_get_boolean (config_get_instance (), "LightDM", "lock-memory"))
304 /* Protect memory from being paged to disk, as we deal with passwords */
305 mlockall (MCL_CURRENT | MCL_FUTURE);
308 /* Make input non-blocking */
309 fd = open ("/dev/null", O_RDONLY);
310 dup2 (fd, STDIN_FILENO);
314 fd = open ("/dev/null", O_WRONLY);
315 dup2 (fd, STDOUT_FILENO);
318 /* Get the pipe from the daemon */
321 g_printerr ("Usage: lightdm --session-child INPUTFD OUTPUTFD\n");
324 from_daemon_output = atoi (argv[2]);
325 to_daemon_input = atoi (argv[3]);
326 if (from_daemon_output == 0 || to_daemon_input == 0)
328 g_printerr ("Invalid file descriptors %s %s\n", argv[2], argv[3]);
332 /* Don't let these pipes leak to the command we will run */
333 fcntl (from_daemon_output, F_SETFD, FD_CLOEXEC);
334 fcntl (to_daemon_input, F_SETFD, FD_CLOEXEC);
336 /* Read a version number so we can handle upgrades (i.e. a newer version of session child is run for an old daemon */
337 read_data (&version, sizeof (version));
339 service = read_string ();
340 username = read_string ();
341 read_data (&do_authenticate, sizeof (do_authenticate));
342 read_data (&is_interactive, sizeof (is_interactive));
343 read_string (); /* Used to be class, now we just use the environment variable */
344 tty = read_string ();
345 remote_host_name = read_string ();
346 xdisplay = read_string ();
347 x_authority = read_xauth ();
350 result = pam_start (service, username, &conversation, &pam_handle);
351 if (result != PAM_SUCCESS)
353 g_printerr ("Failed to start PAM: %s", pam_strerror (NULL, result));
359 pam_set_item (pam_handle, PAM_XDISPLAY, xdisplay);
361 pam_set_item (pam_handle, PAM_TTY, xdisplay);
364 pam_set_item (pam_handle, PAM_TTY, tty);
369 struct pam_xauth_data value;
371 value.name = (char *) x_authority_get_authorization_name (x_authority);
372 value.namelen = strlen (x_authority_get_authorization_name (x_authority));
373 value.data = (char *) x_authority_get_authorization_data (x_authority);
374 value.datalen = x_authority_get_authorization_data_length (x_authority);
375 pam_set_item (pam_handle, PAM_XAUTHDATA, &value);
382 const gchar *new_username;
384 authentication_result = pam_authenticate (pam_handle, 0);
386 /* See what user we ended up as */
387 if (pam_get_item (pam_handle, PAM_USER, (const void **) &new_username) != PAM_SUCCESS)
389 pam_end (pam_handle, 0);
393 username = g_strdup (new_username);
395 /* Write record to btmp database */
396 if (authentication_result == PAM_AUTH_ERR)
401 memset (&ut, 0, sizeof (ut));
402 ut.ut_type = USER_PROCESS;
403 ut.ut_pid = getpid ();
406 strncpy (ut.ut_line, xdisplay, sizeof (ut.ut_line));
407 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
410 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
411 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
413 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
414 else if (remote_host_name)
415 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
416 gettimeofday (&tv, NULL);
417 ut.ut_tv.tv_sec = tv.tv_sec;
418 ut.ut_tv.tv_usec = tv.tv_usec;
420 updwtmpx ("/var/log/btmp", &ut);
423 audit_event (AUDIT_USER_LOGIN, username, -1, remote_host_name, tty, FALSE);
427 /* Check account is valid */
428 if (authentication_result == PAM_SUCCESS)
429 authentication_result = pam_acct_mgmt (pam_handle, 0);
430 if (authentication_result == PAM_NEW_AUTHTOK_REQD)
431 authentication_result = pam_chauthtok (pam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
434 authentication_result = PAM_SUCCESS;
435 authentication_complete = TRUE;
437 if (authentication_result == PAM_SUCCESS)
439 /* Fail authentication if user doesn't actually exist */
440 user = accounts_get_user_by_name (username);
443 g_printerr ("Failed to get information on user %s: %s\n", username, strerror (errno));
444 authentication_result = PAM_USER_UNKNOWN;
448 /* Set POSIX variables */
449 pam_putenv (pam_handle, "PATH=/usr/local/bin:/usr/bin:/bin");
450 pam_putenv (pam_handle, g_strdup_printf ("USER=%s", username));
451 pam_putenv (pam_handle, g_strdup_printf ("LOGNAME=%s", username));
452 pam_putenv (pam_handle, g_strdup_printf ("HOME=%s", user_get_home_directory (user)));
453 pam_putenv (pam_handle, g_strdup_printf ("SHELL=%s", user_get_shell (user)));
455 /* Let the greeter and user session inherit the system default locale */
456 for (i = 0; locale_var_names[i] != NULL; i++)
458 if ((locale_value = g_getenv (locale_var_names[i])) != NULL)
460 locale_var = g_strdup_printf ("%s=%s", locale_var_names[i], locale_value);
461 pam_putenv (pam_handle, locale_var);
468 authentication_result_string = g_strdup (pam_strerror (pam_handle, authentication_result));
470 /* Report authentication result */
471 write_string (username);
472 write_data (&auth_complete, sizeof (auth_complete));
473 write_data (&authentication_result, sizeof (authentication_result));
474 write_string (authentication_result_string);
476 /* Check we got a valid user */
479 g_printerr ("No user selected during authentication\n");
480 pam_end (pam_handle, 0);
484 /* Stop if we didn't authenticated */
485 if (authentication_result != PAM_SUCCESS)
487 pam_end (pam_handle, 0);
491 /* Get the command to run (blocks) */
492 log_filename = read_string ();
494 read_data (&log_mode, sizeof (log_mode));
498 tty = read_string ();
500 x_authority_filename = read_string ();
504 xdisplay = read_string ();
506 g_object_unref (x_authority);
507 x_authority = read_xauth ();
509 read_data (&env_length, sizeof (env_length));
510 for (i = 0; i < env_length; i++)
511 pam_putenv (pam_handle, read_string ());
512 read_data (&command_argc, sizeof (command_argc));
513 command_argv = g_malloc (sizeof (gchar *) * (command_argc + 1));
514 for (i = 0; i < command_argc; i++)
515 command_argv[i] = read_string ();
516 command_argv[i] = NULL;
518 /* If nothing to run just refresh credentials because we successfully authenticated */
519 if (command_argc == 0)
521 pam_setcred (pam_handle, PAM_REINITIALIZE_CRED);
522 pam_end (pam_handle, 0);
526 /* Redirect stderr to a log file */
529 if (g_path_is_absolute (log_filename))
531 fd = log_file_open (log_filename, log_mode);
532 dup2 (fd, STDERR_FILENO);
534 g_free (log_filename);
540 fd = open ("/dev/null", O_WRONLY);
541 dup2 (fd, STDERR_FILENO);
545 /* Set group membership - these can be overriden in pam_setcred */
548 if (initgroups (username, user_get_gid (user)) < 0)
550 g_printerr ("Failed to initialize supplementary groups for %s: %s\n", username, strerror (errno));
551 _exit (EXIT_FAILURE);
555 /* Set credentials */
556 result = pam_setcred (pam_handle, PAM_ESTABLISH_CRED);
557 if (result != PAM_SUCCESS)
559 g_printerr ("Failed to establish PAM credentials: %s\n", pam_strerror (pam_handle, result));
560 pam_end (pam_handle, 0);
564 /* Open the session */
565 result = pam_open_session (pam_handle, 0);
566 if (result != PAM_SUCCESS)
568 g_printerr ("Failed to open PAM session: %s\n", pam_strerror (pam_handle, result));
569 pam_end (pam_handle, 0);
573 /* Open a connection to the system bus for ConsoleKit - we must keep it open or CK will close the session */
574 bus = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, &error);
576 g_printerr ("Unable to contact system bus: %s", error->message);
579 pam_end (pam_handle, 0);
583 /* Check what logind session we are, or fallback to ConsoleKit */
584 login1_session_id = pam_getenv (pam_handle, "XDG_SESSION_ID");
585 if (login1_session_id)
587 write_string (login1_session_id);
593 g_variant_builder_init (&ck_parameters, G_VARIANT_TYPE ("(a(sv))"));
594 g_variant_builder_open (&ck_parameters, G_VARIANT_TYPE ("a(sv)"));
595 g_variant_builder_add (&ck_parameters, "(sv)", "unix-user", g_variant_new_int32 (user_get_uid (user)));
596 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") == 0)
597 g_variant_builder_add (&ck_parameters, "(sv)", "session-type", g_variant_new_string ("LoginWindow"));
600 g_variant_builder_add (&ck_parameters, "(sv)", "x11-display", g_variant_new_string (xdisplay));
602 g_variant_builder_add (&ck_parameters, "(sv)", "x11-display-device", g_variant_new_string (tty));
604 if (remote_host_name)
606 g_variant_builder_add (&ck_parameters, "(sv)", "is-local", g_variant_new_boolean (FALSE));
607 g_variant_builder_add (&ck_parameters, "(sv)", "remote-host-name", g_variant_new_string (remote_host_name));
610 g_variant_builder_add (&ck_parameters, "(sv)", "is-local", g_variant_new_boolean (TRUE));
611 console_kit_cookie = ck_open_session (&ck_parameters);
614 write_string (console_kit_cookie);
615 if (console_kit_cookie)
618 value = g_strdup_printf ("XDG_SESSION_COOKIE=%s", console_kit_cookie);
619 pam_putenv (pam_handle, value);
624 /* Write X authority */
627 gboolean drop_privileges, result;
629 GError *error = NULL;
631 drop_privileges = geteuid () == 0;
633 privileges_drop (user_get_uid (user), user_get_gid (user));
634 result = x_authority_write (x_authority, XAUTH_WRITE_MODE_REPLACE, x_authority_filename, &error);
636 privileges_reclaim ();
639 g_printerr ("Error writing X authority: %s\n", error->message);
640 g_clear_error (&error);
643 pam_end (pam_handle, 0);
647 value = g_strdup_printf ("XAUTHORITY=%s", x_authority_filename);
648 pam_putenv (pam_handle, value);
652 /* Catch terminate signal and pass it to the child */
653 signal (SIGTERM, signal_cb);
655 /* Run the command as the authenticated user */
656 uid = user_get_uid (user);
657 gid = user_get_gid (user);
658 home_directory = user_get_home_directory (user);
662 /* Make this process its own session */
666 /* Change to this user */
669 if (setgid (gid) != 0)
672 if (setuid (uid) != 0)
676 /* Change working directory */
677 /* NOTE: This must be done after the permissions are changed because NFS filesystems can
678 * be setup so the local root user accesses the NFS files as 'nobody'. If the home directories
679 * are not system readable then the chdir can fail */
680 if (chdir (home_directory) != 0)
685 fd = log_file_open (log_filename, log_mode);
688 dup2 (fd, STDERR_FILENO);
693 /* Run the command */
694 execve (command_argv[0], command_argv, pam_getenvlist (pam_handle));
695 _exit (EXIT_FAILURE);
698 /* Bail out if failed to fork */
701 g_printerr ("Failed to fork session child process: %s\n", strerror (errno));
702 return_code = EXIT_FAILURE;
705 /* Wait for the command to complete (blocks) */
709 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") != 0)
714 memset (&ut, 0, sizeof (ut));
715 ut.ut_type = USER_PROCESS;
716 ut.ut_pid = child_pid;
719 strncpy (ut.ut_line, xdisplay, sizeof (ut.ut_line));
720 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
723 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
724 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
726 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
727 else if (remote_host_name)
728 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
729 gettimeofday (&tv, NULL);
730 ut.ut_tv.tv_sec = tv.tv_sec;
731 ut.ut_tv.tv_usec = tv.tv_usec;
733 /* Write records to utmp/wtmp databases */
735 if (!pututxline (&ut))
736 g_printerr ("Failed to write utmpx: %s\n", strerror (errno));
738 updwtmpx ("/var/log/wtmp", &ut);
741 audit_event (AUDIT_USER_LOGIN, username, uid, remote_host_name, tty, TRUE);
745 waitpid (child_pid, &return_code, 0);
749 if (g_strcmp0 (pam_getenv (pam_handle, "XDG_SESSION_CLASS"), "greeter") != 0)
754 memset (&ut, 0, sizeof (ut));
755 ut.ut_type = DEAD_PROCESS;
756 ut.ut_pid = child_pid;
759 strncpy (ut.ut_line, xdisplay, sizeof (ut.ut_line));
760 strncpy (ut.ut_id, xdisplay, sizeof (ut.ut_id));
763 strncpy (ut.ut_line, tty + strlen ("/dev/"), sizeof (ut.ut_line));
764 strncpy (ut.ut_user, username, sizeof (ut.ut_user));
766 strncpy (ut.ut_host, xdisplay, sizeof (ut.ut_host));
767 else if (remote_host_name)
768 strncpy (ut.ut_host, remote_host_name, sizeof (ut.ut_host));
769 gettimeofday (&tv, NULL);
770 ut.ut_tv.tv_sec = tv.tv_sec;
771 ut.ut_tv.tv_usec = tv.tv_usec;
773 /* Write records to utmp/wtmp databases */
775 if (!pututxline (&ut))
776 g_printerr ("Failed to write utmpx: %s\n", strerror (errno));
778 updwtmpx ("/var/log/wtmp", &ut);
781 audit_event (AUDIT_USER_LOGOUT, username, uid, remote_host_name, tty, TRUE);
786 /* Remove X authority */
789 gboolean drop_privileges, result;
790 GError *error = NULL;
792 drop_privileges = geteuid () == 0;
794 privileges_drop (user_get_uid (user), user_get_gid (user));
795 result = x_authority_write (x_authority, XAUTH_WRITE_MODE_REMOVE, x_authority_filename, &error);
797 privileges_reclaim ();
800 g_printerr ("Error removing X authority: %s\n", error->message);
801 g_clear_error (&error);
803 _exit (EXIT_FAILURE);
806 /* Close the Console Kit session */
807 if (console_kit_cookie)
808 ck_close_session (console_kit_cookie);
810 /* Close the session */
811 pam_close_session (pam_handle, 0);
813 /* Remove credentials */
814 pam_setcred (pam_handle, PAM_DELETE_CRED);
816 pam_end (pam_handle, 0);
819 /* Return result of session process to the daemon */