src/sulogin-shell/sulogin-shell.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright © 2017 Felipe Sateler
   4 ***/
   5
   6 #include <errno.h>
   7 #include <sys/prctl.h>
   8
   9 #include "sd-bus.h"
  10
  11 #include "bus-util.h"
  12 #include "bus-error.h"
  13 #include "def.h"
  14 #include "env-util.h"
  15 #include "log.h"
  16 #include "process-util.h"
  17 #include "signal-util.h"
  18 #include "special.h"
  19
  20 static int reload_manager(sd_bus *bus) {
  21         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  22         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  23         int r;
  24
  25         log_info("Reloading system manager configuration");
  26
  27         r = sd_bus_message_new_method_call(
  28                         bus,
  29                         &m,
  30                         "org.freedesktop.systemd1",
  31                         "/org/freedesktop/systemd1",
  32                         "org.freedesktop.systemd1.Manager",
  33                         "Reload");
  34         if (r < 0)
  35                 return bus_log_create_error(r);
  36
  37         /* Note we use an extra-long timeout here. This is because a reload or reexec means generators are rerun which
  38          * are timed out after DEFAULT_TIMEOUT_USEC. Let's use twice that time here, so that the generators can have
  39          * their timeout, and for everything else there's the same time budget in place. */
  40
  41         r = sd_bus_call(bus, m, DEFAULT_TIMEOUT_USEC * 2, &error, NULL);
  42         if (r < 0)
  43                 return log_error_errno(r, "Failed to reload daemon: %s", bus_error_message(&error, r));
  44
  45         return 0;
  46 }
  47
  48 static int start_default_target(sd_bus *bus) {
  49         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
  50         int r;
  51
  52         log_info("Starting default target");
  53
  54         /* Start these units only if we can replace base.target with it */
  55         r = sd_bus_call_method(bus,
  56                                "org.freedesktop.systemd1",
  57                                "/org/freedesktop/systemd1",
  58                                "org.freedesktop.systemd1.Manager",
  59                                "StartUnit",
  60                                &error,
  61                                NULL,
  62                                "ss", SPECIAL_DEFAULT_TARGET, "isolate");
  63
  64         if (r < 0)
  65                 return log_error_errno(r, "Failed to start default target: %s", bus_error_message(&error, r));
  66
  67         return 0;
  68 }
  69
  70 static int fork_wait(const char* const cmdline[]) {
  71         pid_t pid;
  72         int r;
  73
  74         r = safe_fork("(sulogin)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
  75         if (r < 0)
  76                 return r;
  77         if (r == 0) {
  78                 /* Child */
  79                 execv(cmdline[0], (char**) cmdline);
  80                 log_error_errno(errno, "Failed to execute %s: %m", cmdline[0]);
  81                 _exit(EXIT_FAILURE); /* Operational error */
  82         }
  83
  84         return wait_for_terminate_and_check(cmdline[0], pid, WAIT_LOG_ABNORMAL);
  85 }
  86
  87 static void print_mode(const char* mode) {
  88         printf("You are in %s mode. After logging in, type \"journalctl -xb\" to view\n"
  89                 "system logs, \"systemctl reboot\" to reboot, \"systemctl default\" or \"exit\"\n"
  90                 "to boot into default mode.\n", mode);
  91         fflush(stdout);
  92 }
  93
  94 int main(int argc, char *argv[]) {
  95         const char* sulogin_cmdline[] = {
  96                 SULOGIN,
  97                 NULL,             /* --force */
  98                 NULL
  99         };
 100         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
 101         int r;
 102
 103         log_setup_service();
 104
 105         print_mode(argc > 1 ? argv[1] : "");
 106
 107         if (getenv_bool("SYSTEMD_SULOGIN_FORCE") > 0)
 108                 /* allows passwordless logins if root account is locked. */
 109                 sulogin_cmdline[1] = "--force";
 110
 111         (void) fork_wait(sulogin_cmdline);
 112
 113         r = bus_connect_system_systemd(&bus);
 114         if (r < 0) {
 115                 log_warning_errno(r, "Failed to get D-Bus connection: %m");
 116                 r = 0;
 117         } else {
 118                 (void) reload_manager(bus);
 119
 120                 r = start_default_target(bus);
 121         }
 122
 123         return r >= 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 124 }