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