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