src/resolve/resolved.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "sd-daemon.h"
   4 #include "sd-event.h"
   5
   6 #include "capability-util.h"
   7 #include "mkdir.h"
   8 #include "resolved-conf.h"
   9 #include "resolved-manager.h"
  10 #include "resolved-resolv-conf.h"
  11 #include "selinux-util.h"
  12 #include "signal-util.h"
  13 #include "user-util.h"
  14
  15 int main(int argc, char *argv[]) {
  16         _cleanup_(manager_freep) Manager *m = NULL;
  17         const char *user = "systemd-resolve";
  18         uid_t uid;
  19         gid_t gid;
  20         int r;
  21
  22         log_set_target(LOG_TARGET_AUTO);
  23         log_parse_environment();
  24         log_open();
  25
  26         if (argc != 1) {
  27                 log_error("This program takes no arguments.");
  28                 r = -EINVAL;
  29                 goto finish;
  30         }
  31
  32         umask(0022);
  33
  34         r = mac_selinux_init();
  35         if (r < 0) {
  36                 log_error_errno(r, "SELinux setup failed: %m");
  37                 goto finish;
  38         }
  39
  40         r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0);
  41         if (r < 0) {
  42                 log_error_errno(r, "Cannot resolve user name %s: %m", user);
  43                 goto finish;
  44         }
  45
  46         /* Always create the directory where resolv.conf will live */
  47         r = mkdir_safe_label("/run/systemd/resolve", 0755, uid, gid, MKDIR_WARN_MODE);
  48         if (r < 0) {
  49                 log_error_errno(r, "Could not create runtime directory: %m");
  50                 goto finish;
  51         }
  52
  53         /* Drop privileges, but only if we have been started as root. If we are not running as root we assume most
  54          * privileges are already dropped. */
  55         if (getuid() == 0) {
  56
  57                 /* Drop privileges, but keep three caps. Note that we drop those too, later on (see below) */
  58                 r = drop_privileges(uid, gid,
  59                                     (UINT64_C(1) << CAP_NET_RAW)|          /* needed for SO_BINDTODEVICE */
  60                                     (UINT64_C(1) << CAP_NET_BIND_SERVICE)| /* needed to bind on port 53 */
  61                                     (UINT64_C(1) << CAP_SETPCAP)           /* needed in order to drop the caps later */);
  62                 if (r < 0)
  63                         goto finish;
  64         }
  65
  66         assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
  67
  68         r = manager_new(&m);
  69         if (r < 0) {
  70                 log_error_errno(r, "Could not create manager: %m");
  71                 goto finish;
  72         }
  73
  74         r = manager_start(m);
  75         if (r < 0) {
  76                 log_error_errno(r, "Failed to start manager: %m");
  77                 goto finish;
  78         }
  79
  80         /* Write finish default resolv.conf to avoid a dangling symlink */
  81         (void) manager_write_resolv_conf(m);
  82
  83         (void) manager_check_resolv_conf(m);
  84
  85         /* Let's drop the remaining caps now */
  86         r = capability_bounding_set_drop(0, true);
  87         if (r < 0) {
  88                 log_error_errno(r, "Failed to drop remaining caps: %m");
  89                 goto finish;
  90         }
  91
  92         sd_notify(false,
  93                   "READY=1\n"
  94                   "STATUS=Processing requests...");
  95
  96         r = sd_event_loop(m->event);
  97         if (r < 0) {
  98                 log_error_errno(r, "Event loop failed: %m");
  99                 goto finish;
 100         }
 101
 102         sd_event_get_exit_code(m->event, &r);
 103
 104 finish:
 105         sd_notify(false,
 106                   "STOPPING=1\n"
 107                   "STATUS=Shutting down...");
 108
 109         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 110 }