src/resolve/resolved.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2014 Tom Gundersen <teg@jklm.no>
   6 ***/
   7
   8 #include "sd-daemon.h"
   9 #include "sd-event.h"
  10
  11 #include "capability-util.h"
  12 #include "mkdir.h"
  13 #include "resolved-conf.h"
  14 #include "resolved-manager.h"
  15 #include "resolved-resolv-conf.h"
  16 #include "selinux-util.h"
  17 #include "signal-util.h"
  18 #include "user-util.h"
  19
  20 int main(int argc, char *argv[]) {
  21         _cleanup_(manager_freep) Manager *m = NULL;
  22         const char *user = "systemd-resolve";
  23         uid_t uid;
  24         gid_t gid;
  25         int r;
  26
  27         log_set_target(LOG_TARGET_AUTO);
  28         log_parse_environment();
  29         log_open();
  30
  31         if (argc != 1) {
  32                 log_error("This program takes no arguments.");
  33                 r = -EINVAL;
  34                 goto finish;
  35         }
  36
  37         umask(0022);
  38
  39         r = mac_selinux_init();
  40         if (r < 0) {
  41                 log_error_errno(r, "SELinux setup failed: %m");
  42                 goto finish;
  43         }
  44
  45         r = get_user_creds(&user, &uid, &gid, NULL, NULL);
  46         if (r < 0) {
  47                 log_error_errno(r, "Cannot resolve user name %s: %m", user);
  48                 goto finish;
  49         }
  50
  51         /* Always create the directory where resolv.conf will live */
  52         r = mkdir_safe_label("/run/systemd/resolve", 0755, uid, gid, MKDIR_WARN_MODE);
  53         if (r < 0) {
  54                 log_error_errno(r, "Could not create runtime directory: %m");
  55                 goto finish;
  56         }
  57
  58         /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all
  59          * privileges are already dropped. */
  60         if (getuid() == 0) {
  61
  62                 /* Drop privileges, but keep three caps. Note that we drop those too, later on (see below) */
  63                 r = drop_privileges(uid, gid,
  64                                     (UINT64_C(1) << CAP_NET_RAW)|          /* needed for SO_BINDTODEVICE */
  65                                     (UINT64_C(1) << CAP_NET_BIND_SERVICE)| /* needed to bind on port 53 */
  66                                     (UINT64_C(1) << CAP_SETPCAP)           /* needed in order to drop the caps later */);
  67                 if (r < 0)
  68                         goto finish;
  69         }
  70
  71         assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
  72
  73         r = manager_new(&m);
  74         if (r < 0) {
  75                 log_error_errno(r, "Could not create manager: %m");
  76                 goto finish;
  77         }
  78
  79         r = manager_start(m);
  80         if (r < 0) {
  81                 log_error_errno(r, "Failed to start manager: %m");
  82                 goto finish;
  83         }
  84
  85         /* Write finish default resolv.conf to avoid a dangling symlink */
  86         (void) manager_write_resolv_conf(m);
  87
  88         /* Let's drop the remaining caps now */
  89         r = capability_bounding_set_drop(0, true);
  90         if (r < 0) {
  91                 log_error_errno(r, "Failed to drop remaining caps: %m");
  92                 goto finish;
  93         }
  94
  95         sd_notify(false,
  96                   "READY=1\n"
  97                   "STATUS=Processing requests...");
  98
  99         r = sd_event_loop(m->event);
 100         if (r < 0) {
 101                 log_error_errno(r, "Event loop failed: %m");
 102                 goto finish;
 103         }
 104
 105         sd_event_get_exit_code(m->event, &r);
 106
 107 finish:
 108         sd_notify(false,
 109                   "STOPPING=1\n"
 110                   "STATUS=Shutting down...");
 111
 112         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 113 }