src/resolve/resolved.c

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