src/resolve/resolved.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Tom Gundersen <teg@jklm.no>
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include "sd-daemon.h"
  21 #include "sd-event.h"
  22
  23 #include "capability-util.h"
  24 #include "mkdir.h"
  25 #include "resolved-conf.h"
  26 #include "resolved-manager.h"
  27 #include "resolved-resolv-conf.h"
  28 #include "selinux-util.h"
  29 #include "signal-util.h"
  30 #include "user-util.h"
  31
  32 int main(int argc, char *argv[]) {
  33         _cleanup_(manager_freep) Manager *m = NULL;
  34         const char *user = "systemd-resolve";
  35         uid_t uid;
  36         gid_t gid;
  37         int r;
  38
  39         log_set_target(LOG_TARGET_AUTO);
  40         log_parse_environment();
  41         log_open();
  42
  43         if (argc != 1) {
  44                 log_error("This program takes no arguments.");
  45                 r = -EINVAL;
  46                 goto finish;
  47         }
  48
  49         umask(0022);
  50
  51         r = mac_selinux_init();
  52         if (r < 0) {
  53                 log_error_errno(r, "SELinux setup failed: %m");
  54                 goto finish;
  55         }
  56
  57         r = get_user_creds(&user, &uid, &gid, NULL, NULL);
  58         if (r < 0) {
  59                 log_error_errno(r, "Cannot resolve user name %s: %m", user);
  60                 goto finish;
  61         }
  62
  63         /* Always create the directory where resolv.conf will live */
  64         r = mkdir_safe_label("/run/systemd/resolve", 0755, uid, gid);
  65         if (r < 0) {
  66                 log_error_errno(r, "Could not create runtime directory: %m");
  67                 goto finish;
  68         }
  69
  70         /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all
  71          * privileges are already dropped. */
  72         if (getuid() == 0) {
  73
  74                 /* Drop privileges, but keep three caps. Note that we drop those too, later on (see below) */
  75                 r = drop_privileges(uid, gid,
  76                                     (UINT64_C(1) << CAP_NET_RAW)|          /* needed for SO_BINDTODEVICE */
  77                                     (UINT64_C(1) << CAP_NET_BIND_SERVICE)| /* needed to bind on port 53 */
  78                                     (UINT64_C(1) << CAP_SETPCAP)           /* needed in order to drop the caps later */);
  79                 if (r < 0)
  80                         goto finish;
  81         }
  82
  83         assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
  84
  85         r = manager_new(&m);
  86         if (r < 0) {
  87                 log_error_errno(r, "Could not create manager: %m");
  88                 goto finish;
  89         }
  90
  91         r = manager_start(m);
  92         if (r < 0) {
  93                 log_error_errno(r, "Failed to start manager: %m");
  94                 goto finish;
  95         }
  96
  97         /* Write finish default resolv.conf to avoid a dangling symlink */
  98         (void) manager_write_resolv_conf(m);
  99
 100         /* Let's drop the remaining caps now */
 101         r = capability_bounding_set_drop(0, true);
 102         if (r < 0) {
 103                 log_error_errno(r, "Failed to drop remaining caps: %m");
 104                 goto finish;
 105         }
 106
 107         sd_notify(false,
 108                   "READY=1\n"
 109                   "STATUS=Processing requests...");
 110
 111         r = sd_event_loop(m->event);
 112         if (r < 0) {
 113                 log_error_errno(r, "Event loop failed: %m");
 114                 goto finish;
 115         }
 116
 117         sd_event_get_exit_code(m->event, &r);
 118
 119 finish:
 120         /* systemd-nspawn checks for private resolv.conf to decide whether
 121            or not to mount it into the container. So just delete it. */
 122         (void) unlink(PRIVATE_RESOLV_CONF);
 123
 124         sd_notify(false,
 125                   "STOPPING=1\n"
 126                   "STATUS=Shutting down...");
 127
 128         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 129 }