src/core/selinux-setup.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>

#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#endif

#include "selinux-setup.h"
#include "selinux-util.h"
#include "label.h"
#include "mount-setup.h"
#include "macro.h"
#include "util.h"
#include "log.h"

#ifdef HAVE_SELINUX
static int null_log(int type, const char *fmt, ...) {
        return 0;
}
#endif

int selinux_setup(bool *loaded_policy) {

#ifdef HAVE_SELINUX
       int enforce = 0;
       usec_t before_load, after_load;
       security_context_t con;
       int r;
       union selinux_callback cb;

       assert(loaded_policy);

       /* Turn off all of SELinux' own logging, we want to do that */
       cb.func_log = null_log;
       selinux_set_callback(SELINUX_CB_LOG, cb);

       /* Don't load policy in the initrd if we don't appear to have
        * it.  For the real root, we check below if we've already
        * loaded policy, and return gracefully.
        */
       if (in_initrd() && access(selinux_path(), F_OK) < 0)
               return 0;

       /* Already initialized by somebody else? */
       r = getcon_raw(&con);
       if (r == 0) {
               bool initialized;

               initialized = !streq(con, "kernel");
               freecon(con);

               if (initialized)
                       return 0;
       }

       /* Make sure we have no fds open while loading the policy and
        * transitioning */
       log_close();

       /* Now load the policy */
       before_load = now(CLOCK_MONOTONIC);
       r = selinux_init_load_policy(&enforce);
       if (r == 0) {
               char timespan[FORMAT_TIMESPAN_MAX];
               char *label;

               retest_selinux();

               /* Transition to the new context */
               r = label_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
               if (r < 0 || label == NULL) {
                       log_open();
                       log_error("Failed to compute init label, ignoring.");
               } else {
                       r = setcon(label);

                       log_open();
                       if (r < 0)
                               log_error("Failed to transition into init label '%s', ignoring.", label);

                       label_free(label);
               }

               after_load = now(CLOCK_MONOTONIC);

               log_info("Successfully loaded SELinux policy in %s.",
                        format_timespan(timespan, sizeof(timespan), after_load - before_load, 0));

               *loaded_policy = true;

       } else {
               log_open();

               if (enforce > 0) {
                       log_error("Failed to load SELinux policy. Freezing.");
                       return -EIO;
               } else
                       log_debug("Unable to load SELinux policy. Ignoring.");
       }
#endif

       return 0;
}