src/core/selinux-setup.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24
  25 #if HAVE_SELINUX
  26 #include <selinux/selinux.h>
  27 #endif
  28
  29 #include "log.h"
  30 #include "macro.h"
  31 #include "selinux-setup.h"
  32 #include "selinux-util.h"
  33 #include "string-util.h"
  34 #include "util.h"
  35
  36 #if HAVE_SELINUX
  37 _printf_(2,3)
  38 static int null_log(int type, const char *fmt, ...) {
  39         return 0;
  40 }
  41 #endif
  42
  43 int mac_selinux_setup(bool *loaded_policy) {
  44
  45 #if HAVE_SELINUX
  46         int enforce = 0;
  47         usec_t before_load, after_load;
  48         char *con;
  49         int r;
  50         static const union selinux_callback cb = {
  51                 .func_log = null_log,
  52         };
  53
  54         bool initialized = false;
  55
  56         assert(loaded_policy);
  57
  58         /* Turn off all of SELinux' own logging, we want to do that */
  59         selinux_set_callback(SELINUX_CB_LOG, cb);
  60
  61         /* Don't load policy in the initrd if we don't appear to have
  62          * it.  For the real root, we check below if we've already
  63          * loaded policy, and return gracefully.
  64          */
  65         if (in_initrd() && access(selinux_path(), F_OK) < 0)
  66                 return 0;
  67
  68         /* Already initialized by somebody else? */
  69         r = getcon_raw(&con);
  70         if (r == 0) {
  71                 initialized = !streq(con, "kernel");
  72                 freecon(con);
  73         }
  74
  75         /* Make sure we have no fds open while loading the policy and
  76          * transitioning */
  77         log_close();
  78
  79         /* Now load the policy */
  80         before_load = now(CLOCK_MONOTONIC);
  81         r = selinux_init_load_policy(&enforce);
  82         if (r == 0) {
  83                 _cleanup_(mac_selinux_freep) char *label = NULL;
  84                 char timespan[FORMAT_TIMESPAN_MAX];
  85
  86                 mac_selinux_retest();
  87
  88                 /* Transition to the new context */
  89                 r = mac_selinux_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
  90                 if (r < 0 || !label) {
  91                         log_open();
  92                         log_error("Failed to compute init label, ignoring.");
  93                 } else {
  94                         r = setcon_raw(label);
  95
  96                         log_open();
  97                         if (r < 0)
  98                                 log_error("Failed to transition into init label '%s', ignoring.", label);
  99                 }
 100
 101                 after_load = now(CLOCK_MONOTONIC);
 102
 103                 log_info("Successfully loaded SELinux policy in %s.",
 104                          format_timespan(timespan, sizeof(timespan), after_load - before_load, 0));
 105
 106                 *loaded_policy = true;
 107
 108         } else {
 109                 log_open();
 110
 111                 if (enforce > 0) {
 112                         if (!initialized) {
 113                                 log_emergency("Failed to load SELinux policy.");
 114                                 return -EIO;
 115                         }
 116
 117                         log_warning("Failed to load new SELinux policy. Continuing with old policy.");
 118                 } else
 119                         log_debug("Unable to load SELinux policy. Ignoring.");
 120         }
 121 #endif
 122
 123         return 0;
 124 }