src/core/selinux-setup.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <stdio.h>
   5 #include <unistd.h>
   6
   7 #if HAVE_SELINUX
   8 #include <selinux/selinux.h>
   9 #endif
  10
  11 #include "sd-messages.h"
  12
  13 #include "initrd-util.h"
  14 #include "log.h"
  15 #include "macro.h"
  16 #include "selinux-setup.h"
  17 #include "selinux-util.h"
  18 #include "string-util.h"
  19 #include "time-util.h"
  20
  21 #if HAVE_SELINUX
  22 _printf_(2,3)
  23 static int null_log(int type, const char *fmt, ...) {
  24         return 0;
  25 }
  26 #endif
  27
  28 int mac_selinux_setup(bool *loaded_policy) {
  29
  30 #if HAVE_SELINUX
  31         int enforce = 0;
  32         usec_t before_load, after_load;
  33         char *con;
  34         int r;
  35         bool initialized;
  36
  37         assert(loaded_policy);
  38
  39         /* Turn off all of SELinux' own logging, we want to do that */
  40         selinux_set_callback(SELINUX_CB_LOG, (const union selinux_callback) { .func_log = null_log });
  41
  42         /* Don't load policy in the initrd if we don't appear to have it.  For the real root, we check below
  43          * if we've already loaded policy, and return gracefully. */
  44         if (in_initrd() && access(selinux_path(), F_OK) < 0)
  45                 return 0;
  46
  47         /* Already initialized by somebody else? */
  48         r = getcon_raw(&con);
  49         /* getcon_raw can return 0, and still give us a NULL pointer if /proc/self/attr/current is
  50          * empty. SELinux guarantees this won't happen, but that file isn't specific to SELinux, and may be
  51          * provided by some other arbitrary LSM with different semantics. */
  52         if (r == 0 && con) {
  53                 initialized = !streq(con, "kernel");
  54                 freecon(con);
  55         } else
  56                 initialized = false;
  57
  58         /* Make sure we have no fds open while loading the policy and
  59          * transitioning */
  60         log_close();
  61
  62         /* Now load the policy */
  63         before_load = now(CLOCK_MONOTONIC);
  64         r = selinux_init_load_policy(&enforce);
  65         if (r == 0) {
  66                 _cleanup_(mac_selinux_freep) char *label = NULL;
  67
  68                 mac_selinux_retest();
  69
  70                 /* Transition to the new context */
  71                 r = mac_selinux_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
  72                 if (r < 0 || !label) {
  73                         log_open();
  74                         log_error("Failed to compute init label, ignoring.");
  75                 } else {
  76                         r = setcon_raw(label);
  77
  78                         log_open();
  79                         if (r < 0)
  80                                 log_error("Failed to transition into init label '%s', ignoring.", label);
  81                 }
  82
  83                 after_load = now(CLOCK_MONOTONIC);
  84
  85                 log_info("Successfully loaded SELinux policy in %s.",
  86                          FORMAT_TIMESPAN(after_load - before_load, 0));
  87
  88                 *loaded_policy = true;
  89
  90         } else {
  91                 log_open();
  92
  93                 if (enforce > 0) {
  94                         if (!initialized)
  95                                 return log_struct_errno(LOG_EMERG, SYNTHETIC_ERRNO(EIO),
  96                                                         LOG_MESSAGE("Failed to load SELinux policy :%m"),
  97                                                         "MESSAGE_ID=" SD_MESSAGE_SELINUX_FAILED_STR);
  98
  99                         log_warning("Failed to load new SELinux policy. Continuing with old policy.");
 100                 } else
 101                         log_debug("Unable to load SELinux policy. Ignoring.");
 102         }
 103 #endif
 104
 105         return 0;
 106 }