src/core/ima-setup.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7   Copyright (C) 2012 Roberto Sassu - Politecnico di Torino, Italy
   8                                      TORSEC group -- http://security.polito.it
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 ***/
  23
  24 #include <unistd.h>
  25 #include <stdio.h>
  26 #include <errno.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <fcntl.h>
  30 #include <sys/stat.h>
  31 #include <sys/mman.h>
  32
  33 #include "ima-setup.h"
  34 #include "mount-setup.h"
  35 #include "macro.h"
  36 #include "util.h"
  37 #include "log.h"
  38 #include "label.h"
  39
  40 #define IMA_SECFS_DIR "/sys/kernel/security/ima"
  41 #define IMA_SECFS_POLICY IMA_SECFS_DIR "/policy"
  42 #define IMA_POLICY_PATH "/etc/ima/ima-policy"
  43
  44 int ima_setup(void) {
  45
  46 #ifdef HAVE_IMA
  47        struct stat st;
  48        ssize_t policy_size = 0, written = 0;
  49        char *policy;
  50        int policyfd = -1, imafd = -1;
  51        int result = 0;
  52
  53        if (stat(IMA_POLICY_PATH, &st) < 0)
  54                return 0;
  55
  56        policy_size = st.st_size;
  57        if (stat(IMA_SECFS_DIR, &st) < 0) {
  58                log_debug("IMA support is disabled in the kernel, ignoring.");
  59                return 0;
  60        }
  61
  62        if (stat(IMA_SECFS_POLICY, &st) < 0) {
  63                log_error("Another IMA custom policy has already been loaded, "
  64                          "ignoring.");
  65                return 0;
  66        }
  67
  68        policyfd = open(IMA_POLICY_PATH, O_RDONLY|O_CLOEXEC);
  69        if (policyfd < 0) {
  70                log_error("Failed to open the IMA custom policy file %s (%m), "
  71                          "ignoring.", IMA_POLICY_PATH);
  72                return 0;
  73        }
  74
  75        imafd = open(IMA_SECFS_POLICY, O_WRONLY|O_CLOEXEC);
  76        if (imafd < 0) {
  77                log_error("Failed to open the IMA kernel interface %s (%m), "
  78                          "ignoring.", IMA_SECFS_POLICY);
  79                goto out;
  80        }
  81
  82        policy = mmap(NULL, policy_size, PROT_READ, MAP_PRIVATE, policyfd, 0);
  83        if (policy == MAP_FAILED) {
  84                log_error("mmap() failed (%m), freezing");
  85                result = -errno;
  86                goto out;
  87        }
  88
  89        written = loop_write(imafd, policy, (size_t)policy_size, false);
  90        if (written != policy_size) {
  91                log_error("Failed to load the IMA custom policy file %s (%m), "
  92                          "ignoring.", IMA_POLICY_PATH);
  93                goto out_mmap;
  94        }
  95
  96        log_info("Successfully loaded the IMA custom policy %s.",
  97                 IMA_POLICY_PATH);
  98 out_mmap:
  99        munmap(policy, policy_size);
 100 out:
 101        if (policyfd >= 0)
 102                 close_nointr_nofail(policyfd);
 103        if (imafd >= 0)
 104                 close_nointr_nofail(imafd);
 105        if (result)
 106                 return result;
 107 #endif /* HAVE_IMA */
 108
 109        return 0;
 110 }