src/core/ima-setup.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5   Copyright (C) 2012 Roberto Sassu - Politecnico di Torino, Italy
   6                                      TORSEC group — http://security.polito.it
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <unistd.h>
  24
  25 #include "fd-util.h"
  26 #include "fileio.h"
  27 #include "ima-setup.h"
  28 #include "log.h"
  29 #include "util.h"
  30
  31 #define IMA_SECFS_DIR "/sys/kernel/security/ima"
  32 #define IMA_SECFS_POLICY IMA_SECFS_DIR "/policy"
  33 #define IMA_POLICY_PATH "/etc/ima/ima-policy"
  34
  35 int ima_setup(void) {
  36 #if HAVE_IMA
  37         _cleanup_fclose_ FILE *input = NULL;
  38         _cleanup_close_ int imafd = -1;
  39         unsigned lineno = 0;
  40         char line[page_size()];
  41
  42         if (access(IMA_SECFS_DIR, F_OK) < 0) {
  43                 log_debug("IMA support is disabled in the kernel, ignoring.");
  44                 return 0;
  45         }
  46
  47         if (access(IMA_SECFS_POLICY, W_OK) < 0) {
  48                 log_warning("Another IMA custom policy has already been loaded, ignoring.");
  49                 return 0;
  50         }
  51
  52         if (access(IMA_POLICY_PATH, F_OK) < 0) {
  53                 log_debug("No IMA custom policy file "IMA_POLICY_PATH", ignoring.");
  54                 return 0;
  55         }
  56
  57         imafd = open(IMA_SECFS_POLICY, O_WRONLY|O_CLOEXEC);
  58         if (imafd < 0) {
  59                 log_error_errno(errno, "Failed to open the IMA kernel interface "IMA_SECFS_POLICY", ignoring: %m");
  60                 return 0;
  61         }
  62
  63         /* attempt to write the name of the policy file into sysfs file */
  64         if (write(imafd, IMA_POLICY_PATH, strlen(IMA_POLICY_PATH)) > 0)
  65                 goto done;
  66
  67         /* fall back to copying the policy line-by-line */
  68         input = fopen(IMA_POLICY_PATH, "re");
  69         if (!input) {
  70                 log_warning_errno(errno, "Failed to open the IMA custom policy file "IMA_POLICY_PATH", ignoring: %m");
  71                 return 0;
  72         }
  73
  74         close(imafd);
  75
  76         imafd = open(IMA_SECFS_POLICY, O_WRONLY|O_CLOEXEC);
  77         if (imafd < 0) {
  78                 log_error_errno(errno, "Failed to open the IMA kernel interface "IMA_SECFS_POLICY", ignoring: %m");
  79                 return 0;
  80         }
  81
  82         FOREACH_LINE(line, input,
  83                      return log_error_errno(errno, "Failed to read the IMA custom policy file "IMA_POLICY_PATH": %m")) {
  84                 size_t len;
  85
  86                 len = strlen(line);
  87                 lineno++;
  88
  89                 if (len > 0 && write(imafd, line, len) < 0)
  90                         return log_error_errno(errno, "Failed to load the IMA custom policy file "IMA_POLICY_PATH"%u: %m",
  91                                                lineno);
  92         }
  93
  94 done:
  95         log_info("Successfully loaded the IMA custom policy "IMA_POLICY_PATH".");
  96 #endif /* HAVE_IMA */
  97         return 0;
  98 }