security/tomoyo/load_policy.c

   1 /*
   2  * security/tomoyo/load_policy.c
   3  *
   4  * Policy loader launcher for TOMOYO.
   5  *
   6  * Copyright (C) 2005-2010  NTT DATA CORPORATION
   7  */
   8
   9 #include "common.h"
  10
  11 /* path to policy loader */
  12 static const char *tomoyo_loader = "/sbin/tomoyo-init";
  13
  14 /**
  15  * tomoyo_policy_loader_exists - Check whether /sbin/tomoyo-init exists.
  16  *
  17  * Returns true if /sbin/tomoyo-init exists, false otherwise.
  18  */
  19 static bool tomoyo_policy_loader_exists(void)
  20 {
  21         /*
  22          * Don't activate MAC if the policy loader doesn't exist.
  23          * If the initrd includes /sbin/init but real-root-dev has not
  24          * mounted on / yet, activating MAC will block the system since
  25          * policies are not loaded yet.
  26          * Thus, let do_execve() call this function everytime.
  27          */
  28         struct path path;
  29
  30         if (kern_path(tomoyo_loader, LOOKUP_FOLLOW, &path)) {
  31                 printk(KERN_INFO "Not activating Mandatory Access Control now "
  32                        "since %s doesn't exist.\n", tomoyo_loader);
  33                 return false;
  34         }
  35         path_put(&path);
  36         return true;
  37 }
  38
  39 /**
  40  * tomoyo_load_policy - Run external policy loader to load policy.
  41  *
  42  * @filename: The program about to start.
  43  *
  44  * This function checks whether @filename is /sbin/init , and if so
  45  * invoke /sbin/tomoyo-init and wait for the termination of /sbin/tomoyo-init
  46  * and then continues invocation of /sbin/init.
  47  * /sbin/tomoyo-init reads policy files in /etc/tomoyo/ directory and
  48  * writes to /sys/kernel/security/tomoyo/ interfaces.
  49  *
  50  * Returns nothing.
  51  */
  52 void tomoyo_load_policy(const char *filename)
  53 {
  54         char *argv[2];
  55         char *envp[3];
  56
  57         if (tomoyo_policy_loaded)
  58                 return;
  59         /*
  60          * Check filename is /sbin/init or /sbin/tomoyo-start.
  61          * /sbin/tomoyo-start is a dummy filename in case where /sbin/init can't
  62          * be passed.
  63          * You can create /sbin/tomoyo-start by
  64          * "ln -s /bin/true /sbin/tomoyo-start".
  65          */
  66         if (strcmp(filename, "/sbin/init") &&
  67             strcmp(filename, "/sbin/tomoyo-start"))
  68                 return;
  69         if (!tomoyo_policy_loader_exists())
  70                 return;
  71
  72         printk(KERN_INFO "Calling %s to load policy. Please wait.\n",
  73                tomoyo_loader);
  74         argv[0] = (char *) tomoyo_loader;
  75         argv[1] = NULL;
  76         envp[0] = "HOME=/";
  77         envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
  78         envp[2] = NULL;
  79         call_usermodehelper(argv[0], argv, envp, 1);
  80         tomoyo_check_profile();
  81 }