TOMOYO: Make several options configurable.

To be able to start using enforcing mode from the early stage of boot sequence,
this patch adds support for activating access control without calling external
policy loader program. This will be useful for systems where operations which
can lead to the hijacking of the boot sequence are needed before loading the
policy. For example, you can activate immediately after loading the fixed part
of policy which will allow only operations needed for mounting a partition
which contains the variant part of policy and verifying (e.g. running GPG
check) and loading the variant part of policy. Since you can start using
enforcing mode from the beginning, you can reduce the possibility of hijacking
the boot sequence.

This patch makes several variables configurable on build time. This patch also
adds TOMOYO_loader= and TOMOYO_trigger= kernel command line option to boot the
same kernel in two different init systems (BSD-style init and systemd).

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 53 insertions, 23 deletions

diff --git a/security/tomoyo/load_policy.c b/security/tomoyo/load_policy.c
index 3312e5624f2..6a5463d2663 100644
--- a/security/tomoyo/load_policy.c
+++ b/security/tomoyo/load_policy.c
@@ -8,8 +8,27 @@
 
 #include "common.h"
 
-/* path to policy loader */
-static const char *tomoyo_loader = "/sbin/tomoyo-init";
+#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
+
+/*
+ * Path to the policy loader. (default = CONFIG_SECURITY_TOMOYO_POLICY_LOADER)
+ */
+static const char *tomoyo_loader;
+
+/**
+ * tomoyo_loader_setup - Set policy loader.
+ *
+ * @str: Program to use as a policy loader (e.g. /sbin/tomoyo-init ).
+ *
+ * Returns 0.
+ */
+static int __init tomoyo_loader_setup(char *str)
+{
+	tomoyo_loader = str;
+	return 0;
+}
+
+__setup("TOMOYO_loader=", tomoyo_loader_setup);
 
 /**
  * tomoyo_policy_loader_exists - Check whether /sbin/tomoyo-init exists.
@@ -18,24 +37,38 @@ static const char *tomoyo_loader = "/sbin/tomoyo-init";
  */
 static bool tomoyo_policy_loader_exists(void)
 {
-	/*
-	 * Don't activate MAC if the policy loader doesn't exist.
-	 * If the initrd includes /sbin/init but real-root-dev has not
-	 * mounted on / yet, activating MAC will block the system since
-	 * policies are not loaded yet.
-	 * Thus, let do_execve() call this function every time.
-	 */
 	struct path path;
-
+	if (!tomoyo_loader)
+		tomoyo_loader = CONFIG_SECURITY_TOMOYO_POLICY_LOADER;
 	if (kern_path(tomoyo_loader, LOOKUP_FOLLOW, &path)) {
-		printk(KERN_INFO "Not activating Mandatory Access Control now "
-		       "since %s doesn't exist.\n", tomoyo_loader);
+		printk(KERN_INFO "Not activating Mandatory Access Control "
+		       "as %s does not exist.\n", tomoyo_loader);
 		return false;
 	}
 	path_put(&path);
 	return true;
 }
 
+/*
+ * Path to the trigger. (default = CONFIG_SECURITY_TOMOYO_ACTIVATION_TRIGGER)
+ */
+static const char *tomoyo_trigger;
+
+/**
+ * tomoyo_trigger_setup - Set trigger for activation.
+ *
+ * @str: Program to use as an activation trigger (e.g. /sbin/init ).
+ *
+ * Returns 0.
+ */
+static int __init tomoyo_trigger_setup(char *str)
+{
+	tomoyo_trigger = str;
+	return 0;
+}
+
+__setup("TOMOYO_trigger=", tomoyo_trigger_setup);
+
 /**
  * tomoyo_load_policy - Run external policy loader to load policy.
  *
@@ -51,24 +84,19 @@ static bool tomoyo_policy_loader_exists(void)
  */
 void tomoyo_load_policy(const char *filename)
 {
+	static bool done;
 	char *argv[2];
 	char *envp[3];
 
-	if (tomoyo_policy_loaded)
+	if (tomoyo_policy_loaded || done)
 		return;
-	/*
-	 * Check filename is /sbin/init or /sbin/tomoyo-start.
-	 * /sbin/tomoyo-start is a dummy filename in case where /sbin/init can't
-	 * be passed.
-	 * You can create /sbin/tomoyo-start by
-	 * "ln -s /bin/true /sbin/tomoyo-start".
-	 */
-	if (strcmp(filename, "/sbin/init") &&
-	    strcmp(filename, "/sbin/tomoyo-start"))
+	if (!tomoyo_trigger)
+		tomoyo_trigger = CONFIG_SECURITY_TOMOYO_ACTIVATION_TRIGGER;
+	if (strcmp(filename, tomoyo_trigger))
 		return;
 	if (!tomoyo_policy_loader_exists())
 		return;
-
+	done = true;
 	printk(KERN_INFO "Calling %s to load policy. Please wait.\n",
 	       tomoyo_loader);
 	argv[0] = (char *) tomoyo_loader;
@@ -79,3 +107,5 @@ void tomoyo_load_policy(const char *filename)
 	call_usermodehelper(argv[0], argv, envp, 1);
 	tomoyo_check_profile();
 }
+
+#endif