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>

security/tomoyo/Kconfig

@@ -9,3 +9,64 @@ config SECURITY_TOMOYO
 	  Required userspace tools and further information may be
 	  found at <http://tomoyo.sourceforge.jp/>.
 	  If you are unsure how to answer this question, answer N.
+
+config SECURITY_TOMOYO_MAX_ACCEPT_ENTRY
+	int "Default maximal count for learning mode"
+	default 2048
+	range 0 2147483647
+	depends on SECURITY_TOMOYO
+	help
+	  This is the default value for maximal ACL entries
+	  that are automatically appended into policy at "learning mode".
+	  Some programs access thousands of objects, so running
+	  such programs in "learning mode" dulls the system response
+	  and consumes much memory.
+	  This is the safeguard for such programs.
+
+config SECURITY_TOMOYO_MAX_AUDIT_LOG
+	int "Default maximal count for audit log"
+	default 1024
+	range 0 2147483647
+	depends on SECURITY_TOMOYO
+	help
+	  This is the default value for maximal entries for
+	  audit logs that the kernel can hold on memory.
+	  You can read the log via /sys/kernel/security/tomoyo/audit.
+	  If you don't need audit logs, you may set this value to 0.
+
+config SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
+	bool "Activate without calling userspace policy loader."
+	default n
+	depends on SECURITY_TOMOYO
+	---help---
+	  Say Y here if you want to activate access control as soon as built-in
+	  policy was loaded. This option 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.
+
+config SECURITY_TOMOYO_POLICY_LOADER
+	string "Location of userspace policy loader"
+	default "/sbin/tomoyo-init"
+	depends on SECURITY_TOMOYO
+	depends on !SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
+	---help---
+	  This is the default pathname of policy loader which is called before
+	  activation. You can override this setting via TOMOYO_loader= kernel
+	  command line option.
+
+config SECURITY_TOMOYO_ACTIVATION_TRIGGER
+	string "Trigger for calling userspace policy loader"
+	default "/sbin/init"
+	depends on SECURITY_TOMOYO
+	depends on !SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
+	---help---
+	  This is the default pathname of activation trigger.
+	  You can override this setting via TOMOYO_trigger= kernel command line
+	  option. For example, if you pass init=/bin/systemd option, you may
+	  want to also pass TOMOYO_trigger=/bin/systemd option.

security/tomoyo/common.c

@@ -2420,4 +2420,7 @@ void __init tomoyo_load_builtin_policy(void)
 		}
 	}
 	tomoyo_read_unlock(idx);
+#ifdef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
+	tomoyo_check_profile();
+#endif
 }

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