LSM: Introduce LSM_FLAG_LEGACY_MAJOR

This adds a flag for the current "major" LSMs to distinguish them when
we have a universal method for ordering all LSMs. It's called "legacy"
since the distinction of "major" will go away in the blob-sharing world.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>

include/linux/lsm_hooks.h

@@ -2042,8 +2042,11 @@ extern char *lsm_names;
 extern void security_add_hooks(struct security_hook_list *hooks, int count,
 				char *lsm);
 
+#define LSM_FLAG_LEGACY_MAJOR	BIT(0)
+
 struct lsm_info {
 	const char *name;	/* Required. */
+	unsigned long flags;	/* Optional: flags describing LSM */
 	int (*init)(void);	/* Required. */
 };
 

security/apparmor/lsm.c

@@ -1729,5 +1729,6 @@ static int __init apparmor_init(void)
 
 DEFINE_LSM(apparmor) = {
 	.name = "apparmor",
+	.flags = LSM_FLAG_LEGACY_MAJOR,
 	.init = apparmor_init,
 };

security/selinux/hooks.c

@@ -6999,6 +6999,7 @@ void selinux_complete_init(void)
    all processes and objects when they are created. */
 DEFINE_LSM(selinux) = {
 	.name = "selinux",
+	.flags = LSM_FLAG_LEGACY_MAJOR,
 	.init = selinux_init,
 };
 

security/smack/smack_lsm.c

@@ -4812,5 +4812,6 @@ static __init int smack_init(void)
  */
 DEFINE_LSM(smack) = {
 	.name = "smack",
+	.flags = LSM_FLAG_LEGACY_MAJOR,
 	.init = smack_init,
 };

security/tomoyo/tomoyo.c

@@ -552,5 +552,6 @@ static int __init tomoyo_init(void)
 
 DEFINE_LSM(tomoyo) = {
 	.name = "tomoyo",
+	.flags = LSM_FLAG_LEGACY_MAJOR,
 	.init = tomoyo_init,
 };