LSM: Separate idea of "major" LSM from "exclusive" LSM
In order to both support old "security=" Legacy Major LSM selection, and
handling real exclusivity, this creates LSM_FLAG_EXCLUSIVE and updates
the selection logic to handle them.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
diff --git a/security/security.c b/security/security.c
index 88de6b0..a8dd7de 100644
--- a/security/security.c
+++ b/security/security.c
@@ -49,6 +49,7 @@
/* Ordered list of LSMs to initialize. */
static __initdata struct lsm_info **ordered_lsms;
+static __initdata struct lsm_info *exclusive;
static __initdata bool debug;
#define init_debug(...) \
@@ -129,6 +130,12 @@
if (!is_enabled(lsm))
return false;
+ /* Not allowed if another exclusive LSM already initialized. */
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && exclusive) {
+ init_debug("exclusive disabled: %s\n", lsm->name);
+ return false;
+ }
+
return true;
}
@@ -144,6 +151,11 @@
if (enabled) {
int ret;
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
+ exclusive = lsm;
+ init_debug("exclusive chosen: %s\n", lsm->name);
+ }
+
init_debug("initializing %s\n", lsm->name);
ret = lsm->init();
WARN(ret, "%s failed to initialize: %d\n", lsm->name, ret);