LSM: Split LSM preparation from initialization

Since we already have to do a pass through the LSMs to figure out if
exclusive LSMs should be disabled after the first one is seen as enabled,
this splits the logic up a bit more cleanly. Now we do a full "prepare"
pass through the LSMs (which also allows for later use by the blob-sharing
code), before starting the LSM initialization pass.

Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 15 insertions, 6 deletions

diff --git a/security/security.c b/security/security.c
index 2d08a5357bf4..46c5b0fa515e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -139,22 +139,28 @@ static bool __init lsm_allowed(struct lsm_info *lsm)
         return true;
 }
 
-/* Check if LSM should be initialized. */
-static void __init maybe_initialize_lsm(struct lsm_info *lsm)
+/* Prepare LSM for initialization. */
+static void __init prepare_lsm(struct lsm_info *lsm)
 {
         int enabled = lsm_allowed(lsm);
 
         /* Record enablement (to handle any following exclusive LSMs). */
         set_enabled(lsm, enabled);
 
-        /* If selected, initialize the LSM. */
+        /* If enabled, do pre-initialization work. */
         if (enabled) {
-                int ret;
-
                 if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
                         exclusive = lsm;
                         init_debug("exclusive chosen: %s\n", lsm->name);
                 }
+        }
+}
+
+/* Initialize a given LSM, if it is enabled. */
+static void __init initialize_lsm(struct lsm_info *lsm)
+{
+        if (is_enabled(lsm)) {
+                int ret;
 
                 init_debug("initializing %s\n", lsm->name);
                 ret = lsm->init();
@@ -240,7 +246,10 @@ static void __init ordered_lsm_init(void)
                 ordered_lsm_parse(builtin_lsm_order, "builtin");
 
         for (lsm = ordered_lsms; *lsm; lsm++)
-                maybe_initialize_lsm(*lsm);
+                prepare_lsm(*lsm);
+
+        for (lsm = ordered_lsms; *lsm; lsm++)
+                initialize_lsm(*lsm);
 
         kfree(ordered_lsms);
 }