[PATCH security-next v5 26/30] LSM: Split LSM preparation from initialization

From: Kees Cook
Date: Wed Oct 10 2018 - 20:26:43 EST


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@xxxxxxxxxxxx>
---
security/security.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/security/security.c b/security/security.c
index 4f52bd06705f..b40c4c212892 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();
@@ -230,7 +236,10 @@ 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);
}
--
2.17.1