For what are marked as the Legacy Major LSMs, make them effectively
exclusive when selected on the "security=" boot parameter, to handle
the future case of when a previously major LSMs become non-exclusive
(e.g. when TOMOYO starts blob-sharing).
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
---
security/security.c | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/security/security.c b/security/security.c
index f4a7b7d52d71..a7889885585e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -129,14 +129,6 @@ static bool __init lsm_allowed(struct lsm_info *lsm)
if (!is_enabled(lsm))
return false;
- /* Skip major-specific checks if not a major LSM. */
- if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
- return true;
-
- /* Disabled if this LSM isn't the chosen one. */
- if (strcmp(lsm->name, chosen_major_lsm) != 0)
- return false;
-
return true;
}
@@ -164,8 +156,28 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
struct lsm_info *lsm;
char *sep, *name, *next;
+ /* Process "security=", if given. */
if (!chosen_major_lsm)
chosen_major_lsm = CONFIG_DEFAULT_SECURITY;
+ if (chosen_major_lsm) {
+ struct lsm_info *major;
+
+ /*
+ * To match the original "security=" behavior, this
+ * explicitly does NOT fallback to another Legacy Major
+ * if the selected one was separately disabled: disable
+ * all non-matching Legacy Major LSMs.
+ */
+ for (major = __start_lsm_info; major < __end_lsm_info;
+ major++) {
+ if ((major->flags & LSM_FLAG_LEGACY_MAJOR) &&
+ strcmp(major->name, chosen_major_lsm) != 0) {
+ set_enabled(major, false);
+ init_debug("security=%s disabled: %s\n",
+ chosen_major_lsm, major->name);
+ }
+ }
+ }
sep = kstrdup(order, GFP_KERNEL);
next = sep;
--
2.14.5
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