In preparation for distinguishing the "capability" LSM from other LSMs,
it must be ordered first. This introduces LSM_ORDER_MUTABLE for the
general LSMs, LSM_ORDER_FIRST for capabilities, and LSM_ORDER_LAST for
anything that must run last (e.g. Landlock may use this in the future).
Signed-off-by: Kees Cook <keesc...@chromium.org>
Reviewed-by: Casey Schaufler <ca...@schaufler-ca.com>
---
include/linux/lsm_hooks.h | 7 +++++++
security/security.c | 18 ++++++++++++++++--
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 63a6caaee8e6..62bc230826e0 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2041,8 +2041,15 @@ extern void security_add_hooks(struct security_hook_list
*hooks, int count,
#define LSM_FLAG_LEGACY_MAJOR BIT(0)
+enum lsm_order {
+ LSM_ORDER_FIRST = -1, /* This is only for capabilities. */
+ LSM_ORDER_MUTABLE = 0,
+ LSM_ORDER_LAST,
+};
+
struct lsm_info {
const char *name; /* Required. */
+ enum lsm_order order; /* Optional: default is LSM_ORDER_MUTABLE */
unsigned long flags; /* Optional: flags describing LSM */
int *enabled; /* Optional: set based on CONFIG_LSM_ENABLE */
int (*init)(void); /* Required. */
diff --git a/security/security.c b/security/security.c
index 44c23d23158e..dac379518e60 100644
--- a/security/security.c
+++ b/security/security.c
@@ -140,7 +140,8 @@ static void __init parse_lsm_order(const char *order, const
char *origin)
bool found = false;
for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
- if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 &&
+ if (lsm->order == LSM_ORDER_MUTABLE &&
+ (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 &&
strcmp(lsm->name, name) == 0) {
append_ordered_lsm(lsm, origin);
found = true;
@@ -158,6 +159,12 @@ static void __init prepare_lsm_order(void)
{
struct lsm_info *lsm;
+ /* LSM_ORDER_FIRST is always first. */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (lsm->order == LSM_ORDER_FIRST)
+ append_ordered_lsm(lsm, "first");
+ }
+
/* Parse order from commandline, if present. */
parse_lsm_order(chosen_lsm_order, "cmdline");
@@ -166,9 +173,16 @@ static void __init prepare_lsm_order(void)
/* Add any missing LSMs, in link order. */
for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
- if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
+ if (lsm->order == LSM_ORDER_MUTABLE &&
+ (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
append_ordered_lsm(lsm, "link-time");
}
+
+ /* LSM_ORDER_LAST is always last. */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (lsm->order == LSM_ORDER_LAST)
+ append_ordered_lsm(lsm, "last");
+ }
}
/* Is an LSM allowed to be initialized? */
--
2.17.1
