IMA relies on the blocking LSM policy notifier callback to update the
LSM based IMA policy rules.
When SELinux update its policies, IMA would be notified and starts
updating all its lsm rules one-by-one. During this time, -ESTALE would
be returned by ima_filter_rule_match() if it is called with a LSM rule
that has not yet been updated. In ima_match_rules(), -ESTALE is not
handled, and the LSM rule is considered a match, causing extra files
to be measured by IMA.
Fix it by actively updating current rule if -ESTALE is returned by
ima_filter_rule_match().
Fixes: b16942455193 ("ima: use the lsm policy update notifier")
Signed-off-by: GUO Zihua <guozihua@xxxxxxxxxx>
---
v3:
Update current rule instead of just retrying, as suggested by Mimi
v2:
Fixes message errors pointed out by Mimi
---
security/integrity/ima/ima_policy.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index a8802b8da946..62a5b6164923 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -616,6 +616,8 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
else
return false;
}
+
+retry:
switch (i) {
case LSM_OBJ_USER:
case LSM_OBJ_ROLE:
@@ -635,6 +637,12 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
default:
break;
}
+
+ if (rc == -ESTALE) {
+ rc = ima_lsm_update_rule(rule);
+ if (!rc)
+ goto retry;
+ }
if (!rc)
return false;
}
--
2.17.1
