audit: audit feature to set loginuid immutable
This adds a new 'audit_feature' bit which allows userspace to set it
such that the loginuid is absolutely immutable, even if you have
CAP_AUDIT_CONTROL.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 05e5e8f..e2f0d99 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -387,7 +387,8 @@
};
#define AUDIT_FEATURE_ONLY_UNSET_LOGINUID 0
-#define AUDIT_LAST_FEATURE AUDIT_FEATURE_ONLY_UNSET_LOGINUID
+#define AUDIT_FEATURE_LOGINUID_IMMUTABLE 1
+#define AUDIT_LAST_FEATURE AUDIT_FEATURE_LOGINUID_IMMUTABLE
#define audit_feature_valid(x) ((x) >= 0 && (x) <= AUDIT_LAST_FEATURE)
#define AUDIT_FEATURE_TO_MASK(x) (1 << ((x) & 31)) /* mask for __u32 */
diff --git a/kernel/audit.c b/kernel/audit.c
index fbfa3a7..f3f36f5 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -144,8 +144,9 @@
.features = 0,
.lock = 0,};
-static char *audit_feature_names[1] = {
+static char *audit_feature_names[2] = {
"only_unset_loginuid",
+ "loginuid_immutable",
};
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 924c0bf..63223d6 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1971,6 +1971,9 @@
/* if we are unset, we don't need privs */
if (!audit_loginuid_set(current))
return 0;
+ /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
+ if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
+ return -EPERM;
/* it is set, you need permission */
if (!capable(CAP_AUDIT_CONTROL))
return -EPERM;