LSM: shrink sizeof LSM specific portion of common_audit_data

Linus found that the gigantic size of the common audit data caused a big
perf hit on something as simple as running stat() in a loop.  This patch
requires LSMs to declare the LSM specific portion separately rather than
doing it in a union.  Thus each LSM can be responsible for shrinking their
portion and don't have to pay a penalty just because other LSMs have a
bigger space requirement.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index cc7cb6edba0..2af7fcc98a7 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -275,9 +275,9 @@ static inline void smack_str_from_perm(char *string, int access)
 static void smack_log_callback(struct audit_buffer *ab, void *a)
 {
         struct common_audit_data *ad = a;
-        struct smack_audit_data *sad = &ad->smack_audit_data;
+        struct smack_audit_data *sad = ad->smack_audit_data;
         audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
-                         ad->smack_audit_data.function,
+                         ad->smack_audit_data->function,
                          sad->result ? "denied" : "granted");
         audit_log_format(ab, " subject=");
         audit_log_untrustedstring(ab, sad->subject);
@@ -310,11 +310,12 @@ void smack_log(char *subject_label, char *object_label, int request,
         if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
                 return;
 
-        if (a->smack_audit_data.function == NULL)
-                a->smack_audit_data.function = "unknown";
+        sad = a->smack_audit_data;
+
+        if (sad->function == NULL)
+                sad->function = "unknown";
 
         /* end preparing the audit data */
-        sad = &a->smack_audit_data;
         smack_str_from_perm(request_buffer, request);
         sad->subject = subject_label;
         sad->object  = object_label;