SELinux: move common_audit_data to a noinline slow path function

selinux_inode_has_perm is a hot path.  Instead of declaring the
common_audit_data on the stack move it to a noinline function only used in
the rare case we need to send an audit message.
Signed-off-by: NEric Paris <eparis@redhat.com>

security/selinux/hooks.c

@@ -2658,11 +2658,29 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct nameidata *na
 	return dentry_has_perm(cred, dentry, FILE__READ);
 }
 
-static int selinux_inode_permission(struct inode *inode, int mask)
+static noinline int audit_inode_permission(struct inode *inode,
+					   u32 perms, u32 audited, u32 denied,
+					   unsigned flags)
 {
-	const struct cred *cred = current_cred();
 	struct common_audit_data ad;
 	struct selinux_audit_data sad = {0,};
+	struct inode_security_struct *isec = inode->i_security;
+	int rc;
+
+	COMMON_AUDIT_DATA_INIT(&ad, INODE);
+	ad.selinux_audit_data = &sad;
+	ad.u.inode = inode;
+
+	rc = slow_avc_audit(current_sid(), isec->sid, isec->sclass, perms,
+			    audited, denied, &ad, flags);
+	if (rc)
+		return rc;
+	return 0;
+}
+
+static int selinux_inode_permission(struct inode *inode, int mask)
+{
+	const struct cred *cred = current_cred();
 	u32 perms;
 	bool from_access;
 	unsigned flags = mask & MAY_NOT_BLOCK;
@@ -2696,15 +2714,7 @@ static int selinux_inode_permission(struct inode *inode, int mask)
 	if (likely(!audited))
 		return rc;
 
-	COMMON_AUDIT_DATA_INIT(&ad, INODE);
-	ad.selinux_audit_data = &sad;
-	ad.u.inode = inode;
-
-	if (from_access)
-		ad.selinux_audit_data->auditdeny |= FILE__AUDIT_ACCESS;
-
-	rc2 = slow_avc_audit(sid, isec->sid, isec->sclass, perms,
-			     audited, denied, &ad, flags);
+	rc2 = audit_inode_permission(inode, perms, audited, denied, flags);
 	if (rc2)
 		return rc2;
 	return rc;