Return-Path: linux-nfs-owner@vger.kernel.org Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:57008 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271Ab2LGVaA (ORCPT ); Fri, 7 Dec 2012 16:30:00 -0500 Date: Fri, 7 Dec 2012 21:35:20 +0000 From: Alan Cox To: Pavel Shilovsky Cc: Christoph Hellwig , , , , , Subject: Re: [PATCH 0/3] Add O_DENY* flags to fcntl and cifs Message-ID: <20121207213520.05dd5a3b@pyramind.ukuu.org.uk> In-Reply-To: <495d17310e0a687d446afc86def0f058@office.etersoft.ru> References: <1354818391-7968-1-git-send-email-piastry@etersoft.ru> <20121207161602.GA17710@infradead.org> <495d17310e0a687d446afc86def0f058@office.etersoft.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: > The problem is the possibility of denial-of-service attacks here. We > can try to prevent them by: > 1) specifying an extra security bit on the file that indicates that > share flags are accepted (like we have for mandatory locks now) and > setting it for neccessary files only, or > 2) adding a special mount option (but it it probably makes sense if we > decided to add this support for CIFS and NFS only). 3) making it a property that the process opts into - the same fs can have Linux and wine users at once. But for such a big set of changes and with the kind of potential fallout you need to demonstrate a good practical use case IMHO, not just a "neat idea I had". Alan