Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757563AbXLTU4V (ORCPT ); Thu, 20 Dec 2007 15:56:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752830AbXLTU4K (ORCPT ); Thu, 20 Dec 2007 15:56:10 -0500 Received: from moutng.kundenserver.de ([212.227.126.186]:50753 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752526AbXLTU4J (ORCPT ); Thu, 20 Dec 2007 15:56:09 -0500 Date: Thu, 20 Dec 2007 21:55:55 +0100 (CET) From: Bodo Eggert <7eggert@gmx.de> To: Al Viro cc: Bodo Eggert <7eggert@gmx.de>, Mark Lord , Alexander Viro , Andrew Morton , Linux Kernel Subject: Re: RFC: permit link(2) to work across --bind mounts ? In-Reply-To: <20071219142351.GI8181@ftp.linux.org.uk> Message-ID: References: <9BTqk-2ck-31@gated-at.bofh.it> <9BTJN-2Sv-21@gated-at.bofh.it> <9BTTr-35L-13@gated-at.bofh.it> <20071219142351.GI8181@ftp.linux.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii X-be10.7eggert.dyndns.org-MailScanner-Information: See www.mailscanner.info for information X-be10.7eggert.dyndns.org-MailScanner: Found to be clean X-be10.7eggert.dyndns.org-MailScanner-From: 7eggert@gmx.de X-Provags-ID: V01U2FsdGVkX19BFaEXH+nWItQHH2qDn1xCIOhzIkFU1gTXCLd ccLXmunNZFU+9HsvFX8EUsu4Wcuafy1/EazhwvUBTv53JAzyrV CcvxTjBuR01K4dOGOj6tA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1313 Lines: 32 On Wed, 19 Dec 2007, Al Viro wrote: > On Wed, Dec 19, 2007 at 02:43:26PM +0100, Bodo Eggert wrote: > > Since nobody knows about this "security boundary" and everybody knows about > > the annoying "can't link across bind-mountpoints bug", > > ... how about teaching people to RTFM? Starting, perhaps, with man 2 link? What about reading POSIX which says 1264 [EXDEV] 1265 Improper link. A link to a file on another file system was attempted. So if the link creates a file on NOT another filesystem (which is the point of bind mounts), it should NOT return EXDEV. Having an artificial boundary between different views to a fs may happen to be a security feature if used with care, but most users do expect the opposite and wonder why mv is needlessly slow. I'm not even sure if defaulting to having a barrier is sane at all, but if people confuse filesystems and mountpoints^W^W^W^Wuse this feature, they will depend on this feature not changing:-) -- "It is generally inadvisable to eject directly over the area you just bombed." -U.S. Air Force Manual -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/