Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755860AbZCWNWU (ORCPT ); Mon, 23 Mar 2009 09:22:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750756AbZCWNWE (ORCPT ); Mon, 23 Mar 2009 09:22:04 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:35498 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750711AbZCWNWB (ORCPT ); Mon, 23 Mar 2009 09:22:01 -0400 To: serue@us.ibm.com CC: bfields@fieldses.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, ebiederm@xmission.com, linux-fsdevel@vger.kernel.org In-reply-to: <20090316170433.GA2996@us.ibm.com> (serue@us.ibm.com) Subject: unprivileged mounts vs. rmdir (was: VFS, NFS security bug? ...) References: <20090311232356.GP13540@fieldses.org> <20090312161047.GA15209@us.ibm.com> <517f3f820903121321sf6d2014q8165b925d5d44db7@mail.gmail.com> <20090313175848.GB27891@fieldses.org> <20090316163611.GB10959@fieldses.org> <20090316170433.GA2996@us.ibm.com> Message-Id: From: Miklos Szeredi Date: Mon, 23 Mar 2009 14:21:30 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1196 Lines: 32 [CCs trimmed] On Mon, 16 Mar 2009, Serge E. Hallyn wrote: > Quoting J. Bruce Fields (bfields@fieldses.org): > > special privilege, so don't consult filesystem permissions (do I have > > that right? What happened to the attempt to allow ordinary users to > > mount?). > > Well, they keep getting stalled because we don't have a good answer for > what to do about the fact that an unprivileged user can make trees > undeletable by pinning them with mounts. (Miklos and Eric cc'd in case > I didn't explain that well enough). That's correct. The best answer I can come up with is to allow rmdir/unlink to automatically umount trees from their respective dentries. Obviously this can't be done for regular (privileged) mounts, which must keep returning EBUSY in such situations. But for unprivileged mounts I can't see any fundamental issue with such an approach. Does anyone see a problem with this? Is there a better solution? Thanks, Miklos -- 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/