Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S272542AbTHEPo4 (ORCPT ); Tue, 5 Aug 2003 11:44:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272530AbTHEPoz (ORCPT ); Tue, 5 Aug 2003 11:44:55 -0400 Received: from pat.uio.no ([129.240.130.16]:28587 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S272542AbTHEPoy (ORCPT ); Tue, 5 Aug 2003 11:44:54 -0400 To: Jesse Pollard Cc: Stephan von Krawczynski , root@chaos.analogic.com, helgehaf@aitel.hist.no, linux-kernel@vger.kernel.org Subject: Re: FS: hardlinks on directories References: <20030804141548.5060b9db.skraw@ithnet.com> <20030805160435.7b151b0e.skraw@ithnet.com> <03080510020503.05972@tabby> From: Trond Myklebust Date: 05 Aug 2003 17:44:06 +0200 In-Reply-To: <03080510020503.05972@tabby> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Honest Recruiter) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-MailScanner-Information: This message has been scanned for viruses/spam. Contact postmaster@uio.no if you have questions about this scanning. X-UiO-MailScanner: No virus found Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1221 Lines: 21 >>>>> " " == Jesse Pollard writes: > You do have to remember that any NFS export gives IMPLICIT > access to the entire filesystem (it is the device number that > is actually exported). If the attacker can generate > device:inode number, then that file reference can be opened. I > haven't read/seen anything yet that has said different. Not entirely true. The default under Linux is to enable subtree checks. This means that knfsd must establish that the file being accessed lies within a subtree the head of which is the export point. This wreaks havoc with cross-directory renames etc, so a lot of people disable it, however it is a slightly safer default... Of course if you start playing with the idea of hard linked directories then subtree checks are no longer an option as the path connecting an export point and the file is no longer guaranteed to be unique (and some paths may not even be finite). Cheers, Trond - 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/