From owner-freebsd-current Thu Apr 12 11:14:45 2001 Delivered-To: freebsd-current@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id 2B9B937B43E for ; Thu, 12 Apr 2001 11:14:43 -0700 (PDT) (envelope-from bright@fw.wintelcom.net) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id f3CIEfG15562; Thu, 12 Apr 2001 11:14:41 -0700 (PDT) Date: Thu, 12 Apr 2001 11:14:40 -0700 From: Alfred Perlstein To: Thomas Quinot Cc: current@FreeBSD.ORG Subject: Re: NFS export to netgroup with duplicate hosts Message-ID: <20010412111440.F24582@fw.wintelcom.net> References: <20010412182900.B30764@cuivre.fr.eu.org> <20010412110021.D24582@fw.wintelcom.net> <20010412200617.A12763@shalmaneser.enst.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.2.5i In-Reply-To: <20010412200617.A12763@shalmaneser.enst.fr>; from quinot@inf.enst.fr on Thu, Apr 12, 2001 at 08:06:17PM +0200 X-all-your-base: are belong to us. Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG * Thomas Quinot [010412 11:06] wrote: > Le 2001-04-12, Alfred Perlstein écrivait : > > > m: "Don't call me dude." *thwack* "The point is that if the > > workstation is untrusted, what's the stop the mallicious hacker > > from taking a read-only filehandle and swapping the top byte with > > the byte required for write access?" > > The kernel could include a 'signature' in the handle, e.g. in the form of > a hash of (perm-bytes,handle-bytes,secret-key). > > (But the following still holds:) > > > s: "Master, this sounds like hella work!" > (plus some crypto algorithm right in kernel space...) > > > m: "Ahhhh, you are correct, now get cracking!" None of that would protect you when a single client has two exports available, one read and one write on the same filesystem. A machine with just / that exports /usr and /var with different perms... (/usr is rw, /var is ro) Well the untrusted client can use the "magic" from the /usr to access /var rw instead of ro. It's actually not that big of a deal to attach the client/perms though so that seperate machines can access the same mount point differently. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] http://www.egr.unlv.edu/~slumos/on-netbsd.html To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message