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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Andreas Amann <amann@physik.tu-berlin.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>,
	Linus Torvalds <torvalds@osdl.org>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.6 breaks kmail (nfs related?)
Date: Fri, 21 May 2004 23:40:03 -0400	[thread overview]
Message-ID: <20040522034003.GA6415@fieldses.org> (raw)
In-Reply-To: <20040521230545.GA787@bill.physik.tu-berlin.de>

On Sat, May 22, 2004 at 01:05:45AM +0200, Andreas Amann wrote:
> On Fri, May 21, 2004 at 12:40:02PM -0400, Trond Myklebust wrote:
> > 
> > Hmm... It looks to me as if you are exporting that filesystem with the
> > "subtree_check" option enabled. Could you try to set "no_subtree_check"?
> 
> Thanks for that one, with "no_subtree_check" the problem disappears!
> What is the disadvantage of this option?

With "no_subtree_check" the server will not attempt to verify that a
given filehandle points to a file that is beneath an exported directory;
thus an attacker can guess filehandles of files not beneath any exported
directory and use those guessed filehandles to acces files you didn't
mean to export.

Even with "no_subtree_check", the server can still recognize which
filesystem a filehandle belongs to; so you're only in trouble if you
have files you don't want exported on the same partition as files you do
want exported.

See "man exports" for more.

--Bruce Fields

  reply	other threads:[~2004-05-22  3:40 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-13 12:11 2.6.6 breaks kmail (nfs related?) Andreas Amann
2004-05-16  4:46 ` Linus Torvalds
2004-05-16 17:59   ` Trond Myklebust
2004-05-16 18:10     ` Trond Myklebust
2004-05-16 18:19       ` Linus Torvalds
2004-05-16 18:47         ` Trond Myklebust
2004-05-16 18:50           ` Linus Torvalds
2004-05-16 19:10             ` Trond Myklebust
2004-05-17 11:31               ` Andreas Amann
2004-05-17 15:55                 ` Trond Myklebust
2004-05-21 15:27                   ` Andreas Amann
2004-05-21 16:40                     ` Trond Myklebust
2004-05-21 23:05                       ` Andreas Amann
2004-05-22  3:40                         ` J. Bruce Fields [this message]
2004-05-17 21:35                 ` Matthias Urlichs
2004-05-17  6:35 ` Norberto Bensa
2004-05-17  7:14   ` Andrew Morton
2004-05-17 17:35     ` Andrew Morton
2004-05-17 18:01       ` Trond Myklebust
2004-05-17 16:17   ` Frank van Maarseveen

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