From: Pavel Machek <pavel@ucw.cz>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Jan Kara <jack@suse.cz>, "J. Bruce Fields" <bfields@fieldses.org>,
"Serge E. Hallyn" <serue@us.ibm.com>,
kernel list <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk,
jamie@shareable.org
Subject: Re: symlinks with permissions
Date: Tue, 27 Oct 2009 09:11:41 +0100 [thread overview]
Message-ID: <20091027081141.GF5019@elf.ucw.cz> (raw)
In-Reply-To: <1256581336.8576.20.camel@heimdal.trondhjem.org>
On Mon 2009-10-26 14:22:16, Trond Myklebust wrote:
> On Sun, 2009-10-25 at 10:36 +0100, Pavel Machek wrote:
> > Well, it is unexpected and mild security hole.
> >
> > Part of the problem is that even if you have read-only
> > filedescriptor, you can upgrade it to read-write, even if path is
> > inaccessible to you.
> >
> > So if someone passes you read-only filedescriptor, you can still write
> > to it.
>
> If someone passes you a file descriptor, can't you in any case play
> games with, openat(fd,"",O_RDWR), in order to achieve the same thing? I
> must admit I haven't tried it yet, but at a first glance I can't see
> anything that prevents me from doing this...
According to my documentation, openat needs directory fd.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2009-10-27 8:11 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-25 6:29 symlinks with permissions Pavel Machek
2009-10-26 16:31 ` Jan Kara
2009-10-26 16:57 ` Serge E. Hallyn
2009-10-26 17:36 ` J. Bruce Fields
2009-10-26 17:46 ` Jan Kara
2009-10-26 17:57 ` Trond Myklebust
2009-10-25 9:36 ` Pavel Machek
2009-10-26 18:22 ` Trond Myklebust
2009-10-27 8:11 ` Pavel Machek [this message]
2009-10-27 10:27 ` Jamie Lokier
2009-10-26 18:35 ` J. Bruce Fields
2009-10-28 4:15 ` Eric W. Biederman
2009-10-28 8:16 ` Pavel Machek
2009-10-28 11:25 ` Eric W. Biederman
2009-10-28 21:03 ` Pavel Machek
2009-10-29 2:20 ` Eric W. Biederman
2009-10-29 11:03 ` Pavel Machek
2009-10-29 16:23 ` Eric W. Biederman
2009-10-30 18:35 ` Pavel Machek
2009-10-30 20:37 ` Nick Bowler
2009-10-30 23:03 ` Eric W. Biederman
2009-10-31 2:30 ` Jamie Lokier
2009-10-28 16:34 ` Casey Schaufler
2009-10-28 19:44 ` Jamie Lokier
2009-10-28 21:06 ` Pavel Machek
2009-10-26 18:02 ` J. Bruce Fields
2009-10-26 17:57 ` Serge E. Hallyn
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