From: Pavel Machek <pavel@ucw.cz>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Trond Myklebust <trond.myklebust@fys.uio.no>,
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: Wed, 28 Oct 2009 22:06:24 +0100 [thread overview]
Message-ID: <20091028210623.GB4159@elf.ucw.cz> (raw)
In-Reply-To: <4AE87292.20802@schaufler-ca.com>
> > Please see bugtraq discussion at
> > http://seclists.org/bugtraq/2009/Oct/179 .
> >
> > (In short, you get read-only fd, and you can upgrade it to read-write
> > fd. Yes, you are the owner of the process, but you are not owner of
> > the file the fd refers to.)
> >
> > The actual permissions of the file are not ignored, but permissions of
> > the containing directory _are_. If there's 666 file in 700 directory,
> > you can reopen it read-write, in violation of directory's 700
> > permissions.
>
> There is no security violation here. Consider the case where
You are able to write to my files, when unix permissions forbid
that. How do you call that? Strange behaviour of /proc/*/fd/ symlink
that is not really a symlink allows that.
See bugtraq discussion at http://seclists.org/bugtraq/2009/Oct/179 .
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:[~2009-10-28 21:06 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-25 6:29 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
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 [this message]
2009-10-28 22:48 ` David Wagner
2009-10-29 4:13 ` Casey Schaufler
2009-10-29 7:53 ` David Wagner
2009-10-30 14:07 ` Pavel Machek
2009-10-31 4:09 ` Casey Schaufler
2009-11-01 9:23 ` David Wagner
2009-11-01 17:43 ` Casey Schaufler
2009-11-01 20:39 ` David Wagner
2009-11-01 22:05 ` Casey Schaufler
2009-10-26 18:02 ` J. Bruce Fields
2009-10-26 17:57 ` Serge E. Hallyn
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