From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linux FS Devel <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>
Subject: Re: Connecting to sockets on MNT_READONLY mounts?
Date: Fri, 2 May 2014 01:56:59 +0100 [thread overview]
Message-ID: <20140502005659.GF18016@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CALCETrXhVKq33-KWLMVxPtCZgHddKsxCOQX9F-LGerXsCrLH5Q@mail.gmail.com>
On Thu, May 01, 2014 at 04:57:13PM -0700, Andy Lutomirski wrote:
> Suppose I bind-mount /usr into a private namespace with
> nosuid,nodev,ro. How can you use it to attack anything? The only
> thing I've thought of is to open fifos and connect to sockets. I'm
> assuming that there's a pid namespace blocking ptrace and such and a
> network namespace blocking abstract sockets.
How many FIFOs and sockets are there in your /usr? Here all I see
outside of /dev, /run and /tmp (across seven boxen; I can check more, but
I really doubt it'll catch anything) is the grand total of 4:
/lib/cryptsetup/passfifo
/var/lib/oprofile/opd_pipe
/var/lib/nfs/rpc_pipefs/nfs/clnt0/idmap
/var/lib/nfs/rpc_pipefs/gssd/clntXX/gssd
None of those in /usr and I don't believe that you seriously propose to
bind e.g. /lib/cryptsetup into your sandbox. And while we are at it,
exposing host /usr is *not* a good idea - if nothing else, it gives
quite a bit of information about the versions of software installed on
the host. Ability to watch atime of /usr/bin/* also might be interesting,
etc.
Do you, by any chance, plan to expose the host /tmp or /run? Or
rpc_pipefs, for that matter...
prev parent reply other threads:[~2014-05-02 0:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-01 22:20 Connecting to sockets on MNT_READONLY mounts? Andy Lutomirski
2014-05-01 22:34 ` Al Viro
2014-05-01 23:00 ` Andy Lutomirski
2014-05-01 23:51 ` Al Viro
2014-05-01 23:57 ` Andy Lutomirski
2014-05-02 0:56 ` Al Viro [this message]
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