Date: Wed, 23 Jul 2003 10:28:22 -0400 (EDT)
From: David Korn <dgk@research.att.com>
Message-Id: <200307231428.KAA15254@raptor.research.att.com>
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To: davem@redhat.com
Subject: Re: Re: kernel bug in socketpair()
Cc: gsf@research.att.com, linux-kernel@vger.kernel.org, netdev@oss.sgi.com
Sender: linux-kernel-owner@vger.kernel.org
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> On Wed, 23 Jul 2003 09:32:09 -0400 (EDT)
> David Korn <dgk@research.att.com> wrote:
> 
> [ Added netdev@oss.sgi.com, the proper place to discuss networking kernel issues
> . ]
> 
> > The first problem is that files created with socketpair() are not accessible
> > via /dev/fd/n or /proc/$$/fd/n where n is the file descriptor returned
> > by socketpair().  Note that this is not a problem with pipe().
> 
> Not a bug.
> 
> Sockets are not openable via /proc files under any circumstances,
> not just the circumstances you describe.  This is a policy decision and
> prevents a whole slew of potential security holes.
> 
> 

Thanks for you quick response.

This make sense for INET sockets, but I don't understand the security
considerations for UNIX domain sockets.  Could you please elaborate?
Moreover, /dev/fd/n, (as opposed to /proc/$$/n) is restricted to
the current process and its decendents if close-on-exec is not specified.
Again, I don't understand why this would create a security problem
either since the socket is already accesible via the original
descriptor.

Finally if this is a security problem, why is the errno is set to ENXIO 
rather than EACCESS?

David Korn
dgk@research.att.com
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