linux-kernel - Re: Security: information leaks in /proc enable keystroke recovery

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Message-ID: <alpine.LRH.2.00.0908171237050.30748@tundra.namei.org>
Date:	Mon, 17 Aug 2009 12:45:45 +1000 (EST)
From:	James Morris <jmorris@...ei.org>
To:	Theodore Tso <tytso@....edu>
cc:	David Wagner <daw-news@...berkeley.edu>,
	linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: Security: information leaks in /proc enable keystroke recovery

On Sun, 16 Aug 2009, Theodore Tso wrote:

> On Mon, Aug 17, 2009 at 12:31:38AM +0000, David Wagner wrote:
> > 
> > OK.  What about this:
> > 
> > (a) Remove ESP and EIP from /proc/$pid/stat{,us} entirely.  Put them in
> > some other file that is only readable by root and by the owner of the
> > process, but is not world-readable.  We know that ESP and EIP can be used
> > for keystroke recovery, and they are not usually used by administrators,
> > so the first step is to lock them down tightly: there is no downside.
> 
> Agreed.

It might be best to require a capability for this if not root.

The candidates seem to be CAP_SYS_ADMIN and CAP_SYS_PTRACE.

> Maybe we should only be recording the last access and last modified
> time on pseudo-tty's to a second granularity, hmmm?

I can't think of a valid case for finer granularity here, although I guess 
it could be made a sysctl if necessary.

I wonder if there are any other channels?


- James
-- 
James Morris
<jmorris@...ei.org>
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