Re: Security: information leaks in /proc enable keystroke recovery

James Morris
2009-08-17T02:45:50Z

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@namei.org>