Re: When scrubbing secrets in memory doesn't work

[Florian Weimer <Weimer () CERT Uni-Stuttgart DE>]

Richard Moore <rich () westpoint ltd uk> writes:

> It's worth noting that on systems such as linux and solaris, it is
> easy to avoid the paging problem by locking the process into
> memory.

"Locking into memory" does NOT mean "avoid paging".  AFAIK, there are
operating systems in which memory which has been locked is still paged
to disk.

> This is accomplished using the system calls mlock(2) and
> mlockall(2). The former is probably more suitable as the latter
> locks all of pages for the process.

It is very hard to use mlock(2) correctly, and using mlockall(2)
creates a potential for local DoS attacks.

Better disable swap or use encrypted swap on critical systems.

-- 
Florian Weimer                    Weimer () CERT Uni-Stuttgart DE
University of Stuttgart           http://CERT.Uni-Stuttgart.DE/people/fw/
RUS-CERT                          fax +49-711-685-5898