On Thu, Sep 09, 2010 at 10:30:57AM -0400, Gregory Maxwell wrote:
On Thu, Sep 9, 2010 at 9:45 AM, Neal Becker
<ndbecker2(a)gmail.com> wrote:
> This article:
>
>
http://labs.mwrinfosecurity.com/notices/security_mechanisms_in_linux_envi...
>
> seems to say that fedora is ranking poorly in deployment of various
> userspace memory protection mechanisms. Is this information accurate?
I asked about one point of this on LWN:
Library randomization / prelink
Posted Sep 8, 2010 18:26 UTC (Wed) by gmaxwell (subscriber, #30048) [Link]
Anyone know how the library randomization is being counted? 3 bits for
fedora doesn't sound right. Is the 3 bits the value for a system vs
itself or for this system vs all other systems?
"a note here: fedora uses exec-shield which maps libraries in two different
regions: ascii-armor (lower 16MB) and the rest. i think what paxtest
measured there is the former where the usable entropy is necessarily
less than elsewhere and may not be representative of real life apps
and their address spaces (not saying the whole ascii-armor region is
worth anything for security though ;)"
This article was brought up on fedora-kernel-list last week.
In my tests, I've not been able to reproduce the '3 bits' result.
On current kernels, I see 12 bits for 32-bit, and 'no randomisation' for 64-bit.
I'm not entirely sure yet why we're showing different results on some of the
other tests to other distros too.
I'll poke at it some more tomorrow.
Dave