NX emulation

[Kyle McMartin]

On Tue, May 25, 2010 at 09:11:09PM -0700, Kees Cook wrote:
> Yes, the git URL for this is:
> 
> git://kernel.ubuntu.com/kees/linux-2.6.git
> 

Doesn't appear to work? 

kyle at dreadnought ~/src/linux-2.6 $ git remote
add kees-execshield git://kernel.ubuntu.com/kees/linux-2.6.git
kyle at dreadnought ~/src/linux-2.6 $ git fetch kees-execshield
kernel.ubuntu.com[0: 91.189.94.216]: errno=Connection timed out
fatal: unable to connect a socket (Connection timed out)


> In looking at how "exec-shield" is used, I was thinking that maybe the
> "nonexec" flag should be used instead.  It could have multiple settings,
> maybe.  It seems like it could be used for:
> 
> off
> hw-only
> emu-if-needed
> 
> There also seems to be the "2" setting which ignores the stack-exec
> markings, but that seems like it should be a separate feature.  If we can
> clean it up a little more, I'd really like to try to for upstream
> inclusion.  I know there has been resistance to it in the past, but
> nearly every distro includes this patch set now; it's silly not to have it
> upstream.
> 

Yes, we've been saying for a while that the randomization stuff needs to
be gutted from exec-shield. There is still a lot of work left cleaning
up exec-shield, all the hooks are pretty out of order.

> The second commit "x86: clean up nx-emu for ia32-only" adds a bunch more
> #ifdef CONFIG_X86_32 around things, mostly I think the primary change in
> behavior that would be visible to Fedora would be having the "exec-shield"
> sysctl vanish on x86_64, and to fall back to mainline ASLR in the non-emu
> case. 
> 

I suspect all this is still too invasive in the generic code to be
palatable. 

> > > Is there a better place (public Fedora mailing list?) for me to send these?
> > > 
> > 
> > fedora-kernel-list at redhat.com if you want.
> 

Cheers, Kyle