Re: Avoid stack/heap executable memory

[Anthony Green <green@moxielogic.com>]

Can't there be special kernel support for this kind of situation?
Like https://pax.grsecurity.net/docs/emutramp.txt

(resent because original was bounced by sourceware)

AG

On Wed, May 4, 2016 at 6:17 AM, Andrew Haley <aph@redhat.com> wrote:
> On 05/04/2016 12:32 AM, Richard Henderson wrote:
>> Of course, this will change the ABI, but I think we can work around that (at
>> least for ELF with symbol versioning), and also preserve the API.  Of course,
>> there's a *lot* that can be cleaned up if we're willing to change the API...
>
> For a long while now I've wanted to go in the opposite direction: to
> use a small JIT compiler to generate efficient code for invocations in
> both directions.  It doesn't have to be very complicated, and once
> you've generated code for any particular set of arguments that shim
> can be cached for use by any function with the same argument types.
> This could either use an existing JIT library or a custom JIT created
> just for libffi.  It would often be way more efficient than what we do
> at present.
>
> But it would keep bumping up against the "no executable and writable
> memory!" meme.  Of course security is important, but I can't help
> thinking that by being rigid about this we're performing a DOS attack
> on ourselves.
>
> Andrew.