Re: [PATCH] Sample fix for hyperthread exploit

[Con Kolivas <kernel@kolivas.org>]

On Thu, 2 Jun 2005 12:49 pm, Ingo Molnar wrote:
> * Arjan van de Ven <arjan@infradead.org> wrote:
> > > Also, uid is not sufficient.  Something more comprehensive (like
> > > ability to ptrace) would be appropriate.
> >
> > I would go a lot simpler. App says "I want exclusivity" via pctl and
> > NOTHING runs on the other half. Well maybe with exceptions of
> > processes that share the mm with the exclusive one (in practice
> > "threads") since those could just read the memory anyway.
>
> this has the disadvantage of needing changes in the security apps.
> Basing this off the uid (or the ability to ptrace) makes it at least
> automatic - but introduces a permanent penalty not only on multiuser
> boxes, but on basically any server box that runs multiple services.

The performance penalty of the sample patch without extra communication or 
code would be substantial and I should make it clear to any onlookers that it 
is not recommended you use it in any real environment.

Cheers,
Con