* PaX Team <pagee...@freemail.hu> wrote:
> On 29 Nov 2015 at 9:08, Ingo Molnar wrote:
>
> >
> > * PaX Team <pagee...@freemail.hu> wrote:
> >
> > > i don't see the compile time vs. runtime detection as 'competing'
> > > approaches,
> > > both have their own role. [...]
> >
> > That's true - but only as long as 'this can be solved in tooling!' is not
> > used as
> > an excuse to oppose the runtime solution and we end up doing neither.
>
> actually, i already voiced my opinion elsewhere in the constify thread on the
> kernel hardening list that adding/using __read_only is somewhat premature
> without also adding the compile time verification part (as part of the
> constify
> plugin for example). right now its use on the embedded vdso image is simple
> and
> easy to verify but once people begin to add it to variables that the compiler
> knows and cares about (say, the ops structures) then things can become
> fragile
> without compile checking. so yes, i'd also advise to get such tooling in
> *before* more __read_only usage is added.
I think you are mistaken there: if we add the page fault fixup to make sure we
don't crash if a read-only variable is accessed, then we'll have most of the
benefits of read-only mappings and no fragility - without having to wait for
tooling.
Thanks,
Ingo
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