Re: [kernel-hardening] [PATCH 4/6] Protectable Memory

[Laura Abbott]

On 02/12/2018 03:27 PM, Kees Cook wrote:
> On Sun, Feb 4, 2018 at 7:05 AM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> wrote:
> > On 04/02/18 00:29, Boris Lukashev wrote:
> > > On Sat, Feb 3, 2018 at 3:32 PM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> wrote:
> >
> > [...]
> >
> > > > What you are suggesting, if I have understood it correctly, is that,
> > > > when the pool is protected, the addresses already given out, will become
> > > > traps that get resolved through a lookup table that is built based on
> > > > the content of each allocation.
> > > >
> > > > That seems to generate a lot of overhead, not to mention the fact that
> > > > it might not play very well with the MMU.
> > >
> > > That is effectively what i'm suggesting - as a form of protection for
> > > consumers against direct reads of data which may have been corrupted
> > > by some irrelevant means. In the context of pmalloc, it would probably
> > > be a separate type of ro+verified pool
> > ok, that seems more like an extension though.
> >
> > ATM I am having problems gaining traction to get even the basic merged :-)
> >
> > I would consider this as a possibility for future work, unless it is
> > said that it's necessary for pmalloc to be accepted ...
>
> I would agree: let's get basic functionality in first. Both
> verification and the physmap part can be done separately, IMO.

Skipping over physmap leaves a pretty big area of exposure that could
be difficult to solve later. I appreciate this might block basic
functionality but I don't think we should just gloss over it without
at least some idea of what we would do.

Thanks,
Laura