On Wed, 14 Feb 2024 10:42:57 -0800
Dave Hansen [off-list ref] wrote:

On 2/14/24 10:22, Petr Tesařík wrote:

quoted

Anyway, in the long term I would like to work on gradual decomposition
of the kernel into a core part and many self-contained components.
Sandbox mode is a useful tool to enforce isolation.  

I'd want to see at least a few examples of how this decomposition would
work and how much of a burden it is on each site that deployed it.

Got it. Are you okay with a couple of examples to illustrate the
concept? Because if you want patches that have been acked by the
respective maintainers, it somehow becomes a chicken-and-egg kind of
problem...

But I'm skeptical that this could ever work.  Ring-0 execution really is
special and it's _increasingly_ so.  Think of LASS or SMAP or SMEP.

I have just answered a similar concern by hpa. In short, I don't think
these features are relevant, because by definition sandbox mode does
not share anything with user mode address space.

We're even seeing hardware designers add hardware security defenses to
ring-0 that are not applied to ring-3.

In other words, ring-3 isn't just a deprivileged ring-0, it's more
exposed to attacks.

quoted

I'd rather fail fast than maintain hundreds of patches in an
out-of-tree branch before submitting (and failing anyway).  

I don't see any remotely feasible path forward for this approach.

I can live with such decision. But first, I want to make sure that the
concept has been understood correctly. So far, at least some concerns
suggest an understanding that is not quite accurate.

Is this sandbox idea a bit too much out-of-the-box?

Petr T