Re: seccomp feature development

On Mon, May 18, 2020 at 02:04:57PM -0700, Kees Cook wrote:

Hi!

This is my attempt at a brain-dump on my plans for nearish-term seccomp
features. Welcome to my TED talk... ;)

These are the things I've been thinking about:

- fd passing
- deep argument inspection
- changing structure sizes
- syscall bitmasks

What's your take on enabling multiple filters with listeners being attached,
so that different seccomp interceptors can operate together. I'm wondering
how this would work.

One idea that I had is adding a new flag to the seccomp filter
installation -- something like NEXT_FILTER_COMPATIBLE. When a filter is
installed with a listener, it will check if all previous filters were
instaled with NEXT_FILTER_COMPATIBLE.

If the call is intercepted by a listener, and the return is overriden,
then it short-circuits, and the subsequent filters are not evaluated.

On the other hand, if the continue response is send, then the
subsequent filters are called.

What do you think?