Re: [PATCH v13 net-next 07/11] bpf: verifier (add ability to receive verification log)

On Thu, Sep 18, 2014 at 10:28 AM, Daniel Borkmann [off-list ref] wrote:

On 09/18/2014 05:24 PM, Alexei Starovoitov wrote:
...

quoted

solve or not. If we decide to solve it, we need to have
a plan to solve it all the way. Partial fix for size of bpf_attr
is not a plan. It's something that is not addressing the problem
completely. Little bit of help is not useful for userspace. It
would need to deal with new types, verifier differences and
other things that I mentioned earlier.

Hm, I don't think it would be a strict requirement to solve it
all the way, and I think that perf_event_open() with perf_copy_attr()
is not trying to do so either. It, however, is trying on a ``best
effort basis'' to still load something if new features are unused
by the binary (I guess you saw the comment in perf_copy_attr()).

Iff, e.g. due to new types we fail at the verifier stage, sure,
that's life since we only have backwards-compatible guarantee,
but in case we tried to use features we support, we're still able
to load the eBPF program while right now, we're rejecting it right
up-front. That's just my $0.02 ...

David,

the 'changes requested' status means that you want me to
address this forward compatibility now instead of later?
Or something else?
I don't want to second guess, respin and spam people
unnecessary. In this case I don't think Daniel is insisting
on doing it in this patch set. The things discussed above
are not urgent. Unless I'm missing something.
Please clarify.

Thanks

From: Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
Date: Fri, 19 Sep 2014 14:04:50 -0700

the 'changes requested' status means that you want me to
address this forward compatibility now instead of later?

I want you to address this now.