netdev - Re: [PATCH bpf-next v2 1/6] bpf: introduce BPF dispatcher

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20191124170841.x4ohh7sy6kbjnbno@ast-mbp>
Date:   Sun, 24 Nov 2019 09:08:43 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Björn Töpel <bjorn.topel@...il.com>
Cc:     Netdev <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        bpf <bpf@...r.kernel.org>,
        Magnus Karlsson <magnus.karlsson@...il.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Edward Cree <ecree@...arflare.com>,
        Toke Høiland-Jørgensen 
        <thoiland@...hat.com>, Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Maxim Mikityanskiy <maximmi@...lanox.com>
Subject: Re: [PATCH bpf-next v2 1/6] bpf: introduce BPF dispatcher

On Sun, Nov 24, 2019 at 07:55:07AM +0100, Björn Töpel wrote:
> >
> > I think I got it why it works.
> > Every time the prog cnt goes to zero you free the trampoline right away
> > and next time it will be allocated again and kzalloc() will zero selector.
> > That's hard to spot.
> > Also if user space does for(;;) attach/detach;
> > it will keep stressing bpf_jit_alloc_exec.
> > In case of bpf trampoline attach/detach won't be stressing it.
> > Only load/unload which are much slower due to verification.
> > I guess such difference is ok.
> >
> 
> Alexei, thanks for all feedback (on the weekend)! I agree with all of
> above, and especially missing selftests and too much code duplication.
> 
> I'll do a respin, but that'll be in the next window, given that Linus
> will (probably) tag the release today.

I want it to land just as much as you do :) Two weeks is not a big deal. We
backport all of bpf and xdp as soon as it lands in bpf-next/net-next. We don't
wait for patches to reach Linus's tree. So this dispatch logic will be running
on our servers way sooner than you'd expect. I guess that explains my obsession
with quality. Same goes for libbpf.