From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Jakub Kicinski <kuba@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 0/3] Introduce pinnable bpf_link kernel abstraction
Date: Thu, 05 Mar 2020 12:05:23 +0100 [thread overview]
Message-ID: <87tv332hak.fsf@toke.dk> (raw)
In-Reply-To: <20200305001620.204c292e@cakuba.hsd1.ca.comcast.net>
Jakub Kicinski <kuba@kernel.org> writes:
> On Wed, 4 Mar 2020 17:07:08 -0800, Alexei Starovoitov wrote:
>> > Maybe also the thief should not have CAP_ADMIN in the first place?
>> > And ask a daemon to perform its actions..
>>
>> a daemon idea keeps coming back in circles.
>> With FD-based kprobe/uprobe/tracepoint/fexit/fentry that problem is gone,
>> but xdp, tc, cgroup still don't have the owner concept.
>> Some people argued that these three need three separate daemons.
>> Especially since cgroups are mainly managed by systemd plus container
>> manager it's quite different from networking (xdp, tc) where something
>> like 'networkd' might makes sense.
>> But if you take this line of thought all the ways systemd should be that
>> single daemon to coordinate attaching to xdp, tc, cgroup because
>> in many cases cgroup and tc progs have to coordinate the work.
>
> The feature creep could happen, but Toke's proposal has a fairly simple
> feature set, which should be easy to cover by a stand alone daemon.
>
> Toke, I saw that in the library discussion there was no mention of
> a daemon, what makes a daemon solution unsuitable?
Quoting from the last discussion[0]:
> - Introducing a new, separate code base that we'll have to write, support
> and manage updates to.
>
> - Add a new dependency to using XDP (now you not only need the kernel
> and libraries, you'll also need the daemon).
>
> - Have to duplicate or wrap functionality currently found in the kernel;
> at least:
>
> - Keeping track of which XDP programs are loaded and attached to
> each interface (as well as the "new state" of their attachment
> order).
>
> - Some kind of interface with the verifier; if an app does
> xdpd_rpc_load(prog), how is the verifier result going to get back
> to the caller?
>
> - Have to deal with state synchronisation issues (how does xdpd handle
> kernel state changing from underneath it?).
>
> While these are issues that are (probably) all solvable, I think the
> cost of solving them is far higher than putting the support into the
> kernel. Which is why I think kernel support is the best solution :)
The context was slightly different, since this was before we had
freplace support in the kernel. But apart from the point about the
verifier, I think the arguments still stand. In fact, now that we have
that, we don't even need userspace linking, so basically a daemon's only
task would be to arbitrate access to the XDP hook? In my book,
arbitrating access to resources is what the kernel is all about...
-Toke
[0] https://lore.kernel.org/bpf/m/874l07fu61.fsf@toke.dk
next prev parent reply other threads:[~2020-03-05 11:05 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 22:39 [PATCH bpf-next 0/3] Introduce pinnable bpf_link kernel abstraction Andrii Nakryiko
2020-02-28 22:39 ` [PATCH bpf-next 1/3] bpf: introduce pinnable bpf_link abstraction Andrii Nakryiko
2020-03-02 10:13 ` Toke Høiland-Jørgensen
2020-03-02 18:06 ` Andrii Nakryiko
2020-03-02 21:40 ` Toke Høiland-Jørgensen
2020-03-02 23:37 ` Andrii Nakryiko
2020-03-03 2:50 ` Alexei Starovoitov
2020-03-03 4:18 ` Andrii Nakryiko
2020-02-28 22:39 ` [PATCH bpf-next 2/3] libbpf: add bpf_link pinning/unpinning Andrii Nakryiko
2020-03-02 10:16 ` Toke Høiland-Jørgensen
2020-03-02 18:09 ` Andrii Nakryiko
2020-03-02 21:45 ` Toke Høiland-Jørgensen
2020-02-28 22:39 ` [PATCH bpf-next 3/3] selftests/bpf: add link pinning selftests Andrii Nakryiko
2020-03-02 10:11 ` [PATCH bpf-next 0/3] Introduce pinnable bpf_link kernel abstraction Toke Høiland-Jørgensen
2020-03-02 18:05 ` Andrii Nakryiko
2020-03-02 22:24 ` Toke Høiland-Jørgensen
2020-03-02 23:35 ` Andrii Nakryiko
2020-03-03 8:12 ` Toke Høiland-Jørgensen
2020-03-03 8:12 ` Daniel Borkmann
2020-03-03 15:46 ` Alexei Starovoitov
2020-03-03 19:23 ` Daniel Borkmann
2020-03-03 19:46 ` Andrii Nakryiko
2020-03-03 20:24 ` Toke Høiland-Jørgensen
2020-03-03 20:53 ` Daniel Borkmann
2020-03-03 22:01 ` Alexei Starovoitov
2020-03-03 22:27 ` Toke Høiland-Jørgensen
2020-03-04 4:36 ` Alexei Starovoitov
2020-03-04 7:47 ` Toke Høiland-Jørgensen
2020-03-04 15:47 ` Alexei Starovoitov
2020-03-05 10:37 ` Toke Høiland-Jørgensen
2020-03-05 16:34 ` Alexei Starovoitov
2020-03-05 22:34 ` Daniel Borkmann
2020-03-05 22:50 ` Alexei Starovoitov
2020-03-05 23:42 ` Daniel Borkmann
2020-03-06 8:31 ` Toke Høiland-Jørgensen
2020-03-06 10:25 ` Daniel Borkmann
2020-03-06 10:42 ` Toke Høiland-Jørgensen
2020-03-06 18:09 ` David Ahern
2020-03-04 19:41 ` Jakub Kicinski
2020-03-04 20:45 ` Alexei Starovoitov
2020-03-04 21:24 ` Jakub Kicinski
2020-03-05 1:07 ` Alexei Starovoitov
2020-03-05 8:16 ` Jakub Kicinski
2020-03-05 11:05 ` Toke Høiland-Jørgensen [this message]
2020-03-05 18:13 ` Jakub Kicinski
2020-03-09 11:41 ` Toke Høiland-Jørgensen
2020-03-09 18:50 ` Jakub Kicinski
2020-03-10 12:22 ` Toke Høiland-Jørgensen
2020-03-05 16:39 ` Alexei Starovoitov
2020-03-03 22:40 ` Jakub Kicinski
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