netdev - Re: [PATCH net-next v8 00/15] Introducing P4TC

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: <ZV+VVLWzL/j4ayAt@nanopsycho>
Date: Thu, 23 Nov 2023 19:09:24 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Edward Cree <ecree.xilinx@...il.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>, netdev@...r.kernel.org,
	deb.chatterjee@...el.com, anjali.singhai@...el.com,
	Vipin.Jain@....com, namrata.limaye@...el.com, tom@...anda.io,
	mleitner@...hat.com, Mahesh.Shirshyad@....com,
	tomasz.osinski@...el.com, xiyou.wangcong@...il.com,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, vladbu@...dia.com, horms@...nel.org,
	bpf@...r.kernel.org, khalidm@...dia.com, toke@...hat.com,
	mattyk@...dia.com, dan.daly@...el.com, chris.sommers@...sight.com,
	john.andy.fingerhut@...el.com
Subject: Re: [PATCH net-next v8 00/15] Introducing P4TC

Thu, Nov 23, 2023 at 06:53:42PM CET, ecree.xilinx@...il.com wrote:
>On 23/11/2023 16:30, Jamal Hadi Salim wrote:
>> I was hoping not to say anything but my fingers couldnt help themselves:
>> So "unoffloadable" means there is a binary blob and this doesnt work
>> per your design idea of how it should work?
>> Not that it cant be implemented (clearly it has been implemented), it
>> is just not how _you_ would implement it? All along I thought this was
>> an issue with your hardware.
>
>The kernel doesn't like to trust offload blobs from a userspace compiler,
> because it has no way to be sure that what comes out of the compiler
> matches the rules/tables/whatever it has in the SW datapath.
>It's also a support nightmare because it's basically like each user
> compiling their own device firmware.  At least normally with device
> firmware the driver side is talking to something with narrow/fixed
> semantics and went through upstream review, even if the firmware side is
> still a black box.
>Just to prove I'm not playing favourites: this is *also* a problem with
> eBPF offloads like Nanotubes, and I'm not convinced we have a viable
> solution yet.

Just for the record, I'm not aware of anyone suggesting p4 eBPF offload
in this thread.


>
>The only way I can see to handle it is something analogous to proof-
> carrying code, where the kernel (driver, since the blob is likely to be
> wholly vendor-specific) can inspect the binary blob and verify somehow
> that (assuming the HW behaves according to its datasheet) it implements
> the same thing that exists in SW.
>Or simplify the hardware design enough that the compiler can be small
> and tight enough to live in-kernel, but that's often impossible.

Yeah, that would solve the offloading problem. From what I'm hearing
from multiple sides, not going to happen.

>
>-ed