netdev - Re: [PATCH bpf-next v3 1/3] xsk: Support UMEM chunk_size > PAGE

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]

Date:   Tue, 18 Apr 2023 12:16:58 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Kal Cutter Conley <kal.conley@...tris.com>
Cc:     Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 1/3] xsk: Support UMEM chunk_size > PAGE_SIZE

Kal Cutter Conley <kal.conley@...tris.com> writes:

>> In addition, presumably when using this mode, the other XDP actions
>> (XDP_PASS, XDP_REDIRECT to other targets) would stop working unless we
>> add special handling for that in the kernel? We'll definitely need to
>> handle that somehow...
>
> I am not familiar with all the details here. Do you know a reason why
> these cases would stop working / why special handling would be needed?
> For example, if I have a UMEM that uses hugepages and XDP_PASS is
> returned, then the data is just copied into an SKB right? SKBs can
> also be created directly from hugepages AFAIK. So I don't understand
> what the issue would be. Can someone explain this concern?

Well, I was asking :) It may well be that the SKB path just works; did
you test this? Pretty sure XDP_REDIRECT to another device won't, though?

-Toke