netdev - Re: bpf redirect will loop the packets

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] [day] [month] [year] [list]

Message-ID: <CAMDZJNVfpKks8pqjMRp4Kj6-+X=i7bUEO3-vFoAVnuR1iOMJhg@mail.gmail.com>
Date:   Tue, 2 Nov 2021 09:40:58 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Cong Wang <xiyou.wangcong@...il.com>, ast@...nel.org,
        andrii@...nel.org, songliubraving@...com, yhs@...com,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: bpf redirect will loop the packets

On Mon, Nov 1, 2021 at 10:41 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 11/1/21 7:32 AM, Tonghao Zhang wrote:
> > Hi
> > I found the issue,
> > if we use the bpf_redirect to the same netdevice in the ingress path.
> > the packet loop.
> > and now linux doesn't check that. In tx path,
> > softnet_data.xmit.recursion will limit the recursion.
> > I think we should check that in ingress. any thoughts?
>
> Nope, since this is xmit, not receive. This goes through a rescheduling
> point and could end up on a different CPU potentially. This is not any
> different in than how other infra handles this case. Point here is that
> it's not freezing the box, so admin can react to misconfig and then undo
> it again.
Yes, Should we print a warning msg when packets loop in ingress. in
__dev_queue_xmit
we print an msg, and admin may find that issue.

Thanks Daniel



-- 
Best regards, Tonghao