linux-kernel - Re: [PATCH v4,bpf-next] bpf: Don't redirect packets with invalid pkt

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, 20 Sep 2022 15:42:31 +0100
From:   "Lorenz Bauer" <oss@....io>
To:     shaozhengchao <shaozhengchao@...wei.com>,
        "Stanislav Fomichev" <sdf@...gle.com>
Cc:     ast@...nel.org, daniel@...earbox.net, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, yuehaibing@...wei.com
Subject: Re: [PATCH v4,bpf-next] bpf: Don't redirect packets with invalid pkt_len

On Mon, 19 Sep 2022, at 11:55, shaozhengchao wrote:
> Sorry for the delay. I'm busy testing the TC module recently. I'm very 
> sorry for the user-space breakage.
>
> The root cause of this problem is that eth_type_trans() is called when
> the protocol type of the SKB is parsed. The len value of the SKB is
> reduced to 0. If the user mode requires that the forwarding succeed, or
>   if the MAC header is added again after the MAC header is subtracted, 
> is this appropriate?

We don't require forwarding to succeed with a 14 byte input buffer. We also don't look at the MAC header.

I think refusing to forward 0 length packets would be OK. Not 100% certain I understood you correctly, let me know if this helps.

Best
Lorenz