netdev - Help with source of ebtables extension vlan

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

Message-ID: <CAJGeiUjDcuC4=b5Cy8HFMKt7iDZjm0CU5w+2e=r-hCEuMD4UWg@mail.gmail.com>
Date:   Mon, 20 Mar 2023 22:08:45 +0200
From:   Rom Yar <rom.yar.progit@...il.com>
To:     netdev@...r.kernel.org
Subject: Help with source of ebtables extension vlan

Hello,
I'm developing an ebtables extension that works with vlan tag.
As an example, I took a standard vlan matcher
https://elixir.bootlin.com/linux/v5.17.15/source/net/bridge/netfilter/ebt_vlan.c#L36
And it remains unclear to me under what conditions
skb_vlan_tag_present (skb) can return false?
More precisely, under what conditions can an ethernet frame having a
vlan tag not be translated into the flag skb-> vlan_present?
Thanks for any help you can provide!
Regards Rom