netdev - vlan tagging problem

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-next>] [day] [month] [year] [list]

Date:   Tue, 11 Apr 2017 15:36:50 -0400
From:   carl h <heyen2000@...il.com>
To:     netdev@...r.kernel.org
Subject: vlan tagging problem

Hi

Hope this is right place to ask this. Looking for help regarding vlan
tagging done by the 8021q driver.

I tried to manually configure a vlan on my target device. I use these
2 vlan config commands, then I ping an IP address and sniff the
packets to look for the vlan tag in the messages.

   vconfig add esw0
   ifconfig esw0.10 10.93.1.2 netmask 255.255.255.0

Despite my attempts, tagging does not occur in any outgoing packets.
However when I tried the exact same method and commands on my Ubuntu
workstation vlan tagging did work without problems.

    Target: mips32, Linux 2.6.39, 802.1Q driver version 1.8

I have looked at the source for the 8021q.ko driver and I keep running
into a dead end trying to figure out where the 4 bytes of vlan data
gets added to the IP header. There are 2 key functions where vlan
information is deciphered and added to a structure that contains vlan
info, but the information never gets added to the header for some
reason.

   vlan_dev_hard_header()
   vlan_dev_hard_start_xmit()

It is clear in the code where vlan information in receive packets gets
removed, but not so clear in the transmit direction where this is
supposed to happen.

Could someone explain to me what I'm missing, and where and how vlan
info gets added to the header for outgoing packets?

thx
/carl