On Tue, Oct 1, 2019 at 11:44 AM Stephen Hemminger
[off-list ref] wrote:

On Mon, 30 Sep 2019 11:16:14 -0400
Willem de Bruijn [off-list ref] wrote:

quoted

On Mon, Sep 30, 2019 at 1:24 AM Sriram Krishnan [off-list ref] wrote:

quoted

When an application sends with AF_PACKET and places a vlan header on
the raw packet; then the AF_PACKET needs to move the tag into the skb
so that it gets processed normally through the rest of the transmit
path.

This is particularly a problem on Hyper-V where the host only allows
vlan in the offload info.

This sounds like behavior that needs to be addressed in the driver, instead?

This was what we did first, but the problem was more general.
For example, many filtering functions assume that vlan tag is in
skb meta data, not the packet data itself.

Out of curiosity, can you share an example?

Therefore AF_PACKET would
get around any filter rules.

Packet sockets are not the only way to inject packets into the kernel.
This probably also affects tap.