Re: [PATCH net-next] macvlan: pass get_ts_info and SIOC[SG]HWTSTAMP ioctl to real device

[Hangbin Liu <liuhangbin@gmail.com>]

Hi Miroslav,
On Thu, Apr 18, 2019 at 10:05:09AM +0200, Miroslav Lichvar wrote:
> > So I guess the macvlan should reject SIOCSHWTSTAMP but allow
> > SIOCGHWTSTAMP.
> 
> FWIW, my suggestion was to limit what the SIOCSHWTSTAMP ioctl can do
> on the virtual interface. It could only enable HW timestamping or

I think this is not enough as user could enable HWTSTAMP_FILTER_NONE.

> select a more general filter. A container could run a PTP clock if it

Do you have an idea about how to select a general filter? If we have enabled
HWTSTAMP_FILTER_PTP_V2_L4_SYNC on host and a user in container want to enable
HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ, then which one is more general?

> had also access to the PHC device, or it could have the NET_ADMIN
> capability for other reasons, but it couldn't disable HW timestamping
> enabled by the host or other container.
> 
> If I understand it correctly, even without this ioctl a container can
> prevent the host or other containers from getting some of the HW
> timestamps by requesting TX timestamps at a high rate. I suspect the

Could traffic sharping/limitation fix it?

> timestamping would need to be restricted to the real interface to
> fully protect it from applications having access to the virtual
> interfaces.

Thanks
Hangbin