Re: [PATCH net-next 0/5] net: make xdp config checks effective vs netif_xdp_propagate()

[Stanislav Fomichev <sdf.kernel@gmail.com>]

On 11/12, Jakub Kicinski wrote:
> Bonding (and netvsc) try to auto-propagate XDP programs down
> to their lower devices. These programs were installed directly
> with .ndo_bpf and not recorded in struct net_device of the lowers.
> This makes all the config checks for features incompatible with XDP
> ineffective - HDS, memory providers etc. use dev_xdp_prog_count()
> and do not call down to the driver to ask it whether it has XDP
> installed.
> 
> Record the state appropriately. dev_xdp_prog_count() will now
> "see" the propagated programs.
> 
> The issue was discovered when reworking HW-GRO and XDP interactions.
> I was trying to make sure HW-GRO is reliably disabled with XDP,
> and discovered we have a way to bypass all checks with bonding.
> Not treating this as a fix since it's admin-only self-inflicted
> damage that nobody is reporting being bothered by in real life.
> 
> Jakub Kicinski (5):
>   net: don't safety-check device features for XDP uninstall
>   net: move dev_xdp_set_link() and dev_xdp_set_prog() up
>   net: record XDP programs propagated to lower devices
>   selftests/bpf: check XDP attach on a nested bond slave
>   selftests/bpf: check replacing and detaching XDP on a bond through a
>     link

Acked-by: Stanislav Fomichev <sdf@fomichev.me>