netdev - Re: [RFC PATCH v2 06/10] udp: cope with UDP GRO packet misdirection

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Date:   Tue, 23 Oct 2018 12:29:06 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Paolo Abeni <pabeni@...hat.com>
CC:     <netdev@...r.kernel.org>, Willem de Bruijn <willemb@...gle.com>
Subject: Re: [RFC PATCH v2 06/10] udp: cope with UDP GRO packet misdirection

On Mon, Oct 22, 2018 at 02:51:56PM +0200, Paolo Abeni wrote:
> > > +
> > > +static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > > +{
> > > +	struct sk_buff *next, *segs;
> > > +	int ret;
> > > +
> > > +	if (likely(!udp_unexpected_gso(sk, skb)))
> > > +		return udp_queue_rcv_one_skb(sk, skb);
> > > +
> > > +	BUILD_BUG_ON(sizeof(struct udp_skb_cb) > SKB_SGO_CB_OFFSET);
> > > +	__skb_push(skb, -skb_mac_offset(skb));
> > > +	segs = udp_rcv_segment(sk, skb);
> > > +	for (skb = segs; skb; skb = next) {
> > > +		next = skb->next;
> > > +		__skb_pull(skb, skb_transport_offset(skb));
> > > +		ret = udp_queue_rcv_one_skb(sk, skb);
> > 
> > udp_queue_rcv_one_skb() starts with doing a xfrm4_policy_check().
> > Maybe we can do this on the GSO packet instead of the segments.
> > So far this code is just for handling a corner case, but this might
> > change.
> 
> I thought about keeping the policy check here, but then I preferred
> what looked the safest option. Perhaps we can improve with a follow-up?

Fair enough. Let's keep it in mind and do it later.