Re: [PATCH nf-next v4 1/2] net: netfilter: Add IPIP flowtable SW acceleration

[Florian Westphal <fw@strlen.de>]

Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> > Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> > > +static bool nf_flow_ip4_encap_proto(struct sk_buff *skb, u16 *size)
> > > +{
> > > +	struct iphdr *iph;
> > > +
> > > +	if (!pskb_may_pull(skb, sizeof(*iph)))
> > > +		return false;
> > 
> > Nit: I think this could be 2 * sizeof() and a comment that we will
> > also need the inner ip header later, might save one reallocation.
> 
> nf_flow_ip4_encap_proto() is used even for plain IP traffic but I guess we can
> assume the IP payload is at least 20B, right?

Oh, right, I missed that.  But even if we have a.g. ip header with icmp
header, then the postconditions are the same, no?

as-is:
pskb_may_pull -> ok, then iph->protocol == IPPROTO_IPIP -> return false

with 2*iph:
pskb_may_pull -> return false

... but I'll leave it up to you, if you prefer pskb_may_pull(skb, sizeof(*iph)))
for clarity then lets keep it as-is.

> > > +	iph = (struct iphdr *)skb_network_header(skb);
> > > +	*size = iph->ihl << 2;
> > 
> > I think this should be sanity tested vs. sizeof(iph).
> 
> I guess this is already done in ip_has_options(), agree?

Indeed it is!  Nevermind then :-)