On Fri, Dec 08, 2017 at 07:47:02AM +0100, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> > diff --git a/include/uapi/linux/netfilter/nf_conntrack_common.h b/include/uapi/linux/netfilter/nf_conntrack_common.h
> > index dc947e59d03a..6b463b88182d 100644
> > --- a/include/uapi/linux/netfilter/nf_conntrack_common.h
> > +++ b/include/uapi/linux/netfilter/nf_conntrack_common.h
> > @@ -100,6 +100,10 @@ enum ip_conntrack_status {
> > IPS_HELPER_BIT = 13,
> > IPS_HELPER = (1 << IPS_HELPER_BIT),
> >
> > + /* Conntrack has been offloaded to flow table. */
> > + IPS_OFFLOAD_BIT = 14,
> > + IPS_OFFLOAD = (1 << IPS_OFFLOAD_BIT),
> > +
> > /* Be careful here, modifying these bits can make things messy,
> > * so don't let users modify them directly.
> > */
>
> I think this new bit has to be added to the UNCHANGEABLE mask below.
Right.
> > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> > index 01130392b7c0..02e195accd47 100644
> > --- a/net/netfilter/nf_conntrack_core.c
> > +++ b/net/netfilter/nf_conntrack_core.c
> > @@ -901,6 +901,9 @@ static unsigned int early_drop_list(struct net *net,
> > hlist_nulls_for_each_entry_rcu(h, n, head, hnnode) {
> > tmp = nf_ct_tuplehash_to_ctrack(h);
> >
> > + if (test_bit(IPS_OFFLOAD_BIT, &tmp->status))
> > + continue;
> > +
>
> nit: I would move this below the ASSURED bit check, AFAIU most
> (all?) offloaded conntracks are not in ASSURED state since they never
> see two-way communication but in case we've mixed flows or no offloading
> in place then the ASSURED check takes care of skipping earlydrop
> already.
Offload happens once we enter established state (or later if your rule
postpone it to a later stage), that is before we observe the full
3-way handshake in tcp, hence the assured bit. So I think we still
need this here.
> > +/* Set an arbitrary timeout large enough not to ever expire, this save
> > + * us a check for the IPS_OFFLOAD_BIT from the packet path via
> > + * nf_ct_is_expired().
> > + */
> > +static void nf_ct_offload_timeout(struct nf_conn *ct)
> > +{
> > + ct->timeout = nfct_time_stamp + DAY;
> > +}
>
> Not sure if its worth adding a test to avoid unconditional write,
> e.g. something like
>
> > +static void nf_ct_offload_timeout(struct nf_conn *ct)
> > +{
> if (nf_ct_expires(ct) < DAY/2))
> > + ct->timeout = nfct_time_stamp + DAY;
>
> but perhaps not worth it, gc_worker is infrequent.
That's fine, I'll do this.
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