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Message-ID: <CADvbK_cungrr_D5VAiL8C+FSJEoLFYtMxV5foU0XA9E4zrcegA@mail.gmail.com>
Date: Sun, 2 Mar 2025 13:22:59 -0500
From: Xin Long <lucien.xin@...il.com>
To: Jianbo Liu <jianbol@...dia.com>
Cc: network dev <netdev@...r.kernel.org>, dev@...nvswitch.org, ovs-dev@...nvswitch.org,
davem@...emloft.net, kuba@...nel.org, Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, Pravin B Shelar <pshelar@....org>, Ilya Maximets <i.maximets@....org>,
Aaron Conole <aconole@...hat.com>, Florian Westphal <fw@...len.de>
Subject: Re: [PATCHv2 net-next] openvswitch: switch to per-action label
counting in conntrack
On Tue, Feb 25, 2025 at 9:57 AM Xin Long <lucien.xin@...il.com> wrote:
>
> On Mon, Feb 24, 2025 at 8:38 PM Jianbo Liu <jianbol@...dia.com> wrote:
> >
> >
> >
> > On 2/25/2025 3:55 AM, Xin Long wrote:
> > > On Mon, Feb 24, 2025 at 4:01 AM Jianbo Liu <jianbol@...dia.com> wrote:
> > >>
> > >>
> > >>
> > >> On 8/13/2024 1:17 AM, Xin Long wrote:
> > >>> Similar to commit 70f06c115bcc ("sched: act_ct: switch to per-action
> > >>> label counting"), we should also switch to per-action label counting
> > >>> in openvswitch conntrack, as Florian suggested.
> > >>>
> > >>> The difference is that nf_connlabels_get() is called unconditionally
> > >>> when creating an ct action in ovs_ct_copy_action(). As with these
> > >>> flows:
> > >>>
> > >>> table=0,ip,actions=ct(commit,table=1)
> > >>> table=1,ip,actions=ct(commit,exec(set_field:0xac->ct_label),table=2)
> > >>>
> > >>> it needs to make sure the label ext is created in the 1st flow before
> > >>> the ct is committed in ovs_ct_commit(). Otherwise, the warning in
> > >>> nf_ct_ext_add() when creating the label ext in the 2nd flow will
> > >>> be triggered:
> > >>>
> > >>> WARN_ON(nf_ct_is_confirmed(ct));
> > >>>
> > >>
> > >> Hi Xin Long,
> > >>
> > >> The ct can be committed before openvswitch handles packets with CT
> > >> actions. And we can trigger the warning by creating VF and running ping
> > >> over it with the following configurations:
> > >>
> > >> ovs-vsctl add-br br
> > >> ovs-vsctl add-port br eth2
> > >> ovs-vsctl add-port br eth4
> > >> ovs-ofctl add-flow br "table=0, in_port=eth4,ip,ct_state=-trk
> > >> actions=ct(table=1)"
> > >> ovs-ofctl add-flow br "table=1, in_port=eth4,ip,ct_state=+trk+new
> > >> actions=ct(exec(set_field:0xef7d->ct_label), commit), output:eth2"
> > >> ovs-ofctl add-flow br "table=1, in_port=eth4,ip,ct_label=0xef7d,
> > >> ct_state=+trk+est actions=output:eth2"
> > >>
> > >> The eth2 is PF, and eth4 is VF's representor.
> > >> Would you like to fix it?
> > > Hi, Jianbo,
> > >
> > > Sure, we have to attach a new ct to the skb in __ovs_ct_lookup() for
> > > this case, and even delete the one created before ovs_ct.
> > >
> > > Can you check if this works on your env?
> >
> > Yes, it works.
> > Could you please submit the formal patch? Thanks!
> Great, I will post after running some of my local tests.
>
Hi Jianbo,
I recently ran some tests and observed that the current approach cannot
completely avoid the warning. If an skb enters __ovs_ct_lookup() without
an attached connection tracking (ct) entry, it may still acquire an
existing ct created outside of OVS (possibly by netfilter) through
nf_conntrack_in(). This will trigger the warning in ovs_ct_set_labels().
Deleting a ct created outside OVS and creating a new one within
__ovs_ct_lookup() doesn't seem reasonable and would be difficult to
implement. However, since OVS is not supposed to use ct entries created
externally, I believe ct zones can be used to prevent this issue.
In your case, the following flows should work:
ovs-ofctl add-flow br "table=0, in_port=eth4,ip,ct_state=-trk
actions=ct(table=1,zone=1)"
ovs-ofctl add-flow br "table=1,
in_port=eth4,ip,ct_state=+trk+new,ct_zone=1
actions=ct(exec(set_field:0xef7d->ct_label),commit,zone=1),
output:eth2"
ovs-ofctl add-flow br "table=1,
in_port=eth4,ip,ct_label=0xef7d,ct_state=+trk+est,ct_zone=1
actions=output:eth2"
Regarding the warning triggered by externally created ct entries, I plan
to remove the ovs_ct_get_conn_labels() call from ovs_ct_set_labels() and
I'll let nf_connlabels_replace() return an error in such cases, similar
to how tcf_ct_act_set_labels() handles this scenario in tc act_ct.
Thanks.
> >
> > >
> > > diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> > > index 3bb4810234aa..c599ee013dfe 100644
> > > --- a/net/openvswitch/conntrack.c
> > > +++ b/net/openvswitch/conntrack.c
> > > @@ -595,6 +595,11 @@ static bool skb_nfct_cached(struct net *net,
> > > rcu_dereference(timeout_ext->timeout))
> > > return false;
> > > }
> > > + if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) && !nf_ct_labels_find(ct)) {
> > > + if (nf_ct_is_confirmed(ct))
> > > + nf_ct_delete(ct, 0, 0);
> > > + return false;
> > > + }
> > >
> > > Thanks.
> > >
> > >>
> > >> Thanks!
> > >> Jianbo
> > >>
> > >>> Signed-off-by: Xin Long <lucien.xin@...il.com>
> > >>> ---
> > >>> v2: move ovs_net into #if in ovs_ct_exit() as Jakub noticed.
> > >>> ---
> > >>> net/openvswitch/conntrack.c | 30 ++++++++++++------------------
> > >>> net/openvswitch/datapath.h | 3 ---
> > >>> 2 files changed, 12 insertions(+), 21 deletions(-)
> > >>>
> > >>> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> > >>> index 8eb1d644b741..a3da5ee34f92 100644
> > >>> --- a/net/openvswitch/conntrack.c
> > >>> +++ b/net/openvswitch/conntrack.c
> > >>> @@ -1368,11 +1368,8 @@ bool ovs_ct_verify(struct net *net, enum ovs_key_attr attr)
> > >>> attr == OVS_KEY_ATTR_CT_MARK)
> > >>> return true;
> > >>> if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
> > >>> - attr == OVS_KEY_ATTR_CT_LABELS) {
> > >>> - struct ovs_net *ovs_net = net_generic(net, ovs_net_id);
> > >>> -
> > >>> - return ovs_net->xt_label;
> > >>> - }
> > >>> + attr == OVS_KEY_ATTR_CT_LABELS)
> > >>> + return true;
> > >>>
> > >>> return false;
> > >>> }
> > >>> @@ -1381,6 +1378,7 @@ int ovs_ct_copy_action(struct net *net, const struct nlattr *attr,
> > >>> const struct sw_flow_key *key,
> > >>> struct sw_flow_actions **sfa, bool log)
> > >>> {
> > >>> + unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
> > >>> struct ovs_conntrack_info ct_info;
> > >>> const char *helper = NULL;
> > >>> u16 family;
> > >>> @@ -1409,6 +1407,12 @@ int ovs_ct_copy_action(struct net *net, const struct nlattr *attr,
> > >>> return -ENOMEM;
> > >>> }
> > >>>
> > >>> + if (nf_connlabels_get(net, n_bits - 1)) {
> > >>> + nf_ct_tmpl_free(ct_info.ct);
> > >>> + OVS_NLERR(log, "Failed to set connlabel length");
> > >>> + return -EOPNOTSUPP;
> > >>> + }
> > >>> +
> > >>> if (ct_info.timeout[0]) {
> > >>> if (nf_ct_set_timeout(net, ct_info.ct, family, key->ip.proto,
> > >>> ct_info.timeout))
> > >>> @@ -1577,6 +1581,7 @@ static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info)
> > >>> if (ct_info->ct) {
> > >>> if (ct_info->timeout[0])
> > >>> nf_ct_destroy_timeout(ct_info->ct);
> > >>> + nf_connlabels_put(nf_ct_net(ct_info->ct));
> > >>> nf_ct_tmpl_free(ct_info->ct);
> > >>> }
> > >>> }
> > >>> @@ -2002,17 +2007,9 @@ struct genl_family dp_ct_limit_genl_family __ro_after_init = {
> > >>>
> > >>> int ovs_ct_init(struct net *net)
> > >>> {
> > >>> - unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
> > >>> +#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> > >>> struct ovs_net *ovs_net = net_generic(net, ovs_net_id);
> > >>>
> > >>> - if (nf_connlabels_get(net, n_bits - 1)) {
> > >>> - ovs_net->xt_label = false;
> > >>> - OVS_NLERR(true, "Failed to set connlabel length");
> > >>> - } else {
> > >>> - ovs_net->xt_label = true;
> > >>> - }
> > >>> -
> > >>> -#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> > >>> return ovs_ct_limit_init(net, ovs_net);
> > >>> #else
> > >>> return 0;
> > >>> @@ -2021,12 +2018,9 @@ int ovs_ct_init(struct net *net)
> > >>>
> > >>> void ovs_ct_exit(struct net *net)
> > >>> {
> > >>> +#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> > >>> struct ovs_net *ovs_net = net_generic(net, ovs_net_id);
> > >>>
> > >>> -#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> > >>> ovs_ct_limit_exit(net, ovs_net);
> > >>> #endif
> > >>> -
> > >>> - if (ovs_net->xt_label)
> > >>> - nf_connlabels_put(net);
> > >>> }
> > >>> diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
> > >>> index 9ca6231ea647..365b9bb7f546 100644
> > >>> --- a/net/openvswitch/datapath.h
> > >>> +++ b/net/openvswitch/datapath.h
> > >>> @@ -160,9 +160,6 @@ struct ovs_net {
> > >>> #if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> > >>> struct ovs_ct_limit_info *ct_limit_info;
> > >>> #endif
> > >>> -
> > >>> - /* Module reference for configuring conntrack. */
> > >>> - bool xt_label;
> > >>> };
> > >>>
> > >>> /**
> > >>
> >
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