Re: [ovs-dev] [PATCH net] Revert "openvswitch: switch to per-action label counting in conntrack"

[Aaron Conole <aconole@redhat.com>]

Xin Long <lucien.xin@gmail.com> writes:

> Currently, ovs_ct_set_labels() is only called for confirmed conntrack
> entries (ct) within ovs_ct_commit(). However, if the conntrack entry
> does not have the labels_ext extension, attempting to allocate it in
> ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in
> nf_ct_ext_add():
>
>   WARN_ON(nf_ct_is_confirmed(ct));
>
> This happens when the conntrack entry is created externally before OVS
> increments net->ct.labels_used. The issue has become more likely since
> commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting
> in conntrack"), which changed to use per-action label counting and
> increment net->ct.labels_used when a flow with ct action is added.
>
> Since there’s no straightforward way to fully resolve this issue at the
> moment, this reverts the commit to avoid breaking existing use cases.
>
> Fixes: fcb1aa5163b1 ("openvswitch: switch to per-action label counting in conntrack")
> Reported-by: Jianbo Liu <jianbol@nvidia.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---

I did a quick test using the case provided by Jianbo and I wasn't able
to generate the warning.  If possible, I'd like Jianbo to confirm that
it works as well.

Acked-by: Aaron Conole <aconole@redhat.com>

>  net/openvswitch/conntrack.c | 30 ++++++++++++++++++------------
>  net/openvswitch/datapath.h  |  3 +++
>  2 files changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> index 3bb4810234aa..e573e9221302 100644
> --- a/net/openvswitch/conntrack.c
> +++ b/net/openvswitch/conntrack.c
> @@ -1368,8 +1368,11 @@ 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)
> -		return true;
> +	    attr == OVS_KEY_ATTR_CT_LABELS) {
> +		struct ovs_net *ovs_net = net_generic(net, ovs_net_id);
> +
> +		return ovs_net->xt_label;
> +	}
>  
>  	return false;
>  }
> @@ -1378,7 +1381,6 @@ 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;
> @@ -1407,12 +1409,6 @@ 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))
> @@ -1581,7 +1577,6 @@ 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);
>  	}
>  }
> @@ -2006,9 +2001,17 @@ struct genl_family dp_ct_limit_genl_family __ro_after_init = {
>  
>  int ovs_ct_init(struct net *net)
>  {
> -#if	IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
> +	unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
>  	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;
> @@ -2017,9 +2020,12 @@ 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 365b9bb7f546..9ca6231ea647 100644
> --- a/net/openvswitch/datapath.h
> +++ b/net/openvswitch/datapath.h
> @@ -160,6 +160,9 @@ 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;
>  };
>  
>  /**