Re: [RFC PATCH net-next v2 7/8] openvswitch: Delay conntrack helper call for new connections.

[Patrick McHardy <kaber-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>]

On 06.11, Jarno Rajahalme wrote:
> There is no need to help connections that are not confirmed, so we can
> delay helping new connections to the time when they are confirmed.
> This change is needed for NAT support, and having this as a separate
> patch will make the following NAT patch a bit easier to review.

For the first packet a helper receives the connection is always unconfirmed.
It makes no sense to confirm it if the helper drops the packet.

> Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
> ---
>  net/openvswitch/conntrack.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> index 7aa38fa..ba44287 100644
> --- a/net/openvswitch/conntrack.c
> +++ b/net/openvswitch/conntrack.c
> @@ -458,6 +458,7 @@ static bool skb_nfct_cached(struct net *net,
>  /* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if
>   * not done already.  Update key with new CT state after passing the packet
>   * through conntrack.
> + * Note that invalid packets are accepted while the skb->nfct remains unset!
>   */
>  static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  			   const struct ovs_conntrack_info *info,
> @@ -468,7 +469,11 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  	 * actually run the packet through conntrack twice unless it's for a
>  	 * different zone.
>  	 */
> -	if (!skb_nfct_cached(net, key, info, skb)) {
> +	bool cached = skb_nfct_cached(net, key, info, skb);
> +	enum ip_conntrack_info ctinfo;
> +	struct nf_conn *ct;
> +
> +	if (!cached) {
>  		struct nf_conn *tmpl = info->ct;
>  		int err;
>  
> @@ -491,11 +496,16 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  			return -ENOENT;
>  
>  		ovs_ct_update_key(skb, key, true);
> +	}
>  
> -		if (ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> -			WARN_ONCE(1, "helper rejected packet");
> -			return -EINVAL;
> -		}
> +	/* Call the helper right after nf_conntrack_in() for confirmed
> +	 * connections, but only when commiting for unconfirmed connections.
> +	 */
> +	ct = nf_ct_get(skb, &ctinfo);
> +	if (ct && (nf_ct_is_confirmed(ct) ? !cached : info->commit)
> +	    && ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> +		WARN_ONCE(1, "helper rejected packet");
> +		return -EINVAL;
>  	}
>  
>  	return 0;
> -- 
> 2.1.4
> 
> --
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