From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Brivio Subject: Re: [PATCH net-next 00/11] ICMP error handling for UDP tunnels Date: Wed, 7 Nov 2018 16:21:48 +0100 Message-ID: <20181107162148.447bc995@redhat.com> References: <20181107120951.2a9af149@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , Sabrina Dubroca , Xin Long , netdev@vger.kernel.org To: Jiri Benc Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34802 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726635AbeKHAwo (ORCPT ); Wed, 7 Nov 2018 19:52:44 -0500 In-Reply-To: <20181107120951.2a9af149@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 7 Nov 2018 12:09:51 +0100 Jiri Benc wrote: > On Tue, 6 Nov 2018 22:38:56 +0100, Stefano Brivio wrote: > > - patch 1/11 adds a socket lookup for UDP tunnels that use, by design, > > the same destination port on both endpoints -- i.e. VxLAN and GENEVE > > This is not necessarily true with lwtunnels (collect_md mode of VXLAN > and GENEVE). While any sane setup will use the same dst ports, there's > really nothing that enforces it. Of course, in that case we have no way > to map the ICMP error back to the tunnel. Right, thanks for pointing that out. I will expand on that in the comments to __udp{4,6}_lib_err_encap(). > Generally speaking, I'm not sure how ICMP error handling should work > for external control planes. Are we sure they want PMTU discovery and > route redirection done by the kernel? (I am not sure, neither way.) I'm not sure either, even though I have a slight preference on making this work by default, rather than not even giving lwtunnels a chance by dropping ICMP messages, as it currently stands. By the way, if needed, it's easy to disable or make it configurable: - in geneve_udp_encap_err_lookup(): if (gs->collect_md) return -ENOENT; - in vxlan_err_lookup(): if (vxlan_collect_metadata(gs)) return -ENOENT; but I would rather deal with this at a later moment, and only if the need arises. -- Stefano