> > That generates TCP packets with different MSS within the same stream. > > > > My suggestion remains to just not change MSS at all. But this has to > > be a new flag to avoid changing established behavior. > > I don't understand why the mss size should be kept in GSO step. Will > there be any issue with different mss? This issue has come up before and that has been the feedback from TCP experts at one point. > In general, upgrading mss make sense when 6 to 4. The new flag would be > set by user to not change mss. What happened if user does not set the > flag? I still think we should fix the issue with a general approach. Or > can we remove the skb_increase_gso_size line? Admins that insert such BPF packets should be aware of these issues. And likely be using clamping. This is a known issue. We arrived that the flag approach in bpf_skb_net_shrink. Extending that to bpf_skb_change_proto would be consistent.
