On Thu, 2017-07-13 at 10:56 -0700, Shaohua Li wrote: > From: Shaohua Li <s...@fb.com> > > Please see below tcpdump output:
> The tcp reset packet has a different flowlabel, which causes our router > doesn't correctly close tcp connection. This looks a bug in your router, because (IPv6 only) flowlabel is not part of the tuple identifying a TCP flow. > The reason is the normal packet > gets the skb->hash from sk->sk_txhash, which is generated randomly. > ip6_make_flowlabel then uses the hash to create a flowlabel. The reset > packet doesn't get assigned a hash, so the flowlabel is calculated with > flowi6. > > The solution is to save the hash value for timeout sock and use it for > reset packet. I am a bit unsure why we need to add yet another field in TCP timewait structure, since : 1) flowlabel can vary during a TCP flow lifetime. 2) flowlabel is different unde synflood (each syncookie gets a random flowlabel), and if 3rd packet comes back from the client to finish 3WHS, the flowlabel will again be different from the one that SYNACK used.
