netdev - Re: [PATCH net-next 0/5] tcp: Introduce a TFO key-pool for clean cookie-rotation

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Date:   Sun, 16 Dec 2018 21:54:49 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>, cpaasch@...le.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, ycheng@...gle.com
Subject: Re: [PATCH net-next 0/5] tcp: Introduce a TFO key-pool for clean
 cookie-rotation



On 12/16/2018 12:19 PM, David Miller wrote:
> From: Christoph Paasch <cpaasch@...le.com>
> Date: Fri, 14 Dec 2018 14:40:02 -0800
> 
>> Currently, TFO only allows a single TFO-secret. This means that whenever
>> the secret gets changed for key-rotation purposes, all the previously
>> issued TFO-cookies become invalid. This means that clients will fallback
>> to "regular" TCP, incurring a cost of one additional round-trip.
>>
>> This patchset introduces a TFO key-pool that allows to more gracefully
>> change the key. The size of the pool is 2 (this could be changed in the
>> future through a sysctl if needed). When a client connects with an "old"
>> TFO cookie, the server will now accept the data in the SYN and at the
>> same time announce a new TFO-cookie to the client.
>>
>> We have seen a significant reduction of LINUX_MIB_TCPFASTOPENPASSIVEFAIL
>> thanks to these patches. Invalid cookies are now solely observed when
>> clients behind a NAT are getting a new public IP.
> 
> Yuchung and Eric, please review.
> 

Thanks David, I will do now.