netdev - Re: [PATCH net] tcp: do not accept ACK of bytes we never sent

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Message-Id: 
 <170191862414.7525.5415234550799392597.git-patchwork-notify@kernel.org>
Date: Thu, 07 Dec 2023 03:10:24 +0000
From: patchwork-bot+netdevbpf@...nel.org
To: Eric Dumazet <edumazet@...gle.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 ncardwell@...gle.com, ycheng@...gle.com, soheil@...gle.com,
 netdev@...r.kernel.org, eric.dumazet@...il.com, yepeng.pan@...pa.de,
 rossow@...pa.de
Subject: Re: [PATCH net] tcp: do not accept ACK of bytes we never sent

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@...nel.org>:

On Tue,  5 Dec 2023 16:18:41 +0000 you wrote:
> This patch is based on a detailed report and ideas from Yepeng Pan
> and Christian Rossow.
> 
> ACK seq validation is currently following RFC 5961 5.2 guidelines:
> 
>    The ACK value is considered acceptable only if
>    it is in the range of ((SND.UNA - MAX.SND.WND) <= SEG.ACK <=
>    SND.NXT).  All incoming segments whose ACK value doesn't satisfy the
>    above condition MUST be discarded and an ACK sent back.  It needs to
>    be noted that RFC 793 on page 72 (fifth check) says: "If the ACK is a
>    duplicate (SEG.ACK < SND.UNA), it can be ignored.  If the ACK
>    acknowledges something not yet sent (SEG.ACK > SND.NXT) then send an
>    ACK, drop the segment, and return".  The "ignored" above implies that
>    the processing of the incoming data segment continues, which means
>    the ACK value is treated as acceptable.  This mitigation makes the
>    ACK check more stringent since any ACK < SND.UNA wouldn't be
>    accepted, instead only ACKs that are in the range ((SND.UNA -
>    MAX.SND.WND) <= SEG.ACK <= SND.NXT) get through.
> 
> [...]

Here is the summary with links:
  - [net] tcp: do not accept ACK of bytes we never sent
    https://git.kernel.org/netdev/net/c/3d501dd326fb

You are awesome, thank you!
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