From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>, netdev@vger.kernel.org
Subject: Re: [PATCH net 5/5] tcp: send real dupACKs by locking advertized window for non-SACK flows
Date: Wed, 07 Mar 2018 07:58:22 -0800 [thread overview]
Message-ID: <1520438302.109662.42.camel@gmail.com> (raw)
In-Reply-To: <1520427569-14365-6-git-send-email-ilpo.jarvinen@helsinki.fi>
On Wed, 2018-03-07 at 14:59 +0200, Ilpo Järvinen wrote:
> Currently, the TCP code is overly eager to update window on
> every ACK. It makes some of the ACKs that the receiver should
> sent as dupACKs look like they update window update that are
> not considered real dupACKs by the non-SACK sender-side code.
>
> Make sure that when an ofo segment is received, no change to
> window is applied if we are going to send a dupACK. It's ok
> to change the window for non-dupACKs (such as the first ACK
> after ofo arrivals start if that ACK was using delayed ACKs).
This looks dangerous to me.
We certainly want to lower the window at some point, or risk expensive
pruning and/or drops.
It is not clear by reading your changelog/patch, but it looks like some
malicious peers could hurt us.
By current standards, non TCP sack flows are not worth any potential
issues.
next prev parent reply other threads:[~2018-03-07 15:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-07 12:59 [PATCH net 0/5] tcp: fixes to non-SACK TCP Ilpo Järvinen
2018-03-07 12:59 ` [PATCH net 1/5] tcp: feed correct number of pkts acked to cc modules also in recovery Ilpo Järvinen
2018-03-07 12:59 ` [PATCH net 2/5] tcp: prevent bogus FRTO undos with non-SACK flows Ilpo Järvinen
2018-03-07 19:24 ` Neal Cardwell
2018-03-07 19:54 ` Yuchung Cheng
2018-03-07 22:19 ` Ilpo Järvinen
2018-03-07 12:59 ` [PATCH net 3/5] tcp: move false FR condition into tcp_false_fast_retrans_possible() Ilpo Järvinen
2018-03-07 15:50 ` Eric Dumazet
2018-03-07 12:59 ` [PATCH net 4/5] tcp: prevent bogus undos when SACK is not enabled Ilpo Järvinen
2018-03-07 20:19 ` Neal Cardwell
2018-03-07 23:48 ` Yuchung Cheng
2018-03-09 14:11 ` Ilpo Järvinen
2018-03-09 14:32 ` Eric Dumazet
2018-03-09 15:28 ` David Miller
2018-03-09 15:23 ` David Miller
2018-03-09 19:23 ` Ilpo Järvinen
2018-03-13 10:24 ` Ilpo Järvinen
2018-03-07 12:59 ` [PATCH net 5/5] tcp: send real dupACKs by locking advertized window for non-SACK flows Ilpo Järvinen
2018-03-07 15:58 ` Eric Dumazet [this message]
2018-03-07 20:09 ` Ilpo Järvinen
2018-03-07 20:13 ` Eric Dumazet
2018-03-07 21:39 ` Ilpo Järvinen
2018-03-07 22:01 ` Eric Dumazet
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