netdev - Re: [net v3] net/tls: missing received data after fast remote close

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Message-ID: <20201120102637.7d36a9f1@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 20 Nov 2020 10:26:37 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vadim Fedorenko <vfedorenko@...ek.ru>
Cc:     Boris Pismenny <borisp@...dia.com>,
        Aviad Yehezkel <aviadye@...dia.com>, netdev@...r.kernel.org
Subject: Re: [net v3] net/tls: missing received data after fast remote close

On Thu, 19 Nov 2020 18:59:48 +0300 Vadim Fedorenko wrote:
> In case when tcp socket received FIN after some data and the
> parser haven't started before reading data caller will receive
> an empty buffer. This behavior differs from plain TCP socket and
> leads to special treating in user-space.
> The flow that triggers the race is simple. Server sends small
> amount of data right after the connection is configured to use TLS
> and closes the connection. In this case receiver sees TLS Handshake
> data, configures TLS socket right after Change Cipher Spec record.
> While the configuration is in process, TCP socket receives small
> Application Data record, Encrypted Alert record and FIN packet. So
> the TCP socket changes sk_shutdown to RCV_SHUTDOWN and sk_flag with
> SK_DONE bit set. The received data is not parsed upon arrival and is
> never sent to user-space.
> 
> Patch unpauses parser directly if we have unparsed data in tcp
> receive queue.
> 
> Signed-off-by: Vadim Fedorenko <vfedorenko@...ek.ru>

Applied, thanks!