netdev - Re: [bpf PATCH 1/3] bpf: tls, implement unhash to avoid transition out of ESTABLISHED

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Date:   Wed, 24 Apr 2019 15:40:36 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [bpf PATCH 1/3] bpf: tls, implement unhash to avoid transition
 out of ESTABLISHED

On Wed, 24 Apr 2019 12:21:03 -0700, John Fastabend wrote:
> It is possible (via shutdown()) for TCP socks to go through TCP_CLOSE
> state via tcp_disconnect() without calling into close callback. This
> would allow a kTLS enabled socket to exist outside of ESTABLISHED
> state which is not supported.
> 
> Solve this the same way we solved the sock{map|hash} case by adding
> an unhash hook to remove tear down the TLS state.
> 
> In the process we also make the close hook more robust. We add a put
> call into the close path, also in the unhash path, to remove the
> reference to ulp data after free. Its no longer valid and may confuse
> things later if the socket (re)enters kTLS code paths. Second we add
> an 'if(ctx)' check to ensure the ctx is still valid and not released
> from a previous unhash/close path.
> 
> Fixes: d91c3e17f75f2 ("net/tls: Only attach to sockets in ESTABLISHED state")
> Reported-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: John Fastabend <john.fastabend@...il.com>

Nice, I think we were running into this!