netdev - Re: [bpf PATCH v2 2/6] bpf: tls fix transition through disconnect with close

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Date:   Thu, 11 Jul 2019 09:47:16 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        edumazet@...gle.com, bpf@...r.kernel.org
Subject: Re: [bpf PATCH v2 2/6] bpf: tls fix transition through disconnect
 with close

Jakub Kicinski wrote:
> On Wed, 10 Jul 2019 12:34:17 -0700, Jakub Kicinski wrote:
> > > > > +		if (sk->sk_prot->unhash)
> > > > > +			sk->sk_prot->unhash(sk);
> > > > > +	}
> > > > > +
> > > > > +	ctx = tls_get_ctx(sk);
> > > > > +	if (ctx->tx_conf == TLS_SW || ctx->rx_conf == TLS_SW)
> > > > > +		tls_sk_proto_cleanup(sk, ctx, timeo);
> 
> Do we still need to hook into unhash? With patch 6 in place perhaps we
> can just do disconnect 🥺

?? "can just do a disconnect", not sure I folow. We still need unhash
in cases where we have a TLS socket transition from ESTABLISHED
to LISTEN state without calling close(). This is independent of if
sockmap is running or not.

Originally, I thought this would be extremely rare but I did see it
in real applications on the sockmap side so presumably it is possible
here as well.

> 
> cleanup is going to kick off TX but also:
> 
> 	if (unlikely(sk->sk_write_pending) &&
> 	    !wait_on_pending_writer(sk, &timeo))
> 		tls_handle_open_record(sk, 0);
> 
> Are we guaranteed that sk_write_pending is 0?  Otherwise
> wait_on_pending_writer is hiding yet another release_sock() :(

Not seeing the path to release_sock() at the moment?

   tls_handle_open_record
     push_pending_record
      tls_sw_push_pending_record
        bpf_exec_tx_verdict

If bpf_exec_tx_verdict does a redirect we could hit a relase but that
is another fix I have to get queued up shortly. I think we can fix
that in another series.