netdev - Re: combining sockmap + ktls

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Message-ID: <CA+FuTSfdx-T5teraitmFuT-D+8O_LM03MEj6tXgTmr+EB0Zi+A@mail.gmail.com>
Date:   Mon, 18 Nov 2019 10:45:09 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: combining sockmap + ktls

> > > >         @@ -859,6 +861,7 @@ static int __init tls_register(void)
> > > >
> > > >                 tls_sw_proto_ops = inet_stream_ops;
> > > >                 tls_sw_proto_ops.splice_read = tls_sw_splice_read;
> > > >         +       tls_sw_proto_ops.sendpage_locked   = tls_sw_sendpage_locked,
> > > >
> > > > and additionally allowing MSG_NO_SHARED_FRAGS:
> > > >
> > > >          int tls_sw_sendpage_locked(struct sock *sk, struct page *page,
> > > >                                     int offset, size_t size, int flags)
> > > >          {
> > > >                if (flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
> > > >         -                     MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
> > > >         +                     MSG_SENDPAGE_NOTLAST |
> > > > MSG_SENDPAGE_NOPOLICY | MSG_NO_SHARED_FRAGS))
> > > >                          return -ENOTSUPP;
> > > >
> > >
> > > If you had added MSG_NO_SHARED_FRAGS to the existing tls_sw_sendpage
> > > would that have been sufficient?
> >
> > No, the stack trace I observed is
> >
> >   tcp_bpf_sendmsg_redir
> >     tcp_bpf_push_locked
> >       tcp_bpf_push
> >         kernel_sendpage_locked
> >           sock->ops->sendpage_locked
> >
> > which never tries tls_sw_sendpage. Perhaps the relevant part is the
> > following in tcp_bpf_push?
> >
> >                 if (has_tx_ulp) {
> >                         flags |= MSG_SENDPAGE_NOPOLICY;
> >                         ret = kernel_sendpage_locked(sk,
> >                                                      page, off, size, flags);
> >                 } else {
> >                         ret = do_tcp_sendpages(sk, page, off, size, flags);
> >                 }
> >
>
> Got it, want to submit a fix? Or I can this is a bug.
>
> > Do let me know if there's anything I can help out with. Thanks for
> > your quick answer!
>
> Can you send out a fix for above sendpage_locked case?

Done:

 net/tls: enable sk_msg redirect to tls socket egress
 http://patchwork.ozlabs.org/patch/1196825/

It addresses both issues at the same time. This seemed preferable than
two separate patches. MSG_NO_SHARED_FRAGS precedes commit 0608c69c9a80
("bpf: sk_msg, sock{map|hash} redirect through ULP"), so no additional
Fixes tag for that.