From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:44146) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gjWfu-0005NF-3u for qemu-devel@nongnu.org; Tue, 15 Jan 2019 16:55:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gjWfr-0007hg-0f for qemu-devel@nongnu.org; Tue, 15 Jan 2019 16:55:09 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:32807) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gjWfq-0007gG-Q8 for qemu-devel@nongnu.org; Tue, 15 Jan 2019 16:55:06 -0500 Received: by mail-qt1-f194.google.com with SMTP id l11so4895169qtp.0 for ; Tue, 15 Jan 2019 13:55:06 -0800 (PST) MIME-Version: 1.0 References: <20190115145256.9593-1-berrange@redhat.com> <20190115145256.9593-12-berrange@redhat.com> In-Reply-To: <20190115145256.9593-12-berrange@redhat.com> From: =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= Date: Wed, 16 Jan 2019 01:54:54 +0400 Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 11/12] chardev: disallow TLS/telnet/websocket with tcp_chr_wait_connected List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= Cc: qemu-devel , Thomas Huth , Yongji Xie , Laurent Vivier , Paolo Bonzini On Tue, Jan 15, 2019 at 6:54 PM Daniel P. Berrang=C3=A9 wrote: > > In the previous commit > > commit 1dc8a6695c731abb7461c637b2512c3670d82be4 > Author: Marc-Andr=C3=A9 Lureau > Date: Tue Aug 16 12:33:32 2016 +0400 > > char: fix waiting for TLS and telnet connection > > the tcp_chr_wait_connected() method was changed to check for a non-NULL > 's->ioc' as a sign that there is already a connection present, as > opposed to checking the "connected" flag to supposedly fix handling of > TLS/telnet connections. > > The original code would repeatedly call tcp_chr_wait_connected creating > many connections as 'connected' would never become true. The changed > code would still repeatedly call tcp_chr_wait_connected busy waiting > because s->ioc is set but the chardev will never see CHR_EVENT_OPENED. > IOW, the code is still broken with TLS/telnet, but in a different way. > > Checking for a non-NULL 's->ioc' does not mean that a CHR_EVENT_OPENED > will be ready for a TLS/telnet connection. These protocols (and the > websocket protocol) all require the main loop to be running in order > to complete the protocol handshake before emitting CHR_EVENT_OPENED. > The tcp_chr_wait_connected() method is only used during early startup > before a main loop is running, so TLS/telnet/websock connections can > never complete initialization. > > Making this work would require changing tcp_chr_wait_connected to run > a main loop. This is quite complex since we must not allow GSource's > that other parts of QEMU have registered to run yet. The current callers > of tcp_chr_wait_connected do not require use of the TLS/telnet/websocket > protocols, so the simplest option is to just forbid this combination > completely for now. > > Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Marc-Andr=C3=A9 Lureau > --- > chardev/char-socket.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/chardev/char-socket.c b/chardev/char-socket.c > index 91d775e9c5..7e98a95bbd 100644 > --- a/chardev/char-socket.c > +++ b/chardev/char-socket.c > @@ -951,8 +951,20 @@ static void tcp_chr_accept_server_sync(Chardev *chr) > static int tcp_chr_wait_connected(Chardev *chr, Error **errp) > { > SocketChardev *s =3D SOCKET_CHARDEV(chr); > - /* It can't wait on s->connected, since it is set asynchronously > - * in TLS and telnet cases, only wait for an accepted socket */ > + const char *opts[] =3D { "telnet", "tn3270", "websock", "tls-creds" = }; > + bool optset[] =3D { s->is_telnet, s->is_tn3270, s->is_websock, s->tl= s_creds }; > + size_t i; > + > + QEMU_BUILD_BUG_ON(G_N_ELEMENTS(opts) !=3D G_N_ELEMENTS(optset)); > + for (i =3D 0; i < G_N_ELEMENTS(opts); i++) { > + if (optset[i]) { > + error_setg(errp, > + "'%s' option is incompatible with waiting for " > + "connection during early startup", opts[i]); "during early startup" ? I think you could also reach this by using chardev-add & netdev_add. > + return -1; > + } > + } > + > while (!s->ioc) { > if (s->is_listen) { > tcp_chr_accept_server_sync(chr); > -- > 2.20.1 >