From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAD13C433E0 for ; Fri, 29 Jan 2021 10:03:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1DC6664E06 for ; Fri, 29 Jan 2021 10:03:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DC6664E06 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41088 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l5Qcz-00081n-Pl for qemu-devel@archiver.kernel.org; Fri, 29 Jan 2021 05:03:45 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:51244) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l5Qbz-0007Xu-VD for qemu-devel@nongnu.org; Fri, 29 Jan 2021 05:02:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25818) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l5Qbw-0007c3-AK for qemu-devel@nongnu.org; Fri, 29 Jan 2021 05:02:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611914556; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tuj2QxTlXChf1k6zSNCZTpbI1/Qd3/T77oxmpbNdEmI=; b=Lngi3ofO8Yqp8g3WyZsYlAzKYUjpX2H8B+ouAXCiNgYZGgE100aH5WaBWVVd6bUxTIveAA H2x1O2XtGItBr4E8FWrD/lF0UI5P3gvzpL1sdvPOJ381GKbKB2AmK5+jvO5XTzBrAHsNvf KJwKcFjEU/lawStAnmVGp3rdKI0JYfE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-459-Ii8mqpt0NHWn1JlPEIz_OA-1; Fri, 29 Jan 2021 05:02:34 -0500 X-MC-Unique: Ii8mqpt0NHWn1JlPEIz_OA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7D1DE107ACE3 for ; Fri, 29 Jan 2021 10:02:33 +0000 (UTC) Received: from redhat.com (ovpn-115-94.ams2.redhat.com [10.36.115.94]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 90E5860BE2; Fri, 29 Jan 2021 10:02:29 +0000 (UTC) Date: Fri, 29 Jan 2021 10:02:26 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Laszlo Ersek Subject: Re: vnc clipboard support Message-ID: <20210129100226.GD4001740@redhat.com> References: <20210128171224.exbklnwtyb232oe2@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.252, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Gerd Hoffmann , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jan 28, 2021 at 06:57:24PM +0100, Laszlo Ersek wrote: > On 01/28/21 18:12, Gerd Hoffmann wrote: > > Hi folks, > > > > I'm looking for a good way to implement cut+paste support for vnc. > > > > The vnc core protocol has support for text/plain cut+paste, and there > > is an extension adding support for other formats. That'll cover one > > part of the problem, exchanging cut+paste data between vnc client and > > qemu vnc server. > > > > The tricky part is the second: the guest <=> qemu communication. > > I see basically two possible approaches here: > > > > (1) Have some guest agent (spice does it that way). > > Advantage: more flexible, allows more features. > > Disadvantage: requires agent in the guest. > > > > (2) Send text as key events. > > Advantage: no guest agent needed. > > Disadvantage: is translated by guests keyboard map, so qemu > > needs to know the map for proper char -> key event translation. > > Only works for text/plain and only for chars you can easily > > type, anything needing input methods (emoji 😊 for example) > > isn't going to fly. > > > > I think that (1) is clearly the better way. Given that the agent > > would need to run in user wayland/xorg session context the existing > > qemu-guest-agent will not work. Also linking against some UI library > > like gtk3 for clipboard handling is not something we want for the > > qemu-guest-agent. So we need another one, I'll name it > > qemu-clipboard-agent for the rest of this mail. And we need a > > communication channel. > > > > I'd tend to model the qemu-clipboard-agent simliar to the > > qemu-guest-agent, i.e. have some stream as communication path and run > > some stream protocol over it. > > > > Stream options I see are (in order of personal preference): > > > > (1) New virtio-serial port. virtio-serial likely is there anyway > > for the qemu-guest-agent ... > > > > (2) Have qemu-clipboard-agent and qemu-guest-agent share the agent > > channel, i.e. qemu-clipboard-agent will proxy everything through > > qemu-guest-agent (spice does it that way). > > > > Protocol options I see are (not sure yet which to prefer, need to have > > a closer look at the candidates): > > > > (1) Add clipboard commands to QMP and use these. > > > > (2) Reuse the clipboard bits of the vnc protocol (forward > > VNC_MSG_CLIENT_CUT_TEXT messages to the guest agent) > > > > (3) Reuse the clipboard bits of the spice-agent protocol. > > > > (4) Reuse the clipboard bits of the wayland protocol. > > > > Once we have sorted the qemu <-> guest communication path it should be > > possible to also hook up other UIs (specifically gtk) without too much > > effort. Which probably makes (2) a rather poor choice. > > > > Comments? > > Suggestions? > > Other ideas? > > Just a random thought: the guest should not be able to sniff, steal, or > overwrite host-side clipboard (selection) content, without the host user > explicitly requesting a clipboard operation. I understand this is > generally a problem between X11 applications (not so on Wayland, if I > understand correctly), but I assume it becomes graver with > virtualization -- there shouldn't be an unintended channel between > host/guest, or even multiple guests. (Analogy: you can "ssh -X -Y" to > two remote machines at the same time, and assuming "xauth" etc on both > of those remote machines, you can run "gedit" on each of those remote > machines, and cut'n'paste will work between them, *even if* you don't > ask for it -- that's why ssh has a separate option called "-Y". > Cut'n'paste does not work without "-Y". So I believe this is something > to consider here.) Yes, that's a known risk. SPICE lets you disable clipboard synchronization in QEMU, and any client app should also support doing the same. Basically only want clipboard sync if you're using a trustworthy guest. eg where both host and guest admin are the same person, and even then you might not want it sometimes. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|