From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5115606A31E for ; Thu, 29 Oct 2026 10:57:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=F/yoLZPD Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xMNoJ-0004FR-Hx; Thu, 29 Oct 2026 06:56:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xMNoH-0004Ey-0o for qemu-devel@nongnu.org; Thu, 29 Oct 2026 06:56:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xMNoF-000804-2M for qemu-devel@nongnu.org; Thu, 29 Oct 2026 06:56:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1793271396; 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=d/TObVUdpEQS51CMLsBlkgOOzxelRzlOJyei+dyv4yM=; b=F/yoLZPDv480D1HOWJrDS/a4vQB+AyQuUHURP8rZGY/f/sc4pTGjzZlfM/jXnutOVUVBv2 eWX0K5DUmLdOdGA/xVABq1lxYYnb0HgMUGH355X53a+gFjKwck4sEnCjmYZobXPTayS1ee BRRlgWzhEG2NpEXq53ilCLa8CvP9g40= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-640-F7EVaGa5PJefAuwbiP1JxQ-1; Thu, 29 Oct 2026 06:56:35 -0400 X-MC-Unique: F7EVaGa5PJefAuwbiP1JxQ-1 X-Mimecast-MFC-AGG-ID: F7EVaGa5PJefAuwbiP1JxQ_1793271394 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 76C381955EAA for ; Thu, 29 Oct 2026 10:56:34 +0000 (UTC) Received: from redhat.com (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A10A91956088; Thu, 29 Oct 2026 10:56:33 +0000 (UTC) Date: Thu, 29 Oct 2026 10:56:30 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: qemu-devel@nongnu.org Subject: Re: [PATCH 7/8] qemu-options: document -compat insecure-input parameter Message-ID: References: <20261028133603.1893289-1-berrange@redhat.com> <20261028133603.1893289-8-berrange@redhat.com> <871p99gfrf.fsf@pond.sub.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <871p99gfrf.fsf@pond.sub.org> User-Agent: Mutt/2.4.2 (2026-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, GB_FAKE_RF=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Oct 29, 2026 at 07:52:36AM +0100, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > This adds documentation for the previously added 'insecure-input' > > parameter to -compat, which controls policy for insecure > > configuration requests. > > > > Signed-off-by: Daniel P. Berrangé > > --- > > qemu-options.hx | 22 +++++++++++++++++++++- > > 1 file changed, 21 insertions(+), 1 deletion(-) > > > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 16d9c6c9072..0487e74bb3e 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -4696,7 +4696,9 @@ DEF("compat", HAS_ARG, QEMU_OPTION_compat, > > "-compat [deprecated-input=accept|reject|crash|warn][,deprecated-output=accept|hide]\n" > > " Policy for handling deprecated management interfaces\n" > > "-compat [unstable-input=accept|reject|crash|warn][,unstable-output=accept|hide]\n" > > - " Policy for handling unstable management interfaces\n", > > + " Policy for handling unstable management interfaces\n" > > + "-compat [insecure-input=accept|reject|crash|warn]\n" > > + " Policy for handling requests for insecure configuration requests\n", > > QEMU_ARCH_ALL) > > SRST > > ``-compat [deprecated-input=][,deprecated-output=]`` > > @@ -4734,6 +4736,24 @@ SRST > > Suppress unstable command results and events > > > > Limitation: covers only syntactic aspects of QMP. > > + > > +``-compat [insecure-input=] > > + Set policy for handling requests for insecure configuration > > + requests: > > + > > + ``insecure-input=accept`` (default) > > + Accept insecure configurations requests silently > > + ``insecure-input=warn`` > > + Accept insecure configuration requests with warning on stderr > > + ``insecure-input=reject`` > > + Reject insecure configuration requests > > + ``insecure-input=crash`` > > + Crash on insecure configuration requests > > + > > + Limitation: an insecure configuration is one where QEMU has > > + not intended to provide a security boundary to protect against > > "Where QEMU has not intended to provide" sounds odd to me. Mind, I'm > not a native speaker. "Where QEMU does not provide". Yeah, that language choice was me by pessimistic expecting that QEMU is full of undiscovered flaws. I'll change to what you suggested. > > + malicious usage. Covers only QOM types for devices, machine types > > + and accelerators. > > The policy check is in > > * qemu_create_machine(), which covers machine creation. > > * do_configure_accelerator(), which covers accelerator creation. > > * qdev_device_add_from_qdict(), which covers *some* device creation: > > * device_add and -device always > > * Half of -audio model=hda: covers the "intel-hda" device, but not the > "hda-duplex" device. See intel_hda_and_codec_init(). > > * The "primary device" created in failover_hide_primary_device() for > the virtio-net standby feature. > > * The "usb-host" device device created in xen-usb.c for some reason. > > There's plenty of device creation it doesn't cover. Isn't this > problematic? I certainly expected it to cover *all* device creation! Yes, eventually, but not yet.... > > Say board code creates a certain onboard device with the usual low > level interfaces like qdev_new() and qdev_realize(). Say we mark the > onboard device insecure. The policy check doesn't apply. We need to > manually mark the machine type insecure as well. Feels awfully prone > to human error. > > Moreover, what if the onboard device is configurable? Then the > machine type may be secure unless you configure this insecure device. > Marking the machine type would be too coarse. > > Could we check policy in qdev_realize() instead? Yes and no. To make this a tractable problem I only wanted to add '.secure = true' annotations for public facing types initially, so needed the check in the device_add/-device code path only. This is sufficient to let us tell bug report filers to take their demo command line and add '-compat insecure-input=reject -nodfaults' as a pre-requisite for a bug being considered a security flaw egligible for CVE handling. If we put a check in qdev_realize(), then we need to add annotations for *all* types, before the -compat insecure-input=.... option is viable to use. That requires a much bigger effort to mark all types. In the 12.0 dev cycle, my intention is to a) Expand ".secure = true" markers to all parents of leaf node types marked secure, and enforce them. b) Expand ".secure = true" markers to all built-in devices that are indirectly created by a leaf node type marked secure, when -nodefaults is present Once (b) is done, then qdev_realize() will likely be the better place to put the policy check. With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|