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 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B105DC43458 for ; Tue, 7 Jul 2026 16:36:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wh8lx-0005ix-Jq; Tue, 07 Jul 2026 12:35:50 -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 1wh8lt-0005iR-KG for qemu-devel@nongnu.org; Tue, 07 Jul 2026 12:35:46 -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 1wh8lr-0003pH-GY for qemu-devel@nongnu.org; Tue, 07 Jul 2026 12:35:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783442142; 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=eUEXje23F2Uj4VPRMzXqFEoH1A0rwil4OjB+w9qljAs=; b=NOn6fDHN7y2VXprnzCRsFbmVtym+KiNzR58eKl8f/8RP30yjurBY+E+NPDyU7u3YKQAjs5 GO7OkZa1ZeQYbQSZdAqgo92N7EBSkOofuk6kEU4nGTXMVa/ZIZ0BMkyS2Erj1hfX9BjyOy OZD/IDI5eWNTMrT4EzpE9jdgGtn1YtY= 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-676-wVY-AThFOxu4z7lhyR-voQ-1; Tue, 07 Jul 2026 12:35:38 -0400 X-MC-Unique: wVY-AThFOxu4z7lhyR-voQ-1 X-Mimecast-MFC-AGG-ID: wVY-AThFOxu4z7lhyR-voQ_1783442137 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 63BA919540D2; Tue, 7 Jul 2026 16:35:37 +0000 (UTC) Received: from redhat.com (unknown [10.44.33.142]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B2319180075D; Tue, 7 Jul 2026 16:35:33 +0000 (UTC) Date: Tue, 7 Jul 2026 17:35:30 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Cc: qemu-devel@nongnu.org, Thomas Huth , Alex =?utf-8?Q?Benn=C3=A9e?= , =?utf-8?Q?C=C3=A9dric?= Le Goater , Peter Maydell , Mauro Matteo Cascella , "Michael S. Tsirkin" , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Pierrick Bouvier Subject: Re: [PATCH] docs: outline some guidelines for security classification Message-ID: References: <20260707105927.2776822-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.3.2 (2026-04-26) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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: 8 X-Spam_score: 0.8 X-Spam_bar: / X-Spam_report: (0.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=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-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Jul 07, 2026 at 04:43:43PM +0400, Marc-André Lureau wrote: > Hi > > On Tue, Jul 7, 2026 at 2:59 PM Daniel P. Berrangé wrote: > > > > Beyond the overall virt/non-virt use case classification, there are > > a number of scenarios which we have decided will not be treated as > > security issues. Start to document some of these to give consistency > > in our treatemnt of incoming disclosures. > > > > Signed-off-by: Daniel P. Berrangé > > --- > > > > Mauro / Michael: please suggest any other rules which we have applied > > historically on qemu-security disclosures that we should capture here. > > > > The vfio-user/vhost-user addition is a new one based on discussions > > in some GitLab issues today/yesterday > > > > docs/system/security.rst | 63 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 63 insertions(+) > > > > diff --git a/docs/system/security.rst b/docs/system/security.rst > > index 53992048e6..fbbca50f95 100644 > > --- a/docs/system/security.rst > > +++ b/docs/system/security.rst > > @@ -75,6 +75,69 @@ Bugs affecting the non-virtualization use case are not considered security > > bugs at this time. Users with non-virtualization use cases must not rely on > > QEMU to provide guest isolation or any security guarantees. > > > > +Security boundary scope > > +''''''''''''''''''''''' > > + > > +Even where a flaw affects the virtualization use case described above, > > +not all scenarios will be considered in scope. The following guidelines > > +are used to evaluate whether to apply the full security process, or treat > > +an issue as a normal bug. > > + > > +* **assert** / **abort**. If triggering the code path requires kernel > > + privileges (or root account access) in the guest, asserts/aborts in > > + QEMU are a self inflicted denial of service. These will **not** be > > + treated as security flaws, at most hardening bugs. If triggering the > > + code path can be done by an unprivileged guest OS account, this > > + **may** justify handling as a security bug. > > + > > +* **vhost-user/vfio-user backends**. The backend processes have > > + shared memory regions co-mapped with the QEMU process. The intent > > + of the process separation is operational resilience & flexibility > > + and allowing for independent software suppliers. There is not > > + considered to be security boundary between QEMU and the vhost-user > > + & vfio-user backends. Thus flaws in the backends which can cause > > + crashes / undesirable behaviour in QEMU will **not** be treated as > > + security flaws, but should be fixed as hardening bugs. > > + > > +* **memory allocation bounds**. There are many ways in which a QEMU > > + process can legitimately consume an amount of memory that is > > + significantly larger than the assigned guest RAM. QEMU's worst > > + case memory usage should be considered effectively unbounded. As > > + such the QEMU deployment on the host should account for the > > + possibility of large memory peaks and apply countermeasures to > > + provide continuity of host operations. It is typical for the Linux > > + OOM killer to reap the process triggering host memory overcommit > > + in the case of exccessive usage, offering a degree of protection. > > + As such, bugs which can lead to excessive/unbounded memory allocations > > + will usually not be classified as security flaws, but should be > > + fixed as hardening bugs. > > + > > +* **degraded guest behaviour**. There are a set of bugs which can > > + lead guest hardware devices to misbehave. For example, a flawed > > + virtual IOMMU operation may not offer the guest device isolation > > + that would otherwise be expected. If a guest triggered exploit > > + requires kernel privileges (or root account access), and leads > > + to sub-optimal behaviour of the virtual device this is considered > > + a self inflicted service degradation. These will **not** be > > + treated as security flaws, at most hardening bugs. If triggernig > > + the code path can be done by an unprivileged guest OS account, > > + this may justify handling as a security bug. > > + > > +* **nested virtualization**. The scope for nested virtualization > > + is to prevent a level 2 guest from breaking out into a level > > + 1 guest. As noted above, a number of scenarios exclude security > > + handling for flaws only exploitable by the guest kernel / root > > + account with affect the guest's own service/availability. In the > > + context of nested virtualization with PCI device assignment, it > > + may may be possible for a level 2 guest kernel to trigger flaws > > + that affect the level 0 QEMU process. While these bugs should be > > + fixed, they will not be triaged as security flaws at this time. > > + > > +* **low severity impact**. As a catch all rule, issues which > > + are judged to have a "low" severity impact on the system will > > + usually not justify handling as security bugs, nor assignment > > + of CVEs. They will be fixed as routine bugs when time allows. > > Should we have a section about management-plane protocols? (migration, > QMP, monitor), since they already require trusted network access? There is a section later about QMP/monitor https://www.qemu.org/docs/master/system/security.html#sensitive-configurations For migration we do need to think of something to explain our approach more clearly, and indeed document our expectations for configuration for migration (trusted LAN vs TLS + certs). 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 :|