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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id ABB7BC433F5 for ; Mon, 7 Feb 2022 21:21:48 +0000 (UTC) Received: from localhost ([::1]:47146 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nHBSF-0002Ti-8R for qemu-devel@archiver.kernel.org; Mon, 07 Feb 2022 16:21:47 -0500 Received: from eggs.gnu.org ([209.51.188.92]:43712) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nHBQL-0001lJ-ME for qemu-devel@nongnu.org; Mon, 07 Feb 2022 16:19:49 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:52391) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nHBQI-0001o2-7n for qemu-devel@nongnu.org; Mon, 07 Feb 2022 16:19:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1644268785; h=from:from: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=hQUfszrR4zjJJ0QiyJDtMS6qhP+C37t/yJKeCYozeEA=; b=YQKn+6J0eg1JlrJDdv81QyVE+GB9R87qW9Hrp5aET0ufzKQ+dSIWOk0J5T7f+RANP9lKjw BX1hNbAkGvYWLUEh3D56zD9VZ83fzQ/nBu5dGIq9Kz7pVR3IIcmGz2SDi3l03Z5CahSPnn Yeosp2vOJvfYtMYSwkCzz2K7N8HuQrY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-274-ieIZsyC0MDSGObD8X1TwAw-1; Mon, 07 Feb 2022 16:19:39 -0500 X-MC-Unique: ieIZsyC0MDSGObD8X1TwAw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BEFFA192AB6E for ; Mon, 7 Feb 2022 21:19:38 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.9.190]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9C10F4BC52; Mon, 7 Feb 2022 21:19:38 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 1098D22045A; Mon, 7 Feb 2022 16:19:38 -0500 (EST) Date: Mon, 7 Feb 2022 16:19:38 -0500 From: Vivek Goyal To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH v5 0/9] virtiofsd: Add support for file security context at file creation Message-ID: References: <20220202193935.268777-1-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vgoyal@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, mszeredi@redhat.com, Daniel J Walsh , qemu-devel@nongnu.org, dgilbert@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Feb 07, 2022 at 01:05:16PM +0000, Daniel P. Berrangé wrote: > On Wed, Feb 02, 2022 at 02:39:26PM -0500, Vivek Goyal wrote: > > Hi, > > > > This is V5 of the patches. I posted V4 here. > > > > https://listman.redhat.com/archives/virtio-fs/2022-January/msg00041.html > > > > These will allow us to support SELinux with virtiofs. This will send > > SELinux context at file creation to server and server can set it on > > file. > > I've not entirely figured it out from the code, so easier for me > to ask... > > How is the SELinux labelled stored on the host side ? It is stored > directly in the security.* xattr namespace, [ CC Dan Walsh ] I just tried to test the mode where I don't do xattr remapping and try to set /proc/pid/attr/fscreate with the context I want to set. It will set security.selinux xattr on host. But write to /proc/pid/attr/fscreate fails if host does not recognize the label sent by guest. I am running virtiofsd with unconfined_t but it still fails because guest is trying to create a file with "test_filesystem_filetranscon_t" and host does not recognize this label. Seeing following in audit logs. type=SELINUX_ERR msg=audit(1644268262.666:8111): op=fscreate invalid_context="unconfined_u:object_r:test_filesystem_filetranscon_t:s0" So if we don't remap xattrs and host has SELinux enabled, then it probably work in very limited circumstances where host and guest policies don't conflict. I guess its like running fedora 34 guest on fedora 34 host. I suspect that this will see very limited use. Though I have put the code in for the sake of completeness. Thanks Vivek > or is is subject to > xattr remapping that virtiofsd already supports. > > Storing directly means virtiofsd has to run in an essentially > unconfined context, to let it do arbitrary changes on security.* > xattrs without being blocked by SELinux) and has risk that guest > initiated changes can open holes in the host confinement if > the exported FS is generally visible to processes on the host. > > > Using remapping lets virtiofsd be strictly isolated by SELinux > policy on the host, and ensures that guest context changes > can't open up holes in the host. > > Both are valid use cases, so I'd ultimately expect us to want > to support both, but my preference for a "default" behaviour > would be remapping. > > 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 :| >