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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 32ACBC433F5 for ; Wed, 22 Sep 2021 12:38:37 +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 D721260F9D for ; Wed, 22 Sep 2021 12:38:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D721260F9D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:34614 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mT1WG-0004i4-3Y for qemu-devel@archiver.kernel.org; Wed, 22 Sep 2021 08:38:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41294) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mT1ON-0004oS-Be for qemu-devel@nongnu.org; Wed, 22 Sep 2021 08:30:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:46686) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mT1OJ-0007E1-0r for qemu-devel@nongnu.org; Wed, 22 Sep 2021 08:30:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632313820; 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: in-reply-to:in-reply-to:references:references; bh=jxYBomOSutjGd4VUrWwmss+Iqr0DKxw9CJsdofGJXFo=; b=cweUPWWIuU7fYCFWr6MxiVAcw0pIZogfOt/4kh9ytpYb2OFJOKh4WcU5RmqWwNhA8Vxa3p Apz79u0Ja+yig+xm8TlwjvdkCksAuf8AzwIF1US0ElWbjXn9m9SSiDD7tT3C4kDjj8pJCY 1jGNZKYXNsbCed5SVR5fHP6QQo5RjTk= 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-36-0EPz-w6NNquGCy7dFha9AA-1; Wed, 22 Sep 2021 08:30:19 -0400 X-MC-Unique: 0EPz-w6NNquGCy7dFha9AA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0B5A719067E7 for ; Wed, 22 Sep 2021 12:30:19 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.9.102]) by smtp.corp.redhat.com (Postfix) with ESMTP id DDF2E19C79; Wed, 22 Sep 2021 12:30:18 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 5F301222E4F; Wed, 22 Sep 2021 08:30:18 -0400 (EDT) Date: Wed, 22 Sep 2021 08:30:18 -0400 From: Vivek Goyal To: "Dr. David Alan Gilbert" Subject: Re: [PATCH 0/2] virtiofsd: Add capability to block xattrs Message-ID: References: <20210826211937.317558-1-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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=us-ascii Content-Disposition: inline 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: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.472, 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_H2=-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: , Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 22, 2021 at 12:00:17PM +0100, Dr. David Alan Gilbert wrote: > * Vivek Goyal (vgoyal@redhat.com) wrote: > > As of now we have a knob "-o xattr/no_xattr" which either enables > > all xattrs or disables all xattrs. > > Hi Vivek, > Thanks for this. > > > We need something more fine grained where we can selectively disable > > only certain xattrs (and not all). > > > > For example, in some cases we want to disable "security.selinux" > > xattr. This is equivalent to virtiofs not supporting security.selinux > > and guest kernel will fallback to a single label for whole fs > > (virtiofs_t). > > > > So add an option "-o block_xattr=" which will allow > > specifying a list of xattrs to block. > > This is quite interesting; I'd not noticed you had the exisitng blocking > mechanism, Yes, that's for blocking posix acl xattrs if needed. If xattr map support blocking, then we could probably insert an internal rule to block posix acl xattrs. But that's more of a cleanup exercise I will take up some other time. > however, as discussed, I think my preference is if this could > be done as a modification of the xattrmap it would avoid another set of > options. > > The mapping code already has 'type's of: > > prefix, ok, bad > > I think you just need to add a 'reject' type > that produces the error code you need. How about "unsupported" and then return -EOPNOTSUPP? I am looking at selinux kernel code and it expect -EOPNOTSUPP to decide that selinux xattr is not supported and looks into fallback options. static int sb_check_xattr_support(struct super_block *sb) { rc = __vfs_getxattr(root, root_inode, XATTR_NAME_SELINUX, NULL, 0); if (rc < 0 && rc != -ENODATA) { if (rc == -EOPNOTSUPP) { pr_warn("SELinux: (dev %s, type %s) has no security xattr handler\n", sb->s_id, sb->s_type->name); goto fallback; ... ... } Vivek From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 22 Sep 2021 08:30:18 -0400 From: Vivek Goyal Message-ID: References: <20210826211937.317558-1-vgoyal@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] [PATCH 0/2] virtiofsd: Add capability to block xattrs List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org On Wed, Sep 22, 2021 at 12:00:17PM +0100, Dr. David Alan Gilbert wrote: > * Vivek Goyal (vgoyal@redhat.com) wrote: > > As of now we have a knob "-o xattr/no_xattr" which either enables > > all xattrs or disables all xattrs. > > Hi Vivek, > Thanks for this. > > > We need something more fine grained where we can selectively disable > > only certain xattrs (and not all). > > > > For example, in some cases we want to disable "security.selinux" > > xattr. This is equivalent to virtiofs not supporting security.selinux > > and guest kernel will fallback to a single label for whole fs > > (virtiofs_t). > > > > So add an option "-o block_xattr=" which will allow > > specifying a list of xattrs to block. > > This is quite interesting; I'd not noticed you had the exisitng blocking > mechanism, Yes, that's for blocking posix acl xattrs if needed. If xattr map support blocking, then we could probably insert an internal rule to block posix acl xattrs. But that's more of a cleanup exercise I will take up some other time. > however, as discussed, I think my preference is if this could > be done as a modification of the xattrmap it would avoid another set of > options. > > The mapping code already has 'type's of: > > prefix, ok, bad > > I think you just need to add a 'reject' type > that produces the error code you need. How about "unsupported" and then return -EOPNOTSUPP? I am looking at selinux kernel code and it expect -EOPNOTSUPP to decide that selinux xattr is not supported and looks into fallback options. static int sb_check_xattr_support(struct super_block *sb) { rc = __vfs_getxattr(root, root_inode, XATTR_NAME_SELINUX, NULL, 0); if (rc < 0 && rc != -ENODATA) { if (rc == -EOPNOTSUPP) { pr_warn("SELinux: (dev %s, type %s) has no security xattr handler\n", sb->s_id, sb->s_type->name); goto fallback; ... ... } Vivek