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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 E616BC2B9F4 for ; Thu, 17 Jun 2021 14:31:00 +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 49BC8613CB for ; Thu, 17 Jun 2021 14:31:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 49BC8613CB 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]:38456 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ltt2p-000382-5r for qemu-devel@archiver.kernel.org; Thu, 17 Jun 2021 10:30:59 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46234) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltt1P-0001pr-Kx for qemu-devel@nongnu.org; Thu, 17 Jun 2021 10:29:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29386) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltt1L-0007FT-Gd for qemu-devel@nongnu.org; Thu, 17 Jun 2021 10:29:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623940165; 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=ibo9MS+qk03gvsK8YAdud6h+V6gbxjFkTuT1dz3LmHM=; b=Uux60lrv16E81DTNVntRf08ieKUv05ln06TahDdwAtUiKuAvenByStlbaJlCsbw/yKtjDi ZLtn2EYZBJZpakJGPgMu2JacJrs4AcXVPYIkMUrNgFaaZ8iJaUZSUWmVCAiXHvPxwBoQd8 wO0b7gipny4ydqrSGP5mtElVtvWdOsg= 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-198-ZbDzXL-oONWeYLeR7UjMZQ-1; Thu, 17 Jun 2021 10:29:24 -0400 X-MC-Unique: ZbDzXL-oONWeYLeR7UjMZQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3CC088015F5; Thu, 17 Jun 2021 14:29:23 +0000 (UTC) Received: from work-vm (ovpn-115-22.ams2.redhat.com [10.36.115.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3279C10023AF; Thu, 17 Jun 2021 14:29:15 +0000 (UTC) Date: Thu, 17 Jun 2021 15:29:12 +0100 From: "Dr. David Alan Gilbert" To: Greg Kurz Subject: Re: [PATCH] virtiofsd: Don't allow file creation with FUSE_OPEN Message-ID: References: <20210617141518.304659-1-groug@kaod.org> MIME-Version: 1.0 In-Reply-To: <20210617141518.304659-1-groug@kaod.org> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@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=dgilbert@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=-0.197, 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_H4=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: , Cc: virtio-fs@redhat.com, Stefan Hajnoczi , qemu-devel@nongnu.org, Vivek Goyal , Miklos Szeredi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Greg Kurz (groug@kaod.org) wrote: > A well behaved FUSE client uses FUSE_CREATE to create files. It isn't > supposed to pass O_CREAT along a FUSE_OPEN request, as documented in > the "fuse_lowlevel.h" header : > > /** > * Open a file > * > * Open flags are available in fi->flags. The following rules > * apply. > * > * - Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be > * filtered out / handled by the kernel. > > But if it does anyway, virtiofsd crashes with: > > *** invalid openat64 call: O_CREAT or O_TMPFILE without mode ***: terminated > > This is because virtiofsd ends up passing this flag to openat() without > passing a mode_t 4th argument which is mandatory with O_CREAT, and glibc > aborts. > > The offending path is: > > lo_open() > lo_do_open() > lo_inode_open() > > Other callers of lo_inode_open() only pass O_RDWR and lo_create() > passes a valid fd to lo_do_open() which thus doesn't even call > lo_inode_open() in this case. > > Specifying O_CREAT with FUSE_OPEN is a protocol violation. Check this > in lo_open() and return an error to the client : EINVAL since this is > already what glibc returns with other illegal flag combinations. > > The FUSE filesystem doesn't currently support O_TMPFILE, but the very > same would happen if O_TMPFILE was passed in a FUSE_OPEN request. Check > that as well. > > Signed-off-by: Greg Kurz That seems reasonable, so Reviewed-by: Dr. David Alan Gilbert should you also send a corresponding patch for libfuse's example code we're based on? Dave > --- > tools/virtiofsd/passthrough_ll.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 49c21fd85570..14f62133131c 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -2145,6 +2145,12 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) > return; > } > > + /* File creation is handled by lo_create() */ > + if (fi->flags & (O_CREAT | O_TMPFILE)) { > + fuse_reply_err(req, EINVAL); > + return; > + } > + > err = lo_do_open(lo, inode, -1, fi); > lo_inode_put(lo, &inode); > if (err) { > -- > 2.31.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK