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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1357DC2B9F4 for ; Thu, 17 Jun 2021 16:20:00 +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 881866117A for ; Thu, 17 Jun 2021 16:19:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 881866117A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:32954 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ltukI-0005hA-IC for qemu-devel@archiver.kernel.org; Thu, 17 Jun 2021 12:19:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49196) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltujH-0004LL-Se for qemu-devel@nongnu.org; Thu, 17 Jun 2021 12:18:57 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:53582) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltujE-00073E-Hj for qemu-devel@nongnu.org; Thu, 17 Jun 2021 12:18:54 -0400 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-386-OWQ3pKCgNSKBYL1j52pt7A-1; Thu, 17 Jun 2021 12:18:48 -0400 X-MC-Unique: OWQ3pKCgNSKBYL1j52pt7A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DC4608031FA; Thu, 17 Jun 2021 16:18:47 +0000 (UTC) Received: from bahia.lan (ovpn-112-206.ams2.redhat.com [10.36.112.206]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1D95D60C05; Thu, 17 Jun 2021 16:18:39 +0000 (UTC) Date: Thu, 17 Jun 2021 18:18:38 +0200 From: Greg Kurz To: "Dr. David Alan Gilbert" Subject: Re: [PATCH] virtiofsd: Don't allow file creation with FUSE_OPEN Message-ID: <20210617181838.1b6fc592@bahia.lan> In-Reply-To: References: <20210617141518.304659-1-groug@kaod.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kaod.org Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Received-SPF: softfail client-ip=205.139.111.44; envelope-from=groug@kaod.org; helo=us-smtp-delivery-44.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665 autolearn=no 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" On Thu, 17 Jun 2021 15:29:12 +0100 "Dr. David Alan Gilbert" wrote: > * 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 : > >=20 > > /** > > * 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. > >=20 > > But if it does anyway, virtiofsd crashes with: > >=20 > > *** invalid openat64 call: O_CREAT or O_TMPFILE without mode ***: termi= nated > >=20 > > 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 glib= c > > aborts. > >=20 > > The offending path is: > >=20 > > lo_open() > > lo_do_open() > > lo_inode_open() > >=20 > > 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. > >=20 > > 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. > >=20 > > 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. > >=20 > > Signed-off-by: Greg Kurz >=20 > That seems reasonable, so >=20 > Reviewed-by: Dr. David Alan Gilbert >=20 > should you also send a corresponding patch for libfuse's example code > we're based on? >=20 Good idea. I've just done that. Cheers, -- Greg > Dave >=20 > > --- > > tools/virtiofsd/passthrough_ll.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > >=20 > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthr= ough_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 i= no, struct fuse_file_info *fi) > > return; > > } > > =20 > > + /* File creation is handled by lo_create() */ > > + if (fi->flags & (O_CREAT | O_TMPFILE)) { > > + fuse_reply_err(req, EINVAL); > > + return; > > + } > > + > > err =3D lo_do_open(lo, inode, -1, fi); > > lo_inode_put(lo, &inode); > > if (err) { > > --=20 > > 2.31.1 > >=20