From patchwork Thu Jun 17 14:15:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kurz X-Patchwork-Id: 12327987 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 1BF69C2B9F4 for ; Thu, 17 Jun 2021 14:18:26 +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 82AE46135C for ; Thu, 17 Jun 2021 14:18:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82AE46135C 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]:59034 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ltsqe-0005vJ-O8 for qemu-devel@archiver.kernel.org; Thu, 17 Jun 2021 10:18:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39922) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltso5-00034e-FP for qemu-devel@nongnu.org; Thu, 17 Jun 2021 10:15:45 -0400 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:27890) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ltso3-0007kv-F0 for qemu-devel@nongnu.org; Thu, 17 Jun 2021 10:15:45 -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-485-yslf7ReKOXum6zuzzDMCQA-1; Thu, 17 Jun 2021 10:15:30 -0400 X-MC-Unique: yslf7ReKOXum6zuzzDMCQA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EDF1A1084F46; Thu, 17 Jun 2021 14:15:28 +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 0B7A260875; Thu, 17 Jun 2021 14:15:18 +0000 (UTC) From: Greg Kurz To: qemu-devel@nongnu.org Subject: [PATCH] virtiofsd: Don't allow file creation with FUSE_OPEN Date: Thu, 17 Jun 2021 16:15:18 +0200 Message-Id: <20210617141518.304659-1-groug@kaod.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=groug@kaod.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kaod.org Received-SPF: softfail client-ip=207.211.30.44; 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: Miklos Szeredi , Greg Kurz , "Dr. David Alan Gilbert" , virtio-fs@redhat.com, Stefan Hajnoczi , Vivek Goyal Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Stefan Hajnoczi --- 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) {