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=-13.6 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 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 A114CC433DB for ; Mon, 15 Mar 2021 18:21:59 +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 7F44C64F4C for ; Mon, 15 Mar 2021 18:21:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F44C64F4C 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]:37774 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lLrqn-0008B8-GP for qemu-devel@archiver.kernel.org; Mon, 15 Mar 2021 14:21:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59722) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lLrR0-0002sd-8X for qemu-devel@nongnu.org; Mon, 15 Mar 2021 13:55:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:56311) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lLrQv-0005Se-3M for qemu-devel@nongnu.org; Mon, 15 Mar 2021 13:55:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615830911; 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=RaX8PtxvvCwWrWDtTKB+PAMU+2yDEIp/TMlRrmexpI8=; b=AcilsTNwxceDiDABJcG8wvNNQkgMLpfLHkZzyy6ImpHxlO/6apNj9v7qWo8OzH2Nz5DYl7 VimfbDOVruqPanNGZqoVqB2wtpsg1WnBA1/sq/TccgQFdDxZdTWIwNAJAf5/5Or59XHobN GzzoaXYWYHEzAYlWUiYb7K9eBlg8oRo= 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-568-DhQmLjycO2Ot2wkmu22bqA-1; Mon, 15 Mar 2021 13:55:09 -0400 X-MC-Unique: DhQmLjycO2Ot2wkmu22bqA-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 38E061054F97; Mon, 15 Mar 2021 17:55:08 +0000 (UTC) Received: from horse.redhat.com (ovpn-115-135.rdu2.redhat.com [10.10.115.135]) by smtp.corp.redhat.com (Postfix) with ESMTP id B07D516920; Mon, 15 Mar 2021 17:55:04 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 3C3BA220BCF; Mon, 15 Mar 2021 13:55:04 -0400 (EDT) Date: Mon, 15 Mar 2021 13:55:04 -0400 From: Vivek Goyal To: Greg Kurz Subject: Re: [Virtio-fs] [PATCH 3/3] virtiofsd: Don't allow empty filenames Message-ID: <20210315175504.GD235521@redhat.com> References: <20210312141003.819108-1-groug@kaod.org> <20210312141003.819108-4-groug@kaod.org> <20210314233604.GC223210@redhat.com> <20210315110630.5ae99490@bahia.lan> MIME-Version: 1.0 In-Reply-To: <20210315110630.5ae99490@bahia.lan> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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=63.128.21.124; envelope-from=vgoyal@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=-0.25, 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, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Mar 15, 2021 at 11:06:30AM +0100, Greg Kurz wrote: > On Sun, 14 Mar 2021 19:36:04 -0400 > Vivek Goyal wrote: > > > On Fri, Mar 12, 2021 at 03:10:03PM +0100, Greg Kurz wrote: > > > POSIX.1-2017 clearly stipulates that empty filenames aren't > > > allowed ([1] and [2]). Since virtiofsd is supposed to mirror > > > the host file system hierarchy and the host can be assumed to > > > be linux, we don't really expect clients to pass requests with > > > an empty path in it. If they do so anyway, this would eventually > > > cause an error when trying to create/lookup the actual inode > > > on the underlying POSIX filesystem. But this could still confuse > > > some code that wouldn't be ready to cope with this. > > > > > > Filter out empty names coming from the client at the top level, > > > so that the rest doesn't have to care about it. This is done > > > everywhere we already call is_safe_path_component(), but > > > in a separate helper since the usual error for empty path > > > names is ENOENT instead of EINVAL. > > > > > > [1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_170 > > > [2] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13 > > > > > > Signed-off-by: Greg Kurz > > > > Hi Greg, > > > > Minor nit, if you happen to respin this patch, it probably should come > > before the first patch in series. Once we make it clear that file server > > is not expecting empty path in these top level functions, then it is > > easy to clear AT_EMPTY_PATH in function these paths are calling as > > appropriate. > > > > The patch order is chronological : I just spotted the AT_EMPTY_PATH > oddity before coming up with the bigger hammer of patch 3. But you're > right, it probably makes more sense to do the other way around. > > > What about lo_create(). Should we put a check in there as well. > > > > Good catch ! I'll post a v2 then ;) > > > We are passed xattr names in lo_getxattr()/lo_removexattr()/lo_setxattr(). > > In general, should we put an empty in_name check there as well and > > probably simply return -EINVAL. > > > > An empty xattr name doesn't likely make sense either, even if this > isn't written down anywhere, not in an explicit manner at least. > > The kernel checks this in setxattr() and errors out with -ERANGE > in this case. > > error = strncpy_from_user(kname, name, sizeof(kname)); > if (error == 0 || error == sizeof(kname)) > error = -ERANGE; > if (error < 0) > return error; > > Same goes for the other *xattr() syscalls, i.e. nothing nasty can ever > happen with an empty xattr name since this is always considered as an > error by the kernel. Not sure this would bring much to also check this > in QEMU. This is a bit different from the empty path name case because > an empty path name is valid for syscalls that support AT_EMPTY_PATH, > and we just want to make sure these are never exercised with names > from the client. Fair enough. Lets not worry about empty name for xattr calls. That's probably for some other day. Vivek > > Cheers, > > -- > Greg > > > Thanks > > Vivek > > > > > --- > > > tools/virtiofsd/passthrough_ll.c | 35 ++++++++++++++++++++++++++++++++ > > > 1 file changed, 35 insertions(+) > > > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > > index f63016d35626..bff9dc2cd26d 100644 > > > --- a/tools/virtiofsd/passthrough_ll.c > > > +++ b/tools/virtiofsd/passthrough_ll.c > > > @@ -237,6 +237,11 @@ static bool is_safe_path_component(const char *path) > > > return !is_dot_or_dotdot(path); > > > } > > > > > > +static bool is_empty(const char *name) > > > +{ > > > + return name[0] == '\0'; > > > +} > > > + > > > static struct lo_data *lo_data(fuse_req_t req) > > > { > > > return (struct lo_data *)fuse_req_userdata(req); > > > @@ -1083,6 +1088,11 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t parent, const char *name) > > > fuse_log(FUSE_LOG_DEBUG, "lo_lookup(parent=%" PRIu64 ", name=%s)\n", parent, > > > name); > > > > > > + if (is_empty(name)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > /* > > > * Don't use is_safe_path_component(), allow "." and ".." for NFS export > > > * support. > > > @@ -1174,6 +1184,11 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent, > > > struct fuse_entry_param e; > > > struct lo_cred old = {}; > > > > > > + if (is_empty(name)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > if (!is_safe_path_component(name)) { > > > fuse_reply_err(req, EINVAL); > > > return; > > > @@ -1246,6 +1261,11 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > > > char procname[64]; > > > int saverr; > > > > > > + if (is_empty(name)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > if (!is_safe_path_component(name)) { > > > fuse_reply_err(req, EINVAL); > > > return; > > > @@ -1323,6 +1343,11 @@ static void lo_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name) > > > struct lo_inode *inode; > > > struct lo_data *lo = lo_data(req); > > > > > > + if (is_empty(name)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > if (!is_safe_path_component(name)) { > > > fuse_reply_err(req, EINVAL); > > > return; > > > @@ -1352,6 +1377,11 @@ static void lo_rename(fuse_req_t req, fuse_ino_t parent, const char *name, > > > struct lo_inode *newinode = NULL; > > > struct lo_data *lo = lo_data(req); > > > > > > + if (is_empty(name) || is_empty(newname)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > if (!is_safe_path_component(name) || !is_safe_path_component(newname)) { > > > fuse_reply_err(req, EINVAL); > > > return; > > > @@ -1405,6 +1435,11 @@ static void lo_unlink(fuse_req_t req, fuse_ino_t parent, const char *name) > > > struct lo_inode *inode; > > > struct lo_data *lo = lo_data(req); > > > > > > + if (is_empty(name)) { > > > + fuse_reply_err(req, ENOENT); > > > + return; > > > + } > > > + > > > if (!is_safe_path_component(name)) { > > > fuse_reply_err(req, EINVAL); > > > return; > > > -- > > > 2.26.2 > > > > > > _______________________________________________ > > > Virtio-fs mailing list > > > Virtio-fs@redhat.com > > > https://listman.redhat.com/mailman/listinfo/virtio-fs > > >