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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 AFE14C55189 for ; Thu, 23 Apr 2020 01:36:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90A712098B for ; Thu, 23 Apr 2020 01:36:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726535AbgDWBgn (ORCPT ); Wed, 22 Apr 2020 21:36:43 -0400 Received: from mail.hallyn.com ([178.63.66.53]:53178 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725961AbgDWBgm (ORCPT ); Wed, 22 Apr 2020 21:36:42 -0400 Received: by mail.hallyn.com (Postfix, from userid 1001) id AFB809D0; Wed, 22 Apr 2020 20:36:39 -0500 (CDT) Date: Wed, 22 Apr 2020 20:36:39 -0500 From: "Serge E. Hallyn" To: Christian Brauner Cc: Jens Axboe , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-api@vger.kernel.org, Jonathan Corbet , Serge Hallyn , "Rafael J. Wysocki" , Tejun Heo , "David S. Miller" , Saravana Kannan , Jan Kara , David Howells , Seth Forshee , David Rheinsberg , Tom Gundersen , Christian Kellner , Dmitry Vyukov , =?iso-8859-1?Q?St=E9phane?= Graber , linux-doc@vger.kernel.org, netdev@vger.kernel.org, Steve Barber , Dylan Reid , Filipe Brandenburger , Kees Cook , Benjamin Elder , Akihiro Suda Subject: Re: [PATCH v2 6/7] loopfs: start attaching correct namespace during loop_add() Message-ID: <20200423013639.GB2982@mail.hallyn.com> References: <20200422145437.176057-1-christian.brauner@ubuntu.com> <20200422145437.176057-7-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422145437.176057-7-christian.brauner@ubuntu.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 22, 2020 at 04:54:36PM +0200, Christian Brauner wrote: > Tag loop devices with the namespace the loopfs instance was mounted in. > This has the consequence that loopfs devices carry the correct sysfs > permissions for all their core files. All other devices files will > continue to be correctly owned by the initial namespaces. Here is sample > output: > > root@b1:~# mount -t loop loop /mnt > root@b1:~# ln -sf /mnt/loop-control /dev/loop-control > root@b1:~# losetup -f > /dev/loop8 > root@b1:~# ln -sf /mnt/loop8 /dev/loop8 > root@b1:~# ls -al /sys/class/block/loop8 > lrwxrwxrwx 1 root root 0 Apr 7 13:06 /sys/class/block/loop8 -> ../../devices/virtual/block/loop8 > root@b1:~# ls -al /sys/class/block/loop8/ > total 0 > drwxr-xr-x 9 root root 0 Apr 7 13:06 . > drwxr-xr-x 18 nobody nogroup 0 Apr 7 13:07 .. > -r--r--r-- 1 root root 4096 Apr 7 13:06 alignment_offset > lrwxrwxrwx 1 nobody nogroup 0 Apr 7 13:07 bdi -> ../../bdi/7:8 > -r--r--r-- 1 root root 4096 Apr 7 13:06 capability > -r--r--r-- 1 root root 4096 Apr 7 13:06 dev > -r--r--r-- 1 root root 4096 Apr 7 13:06 discard_alignment > -r--r--r-- 1 root root 4096 Apr 7 13:06 events > -r--r--r-- 1 root root 4096 Apr 7 13:06 events_async > -rw-r--r-- 1 root root 4096 Apr 7 13:06 events_poll_msecs > -r--r--r-- 1 root root 4096 Apr 7 13:06 ext_range > -r--r--r-- 1 root root 4096 Apr 7 13:06 hidden > drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 holders > -r--r--r-- 1 root root 4096 Apr 7 13:06 inflight > drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 integrity > drwxr-xr-x 3 nobody nogroup 0 Apr 7 13:07 mq > drwxr-xr-x 2 root root 0 Apr 7 13:06 power > drwxr-xr-x 3 nobody nogroup 0 Apr 7 13:07 queue > -r--r--r-- 1 root root 4096 Apr 7 13:06 range > -r--r--r-- 1 root root 4096 Apr 7 13:06 removable > -r--r--r-- 1 root root 4096 Apr 7 13:06 ro > -r--r--r-- 1 root root 4096 Apr 7 13:06 size > drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 slaves > -r--r--r-- 1 root root 4096 Apr 7 13:06 stat > lrwxrwxrwx 1 nobody nogroup 0 Apr 7 13:07 subsystem -> ../../../../class/block > drwxr-xr-x 2 root root 0 Apr 7 13:06 trace > -rw-r--r-- 1 root root 4096 Apr 7 13:06 uevent > root@b1:~# > > Cc: Jens Axboe > Signed-off-by: Christian Brauner I was a *bit* worried about not taking a reference to the user namespace, but it doesn't look like the chain of loop_remove() -> del_gendisk() -> device_del() will allow any later access through sysfs, so I guess it's fine. Reviewed-by: Serge Hallyn > --- > /* v2 */ > unchanged > - Christian Brauner : > - Adapted commit message otherwise unchanged. > --- > drivers/block/loop.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 8e21d4b33e01..2dc53bad4b48 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -2212,6 +2212,10 @@ static int loop_add(struct loop_device **l, int i, struct inode *inode) > disk->private_data = lo; > disk->queue = lo->lo_queue; > sprintf(disk->disk_name, "loop%d", i); > +#ifdef CONFIG_BLK_DEV_LOOPFS > + if (loopfs_i_sb(inode)) > + disk->user_ns = loopfs_i_sb(inode)->s_user_ns; > +#endif > > add_disk(disk); > > -- > 2.26.1