From owner-freebsd-bugs  Fri Oct 19  8:20: 8 2001
Delivered-To: freebsd-bugs@hub.freebsd.org
Received: from freefall.freebsd.org (freefall.FreeBSD.org [216.136.204.21])
	by hub.freebsd.org (Postfix) with ESMTP id D653437B403
	for <freebsd-bugs@hub.freebsd.org>; Fri, 19 Oct 2001 08:20:00 -0700 (PDT)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.11.4/8.11.4) id f9JFK0f06203;
	Fri, 19 Oct 2001 08:20:00 -0700 (PDT)
	(envelope-from gnats)
Received: from hermes.mail.nl.demon.net (hermes.mail.nl.demon.net [194.159.72.197])
	by hub.freebsd.org (Postfix) with ESMTP id 8F1D137B401
	for <FreeBSD-gnats-submit@freebsd.org>; Fri, 19 Oct 2001 08:15:24 -0700 (PDT)
Received: from samhain.noc.nl.demon.net ([194.159.72.214])
	by hermes.mail.nl.demon.net with esmtp (Exim 3.31 #1)
	id 15ubMp-000LmP-00
	for FreeBSD-gnats-submit@freebsd.org; Fri, 19 Oct 2001 17:15:23 +0200
Received: by samhain.noc.nl.demon.net with local id 15ubMp-000DN9-00
	for FreeBSD-gnats-submit@freebsd.org; Fri, 19 Oct 2001 15:15:23 +0000
Message-Id: <E15ubMp-000DN9-00@samhain.noc.nl.demon.net>
Date: Fri, 19 Oct 2001 15:15:23 +0000
From: pdp@nl.demon.net
To: FreeBSD-gnats-submit@freebsd.org
X-Send-Pr-Version: 3.2
Subject: kern/31375: "cd .." at mount-point uses perms of dir under mount
Sender: owner-freebsd-bugs@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-bugs.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-bugs>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-bugs>
X-Loop: FreeBSD.org


>Number:         31375
>Category:       kern
>Synopsis:       "cd .." at mount-point uses perms of dir under mount
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Oct 19 08:20:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Phil Pennock
>Release:        FreeBSD 4.4-STABLE i386
>Organization:
Demon Internet Netherlands
>Environment:
System built to RELENG_4, cvsup'd 2001-10-17.
Kernel config available upon request.
Filesystems used are ufs.
>Description:
It appears that when determining where ".." is, in a directory which is
a mount-point, the file-permissions of the underlying directory are used,
rather than the permissions of the mounted directory.  See below for
evidence backing this analysis.

Found because it breaks /etc/periodic/weekly/310.locate

Note that the practice of "chmod 0 /a/mountpoint" is not unusual.

Workaround: change permissions of mountpoints
>How-To-Repeat:
# mkdir /d/mounthere
# touch /d/mounthere/NOTHING_MOUNTED_HERE
# chmod 0 /d/mounthere
[ have a relevant filesystem in /etc/fstab, or choose one ]
# mount /d/mounthere
# su -m nobody
$ cd /d/mounthere
$ pwd
/d/mounthere
$ ls -ld .
drwxr-xr-x  2 root  wheel  512 Oct 18 20:42 .
$ cd ..
cd: can't cd to ..
$ <control-D>
# umount /d/mounthere
# chmod 555 /d/mounthere
# mount /d/mounthere
# su -m nobody
$ cd /d/mounthere
$ cd ..
$ pwd
/d
$

>Fix:
Unknown
>Release-Note:
>Audit-Trail:
>Unformatted:

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message