kern/39329: [mount] '..' at mountpoint is subject to the ?permissions of the shadowed dir

Oliver Fromme olli at
Tue Aug 17 13:20:05 UTC 2010

The following reply was made to PR kern/39329; it has been noted by GNATS.

From: Oliver Fromme <olli at>
To: freebsd-bugs at FreeBSD.ORG, bug-followup at FreeBSD.ORG, svdb at,
        arundel at FreeBSD.ORG
Subject: Re: kern/39329: [mount] '..' at mountpoint is subject to the ?permissions of the shadowed dir
Date: Tue, 17 Aug 2010 15:12:33 +0200 (CEST)

 arundel at wrote:
  > Synopsis: [mount] '..' at mountpoint is subject to the permissions of the shadowed dir
 That's not a bug.  It's supposed to work that way, and it
 works like this in all UNIX variants that I'm aware of.
 In fact I think it would be a bug if the behaviour was
 changed.  That might even break some legitimate uses of
 the feature.
 It is clearly documented in the mount(8) manual page:
     After a successful mount, the permissions on the original
     mount point determine if '..' is accessible from the mounted
     file system.  The minimum permissions for the mount point
     for traversal across the mount point in both directions to
     be possible for all users is 0111 (execute for all).
 This PR should be closed.
 Best regards
 Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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 FreeBSD-Dienstleistungen, -Produkte und mehr:
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 "python" is more likely to pass unharmed through your spelling
 checker than "perl".
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