[37464] in bugtraq
Re: Changes to the filesystem while find is running - comments?
daemon@ATHENA.MIT.EDU (Paul Szabo)
Tue Nov 23 16:22:22 2004
Date: Wed, 24 Nov 2004 05:59:38 +1100 (EST)
From: psz@maths.usyd.edu.au (Paul Szabo)
Message-Id: <200411231859.iANIxc0313292@milan.maths.usyd.edu.au>
To: bugtraq@excession.spiral-arm.org
Cc: bug-findutils@gnu.org, bugtraq@securityfocus.com, levon@movementarian.org,
martin.buchholz@sun.com, parimiv@deshaw.com, srevilak@speakeasy.net
James,
>> Hmm... It would not descend into just-now-changed automounts (and it may
>> not be able to get back out of them), but it should be able to traverse
>> reasonably long-lived mounts.
>
> The problem is though that when you chdir() into an automount mount
> point, automount aill automatically mount it for you. Hence if an
> automount filesystem wasn't already mounted, if you chdir() into it it
> immediately becomes a "just-now-changed" mount point. That's the
> essensce of the problem I am trying to solve.
I think find should never cause an automount to "trigger" and cause it to
be mounted. It is OK to traverse if it was mounted to start with; is surely
not OK to traverse if it wasn't already mounted. Maybe your problem is
sidestepped by this principle?
[Right now cannot think of examples where find causing automounts to
trigger would be an obvious security or performance issue.]
To prevent find from causing an automount to trigger, maybe you could
somehow detect the presence of the mount point, check its status, and
(after a warning) not descend if it wasn't mounted. [I use the Debian
autofs package; this uses a normally empty directory, which is populated
with mounted directories when in use. Are we talking about the short time
between the mkdir of the mountpoint and the mount?]
Cheers,
Paul Szabo - psz@maths.usyd.edu.au http://www.maths.usyd.edu.au:8000/u/psz/
School of Mathematics and Statistics University of Sydney 2006 Australia
