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Date:      Thu, 14 Sep 2000 00:56:54 -0700
From:      "Crist J . Clark" <cjclark@reflexnet.net>
To:        Paul Jansen <vlaero@yahoo.com.au>
Cc:        questions@FreeBSD.ORG
Subject:   Re: freebsd NFS export limitation?
Message-ID:  <20000914005654.V69158@149.211.6.64.reflexcom.com>
In-Reply-To: <20000914041741.2326.qmail@web5103.mail.yahoo.com>; from vlaero@yahoo.com.au on Thu, Sep 14, 2000 at 03:17:41PM %2B1100
References:  <20000914041741.2326.qmail@web5103.mail.yahoo.com>

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On Thu, Sep 14, 2000 at 03:17:41PM +1100, Paul Jansen wrote:
> Hi,
> 
> I was just reading through
> http://www.netbsd.org/Documentation/network/netboot/nfs.html
> 
> It's a diskless netbsd howto.  I was looking at this
> because there doesn't seem to be a decnt, up-to-date
> diskless freebsd how with step by step instructions.
> Anyway, I came across this bit:
> 
> "FreeBSD
> FreeBSD doesn't support exporting individual
> directories. You need to know the mountpoint of the
> filesystem you will be exporting. This also means that
> the client will have root read/write priveleges on
> that whole filesystem. For example, if you only have
> one filesystem (i.e. /), then you need to export
> everything to the client. "
> 
> Is this true under freeBSD 4.1R?  If so it's a bit of
> a limitation isn't it?

It's never been true in any FreeBSD version I have ever used (all
since 2.2.7). You have always been able to allow directories to be
mounted. There are restrictions on how it is all done, but it's mostly
an issue of getting your /etc/exports set up right.

However, it may be true that once an directory from a filesystem is
exported, the whole filesystem may be exposed. That is, you cannot
mount the filesystem through the usual mount command, but you might be
able to craft special NFS requests to access other parts of the
filesystem. But I also believe this is not a problem unique to
FreeBSD's NFS. I think it's a fundamental NFS weakness. (That's just
from some hazy memories. Most NFS exploits do not require that kind of
skill level. It's a "barring the windows and leaving the front door
unlocked" analogy if you try to fix that issue.)
-- 
Crist J. Clark                           cjclark@alum.mit.edu


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