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Date:      Wed, 07 Jun 2000 18:35:56 -0700
From:      Bengt Richter <bokr@accessone.com>
To:        Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: FreeBSDDEATH.c.txt (mmap dirty page no check bug) 
Message-ID:  <3.0.5.32.20000607183556.00908730@mail.accessone.com>
In-Reply-To: <200006071311.e57DBsW08744@cwsys.cwsent.com>
References:  <Your message of "Wed, 07 Jun 2000 14:44:21 %2B0300."             <20000607144421.A82711@lucky.net>

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At 06:11 2000-06-07 -0700 Cy Schubert - ITSD Open Systems Group wrote:
[...]
>
>Replacement candidates for /tmp and /var/tmp are:
>
>1.  Each user has a subdirectory in /tmp as /tmp/$USER.  An idea brought
>    forth to BUGTRAQ by Theo de Raadt of the OpenBSD project.
>
>2.  Each user maintains their own /tmp as $HOME/tmp or some such thing.
>    An idea I had discussed with my co-workers a number of years ago.
>

I have an inkling of a third way, for backwards compatibility with #2.
Suppose you create a pseudo-device (/dev/home ?) whose only purpose is
to support a pseudo-file-system, whose only purpose is to return
$USER-dependent symbolic links? (A new kind of symbolic link might
be more efficient, but I'm looking for a way to do it within current
mechanisms). /dev/home/xxx would be mounted at /yyy to get the effect of
opening /yyy/file to be opening $HOME/xxx/file. For our case, use tmp for
both xxx and yyy. That's the sketch, anyway.

The above deals with (hidden) partitioning of the /tmp namespace, but does
not address the hint-carrying aspect of "tmp." As other posts have mentioned,
"tmp" might mean:
a.	You want a fast small scratch file
b.	It might not be small
c.	You want garbage collection service
d.	Access may be very public, so think twice
Other usage hints might be:
e.	You want sequential read-only access with huge read-ahead
	buffering for a jitter-glitch-free multimedia stream
f.	You want a no-persistent-cleartext-guaranteed file

You can easily expand on this, but my point is that maybe namespace, access
control, and performance tuning goals should be separated (at least for
discussion purposes ;-) so that if there is going to be changes, solutions
will be implemented in appropriate contexts.

One way of specifying something about a file is by saying it applies to all
files in a particular namespace (or subspace: e.g., leading dot, trailing
.vbs :)
or directory. Another is to mark the files with attribute flags or ACLs.
Another is to pass arguments to access functions like open(), or ioctl(), etc.
Another is to wrap it in some new object. Etc., etc. If we don't identify
what we're doing, and the options, we won't think about them until a legacy
pinches.
HTH.

Regards,
Bengt Richter




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