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Date:      Wed, 07 Jun 2000 06:11:09 -0700
From:      Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>
To:        netch@lucky.net
Cc:        Matthew Dillon <dillon@apollo.backplane.com>, freebsd-security@FreeBSD.ORG
Subject:   Re: FreeBSDDEATH.c.txt (mmap dirty page no check bug) 
Message-ID:  <200006071311.e57DBsW08744@cwsys.cwsent.com>
In-Reply-To: Your message of "Wed, 07 Jun 2000 14:44:21 %2B0300." <20000607144421.A82711@lucky.net> 

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n message <20000607144421.A82711@lucky.net>, Valentin Nechayev writes:
>  Tue, Jun 06, 2000 at 23:55:03, dillon wrote about "Re: FreeBSDDEATH.c.txt (m
> map dirty page no check bug)": 
> 
> >     Maybe on your system it is, but try running a multi-user system that
> >     way and you will quickly find your /var/tmp filled up to the brim.  Or,
> 
> Of course, of course.
> It is general problem of any public-accessable resource.
> Do you think you can really fix this world? Or do you try to emit /tmp
> as philosophical category?

Agreed.  That's why the whole concept of /tmp and /var/tmp is flawed.  
In my original reply in this thread I tried to take a broad as view and 
conciliatory view as possible to satisfy all points of view and 
hopefully have people consider (gently nudge) the idea of the more 
secure approach of no /tmp as an option.  My orignal tactic obviously 
did not work I am now showing my true colours by insisting (like 
everyone else does) that /tmp and /var/tmp as we know them be retired, 
to be replaced by a paradigm that is more secure.  Any less is 
invitation for disaster!

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.

> 
> >     MFS is a terrible idea for /tmp.  Each page in an MFS filesystem eats
> >     *TWO* pages of physical memory (until swapped).  This means that the
> 
> It is problem of one broken realization, isn't it?

Compaq back when they were Digital and Sun both claim that their MFS 
and TMPFS, respectively, are faster than disk.  Agreed, the FreeBSD MFS 
implementation is very much broken.  I'm not sure whether md 
pseudo-devices are stable enough production yet.  Anyone on this list 
with good or bad experience with the new md pseudo-devices?


Regards,                       Phone:  (250)387-8437
Cy Schubert                      Fax:  (250)387-5766
Team Leader, Sun/DEC Team   Internet:  Cy.Schubert@osg.gov.bc.ca
Open Systems Group, ITSD, ISTA
Province of BC

I



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