Re: user flags in public temp space (was Re: chflags() [heads up])

[avalon () COOMBS ANU EDU AU (Darren Reed)]

In some mail from Theo de Raadt, sie said:
[...]
> > a) Root should not use /tmp.  Root is root and, as the proverbial
> > 800-pound gorilla, can make temporary files wherever it pleases.
> > FreeBSD, for example, seems to be doing a lot in /var/run, which is
> > root-owned, and not world-writable.  At least root should use
> > subdirectories of /tmp and test to see if it can mkdir(1) them before use
> > (see OpenBSD2.5's /etc/security, for example).
>
> As much as possible, we've now killed almost all of the /tmp races in
> the system, so root is as safe as any other user.  Even gcc now plays
> things safe, it appears.  But /tmp problems keep occuring in packages
> which people add to the system.

If you're designing a software package, want to use temporary files and
directories but you need the names to be the same every time, where do
you put them ?  Are you required to use open(O_CREAT|O_EXCL) for files
in /tmp ?  Apart from the ability to exchange files between users with
/tmp, having private /tmp's for each uid using the system (with a non-
world writeable /tmp) has a lot of merit which I hope someone will someday
properly explore - i.e. there exist programming languages in which the
buffer overflow is a non-event, now we need an operating system design
where the /tmp file race-condition is a non-event.

Darren