Re: stack protection
* Milan P. Stanic (mps@rns-nis.co.yu) [030823 11:50]:
> On Sat, Aug 23, 2003 at 03:13:25PM +1000, Russell Coker wrote:
> > Allowing the system administrator to write to /dev/mem as part of debugging
> > the kernel is a feature.
> UID 0 must have rights to do everything. root can "format" filesystem,
> by mistake or by intention.
Can you explain that to me why? Why must there be a user id that can
do everything? (The only thing UID 0 can't do is to exclude itself from
access to a piece of the system.) Why is it necessary that UID 0 can
tamper with kernel space in cirumvention of the interfaces from the
kernel on a production system after startup? Why is it necessary that
the same UID that can bind to low ports can also read any files?
It's convinient that UID 0 can do that at startup, at development, at
debugging or at system initalization. But not in a running production
environment.
> > Allowing the dhcp server to write to /dev/mem because it's UID 0 and Unix
> > security sucks is a bug.
> The problem isn't with UID 0, but with bugs in software.
Why does each server need to be started by UID 0 and therefor the
startup programm can do everything? Why does my news server need root,
or a dhcp server, or ...? I can't understand that.
I do understand that it is easier to have an almighty UID 0. But I
really would like a system where the existence of UID 0 is no longer
necessary but optional.
> I think that the problem cannot be solved in wrong place. It isn't
> possible to have secure DHCP server by fixing kernel, but by writing
> secure (OK, with less bugs) DHCP server.
I've never seen a programm that's really secure. There are programms
with more bugs or with less bugs. So it's always strictly necessary to
make programms "fail safe", so that failing does as less harm as
possible. A error in a dhcp server should just make dhcp fail, and
have no negative impact on security.
Cheers,
Andi
--
http://home.arcor.de/andreas-barth/
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