Re: Capabilities

From: Christoph Hellwig (chhellwig@gmx.net)
Date: Mon Feb 21 2000 - 06:04:31 EST


On Sun, Feb 20, 2000 at 09:42:22PM -0300, Horst von Brand wrote:
> Pavel Machek <pavel@suse.cz> said:
> > In-Reply-To: <200002192338.e1JNcw216382@sleipnir.valparaiso.cl>; from vonbrand@
> > ***sleipnir.valparaiso.cl on Sat, Feb 19, 2000 at 08:38:58PM -0300
>
> > > > If you want to elevate some priviledges, make it setuid 0 (that will
> > > > give it all capabilities) and you can now copy forced into
> > > > allowed. You are done. You have nice compatibility (ls) for free, and
> > > > you have 32 more bits for your use!
>
> > > Who says running as UID == 0 gives you all capabilities? Why have a
>
> > Backwards compatibility.
>
> Doesn't cut it: It is _exactly_ what capabilities are designed to avoid.
> You can get (some) backwards compatibility by setting capabilities
> adequately.

I thin we should do it so, but this is a userlevel featue.
We should ad a rc file /etc/capabilitys with following content:

capabyility:passwd:initialusers
             | |
             | | users, whiches login-shell inherits this cap form login
             | the passwd you need to get this cap ( like IRIX su -C <cap> )

   

>
> > > distinguished root user at all? OTOH, it does make sense to have a program
> > > that can modify files belonging to DNS, and which is allowed to bind to a
> > > low port, but nothing else. The UID/GID (and ACL) stuff and capabilities
> > > are complementary.
>
> > I said that different uid is where this gets ugly ;-). Take a look at
> > elfcap.

I think we should get elfcap into the kernel before 2.4. In 2.5 we can replace it with
properly integration of capabilitys in the filesystem.

Christoph

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