Messages in this thread | | | Subject | Re: Capabilities | Date | Sun, 20 Feb 2000 21:42:22 -0300 | From | Horst von Brand <> |
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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.
> > 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.
Unless you cleanly separate UID/GID from capabilities, and place that under the direct control of the kernel (i.e., into the filesystem) all you get is an ugly hybrid with old and new problems.
> (Program that can modify files for DNS and which is allowed to bind > low port is doable with elfcap, but not with this proposal, because > there are no additional bits to store "new uid" as I do in elfcap.
Why can't it be done in this proposal? Binding to a low port is a capability (or should be made one, as it is one of the special powers root enjoys right now). -- Horst von Brand vonbrand@sleipnir.valparaiso.cl Casilla 9G, Viña del Mar, Chile +56 32 672616
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