Re: General flags to turn things off (getrandom, pid lookup, etc)

From: Andy Lutomirski
Date: Fri Jul 25 2014 - 17:42:16 EST

On Fri, Jul 25, 2014 at 2:35 PM, One Thousand Gnomes
<gnomes@xxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 25 Jul 2014 11:30:48 -0700
> Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>> [new thread because this sort of combines two threads]
>> There is recent interest in having a way to turn generally-available
>> kernel features off. Maybe we should add a good one so we can stop
>> bikeshedding and avoid proliferating dumb interfaces.
> We sort of have one. It's called capable(). Just needs extending to cover
> anything else you care about, and probably all the numeric constants
> replacing with textual names.

Except that it's all backwards: these are things that default to *on*,
and people might want them to turn off. capable() is totally fscked
if you want otherwise unprivileged users to carry capabilities around,
and fixing it seems to run into endless claims that the "capability"
system is carefully designed, flawless, perfect, ideal, amazing, and
shouldn't be changed, despite the fact that it's empirically damn near

Also, capabilities do the wrong thing wrt namespaces. The things I'm
talking about aren't namespaced. They're either on or off.

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