Re: [PATCH] 2.6.25: access permission filesystem 0.21

[Olaf Dietsche <olaf+list.linux-kernel@olafdietsche.de>]

Casey Schaufler <casey@schaufler-ca.com> writes:

> --- Olaf Dietsche <olaf+list.linux-kernel@olafdietsche.de> wrote:
>
>> This patch adds a new permission managing file system.
>> Furthermore, it adds two modules, which make use of this file system.
>> 
>> One module allows granting capabilities based on user-/groupid.
>
> Hmm. The primary purpose of the capability mechanism, according
> to the POSIX P1003.1e/2c working group*, is to separate the
> privilege mechanism from the userid mechanism. You are now
> reintegrating them two mechanims, albiet differently than
> they were integrated before. You can already achieve this end
> using filesystem based capabilties and mode bits and/or ACLs,
> so why the change?

This idea is from 2002, when there were neither filesystem based
capabilties nor ACLs. But since even I never used it, see it as an
interesting excercise.

>> The
>> second module allows to grant access to lower numbered ports based on
>> user-/groupid, too.
>
> Woof. As reasonable as mode bits on ports seems, there's an
> awful lot of tradition associated with the privileged port
> model. I can see the value in it, I've actually implemented
> it in the past in the Unix world, but I have never seen anyone
> willing to take advantage of the scheme. 

Well, I'm not in the tradition business :-) but it's fun to do these
things and even useful in this case.

Regards, Olaf