From: Pavel Machek <pavel@ucw.cz>
To: Linus Torvalds <torvalds@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-VServer <vserver@list.linux-vserver.org>
Subject: Re: The Future of Linux Capabilities ...
Date: Mon, 27 Dec 2004 20:36:37 +0100 [thread overview]
Message-ID: <20041227193637.GH1043@openzaurus.ucw.cz> (raw)
In-Reply-To: <20041227014041.GA30550@mail.13thfloor.at>
Hi!
> I would not spend too much time on that, if we would
> not need to improve that system by splitting up (or
> working around) some capabilities which are too coarse
> (or too general) to be useful ...
>
> good examples for such capabilities are:
>
> #define CAP_NET_ADMIN 12
> especially CAP_NET_ADMIN and CAP_SYS_ADMIN contain
> more than 20 different aspects ...
>
> we are currently aware of three different solutions
> to refine the capability system, and I would like to
> hear some opinions and get a statement from mainline
> (good, impossible, crap, don't care, or whatever ;)
>
> I) extend the capability type kernel_cap_t to
> 64 (or more) bit, add new syscalls cap*64()
> and let the 'old' interface just see the lower
> 32 bit
>
> II) add 32 (or more) sub-capabilities which depend
> on the parent capability to be usable, and add
> appropriate syscalls for them.
>
> example: CAP_IPC_LOCK gets two subcapabilities
> (e.g. SCAP_SHM_LOCK and SCAP_MEM_LOCK) which
>
> III) (linux-vserver specific solution)
> add a (compile time) CAP_MASK to declare which
> caps have subcaps, then use per context subcaps
> for known subfeatures and an additional cap_t
> to cover 'all other' aspects of the capability
>
> example: CAP_IPC_LOCK in CAP_MASK, plus the
> SCAP_MEM_LOCK subcapability, now having IPC_LOCK
> in the tasks caps doesn't do anything without
> the corresponding IPC_LOCK in the context or
> the SCAP_MEM_LOCK capability where appropriate
>
> I think that all three solutions are usable for our
> project, so I can live pretty well with III, but I think
> refining the capability system might be something which
> is useful for mainline ...
1) seems acceptable, as long as 64bits is enough. 2) looks ugly.
Pavel
--
64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms
next prev parent reply other threads:[~2005-01-02 19:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-27 1:40 The Future of Linux Capabilities Herbert Poetzl
2004-12-27 19:36 ` Pavel Machek [this message]
2005-01-02 19:43 ` Andreas Schwab
2005-01-03 0:04 ` [Vserver] " Herbert Poetzl
2004-12-27 23:22 ` Ulrich Drepper
2004-12-28 2:21 ` Herbert Poetzl
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