To: Sam Vilain <sam@vilain.net>
Cc: Chris Wright <chrisw@sous-sol.org>, Nick Piggin <nickpiggin@yahoo.com.au>,
       Herbert Poetzl <herbert@13thfloor.at>, Bill Davidsen <davidsen@tmr.com>,
       Linux Kernel ML <linux-kernel@vger.kernel.org>,
       "Serge E. Hallyn" <serue@us.ibm.com>
Subject: Re: [RFC] Virtualization steps
References: <1143228339.19152.91.camel@localhost.localdomain>
	<4428BB5C.3060803@tmr.com> <20060328085206.GA14089@MAIL.13thfloor.at>
	<4428FB29.8020402@yahoo.com.au>
	<20060328142639.GE14576@MAIL.13thfloor.at>
	<44294BE4.2030409@yahoo.com.au>
	<m1psk5kcpj.fsf@ebiederm.dsl.xmission.com> <442A26E9.20608@vilain.net>
	<20060329182027.GB14724@sorel.sous-sol.org>
	<442B0BFE.9080709@vilain.net>
	<20060329225241.GO15997@sorel.sous-sol.org>
	<m1psk4g2xa.fsf@ebiederm.dsl.xmission.com>
	<442B4168.6070806@vilain.net>
From: ebiederm@xmission.com (Eric W. Biederman)
Date: Wed, 29 Mar 2006 20:01:20 -0700
In-Reply-To: <442B4168.6070806@vilain.net> (Sam Vilain's message of "Thu, 30
 Mar 2006 14:24:40 +1200")
Message-ID: <m1wteceiv3.fsf@ebiederm.dsl.xmission.com>
User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1530
Lines: 37

Sam Vilain <sam@vilain.net> writes:

>
> We could even end up making security modules to implement standard unix
> security. ie, which processes can send any signal to other processes.
> Why hardcode the (!sender.user_id || (sender.user_id == target.user_id)
> ) rule at all? That rule should be the default rule in a security module
> chain.
>
> I just think that doing it this way is the wrong way around, but I guess
> I'm hardly qualified to speak on this. Aren't security modules supposed
> to be for custom security policy, not standard system semantics ?

It is simply my contention that you into at least a semi custom
configuration when you have multiple users with the same uid.
Especially when that uid == 0.

For guests you have to change the rule about what permissions
a setuid root executable gets or else it will have CAP_SYS_MKNOD,
and CAP_RAW_IO.  (Unless I didn't read that code right).

Plus all of the /proc and sysfs issues.

Now perhaps we can sit down and figure out how to get completely
isolated and only allow a new uid namespace when that is
the case, but that doesn't sound to interesting.

So at least until I can imagine what the semantics of a new uid
namespace are when we don't have perfect isolation that feels
like a job for a security module.

Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/