linux-kernel - Re: + smack-version-11c-simplified-mandatory-access-control-kernel.patch added to -mm tree

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Date:	Mon, 26 Nov 2007 14:55:10 -0500
From:	Joshua Brindle <method@...icmethod.com>
To:	Kyle Moffett <mrmacman_g4@....com>
CC:	Crispin Cowan <crispin@...spincowan.com>,
	Andrew Morgan <morgan@...nel.org>, casey@...aufler-ca.com,
	Stephen Smalley <sds@...ho.nsa.gov>,
	"Serge E. Hallyn" <serue@...ibm.com>, linux-kernel@...r.kernel.org,
	chrisw@...s-sol.org, darwish.07@...il.com, jmorris@...ei.org,
	paul.moore@...com, LSM List <linux-security-module@...r.kernel.org>
Subject: Re: + smack-version-11c-simplified-mandatory-access-control-kernel.patch
 added to -mm tree

Kyle Moffett wrote:
> On Nov 24, 2007, at 22:36:43, Crispin Cowan wrote:
>> Kyle Moffett wrote:
>>> Actually, a fully-secured strict-mode SELinux system will have no 
>>> unconfined_t processes; none of my test systems have any.  Generally 
>>> "unconfined_t" is used for situations similar to what AppArmor was 
>>> designed for, where the only "interesting" security is that of the 
>>> daemon (which is properly labelled) and one or more of the users are 
>>> unconfined.
>>
>> Interesting. In a Targeted Policy, you do your policy administration 
>> from unconfined_t. But how do you administer a Strict Policy machine? 
>> I can think of 2 ways:
>
> [snip]
>
>> * there is some type that is tighter than unconfined_t but none the
>>   less has sufficient privilege to change policy
>>
>> To me, this would be semantically equivalent to unconfined_t, because 
>> any rogue code or user with this type could then fabricate 
>> unconfined_t and do what they want
>
> Well, in a strict SELinux system, someone who has been permitted the 
> "Security Administrator" role (secadm_r) and who has logged in through 
> a "login_t" process may modify and reload the policy.  They are also 
> permitted to view all files up to their clearance, write files below 
> their level, and relabel files.  On the other hand, they do not have 
> any system-administration privileges (those are reserve for sysadm_r).
>

Ofcourse secadm can give himself privileges to anything he wants, that 
isn't necessarily the point though, he is trusted to change the policy. 
He is, however, protected from other people: he can't, for example, read 
user_home_t files. This protects the integrity of his environment and 
the processes he runs. unconfined_t, of course, does not have this 
protection.

> Under the default policy the security administrator may disable 
> SELinux completely, although that too can be adjusted as "load policy" 
> is yet another specialized permission.
>

load policy is pretty course grained, there are ways to make policy 
modification privileges more fine grained though such as by using the 
policy management server.

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