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

From: Joshua Brindle
Date: Mon Nov 26 2007 - 14:55:45 EST


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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