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Date:      Thu, 23 Oct 1997 14:09:08 +0100
From:      Colman Reilly <careilly@monoid.cs.tcd.ie>
To:        hackers@FreeBSD.ORG
Subject:   Security Policies [Was: ACLs [Was: C2 Trusted FreeBSD?] ]
Message-ID:  <199710231309.OAA04169@monoid.cs.tcd.ie>
In-Reply-To: Your message dated today at 09:28.

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	[Deleted discussion about how difficult ACLs are to implement in UNIX]

The basic problem with implementing ACLs, multi-level labelling and so on is
that FreeBSD has very little support for security policies. It's not really a 
part of the architecture and seems to be done on an ad hoc basis subsystem by
subsystem.

I think we'd be better off considering a more general solution rather than
trying to hack support in on a case by case basis. 

So to this weeks insane plot;

	A layered security model, similiar in conception to the layered
	filesystem, which allows a choice of access control models or model
	and which is used by all subsystems to make access control decisions.

This way an installation could choose between (say) standard UNIX access
control, ACL based access control, MAC style multi-level access control or
role based access control or combinations thereof. It would also allow for
more specialised access control models to be plugged in, and for the layers
to be used on a system by system basis, so that the news directory was using
standard UNIX access control while user directories were using ACLs on top
of MAC based controls.

The system would also be able to control things other than files - it could
give us the socket level controls suggested previously, and possibly access
controls on processes, so that unpriviledged users could send signals to
daemons, that sort of thing.

The main problem see (beyond the size of the task!) is where to store the 
access control information. 

The system tools would need to be changed, but thats doable - that's why we have
a full distribution rather than just a kernel.  We should be able to wrap
most of the required stuff into a library to make changes easier.

Third party tools are more of a problem. How many of them will have 
problems? Should we expect tar to handle this information? Does tar know how 
to preserve ownership even now? 

Colman, rambling again.



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