remember that the windows NT permission model is theoreticly superior to the
Unix permission model.
however there are far more insecure windows boxes out there then Unix boxes
(even if taken as a percentage of the installed base)
I don't think that anyone is claiming that AA is superior to SELinux
what people are claiming is that the model AA is proposing can improve security
in some cases.
to use the example from this thread /etc/resolv.conf
if you have a webserver that wants to do a name lookup you can do one of two
things
1. in AA configure the webserver to have ro access to /etc/resolv.conf
2. in SELinux tag /etc/resolv.conf, figure out every program on the sytem that
accesses it, and then tag those programs with the right permissions.
SELinux is designed to be able to make the box safe against root, AA is designed
to let the admin harden exposed apps without having to think about the other
things on the system.
allow people to use each tool for the appropriate task.
David Lang
On Wed, 18 Apr 2007, Rob Meijer wrote:
Date: Wed, 18 Apr 2007 09:21:13 +0200 (CEST)
From: Rob Meijer <capibara@xxxxxxxxx>
To: Karl MacMillan <kmacmill@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>, John Johansen <jjohansen@xxxxxxx>,
linux-kernel@xxxxxxxxxxxxxxx, linux-security-module@xxxxxxxxxxxxxxx,
linux-fsdevel@xxxxxxxxxxxxxxx
Subject: Re: AppArmor FAQ
On Tue, April 17, 2007 23:55, Karl MacMillan wrote:
On Mon, 2007-04-16 at 20:20 -0400, James Morris wrote:
On Mon, 16 Apr 2007, John Johansen wrote:
Label-based security (exemplified by SELinux, and its predecessors in
MLS systems) attaches security policy to the data. As the data flows
through the system, the label sticks to the data, and so security
policy with respect to this data stays intact. This is a good approach
for ensuring secrecy, the kind of problem that intelligence agencies
have.
Labels are also a good approach for ensuring integrity, which is one of
the most fundamental aspects of the security model implemented by
SELinux.
Some may infer otherwise from your document.
Not only that, the implication that secrecy is only useful to
intelligence agencies is pretty funny. Personally, I think that
protecting the confidentiality of my data is important (and my bank and
health care providers protecting the data they have about me). Type
Enforcement was specifically designed to be able to address integrity
_and_ confidentiality in a way acceptable to commercial organizations.
Karl
Shouldn't that be _OR_, as I have always understood confidentialy
models like BLP are by their very nature incompatible with integrity
models like Biba. Given this incompatibity, I think the idea that
BLP style use of lables (ss/* property and the likes) is only usefull
to intelligence agencies may well be correct, while usage for integrity
models like Biba and CW would be much broader than that.
A path based 'least priviledge' (POLP) solution would I think on its own
address neither integity nor confidentiality, and next to this would
proof to be yet an other 'fat profile' administration hell.
Having said that, I feel a path based solution could have great potential
if it could be used in conjunction with the object capability model, that
I would consider a simple and practical alternative integrity model that
does not require lables in an MLS maner, and that extends on the POLP
concept in a way that would be largely more practical.
That is, using 'thin' path based profiles would become very practical if
all further authority can be communicated using handles in the same way
that an open file handle can be communicated.
Rob
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