On Mon, Sep 25, 2006 at 07:24:13PM +0200, Salvo Giuffrida wrote:
Good morning, is it possible to configure the MLS policy, using
mlsconstraint, to enforce a Biba integrity model of security (no read down,
no write up), instead of the Bell-LaPadula (no read up, no write down)? I'm
reading the book "SELinux by example", and there there's written that the
MLS facility in the Security Server is not very flexible, and allows only
to enforce the rules "no read up, no write down". But, if I'm the one
configuring the policy in the file "mls", shouldn't I be able to change the
rules to the opposite?
Sure, for example the MCS policy implements "no read up, no write up",
have a look at the policy/mcs file in the serefpolicy distribution.
If you need more help please try the SELinux mailing list.
I think an interesting extension would be to split up the category bits
into MLS, MCS, and MIC (integrity) sets, so that you could use all the
models within a single policy.
Something like the following maybe (this doesn't work currently)?
mlsconstrain file write
(((l1 & mls_cats) dom (l2 & mls_cats)) and
((h1 & mcs_cats) dom (h2 & mcs_cats)) and
((l1 & mic_cats) domby (l2 & mic_cats)));
mlsconstrain file read
(((l1 & mls_cats) eq (l2 & mls_cats)) and
((h1 & mcs_cats) dom (h2 & mcs_cats)) and
((l1 & mic_cats) dom (l2 & mic_cats)))
-Klaus