In our 1995 B1 evaluation of Trusted Irix we were told in no
uncertain terms that such a solution was not acceptable under
the TCSEC requirements. Detection and relabel on an unlocked
object creates an obvious window for exploitation. We were told
that such a scheme would be considered a design flaw.
I understand that some of the Common Criteria labs are less
aggressive regarding chasing down these issues than the NCSC
teams were. It might not prevent an evaluation from completing
today. It is still hard to explain why it's ok to have a file
that's labeled incorrectly _even briefly_. It is the systems
job to ensure that that does not happen.
Casey Schaufler
casey@schaufler-ca.com
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