RSN design is supposed to encrypt all Data frames, including EAPOL
frames, once the TK has been configured. However, there are deployed
implementations that do not really follow this design and there are
various examples from the older uses of EAPOL frame where those frames
were not encrypted. As such, strict filtering of unencrypted EAPOL
frames might results in undesired interoperation issues.
However, some of the most important cases of missing EAPOL frame
encryption should be possible to handle without causing too significant
issues. These are for cases where an attacker could potentially cause an
existing association to be dropped when PMF is used. EAPOL-Start and
EAPOL-Logoff are potential candidate for such attacks since those frames
could be used to terminate an authentication or initiate a new EAP
authentication. Such an attack could result in the station ending up
disconnecting or at minimum, getting into somewhat mismatching state
with the AP.
Drop EAPOL-Start/Logoff/EAP frames on the AP/Authenticator when it is
known that it was not encrypted but should have been and when PMF is
enabled. While it would be correct to drop this even without PMF, that
does not provide any significant benefit since it is trivial to force
disconnection in no-PMF cases. It should also be noted that not all
drivers provide information about the encryption status of the EAPOL
frames and this change has no impact with drivers that do not indicate
whether the frame was encrypted.
Signed-off-by: Jouni Malinen <j@w1.fi>
8690374439