eapol: Silently discard invalid EAPoL frames

Do not fail an ongoing handshake when an invalid EAPoL frame is
received.  Instead, follow the intent of 802.11-2020 section 12.7.2:
"EAPOL-Key frames containing invalid field values shall be silently
discarded."

This prevents a denial-of-service attack where receipt of an invalid,
unencrypted EAPoL 1/4 frame generated by an adversary results in iwd
terminating an ongoing connection.

Reported-by: Domien Schepers <schepers.d@northeastern.edu>
1 file changed