If the AP send an associate with an unsupported group status, OWE
was completely starting over and sending out an authenticate frame
when it could instead just resend the associate frame with a
different group.
Now that the OWE failure/retry is handled in netdev, we can catch
all associate error status' inside owe_rx_associate rather than only
catching UNSUPP_FINITE_CYCLIC_GROUP.
Apart from OWE, the association event was disregarded and all association
processing was done in netdev_connect_event. This led to
netdev_connect_event having to handle all the logic of both success and
failure, as well as parsing the association for FT and OWE. Also, without
checking the status code in the associate frame there is the potential
for the kernel to think we are connected even if association failed
(e.g. rogue AP).
This change introduces two flags into netdev, expect_connect_failure and
ignore_connect_event. All the FT processing that was once in
netdev_connect_event has now been moved into netdev_associate_event, as
well as non-FT associate frame processing. The connect event now only
handles failure cases for soft/half MAC cards.
Note: Since fullmac cards rely on the connect event, the eapol_start
and netdev_connect_ok were left in netdev_connect_event. Since neither
auth/assoc events come in on fullmac we shouldn't have any conflict with
the new flags.
Once a connection has completed association, EAPoL is started from
netdev_associate_event (if required) and the ignore_connect_event flag can
be set. This will bypass the connect event.
If a connection has failed during association for whatever reason, we can
set expect_connect_failure, the netdev reason, and the MPDU status code.
This allows netdev_connect_event to both handle the error, and, if required,
send a deauth telling the kernel that we have failed (protecting against the
rogue AP situation).
ELL ECC supports group 20 (P384) so OWE can also support it. This also
adds group negotiation, where OWE can choose a different group than the
default if the AP requests it.
A check needed to be added in netdev in order for the negotiation to work.
The RFC says that if a group is not supported association should be rejected
with code 77 (unsupported finite cyclic group) and association should be
started again. This rejection was causing a connect event to be emitted by
the kernel (in addition to an associate event) which would result in netdev
terminating the connection, which we didn't want. Since OWE receives the
rejected associate event it can intelligently decide whether it really wants
to terminate (out of supported groups) or try the next available group.
This also utilizes the new MIC/KEK/KCK length changes, since OWE dictates
the lengths of those keys.
Rather than hard coding to SHA256, we can pass in l_checksum_type
and use that SHA. This will allow for OWE/SAE/PWD to support more
curves that use different SHA algorithms for hashing.
ECDH was expecting the private key in LE, but the public key in BE byte ordering.
For consistency the ECDH now expect all inputs in LE byte ordering. It is up to
the caller to order the bytes appropriately.
This required adding some ecc_native2be/be2native calls in OWE
This module is similar to SAE in that it communicates over authenticate
and associate frames. Creating a new OWE SM requires registering two TX
functions that handle sending the data out over CMD_AUTHENTICATE/ASSOCIATE,
as well as a complete function.
Once ready, calling owe_start will kick off the OWE process, first by
sending out an authenticate frame. There is nothing special here, since
OWE is done over the associate request/response.
After the authenticate response comes in OWE will send out the associate
frame which includes the ECDH public key, and then receive the AP's
public key via the associate response. From here OWE will use ECDH to
compute the shared secret, and the PMK/PMKID. Both are set into the
handshake object.
Assuming the PMK/PMKID are successfully computed the OWE complete callback
will trigger, meaning the 4-way handshake can begin using the PMK/PMKID
that were set in the handshake object.
Marcel Holtmann