About a month ago hostapd was changed to set the secure bit on
eapol frames during rekeys (bc36991791). The spec is ambiguous
about this and has conflicting info depending on the sections you
read (12.7.2 vs 12.7.6). According to the hostapd commit log TGme
is trying to clarify this and wants to set secure=1 in the case
of rekeys. Because of this, IWD is completely broken with rekeys
since its disallows secure=1 on PTK 1/4 and 2/4.
Now, a bool is passed to the verify functions which signifies if
the PTK has been negotiated already. If secure differs from this
the key frame is not verified.
802.1x offloading needs a way to call SET_PMK after EAP finishes.
In the same manner as set_tk/gtk/igtk a new 'install_pmk' function
was added which eapol can call into after EAP completes.
We were not using or taking into account the noencrypt flag obtained
from the kernel via CONTROL_PORT events. For the most part this still
worked as the kernel would never include NO_ENCRYPT flag (due to a bug).
However, this was actually incorrect and led to loss of synchronization
between the AP and STA 4-Way handshake state machines when certain
packets were lost and had to be re-transmitted.
FILS authentication does away with the MIC, so checking for key_mic
in the eapol key frame does not allow FILS to work. Now we pass in
the mic_len to eapol_verify_gtk_1_of_2, and if it is non-zero we can
check that the MIC is present in the frame.
FILS does not require an eapol_sm for authentication, but rekeys
are still performed using the 4-way handshake. Because of this
FILS needs to create a eapol_sm in a 'started' state, but without
calling eapol_start as this will initialize EAP and create handshake
timeouts.
This allows EAPoL to wait for any 4-way packets, and handle them
as rekeys.
The MIC length was hard coded to 16 bytes everywhere, and since several
AKMs require larger MIC's (24/32) this needed to change. The main issue
was that the MIC was hard coded to 16 bytes inside eapol_key. Instead
of doing this, the MIC, key_data_length, and key_data elements were all
bundled into key_data[0]. In order to retrieve the MIC, key_data_len,
or key_data several macros were introduced which account for the MIC
length provided.
A consequence of this is that all the verify functions inside eapol now
require the MIC length as a parameter because without it they cannot
determine the byte offset of key_data or key_data_length.
The MIC length for a given handshake is set inside the SM when starting
EAPoL. This length is determined by the AKM for the handshake.
After moving AP EAPoL code into eapol.c there were a few functions that
no longer needed to be public API's. These were changed to static's and
the header definition was removed.
This removes the authenticator bit in eapol_sm as well as unifies
eapol_register_authenticator and eapol_register. Taking advantage
of the handshake state authenticator bit we no longer have a need
for 2 separate register functions.
ap, and adhoc were also updated to set the authenticator bit in
the handshake and only use eapol_register to register their sm's.
netdev was updated to use the authenticator bit when choosing the
correct key address for adhoc.
This also required passing in the akm suite in case the key description
version was zero. In the zero case the akm must be checked. For now this
only supports the SAE akm.
Includes:
- support for handling ptk 2/4 and 4/4. Also sending 1/4 and 3/4.
- new API to register an authenticator SM. This automatically
sends 1/4 to kick off authentication with an sta.
With the introduction of Control Port Over NL80211 feature, the
transport details need to be moved out of eapol and into netdev.c.
Whether a given WiFi hardware supports transfer of Control Port packets
over NL80211 is Wiphy and kernel version related, so the transport
decisions need to be made elsewhere.
The eapol handshake timeout can now be configured in main.conf
(/etc/iwd/main.conf) using the key eapol_handshake_timeout. This
allows the user to configure a long timeout if debugging.
Add a utility to append a KDE to the key_data field in an EAPoL frame.
The KDE types enum is actually added to handshake.h because we've got
the utilities for finding those KDEs in a buffer there. The new
function is specific to EAPoL-Key frames though and perhaps to simple to
be split across handshake.c and eapol.c. Also it didn't seem useful to
use the ie_tlv_builder here.
Function to allow netdev.c to explicitly tell eapol.c whether to expect
EAP / 4-Way handshake. This is to potentially make the code more
descriptive, until now we'd look at sm->handshake->ptk_complete to see
if a new PTK was needed.
A 4-Way handshake is required on association to an AP except after FT.
Modify the packet filter to also accept frames with ethertype of 0x88c7
and pass the ethertype value to __eapol_rx_packet so it can filter out
the frames where this value doesn't match the sm->preauth flag.
Add a wrapper for eapol_start that sets the sm->preauth flag and sends
the EAPOL-Start frame immediately to skip the timeout since we know
that the supplicant has to initiate the authentication.
Remove the keys and other data from struct eapol_sm, update device.c,
netdev.c and wsc.c to use the handshake_state object instead of
eapol_sm. This also gets rid of eapol_cancel and the ifindex parameter
in some of the eapol functions where sm->handshake->ifindex can be
used instead.
Add space in the eapol_sm struct for the pieces of information required
for the FT 4-Way Handshake and add setters for device.c and netdev.c to
be able to provide the data.
The len parameter was only used so it could be validated against ie[1],
but since it was not checked to be > 2, it must have been validated
already, the check was redundant. In any case all users directly
passed ie[1] as len anyway. This makes it consistent with the ie
parsers and builders which didn't require a length.
Split eapol_start into two calls, one to register the state machine so
that the PAE read handler knows not to discard frames for that ifindex,
and eapol_start to actually start processing the frames. This is needed
because, as per the comment in netdev.c, due to scheduling the PAE
socket read handler may trigger before the CMD_CONNECT event handler,
which needs to parse the FTE from the Associate Response frame and
supply it to the eapol SM before it can do anything with the message 1
of 4 of the FT handshake.
Another issue is that depending on the driver or timing, the underlying
link might not be marked as 'ready' by the kernel. In this case, our
response to Message 1 of the 4-way Handshake is written and accepted by
the kernel, but gets dropped on the floor internally. Which leads to
timeouts if the AP doesn't retransmit.
We used to open a socket for each wireless interface. This patch uses a
single socket with an attached BPF to handle all EAPoL traffic via a
single file descriptor.
Instead of one global protocol_version, we now store it inside eapol_sm.
This allows us to use the same protocol version for our response as the
request from the authenticator.
For unit tests where we had protocol version mismatches, a new method is
introduced to explicitly set the protocol version to use.
Instead of passing the user_data parameter in every __eapol_rx_packet
call to be used by EAPOL in all tx_packet calls, add
eapol_sm_set_tx_user_data function that sets the value of user_data for
all subsequent tx_packet calls. This way tx_packet can be called from
places that are not necessarily inside an __eapol_rx_packet call.
James Prestwood