Track the contents and size of the GTK and IGTK and if the Authenticator
(or an adversary) tries to set the same GTK/IGTK, process the packet
normally but do not resubmit the GTK/IGTK to the kernel.
GTK KDE was being checked for being a minimum of 6 bytes. Not quite
sure why since the minimum GTK key length is 16 bytes for CCMP.
Similarly make sure that the maximum length is not more than 32, which
is currently the largest key size (TKIP)
This is a bizarre case since MIC calculation succeeded for the incoming
packet. But just in case MIC calculation fails for the outgoing packet,
kill the handshake.
The comments quoted sections of the specification that indicated STA
behavior for verifying Message 3 of 4 or GTK 1 of 2. But in reality the
code directly below simply calculated the MIC for Message 4 of 4 or GTK
2 of 2.
Use eapol_frame_watch_add/eapol_frame_watch_remove in eapol_sm, while
there simplify the early_frame logic and confirm sender address for
received frames.
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.
Refactor management frame structures to take into account optional
presence of some parts of the header:
* drop the single structure for management header and body since
the body offset is variable.
* add mmpdu_get_body to locate the start of frame body.
* drop the union of different management frame type bodies.
* prefix names specific to management frames with "mmpdu" instead
of "mpdu" including any enums based on 802.11-2012 section 8.4.
* move the FC field to the mmpdu_header structure.
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.
Skip the matching of the PMKID KDE to the PMKID list in the RSNE if
we've seen a new EAP authentication before the step 1/4 was received.
That would mean that the server had not accepted the PMKIDs we submitted
and we performed a new 8021X authentication, producing a new PMKSA which
won't be on the list in the RSNE.
Currently we'd send EAPOL-Start whenever EAP was configured and we
received an EAPOL-Key before EAP negotiation. Instead only do that if
we know we can't respond to the 4-Way handshake because we don't have
a PMK yet or the PMKID doesn't match. Require a PMKID in step 1/4 if
we'd sent a list of PMKIDs in our RSNE.
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.
Fix 1a64c4b771 by setting use_eapol_start
by default only when 8021x authentication is configured. Otherwise we'd
be sending EAPOL-Start even for WPA2 Personal possibly after the 4-Way
Handshake success.
Since caab23f192085e6c8e47c41fc1ae9f795d1cbe86 hostapd is going to set
this bit to zero for RSN networks but both values will obviously be in
use. Only check the value if is_wpa is true - in this case check the
value is exactly 16, see hostapd commit:
commit caab23f192085e6c8e47c41fc1ae9f795d1cbe86
Author: Jouni Malinen <j@w1.fi>
Date: Sun Feb 5 13:52:43 2017 +0200
Set EAPOL-Key Key Length field to 0 for group message 1/2 in RSN
P802.11i/D3.0 described the Key Length as having value 16 for the group
key handshake. However, this was changed to 0 in the published IEEE Std
802.11i-2004 amendment (and still remains 0 in the current standard IEEE
Std 802.11-2016). We need to maintain the non-zero value for WPA (v1)
cases, but the RSN case can be changed to 0 to be closer to the current
standard.
Don't start the handshake timeout in eapol_start if either
handshake->ptk_complete is set (handshake already done) or
handshake->have_snonce is set (steps 1&2 done). This accounts for
eapol_start being called after a Fast Transition when a 4-Way handshake
is not expected.
Split the igtk parameter to handshake_state_install_igtk into one
parameter for the actual IGTK buffer and one for the IPN buffer instead
of requiring the caller to have them both in one continuous buffer.
With FT protocol, one is received encrypted and the other in plain text.
Despite RFC3748 mandating MSKs to be at least 256 bits some EAP methods
return shorter MSKs. Since we call handshake_failed when the MSK is too
short, EAP methods have to be careful with their calls to set_key_material
because it may result in a call to the method's .remove method.
EAP-TLS and EAP-TTLS can't handle that currently and would be difficult to
adapt because of the TLS internals but they always set msk_len to 64 so
handshake_failed will not be called.
Make the use of EAPOL-Start the default and send it when configured for
8021x and either we receive no EAPOL-EAP from from the AP before
timeout, or if the AP tries to start a 4-Way Handshake.
On certain routers, the 4-Way handshake message 3 of 4 contains a key iv
field which is not zero as it is supposed to. This causes us to fail
the handshake.
Since the iv field is not utilized in this particular case, it is safe
to simply warn rather than fail the handshake outright.
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.
Tim Kourt