This is needed in order to clear the PMKSA from the handshake state
without actually putting it back into the cache. This is something
that will be needed in case the AP rejects the association due to
an expired (or forgotten) PMKSA.
The majority of this patch was authored by Denis Kenzior, but
I have appended setting the PMK inside handshake_state_set_pmksa
as well as checking if the pmkid exists in
handshake_state_steal_pmkid.
Authored-by: Denis Kenzior <denkenz@gmail.com>
Authored-by: James Prestwood <prestwoj@gmail.com>
This adds a ref count to the handshake state object (as well as
ref/unref APIs). Currently IWD is careful to ensure that netdev
holds the root reference to the handshake state. Other modules do
track it themselves, but ensure that it doesn't get referenced
after netdev frees it.
Future work related to PMKSA will require that station holds a
references to the handshake state, specifically for retry logic,
after netdev is done with it so we need a way to delay the free
until station is also done.
This will help to get rid of magic number use throughout the project.
The definitions should be limited to global magic numbers that are used
throughout the project, for example SSID length, MAC address length,
etc.
If either the settings specify it, or the scan_bss is flagged, set
the use_default_ecc_group flag in the handshake.
This also renames the flag to cover both OWE and SAE
In general only the authenticator FTE is used/validated but with
some FT refactoring coming there needs to be a way to build the
supplicants FTE into the handshake object. Because of this there
needs to be separate FTE buffers for both the authenticator and
supplicant.
The PMKID derivation has gotten messy due to the spec
updating/clarifying the hash size for the FT-8021X AKM. This
has led to hostapd updating the derivation which leaves older
hostapd versions using SHA1 and newer versions using SHA256.
To support this the checksum type is being fed to
handshake_state_get_pmkid so the caller can decide what sha to
use. In addition handshake_state_pmkid_matches is being added
which uses get_pmkid() but handles sorting out the hash type
automatically.
This lets preauthentication use handshake_state_get_pmkid where
there is the potential that a new PMKID is derived and eapol
can use handshake_state_pmkid_matches which only derives the
PMKID to compare against the peers.
Rekeys for station mode don't need to know when complete since
there is nothing to do once done. AP mode on the other hand needs
to know if the rekey was successful in order to reset/set the next
rekey timer.
Commit 4d2176df2985 ("handshake: Allow event handler to free handshake")
introduced a re-entrancy guard so that handshake_state objects that are
destroyed as a result of the event do not cause a crash. It rightly
used a temporary object to store the passed in handshake. Unfortunately
this caused variable shadowing which resulted in crashes fixed by commit
d22b174a7318 ("handshake: use _hs directly in handshake_event").
However, since the temporary was no longer used, this fix itself caused
a crash:
#0 0x00005555f0ba8b3d in eapol_handle_ptk_1_of_4 (sm=sm@entry=0x5555f2b4a920, ek=0x5555f2b62588, ek@entry=0x16, unencrypted=unencrypted@entry=false) at src/eapol.c:1236
1236 handshake_event(sm->handshake,
(gdb) bt
#0 0x00005555f0ba8b3d in eapol_handle_ptk_1_of_4 (sm=sm@entry=0x5555f2b4a920, ek=0x5555f2b62588, ek@entry=0x16, unencrypted=unencrypted@entry=false) at src/eapol.c:1236
#1 0x00005555f0bab118 in eapol_key_handle (unencrypted=<optimized out>, frame=<optimized out>, sm=0x5555f2b4a920) at src/eapol.c:2343
#2 eapol_rx_packet (proto=<optimized out>, from=<optimized out>, frame=<optimized out>, unencrypted=<optimized out>, user_data=0x5555f2b4a920) at src/eapol.c:2665
#3 0x00005555f0bac497 in __eapol_rx_packet (ifindex=62, src=src@entry=0x5555f2b62574 "x\212 J\207\267", proto=proto@entry=34958, frame=frame@entry=0x5555f2b62588 "\002\003",
len=len@entry=121, noencrypt=noencrypt@entry=false) at src/eapol.c:3017
#4 0x00005555f0b8c617 in netdev_control_port_frame_event (netdev=0x5555f2b64450, msg=0x5555f2b62588) at src/netdev.c:5574
#5 netdev_unicast_notify (msg=msg@entry=0x5555f2b619a0, user_data=<optimized out>) at src/netdev.c:5613
#6 0x00007f60084c9a51 in dispatch_unicast_watches (msg=0x5555f2b619a0, id=<optimized out>, genl=0x5555f2b3fc80) at ell/genl.c:954
#7 process_unicast (nlmsg=0x7fff61abeac0, genl=0x5555f2b3fc80) at ell/genl.c:973
#8 received_data (io=<optimized out>, user_data=0x5555f2b3fc80) at ell/genl.c:1098
#9 0x00007f60084c61bd in io_callback (fd=<optimized out>, events=1, user_data=0x5555f2b3fd20) at ell/io.c:120
#10 0x00007f60084c536d in l_main_iterate (timeout=<optimized out>) at ell/main.c:478
#11 0x00007f60084c543e in l_main_run () at ell/main.c:525
#12 l_main_run () at ell/main.c:507
#13 0x00007f60084c5670 in l_main_run_with_signal (callback=callback@entry=0x5555f0b89150 <signal_handler>, user_data=user_data@entry=0x0) at ell/main.c:647
#14 0x00005555f0b886a4 in main (argc=<optimized out>, argv=<optimized out>) at src/main.c:532
This happens when the driver does not support rekeying, which causes iwd to
attempt a disconnect and re-connect. The disconnect action is
taken during the event callback and destroys the underlying eapol state
machine. Since a temporary isn't used, attempting to dereference
sm->handshake results in a crash.
Fix this by introducing a UNIQUE_ID macro which should prevent shadowing
and using a temporary variable as originally intended.
Fixes: d22b174a7318 ("handshake: use _hs directly in handshake_event")
Fixes: 4d2176df2985 ("handshake: Allow event handler to free handshake")
Reported-By: Toke Høiland-Jørgensen <toke@toke.dk>
Tested-by: Toke Høiland-Jørgensen <toke@toke.dk>
Fixes the following crash:
#0 0x000211c4 in netdev_connect_event (msg=<optimized out>, netdev=0x2016940) at src/netdev.c:2915
#1 0x76f11220 in process_multicast (nlmsg=0x7e8acafc, group=<optimized out>, genl=<optimized out>) at ell/genl.c:1029
#2 received_data (io=<optimized out>, user_data=<optimized out>) at ell/genl.c:1096
#3 0x76f0da08 in io_callback (fd=<optimized out>, events=1, user_data=0x200a560) at ell/io.c:120
#4 0x76f0ca78 in l_main_iterate (timeout=<optimized out>) at ell/main.c:478
#5 0x76f0cb74 in l_main_run () at ell/main.c:525
#6 l_main_run () at ell/main.c:507
#7 0x76f0cdd4 in l_main_run_with_signal (callback=callback@entry=0x18c94 <signal_handler>, user_data=user_data@entry=0x0)
at ell/main.c:647
#8 0x00018178 in main (argc=<optimized out>, argv=<optimized out>) at src/main.c:532
This crash was introduced in commit:
4d2176df2985 ("handshake: Allow event handler to free handshake")
The culprit seems to be that 'hs' is being used both in the caller and
in the macro. Since the macro defines a variable 'hs' in local block
scope, it overrides 'hs' from function scope. Yet (_hs) still evaluates
to 'hs' leading the local variable to be initialized with itself. Only
the 'handshake_event(hs, HANDSHAKE_EVENT_SETTING_KEYS))' is affected
since it is the only macro invocation that uses 'hs' from function
scope. Thus, the crash would only happen on hardware supporting handshake
offload (brcmfmac).
Fix this by removing the local scope variable declaration and evaluate
(_hs) instead.
Fixes: 4d2176df2985 ("handshake: Allow event handler to free handshake")
Like in ap.c, allow the event callback to mark the handshake state as
destroyed, without causing invalid accesses after the callback has
returned. In this case the crash was because try_handshake_complete
needed to access members of handshake_state after emitting the event,
as well as access the netdev, which also has been destroyed:
==257707== Invalid read of size 8
==257707== at 0x408C85: try_handshake_complete (netdev.c:1487)
==257707== by 0x408C85: try_handshake_complete (netdev.c:1480)
(...)
==257707== Address 0x4e187e8 is 856 bytes inside a block of size 872 free'd
==257707== at 0x484621F: free (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==257707== by 0x437887: ap_stop_handshake (ap.c:151)
==257707== by 0x439793: ap_del_station (ap.c:316)
==257707== by 0x43EA92: ap_station_disconnect (ap.c:3411)
==257707== by 0x43EA92: ap_station_disconnect (ap.c:3399)
==257707== by 0x454276: p2p_group_event (p2p.c:1006)
==257707== by 0x439147: ap_event (ap.c:281)
==257707== by 0x4393AB: ap_new_rsna (ap.c:390)
==257707== by 0x4393AB: ap_handshake_event (ap.c:1010)
==257707== by 0x408C7F: try_handshake_complete (netdev.c:1485)
==257707== by 0x408C7F: try_handshake_complete (netdev.c:1480)
(...)
The procedure for setting extended key IDs is different from the
single PTK key. The key ID is toggled between 0 and 1 and the new
key is set as RX only, then set to RX/TX after message 4/4 goes
out.
Since netdev needs to set this new key before sending message 4,
eapol can include a built message which netdev will store if
required (i.e. using PAE).
ext_key_id_capable indicates the handshake has set the capability bit
in the RSN info. This will only be set if the AP also has the capability
set.
active_tk_index is the key index the AP chose in message 3. This is
now used for both legacy (always zero) and extended key IDs.
Add a utility for setting the OCI obtained from the hardware (prior to
handshake starting) as well as a utility to validate the OCI obtained
from the peer.
handshake_util_ap_ie_matches() is used to make sure that the RSN element
received from the Authenticator during handshake / association response
is the same as the one advertised in Beacon/Probe Response frames. This
utility tries to bitwise compare the element first, and only if that
fails, compares RSN members individually.
For FT, bitwise comparison will always fail since the PMKID has to be
included by the Authenticator in any RSN IEs included in Authenticate
& Association Response frames.
Perform the bitwise comparison as an optimization only during processing
of eapol message 3/4. Also keep the parsed rsn information for future
use and to possibly avoid re-parsing it during later checks.
Send and receive the FILS IP Address Assignment IEs during association.
As implemented this would work independently of FILS although the only
AP software handling this mechanism without FILS is likely IWD itself.
No support is added for handling the IP assignment information sent from
the server after the initial Association Request/Response frames, i.e.
the information is only used if it is received directly in the
Association Response without the "response pending" bit, otherwise the
DHCP client will be started.
Add a handshake event for use by the AP side for mechanisms that
allocate client IPs during the handshake: P2P address allocation and
FILS address assignment. This is emitted only when EAPOL or the
auth_proto is actually about to send the network configuration data to
the client so that ap.c can skip allocating a DHCP leases altogether if
the client doesn't send the required KDE or IE.
Some connections, like Hotspot require additional IEs to be used during
the Association. These are now passed as 'extra_ies' when invoking
netdev_connect, however they are also needed during ReAssociation and FT
to such APs.
Additionally, it may be that Hotspot-enabled APs will start utilizing
FILS or SAE. In these cases the extra_ies need to be accounted for
somehow, either by making a copy in handshake_state, netdev, or the
auth_proto itself. Similarly, P2P which heavily uses vendor IEs can be
used over SAE in the future.
Since a copy of these IEs is needed, might as well store them in
handshake_state itself for easy book-keeping by network/station.
This indication can come in via EAPoL message 3 or during
FILS Association. It carries information as to whether certain
transition mode options should be disabled. See WPA3 Specification,
version 3 for more details.
station should be isolated as much as possible from the details of the
driver type and how a particular AKM is handled under the hood. It will
be up to wiphy to pick the best AKM for a given bss. netdev in turn
will pick how to drive the particular AKM that was picked.
Support IP allocation during the 4-Way Handshake as defined in the P2P
spec. This is the supplicant side implementation.
The API requires the user to set hs->support_ip_allocation true before
eapol_start(). On HANDSHAKE_EVENT_COMPLETE, if this same flag is still
set, we've received the IP lease, the netmask and the authenticator's
IP from the authenticator and there's no need to start DHCP. If the
flag is cleared, the user needs to use DHCP.
On EAP events, call the handshake_event handler with the new event type
HANDSHAKE_EVENT_EAP_NOTIFY isntead of the eapol_event callback.
This allows the handler to be set before calling
netdev_connect/netdev_connect_wsc. It's also in theory more type-safe
because we don't need the cast in netdev_connect_wsc anymore.
Convert the handshake event callback type to use variable argument
list to allow for more flexibility in event-specific arguments
passed to the callbacks.
Note the uint16_t reason code is promoted to an int when using variable
arguments so va_arg(args, int) has to be used.
The handshake object had 4 setters for authenticator/supplicant IE.
Since the IE ultimately gets put into the same buffer, there really
only needs to be a single setter for authenticator/supplicant. The
handshake object can deal with parsing to decide what kind of IE it
is (WPA or RSN).
FILS-FT is a special case with respect to the PTK keys. The KCK getter
was updated to handle both FT-FILS AKMs, by returning the offset in
the PTK to the special KCK generated during FILS. A getter for the KCK
length was added, which handles the SHA384 variant. The PTK size was
also updated since FILS-FT can generate an additional 56 bytes of PTK
Keeping the ERP cache on the handshake object allows station.c to
handle all the ERP details and encapsulate them into a handshake.
FILS can then use the ERP cache right from the handshake rather
than getting it itself.
With FILS support coming there needs to be a way to set the PTK directly.
Other AKMs derive the PTK via the 4-way handshake, but FILS computes the
PTK on its own.
The handshake_state only holds a single AKM value. FILS depends on the AP
supporting EAP as well as FILS. The first time IWD connects, it will do a
full EAP auth. Subsequent connections (assuming FILS is supported) will use
FILS. But if the AP does not support FILS there is no reason to cache the
ERP keys.
This adds the supp_fils to the handshake_state. Now, station.c can set this
flag while building the handshake. This flag can later be checked when
caching the ERP keys.
