Define minimum delay between roam attempts and add automatic retries.
This handles a few situations:
* roam attempt failing, then RSSI going above the threshold and below
again -- in that case we don't want to reattempt too soon, we'll only
reattempt after 60s.
* roam attempt failing then RSSI staying low for longer than 60 -- in
that case we want to reattempt after 60s too.
* signal being low from the moment we connected -- in that case we also
want to attempt a roam every some time.
Fix a leak of the MDE buffer. It is now only needed for the single call
to handshake_state_set_mde which copies the bytes anyway so use a buffer
on stack.
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.
Add sr NULL check before accessing sr->id. Call scan_request_free on
request structure and call the destroy callback. Cancel the netlink
TRIGGER_SCAN command if still running and try starting the next scan
in the queue. It'll probably still fail with EBUSY but it'll be
reattempted later.
Always call start_next_scan_request when a scan request has finished,
with a success or a failure, including a periodic scan attempt. Inside
that function check if there's any work to be done, either for one-off
scan requests or periodic scan, instead of having this check only inside
get_scan_done. Call start_next_scan_request in scan_periodic_start and
scan_periodic_timeout.
Also call the trigger callback with an error code when sending the
netlink command fails after the scan request has been queued because
another scan was in progress when the scan was requested.
Program received signal SIGSEGV, Segmentation fault.
0x0000000000419d38 in scan_done (msg=0x692580, userdata=0x688250)
at src/scan.c:250
250 sc->state = sr->passive ? SCAN_STATE_PASSIVE : SCAN_STATE_ACTIVE;
(gdb) bt
0 0x0000000000419d38 in scan_done (msg=0x692580, userdata=0x688250)
at src/scan.c:250
1 0x000000000043cac0 in process_unicast (genl=0x686d60, nlmsg=0x7fffffffc3b0)
at ell/genl.c:390
2 0x000000000043ceb0 in received_data (io=0x686e60, user_data=0x686d60)
at ell/genl.c:506
3 0x000000000043967d in io_callback (fd=6, events=1, user_data=0x686e60)
at ell/io.c:120
4 0x000000000043824d in l_main_run () at ell/main.c:381
5 0x000000000040303c in main (argc=1, argv=0x7fffffffe668) at src/main.c:259
The reasoning is that the logic inside scan_common is reversed. Instead
of freeing the scan request on error, we always do it. This causes the
trigger_scan callback to receive invalid userdata.
Save the ids of the netlink trigger scan commands that we send and
cancel them in scan_ifindex_remove to fix a race leading to a
segfault. The segfault would happen every time if scan_ifindex_remove
was called in the same main loop iteration in which we sent the
command, on shutdown:
^CTerminate
src/netdev.c:netdev_free() Freeing netdev wlan3[6]
src/device.c:device_disassociated() 6
src/device.c:device_enter_state() Old State: connected, new state:
disconnected
src/device.c:device_enter_state() Old State: disconnected, new state:
autoconnect
src/scan.c:scan_periodic_start() Starting periodic scan for ifindex: 6
src/device.c:device_free()
src/device.c:bss_free() Freeing BSS 02:00:00:00:00:00
src/device.c:bss_free() Freeing BSS 02:00:00:00:01:00
Removing scan context for ifindex: 6
src/scan.c:scan_context_free() sc: 0x5555557ca290
src/scan.c:scan_notify() Scan notification 33
src/netdev.c:netdev_operstate_down_cb() netdev: 6, success: 1
src/scan.c:scan_periodic_done()
src/scan.c:scan_periodic_done() Periodic scan triggered for ifindex:
1434209520
Program received signal SIGSEGV, Segmentation fault.
0x0000000000000064 in ?? ()
(gdb) bt
#0 0x0000000000000064 in ?? ()
#1 0x0000555555583560 in process_unicast (nlmsg=0x7fffffffc1a0,
genl=0x5555557c1d60) at ell/genl.c:390
#2 received_data (io=<optimized out>, user_data=0x5555557c1d60)
at ell/genl.c:506
#3 0x0000555555580d45 in io_callback (fd=<optimized out>,
events=1, user_data=0x5555557c1e60) at ell/io.c:120
#4 0x000055555558005f in l_main_run () at ell/main.c:381
#5 0x00005555555599c1 in main (argc=<optimized out>, argv=<optimized out>)
at src/main.c:259
Parse the contents of the GTK and IGTK subelements in an FT IE instead
of working with buffers containing the whole subelement. Some more
validation of the subelement contents. Drop support for GTK / IGTK when
building the FTE (unused).
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.
Add a flush flag to scan_parameters to tell the kernel to flush the
cache of scan results before the new scan. Use this flag in the
active scan during roaming.
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.
Make sure that the Neighbor Report timeout is cancelled when connection
breaks or device is being destroyed, and call the callback. Add an
errno parameter to the callback to indicate the cause.
With this patch an actual fast transition should happen when the signal
strength goes low but there are still various details to be fixed before
this becomes useful:
* the kernel tends to return cached scan results and won't update the
rssi values,
* there's no timer to prevent too frequent transition attempts or to
retry after some time if the signal is still low,
* no candidate other than the top ranked BSS is tried. With FT it
may be impossible to try another BSS anyway although there isn't
anything in the spec to imply this. It would require keeping the
handshake_state around after netdev gives up on the transition
attempt.
Trigger a scan of the selected channels or all channels if no useful
neighbor list was obtained, then process the scan results to select the
final target BSS.
The actual transition to the new BSS is not included in this patch for
readability.
Trigger a roam attempt when the RSSI level has been low for at least 5
seconds using the netdev RSSI LOW/HIGH events. See if neighbor reports
are supported and if so, request and process the neighbor reports list
to restrict the number of channels to be scanned. The scanning part is
not included in this patch for readability.
Validate the fourth message of the fast transition sequence and save the
new keys and state as current values in the netdev object. The
FT-specific IE validation that was already present in the initial MD
is moved to a new function.
Build and send the FT Authentication Request frame, the initial Fast
Transition message.
In this version the assumption is that once we start a transition attempt
there's no going back so the old handshake_state, scan_bss, etc. can be
replaced by the new objects immediately and there's no point at which both
the old and the new connection states are needed. Also the disconnect
event for the old connection is implicit. At netdev level the state
during a transition is almost the same with a new connection setup.
The first disconnect event on the netlink socket after the FT Authenticate
is assumed to be the one generated by the kernel for the old connection.
The disconnect event doesn't contain the AP bssid (unlike the
deauthenticate event preceding it), otherwise we could check to see if
the bssid is the one we are interested in or could check connect_cmd_id
assuming a disconnect doesn't happen before the connect command finishes.
