On 12/06/2016 09:02 AM, Jean-Pierre Tosoni wrote:
This follows on the previous discussion
"Client station sends probes on DFS channels"
Problem:
The combination of QCA988X firmware v10.2.4.70-2 + ath10k +
wpa_supplicant do not comply with the norm ETSI/EN 301-893
section 4.7; because they can send probes for 600s when no
AP is around.
Analysis:
The problem seems to lie in the firmware, which regards the presence
of *any* beacon as a proof that the channel is radar-clean for 600s.
This is a wrong hypothesis, since a rogue AP sending fraudulent
beacons should not induce a scrupulous STA in sending illegal probes.
Moreover, the norm (table D.1) sets a time limit of 10s to
shutdown when no AP positively allows the STA to transmit on
the DFS channel.
Status:
- there is no known plan at QCA to fix the issue.
- ath10k firmware is not publicly available for fixes.
- there is no obvious fix working in ath10k.
- the issue does not show up with other mac80211 devices like ath9k.
- wpa_supplicant considers this is a kernel issue [2]
Have you confirmed that there are no probe requests being sent by
ath10k driver?
You could also try disabling the station keep-alive and roaming logic in the firmware by
tweaking the wmi initial setup logic. I disable that in my firmware,
for instance, because mac80211 can do a better job and then I can
save resources in the firmware.
Finally, if that doesn't work, then I could probably fix that in CT firmware
in case that is of interest.
Thanks,
Ben
Jean-Pierre Tosoni
-----Message d'origine-----
De : ath10k [mailto:ath10k-bounces@xxxxxxxxxxxxxxxxxxx] De la part de
Jean-Pierre Tosoni
Envoyé : mercredi 30 novembre 2016 19:04
À : ath10k@xxxxxxxxxxxxxxxxxxx
Objet : Client station sends probes on DFS channels
Hello list,
There is a case where I can see probes on a DFS channel, from a non-
associated station using ath10k. (note that the problem does not arise
when using ath9k).
*The setup*
I am using Openwrt, wpa_supplicant and compat-wireless 2016-10-08,
Card firmware is ath10k_pci: qca988x hw2.0 (0x4100016c, 0x043202ff)
fw 10.2.4.70-2 api 5 htt-ver 2.1 wmi-op 5 htt-op 2
cal otp max-sta 128 features no-p2p
ath10k_pci: debug 0 debugfs 1 tracing 0 dfs 1 testmode 1
I am using channel 116, regdom US or FR, where I see no traffic at all
using wireshark+Airpcap.
I set wpa_supplicant to scan this channel only for a specific SSID
"ssid1".
At initial startup of the client device, no probes are going out, which
is OK.
Then, on another device, I start a hostapd set to channel 116, with a
different SSID "otherssid" so that the supplicant will not associate.
Shortly (1-2s) after the beacons appear in the air, the client begins to
Send probe request in the air, which is unexpected, but acceptable since
the client can infer absence of radars from the presence of beacons.
*The problem*
If I power down the AP, the client continues to send probes for around
10 minutes, which is unacceptable since it cannot handle radar detection,
as it is a slave device in the meaning of ETSI/EN 301-893[1].
Some tests I made:
- I tried to investigate the "beacon hint" mechanism but it appears
that it is not used on DFS channels.
- I tried to force the IEEE80211_NO_IR flag when IEEE80211_CHAN_DFS
is set.
- When I reload the reg. domain using "iw reg set", the probes cease,
but will reappear if I cycle my AP again On then Off.
- When I let the client associate, then disassociate and stop the AP,
the same problem arises. It disappears if I add a call to
ath10k_regd_update() in mac.c after a disconnection (This is not a
fix, since in my case the client never associates).
- Since at startup, the client does not send probes, I infer that the
problem is *not* caused by a hidden AP that the card could see but
not airpcap.
- I tried with channels 52 and 100, with regdom FR or US: same problem.
Any ideas?
[1] http://www.etsi.org/deliver/etsi_en/301800_301899/301893/
01.08.01_60/en_301893v010801p.pdf
[2] http://lists.shmoo.com/pipermail/hostap/2015-January/031906.html
J.P. Tosoni - ACKSYS
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--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
