Question on software-crypt mode.

Question on software-crypt mode.

[Ben Greear]

Hello!

I am trying to implement software-crypt for ath10k so that it can do crypt
with multiple stations connected to same AP.

I tried using ath9k's approach and just not setting keys, but that does not work at all
(no stations can communicate).

If I basically leave code as is, then secondary stations can associate but never
get DHCP.  I see FCS and hw-crypt errored packets being received from the
ath10k firmware/chip.  This is probably because the chip/firmware decodes the
secondary station's packets with the first station's keys.
Transmitted packets (as sniffed from the AP) do appear fine.

I was thinking to just take all fcs and/or crypt-errored packets in
the receive path and somehow send them up the stack for the software-crypt
layer to (re)decrypt.  I think I have managed to get ath10k to send them
up, but still DHCP does not complete.

Does anyone have any suggestions for things to try or code to look at in
detail?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com


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Re: Question on software-crypt mode.

[Michal Kazior]

On 11 December 2013 16:07, Ben Greear <greearb@candelatech.com> wrote:
> Hello!
>
> I am trying to implement software-crypt for ath10k so that it can do crypt
> with multiple stations connected to same AP.
>
> I tried using ath9k's approach and just not setting keys, but that does not
> work at all
> (no stations can communicate).
>
> If I basically leave code as is, then secondary stations can associate but
> never
> get DHCP.  I see FCS and hw-crypt errored packets being received from the
> ath10k firmware/chip.  This is probably because the chip/firmware decodes
> the
> secondary station's packets with the first station's keys.
> Transmitted packets (as sniffed from the AP) do appear fine.

This sounds a lot like a multi-BSS issues that were discovered
recently on AP branch firmware.

See commit:

  ath10k: fix multi BSSID with WPA on FW 10.1

You could try applying the commit and remove the following code from it:

  if (arvif->vdev_type != WMI_VDEV_TYPE_AP)
    return;

The commit was originally only tested against AP interfaces but I was
suspecting the same thing (i.e. corrupted Tx) could be happening on
multi-STA.


Michał

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Re: Question on software-crypt mode.

[Ben Greear]

On 12/13/2013 02:53 AM, Michal Kazior wrote:
> On 11 December 2013 16:07, Ben Greear <greearb@candelatech.com> wrote:
>> Hello!
>>
>> I am trying to implement software-crypt for ath10k so that it can do crypt
>> with multiple stations connected to same AP.
>>
>> I tried using ath9k's approach and just not setting keys, but that does not
>> work at all
>> (no stations can communicate).
>>
>> If I basically leave code as is, then secondary stations can associate but
>> never
>> get DHCP.  I see FCS and hw-crypt errored packets being received from the
>> ath10k firmware/chip.  This is probably because the chip/firmware decodes
>> the
>> secondary station's packets with the first station's keys.
>> Transmitted packets (as sniffed from the AP) do appear fine.
>
> This sounds a lot like a multi-BSS issues that were discovered
> recently on AP branch firmware.

I think that it may be mostly impossible to
get hardware to do crypt with multiple STA associated to same AP
because hardware/firmware wants to hash on peer's MAC, and in this case,
I have multiple peers with same MAC.  I wanted to just ignore the RX crypt
errors and have the software RX path handle it up in mac80211, but
I did not make much progress when trying that.

I made some progress with software-only crypt, but I had to modify
firmware because it will not transmit the 4/4 handshake message until
key has been configured, and with sw-crypt, the key will never be
set.

With this change to the firmware, I can authenticate/connect to the AP, but DHCP will not work,
and the AP shows no received data packets.  I suspect the firmware is expecting the
tx packets to be un-encrypted and is either trying to crypt them again or is getting
confused when it cannot find packet headers where it expects them.

When I find time I will dig back into the firmware to work on this some more.

> See commit:
>
>    ath10k: fix multi BSSID with WPA on FW 10.1
>
> You could try applying the commit and remove the following code from it:
>
>    if (arvif->vdev_type != WMI_VDEV_TYPE_AP)
>      return;
>
> The commit was originally only tested against AP interfaces but I was
> suspecting the same thing (i.e. corrupted Tx) could be happening on
> multi-STA.

I will look at that as well.

Thanks,
Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com


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