[ath9k-devel] Cryptography of ath9k driver

From: Adrian Chadd <adrian@freebsd.org>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] Cryptography of ath9k driver
Date: Fri, 4 Nov 2016 22:08:07 -0700	[thread overview]
Message-ID: <CAJ-Vmon+Y-ykZKXkV7Hozm37BJdrfghT0PZYLRX61CayMmayQw@mail.gmail.com> (raw)
In-Reply-To: <CACfn7v75-K44GV_MmSZO9mmHBo71_pB1FxJ7muvy5g5awOP5Eg@mail.gmail.com>

hi,

person who gave talk here :)

so the mac does do wep, tkip, ccmp encryption. the mfp frames use
another encryption type that the mac doesn't do, so it is then done in
software.

each keycache entry in mac80211 tags things as hw or sw handled.

it clears that flag so mac80211 doesn't attempt to treat it as
decrypted by hardware. it overrides whatever the RX path has already
set up in that flag word.

-a

On 26 October 2016 at 04:10, Jeon <sjeon87+ath9k@gmail.com> wrote:
> Thanks for response.
>
> Well, I mean, are those hardware cryptography and nohwcrypt modparam
> applying only to management frames (i.e., are data frames already being
> en/decrypted by using software cryptography in mac/ieee80211 kernel module?)
>
> Regards,
> Jeon.
>
>
> On Wed, Oct 26, 2016 at 7:38 PM, Janusz Dziedzic <janusz.dziedzic@tieto.com>
> wrote:
>>
>>
>>
>> On 26 October 2016 at 08:53, Jeon <sjeon87+ath9k@gmail.com> wrote:
>>>
>>> I am investigating how ath9k performs cryptography.
>>>
>>> In slide 15 of DEFCON conference 2014 (link), it says, ath9k performs
>>> cryptography a on software side.
>>>
>>> On the other hand, when I look into ath9k source codes, I found
>>> somethings like below:
>>>
>>> ath9k/common.c:162-166:
>>>
>>>     if (ah->sw_mgmt_crypto_rx &&
>>>   (rxs->flag & RX_FLAG_DECRYPTED) &&
>>>   ieee80211_is_mgmt(fc))
>>>   /* Use software decrypt for management frames. */
>>>   rxs->flag &= ~RX_FLAG_DECRYPTED;
>>>
>>> As I understand, ath9k can choose hw/sw cryptography for management
>>> frames. However, what about data frames? I couldn't find any clue about
>>> cryptography for data frames.
>>>
>>> Can I take it as ath9k already performs software cryptography for data
>>> frames and shifts the responsibility of cryptography to mac80211 driver? And
>>> exceptionally for management frames, can ath9k choose hw/sw cryptography?
>>>
>>
>> modinfo ath9k (check nohwcrypt param)
>>
>> BR
>> Janusz
>
>
>
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