netdev - Re: [PATCH] mac80211: aes_ccm: move struct aead

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Date:   Fri, 14 Oct 2016 14:19:21 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "<linux-wireless@...r.kernel.org>" <linux-wireless@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jouni Malinen <j@...fi>
Subject: Re: [PATCH] mac80211: aes_ccm: move struct aead_req off the stack

On 14 October 2016 at 14:15, Johannes Berg <johannes@...solutions.net> wrote:
> On Fri, 2016-10-14 at 14:13 +0100, Ard Biesheuvel wrote:
>>
>> > But if we allocate things anyway, is it worth expending per-CPU
>> > buffers on these?
>>
>> Ehmm, maybe not. I could spin a v2 that allocates a bigger buffer,
>> and copies aad[] into it as well
>
> Copies in/out, I guess. Also there's B_0/J_0 for CCM/GCM, and the
> 'zero' thing that GMAC has.
>

Is the aad[] actually reused? I would assume it only affects the mac
on encryption, and the verification on decryption but I don't think we
actually need it back from the crypto routines.

>> That does not help the other algos though
>
> What do you mean?
>

Exactly what you said above :-) My patch only touches CCM but as you said,

"""
'Also there's B_0/J_0 for CCM/GCM, and the 'zero' thing that GMAC has.
"""