Re: [PATCH] crypto: ccm - avoid scatterlist for MAC encryption

On Wed, 2016-10-19 at 11:31 +0800, Herbert Xu wrote:

On Mon, Oct 17, 2016 at 06:21:14PM +0100, Ard Biesheuvel wrote:

quoted

Annoyingly, all this complication with scatterlists etc is for
doing
asynchronous crypto via DMA capable crypto accelerators, and the
networking code (ipsec as well as mac80211, afaik) only allow
synchronous in the first place, given that they execute in softirq
context.

I'm still thinking about the issue (in particular, whether we
should continue to rely on the request context being SG-capable
or allow it to be on the stack for AEAD).

:)

But IPsec definitely supports async crypto.  In fact it was the
very first user of async crypto.

Yeah.

mac80211 on the other hand is currently sync-only.

We could probably make mac80211 do that too, but can we guarantee in-
order processing? Anyway, it's pretty low priority, maybe never
happening, since hardly anyone really uses "software" crypto, the wifi
devices mostly have it built in anyway.

(One problem is that the skb->cb is already completely full, so we
can't stash away the AAD there)

johannes