Re: [PATCH v3 net-next 0/4] kernel TLS

Hi Hannes, 

On 06/14/17 10:15 PM, Hannes Frederic Sowa wrote:

one question for this patch set:

What is the reason for not allowing key updates for the TX path? I was
always loud pointing out the problems with TLSv1.2 renegotiation and
TLSv1.3 key update alerts. This patch set uses encryption in a
synchronous way directly in the socket layer and thus wouldn't suffer
from problems regarding updates of the key. My hunch is that you leave
this option open so you can later on introduce asynchronous crypto which
might be used on hardware? It looks also be doable in case of MSG_MORE.
Otherwise by allowing key updates to the data path I would not see any
problems with key updates in TLS.

I don't currently have any reasons to not support renegotation, we
just don't currently use it, so I didn't add support for it.  I don't
work on the hardware, but yes it looks like it would have to keep the
old keys around until everything sent using them has been acked.

Anyway, this patch seems easy and maybe with key updates added later on
doesn't seem to have any problems pointed out by me so far.

Indeed, it would be easy to flush any unencrypted data, and then
change the keys.