Re: [PATCH v6 1/4] crypto: AF_ALG: add AEAD support

From: Stephan Mueller
Date: Tue Dec 30 2014 - 16:30:36 EST

Am Dienstag, 30. Dezember 2014, 04:33:41 schrieb Herbert Xu:

Hi Herbert,

> On Mon, Dec 29, 2014 at 04:05:40PM +0100, Stephan Mueller wrote:
> > This would mean that the check must stay in recvmsg as only here we know
> > that the caller wants data to be processed.
> On the send side you would do the check when MSG_MORE is unset.
> On the receive side you should stop waiting only when ctx->more
> is false and the send-side check succeeded.
> Perhaps rename ctx->more to ctx->done and then you can use it
> to indicate to the receive side that we're ready and have valid
> data for it. The receive side can then simply wait for ctx->done
> to become true.

I followed your advise and changed the sleep to wait for !ctx->more. Together
with the patch suggested below that was just released, I removed aead_readable
and aead_sufficient_data.

Though, I did not rename ctx->more to ctx->done due to the following:

- other AF_ALG implementations use ctx->more -- to aid code reviewers, I want
to keep the logic as close together as possible

- I do not want to negate the check for MSG_MORE -- at least for me, negating
flags always twists my mind when reading code.

The patch will come shortly after I tested all thoroughly.
> > > PS we should add a length check for missing/partial auth tags
> > > to crypto_aead_decrypt. We can then remove such checks from
> > > individual implementations.
> >
> > I agree in full here. Shall I create such a patch together with the AEAD
> > AF_ALG interface, or can we merge the AEAD without that patch now and
> > create a separate patch later?
> We should at least add a check in crypto_aead_decrypt first so as
> to guarantee nothing slips through.
> Thanks,

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