linux-kernel - Re: [PATCH v6 1/4] crypto: AF

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Message-ID: <2502404.xd4K6Vrf3P@tachyon.chronox.de>
Date:	Tue, 30 Dec 2014 22:30:28 +0100
From:	Stephan Mueller <smueller@...onox.de>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Daniel Borkmann <dborkman@...hat.com>,
	'Quentin Gouchet' <quentin.gouchet@...il.com>,
	'LKML' <linux-kernel@...r.kernel.org>,
	linux-crypto@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH v6 1/4] crypto: AF_ALG: add AEAD support

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,


-- 
Ciao
Stephan
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