From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: Re: [PATCH v7 1/2] crypto: AF_ALG: add AEAD support Date: Mon, 5 Jan 2015 21:51:06 +1100 Message-ID: <20150105105105.GA25517@gondor.apana.org.au> References: <6964260.mNa1jtPz7Z@tachyon.chronox.de> <1609020.xcc11L81HZ@tachyon.chronox.de> <20150105103159.GA24878@gondor.apana.org.au> <6798882.ly1QjqTYep@tachyon.chronox.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <6798882.ly1QjqTYep-PJstQz4BMNNP20K/wil9xYQuADTiUCJX@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephan Mueller Cc: Daniel Borkmann , 'Quentin Gouchet' , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ABI/API List-Id: linux-api@vger.kernel.org On Mon, Jan 05, 2015 at 11:46:50AM +0100, Stephan Mueller wrote: > > The need for that check lies in aead_recvmsg: > > /* > * first chunk of input is AD -- one scatterlist entry is one page, > * and we process only one scatterlist, the maximum size of AD is > * one page > */ > sg_init_table(&assoc, 1); > sg_set_page(&assoc, sg_page(sg), ctx->aead_assoclen, sg->offset); > aead_request_set_assoc(&ctx->aead_req, &assoc, ctx->aead_assoclen); > > There you see that I only create an sg table with one entry for the AD. If we > would allow an arbitrary AD size, I would see the need of a for loop in > addition to the one directly beneath this AD scatterlist setting: one for > identifying how many sg entries I need to allocate and one for the actual > assignment. > > As I felt that one page should be sufficient for the AD, I wanted to avoid the > extra overhead for another for loop. Please remove the limit as otherwise we would never be able to add support for this in a future kernel as appliations won't be able to rely on it. There is no such limit in the kernel interface and we shouldn't be adding one here. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt