From: Ard Biesheuvel Subject: Re: [RFC PATCH 8/9] crypto: arm/poly1305 - add NEON accelerated Poly1305 implementation Date: Wed, 22 Aug 2018 12:00:05 +0200 Message-ID: References: <20180806223300.113891-1-ebiggers@kernel.org> <20180806223300.113891-9-ebiggers@kernel.org> <20180807231941.GC25300@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , linux-fscrypt@vger.kernel.org, linux-arm-kernel , Linux Kernel Mailing List , Herbert Xu , Paul Crowley , Greg Kaiser , Michael Halcrow , "Jason A . Donenfeld" , Samuel Neves , Tomer Ashur , Eric Biggers To: Eric Biggers Return-path: In-Reply-To: <20180807231941.GC25300@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On 8 August 2018 at 01:19, Eric Biggers wrote: > Hi Ard, > > On Tue, Aug 07, 2018 at 02:09:05PM +0200, Ard Biesheuvel wrote: >> On 7 August 2018 at 00:32, Eric Biggers wrote: >> > From: Eric Biggers >> > >> > Add the Poly1305 code from OpenSSL, which was written by Andy Polyakov. >> > I took the .S file from WireGuard, whose author has made the needed >> > tweaks for Linux kernel integration and verified that Andy had given >> > permission for GPLv2 distribution. I didn't make any additional changes >> > to the .S file. >> > >> > Note, for HPolyC I'd eventually like a Poly1305 implementation that >> > allows precomputing powers of the key. But for now this implementation >> > just provides the existing semantics where the key and nonce are treated >> > as a "one-time key" that must be provided for every message. >> > >> > Signed-off-by: Eric Biggers >> >> Hi Eric, >> >> In the past, I worked with Andy on several occasions to get my kernel >> changes incorporated into the upstream OpenSSL version of the >> 'perlasm' .pl file. >> >> This achieves a number of things: >> - we get a readable version of the code in the kernel tree, >> - our changes are reviewed upstream >> - upgrading involves grabbing the latest .pl file rather than merging >> generated code (which requires careful review) >> - GPLv2 permission is made explicit, rather than something someone >> claims to have reached agreement on, >> - no legal ambiguity whether the output of the perl script is covered >> by the license (which is what we incorporate here) >> >> Note that the 'available under GPL depending on where you obtained the >> code' in the CRYPTOGAMS license likely conflicts with the GPL itself, >> but I am not a lawyer so I'd much prefer having the upstream copy >> mention this explicitly. > > First, note that Jason is proposing adding this exact same .S file as part of > his new "zinc" cryptography library, along with 7 other OpenSSL .S files. So it > may really be him you need to convince. > Interesting choice of wording :-) I thought it was usually the other way around, i.e., it is the submitter who needs to convince the reviewers/maintainers. > But yes, I don't really like the approach of just including the .S output of the > .pl script either, as it loses semantic information that was in the .pl script. > Ideally the source should either be the .pl script, or else a real hand written > .S file with the proper comments and macros to make it readable -- not something > in-between. > > Getting the license clarification and possibly other changes upstream is a good > idea too. I noticed, though, that the actual wording used in some files > upstream ("Permission to use under GPLv2 terms is granted") apparently still > isn't considered sufficient by some, so a separate clarification from Andy was > apparently still needed: see kernel commit c2e415fe75bbc83c1... > Yeah. In any case, I don't think we should consider an intermediate solution of merging a chunk of generated asm now and work out these details later. This should be done right from the start.