linux-kernel - Re: [PATCH v3 0/2] arm64: Speed up CRC-32 using PMULL instructions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAMj1kXG50UeOsHdXwEkEqqW9fjTZivGGqO=LdAGQaHOrZ0vrHg@mail.gmail.com>
Date: Fri, 18 Oct 2024 00:40:42 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Eric Biggers <ebiggers@...nel.org>
Cc: Ard Biesheuvel <ardb+git@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, 
	herbert@...dor.apana.org.au, will@...nel.org, catalin.marinas@....com, 
	Kees Cook <kees@...nel.org>
Subject: Re: [PATCH v3 0/2] arm64: Speed up CRC-32 using PMULL instructions

On Fri, 18 Oct 2024 at 00:04, Eric Biggers <ebiggers@...nel.org> wrote:
>
> On Thu, Oct 17, 2024 at 06:30:19PM +0200, Ard Biesheuvel wrote:
> > > Ard Biesheuvel (2):
> > >   arm64/lib: Handle CRC-32 alternative in C code
> > >   arm64/crc32: Implement 4-way interleave using PMULL
> > >
> >
> > I'll need to respin this - the crc32_be code doesn't actually work correctly.
>
> Right, good catch.  It looks like it needs an rbit of the crc value at the
> beginning and end.  lib/crc32test.c doesn't actually test crc32_be_arm64_4way()
> because it runs the tests with IRQs disabled; it probably shouldn't do that.
>

Yeah, we should probably fix that.

> On a slightly related topic, since any crc32_le() and __crc32c_le() functions in
> arch/*/lib/ are automatically exposed as shash algorithms via the crypto API
> (this was already the case, but your other patch makes this more explicit by
> properly separating them from the generic implementation), I wonder if all the
> remaining arch/*/crypto/crc32*.c should be migrated to arch/*/lib/, and then
> users of crc32 and crc32c like ext4 and f2fs should just use the library
> functions instead of shash.  That would simply things greatly.  See e.g. the
> horrible hacks used in ext4_chksum() and __f2fs_crc32()...
>
> The only crc32 and crc32c implementations that *aren't* software based are those
> in drivers/crypto/stm32/stm32-crc32.c and
> drivers/crypto/inside-secure/safexcel_hash.c.  Access to those would be lost by
> going through lib.  But I strongly suspect they exist just because the hardware
> supported it and not because they are actually useful.
>

Indeed. Another case where the flexibility of the shash interface
doesn't buy us anything but overhead and complexity.