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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Fri, 14 Jan 2022 16:36:22 +0100
Message-ID: <CAMuHMdXDmwHaJuvNo8vkzudfhL0E3b=0b4mP_OqDCYFqm82J5Q@mail.gmail.com>
Subject: Re: [PATCH RFC v1 1/3] bpf: move from sha1 to blake2s in tag calculation
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>,
        Network Development <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>
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Hi Jason,

On Fri, Jan 14, 2022 at 4:20 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> I think the reason that Alexei doesn't think that the SHA-1 choice
> really matters is because the result is being truncated to 64-bits, so
> collisions are easy anyway, regardless of which hash function is
> chosen (birthday bound and all). But from Geert's perspective, that
> SHA-1 is still taking up precious bytes in m68k builds. And from my
> perspective, it's poor form and clutters vmlinux, and plus, now I'm
> curious about why this isn't using a more appropriately sized tag in
> the first place.

Not just on m68k. Same on other architectures.
Yes, people do make products with SoCs with 8 MiB of builtin SRAM,
running Linux. They might stay away from BPF, though ;-)

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds