From: <rsbecker@nexbridge.com>
To: "'Jeff King'" <peff@peff.net>,
"'brian m. carlson'" <sandals@crustytoothpaste.net>
Cc: <git@vger.kernel.org>
Subject: RE: [PATCH 1/2] wrapper: add a helper to generate numbers from a CSPRNG
Date: Tue, 16 Nov 2021 11:01:20 -0500 [thread overview]
Message-ID: <009d01d7db03$354ecae0$9fec60a0$@nexbridge.com> (raw)
In-Reply-To: <YZPOzqU0UQDVA57R@coredump.intra.peff.net>
On November 16, 2021 10:31 AM, Jeff King wrote:
> On Tue, Nov 16, 2021 at 03:35:41AM +0000, brian m. carlson wrote:
>
> > The order of options is also important here. On systems with
> > arc4random, which is most of the BSDs, we use that, since, except on
> > MirBSD, it uses ChaCha20, which is extremely fast, and sits entirely
> > in userspace, avoiding a system call. We then prefer getrandom over
> > getentropy, because the former has been available longer on Linux, and
> > finally, if none of those are available, we use /dev/urandom, because
> > most Unix-like operating systems provide that API. We prefer options
> > that don't involve device files when possible because those work in
> > some restricted environments where device files may not be available.
>
> I wonder if we'll need a low-quality fallback for older systems which don't
> even have /dev/urandom. Because it's going to be used in such a core part of
> the system (tempfiles), this basically becomes a hard requirement for using
> Git at all.
>
> I can't say I'm excited in general to be introducing a dependency like this, just
> because of the portability headaches. But it may be the least bad thing
> (especially if we can fall back to the existing behavior).
> One alternative would be to build on top of the system mkstemp(), which
> makes it libc's problem. I'm not sure if we'd run into problems there, though.
None of /dev/urandom, /dev/random, or mkstemp are available on some platforms, including NonStop. This is not a good dependency to add. One variant PRNGD is used in ia64 OpenSSL, while the CPU random generator in hardware is used on x86. I cannot get behind this at all. Libc is also not used in or available to our port. I am very worried about this direction.
-Randall
next prev parent reply other threads:[~2021-11-16 16:01 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-16 3:35 [PATCH 0/2] Generate temporary files using a CSPRNG brian m. carlson
2021-11-16 3:35 ` [PATCH 1/2] wrapper: add a helper to generate numbers from " brian m. carlson
2021-11-16 15:31 ` Jeff King
2021-11-16 16:01 ` rsbecker [this message]
2021-11-16 18:22 ` Taylor Blau
2021-11-16 19:58 ` rsbecker
2021-11-16 22:41 ` brian m. carlson
2021-11-16 23:20 ` rsbecker
2021-11-17 0:47 ` Carlo Arenas
2021-11-17 3:05 ` rsbecker
2021-11-17 1:03 ` brian m. carlson
2021-11-17 1:50 ` Carlo Arenas
2021-11-17 3:04 ` Jeff King
2021-11-17 3:12 ` rsbecker
2021-11-17 3:36 ` Carlo Arenas
2021-11-17 20:01 ` Jeff King
2021-11-17 20:19 ` rsbecker
2021-11-17 23:30 ` brian m. carlson
2021-11-17 23:34 ` rsbecker
2021-11-17 3:03 ` rsbecker
2021-11-17 7:39 ` Junio C Hamano
2021-11-17 23:01 ` brian m. carlson
2021-11-18 7:19 ` Junio C Hamano
2021-11-18 22:16 ` brian m. carlson
2021-11-22 9:10 ` Junio C Hamano
2021-11-16 3:35 ` [PATCH 2/2] wrapper: use a CSPRNG to generate random file names brian m. carlson
2021-11-16 15:36 ` Jeff King
2021-11-16 18:28 ` Taylor Blau
2021-11-16 18:57 ` Junio C Hamano
2021-11-16 19:21 ` Jeff King
2021-11-16 19:33 ` Taylor Blau
2021-11-16 15:44 ` [PATCH 0/2] Generate temporary files using a CSPRNG Jeff King
2021-11-16 22:17 ` brian m. carlson
2021-11-16 22:29 ` rsbecker
2021-11-16 20:35 ` Ævar Arnfjörð Bjarmason
2021-11-16 21:06 ` Jeff King
2021-11-17 8:36 ` Ævar Arnfjörð Bjarmason
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