From: Rich Felker <dalias@libc.org>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Florian Weimer <fweimer@redhat.com>,
Yann Droneaud <ydroneaud@opteya.com>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
libc-alpha@sourceware.org, linux-crypto@vger.kernel,
Michael@phoronix.com, jann@thejh.net
Subject: Re: arc4random - are you sure we want these?
Date: Tue, 26 Jul 2022 22:16:19 -0400 [thread overview]
Message-ID: <20220727021618.GK7074@brightrain.aerifal.cx> (raw)
In-Reply-To: <YuCa1lDqoxdnZut/@mit.edu>
On Tue, Jul 26, 2022 at 09:54:30PM -0400, Theodore Ts'o via Libc-alpha wrote:
> On Mon, Jul 25, 2022 at 02:49:30PM -0400, Rich Felker wrote:
> >
> > You can at least try the sysctl and possibly also /dev approaches and
> > only treat this as fatal as a last resort. If you can inspect
> > entropy_avail or poll /dev/random to determine that the pool is
> > initialized this is very safe, I think. And some research on distro
> > practices might uncover whether this should be believed to be
> > complete.
>
> I think people are *way* too worried about what happens if /dev/random
> is symlinked to /dev/urandom, and/or other bits of insanitry.
>
> The getrandom(3) system call has been around since v3.17. That's
> 2014.
Last year I helped someone get musl up and running with EABI userspace
(all we support) on a pre-EABI kernel (2.6.18 or so?) on embedded
hardware in use in the field that could not be upgraded for hardware
support reasons. Assuming post-2014 kernel may be okay for
desktop/server distros but from my perspective it's pretty
unthinkable.
> Even an ancient, obsolete enterprise distro like RHEL 7
> backported the getrandom system call in 2017 --- a full 5 years ago.
> If someone is still using a pre-2017, or $DEITY help them, pre-2014
> kernel, that kernel will be so riddled with zero-day vulnerabilities
> that some fallback to a /dev/urandom at boot time will be the
> ***least*** of their worries from a security perspective. And that's
> assuming someone who is so hide-bound as to be using a badly obsolete
> kernel would be interested in going to a bleeding edge libc in the
> first place!
There's a huge difference in zero-day vulnerabilities which might
exist nowhere but on a box that's not exposed to the outside world,
and possibly creating compromised key material from said boxes. And
weird embedded stuff that can't be upgraded is *also* the same setting
where you have a complete lack of early boot entropy.
I'm fine with folks who need this stuff coming to musl instead of
glibc, but I think folks on the glibc side are doing right to at least
*consider* whether/how it matters rather than writing anything older
than a few years off as irrelevant.
Rich
next prev parent reply other threads:[~2022-07-27 2:16 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <YtwgTySJyky0OcgG@zx2c4.com>
2022-07-23 16:25 ` Jason A. Donenfeld
2022-07-23 17:18 ` Paul Eggert
2022-07-24 23:55 ` Jason A. Donenfeld
2022-07-25 20:31 ` Paul Eggert
2022-07-23 17:39 ` Adhemerval Zanella Netto
2022-07-23 22:54 ` Jason A. Donenfeld
2022-07-25 15:33 ` Rich Felker
2022-07-25 15:59 ` Adhemerval Zanella Netto
2022-07-25 17:41 ` Rich Felker
2022-07-25 16:18 ` Sandy Harris
2022-07-25 16:40 ` Florian Weimer
2022-07-25 16:49 ` Adhemerval Zanella Netto
2022-07-25 16:51 ` Jason A. Donenfeld
2022-07-25 17:44 ` Rich Felker
2022-07-25 18:33 ` Cristian Rodríguez
2022-07-25 18:49 ` Rich Felker
2022-07-27 1:54 ` Theodore Ts'o
2022-07-27 2:16 ` Rich Felker [this message]
2022-07-27 2:45 ` Theodore Ts'o
2022-07-27 11:34 ` Adhemerval Zanella Netto
2022-07-27 12:32 ` Theodore Ts'o
2022-07-27 12:49 ` Florian Weimer
2022-07-27 20:15 ` Theodore Ts'o
2022-07-27 21:59 ` Rich Felker
2022-07-28 0:30 ` Theodore Ts'o
2022-07-28 0:39 ` Cristian Rodríguez
2022-07-27 15:39 ` Rich Felker
2022-07-23 19:04 ` Cristian Rodríguez
2022-07-23 22:59 ` Jason A. Donenfeld
2022-07-24 16:23 ` Cristian Rodríguez
2022-07-24 21:57 ` Jason A. Donenfeld
2022-07-25 10:14 ` Florian Weimer
2022-07-25 10:11 ` Florian Weimer
2022-07-25 11:04 ` Jason A. Donenfeld
2022-07-25 12:39 ` Florian Weimer
2022-07-25 13:43 ` Jason A. Donenfeld
2022-07-25 13:58 ` Cristian Rodríguez
2022-07-25 16:06 ` Rich Felker
2022-07-25 16:43 ` Florian Weimer
2022-07-26 14:27 ` Overwrittting AT_RANDOM after use (was Re: arc4random - are you sure we want these?) Yann Droneaud
2022-07-26 14:35 ` arc4random - are you sure we want these? Yann Droneaud
2022-07-25 13:25 ` Jeffrey Walton
2022-07-25 13:48 ` Jason A. Donenfeld
2022-07-25 14:56 ` Rich Felker
2022-07-25 22:57 ` [PATCH] arc4random: simplify design for better safety Jason A. Donenfeld
2022-07-25 23:11 ` Jason A. Donenfeld
2022-07-25 23:28 ` [PATCH v2] " Jason A. Donenfeld
2022-07-25 23:59 ` Eric Biggers
2022-07-26 10:26 ` Jason A. Donenfeld
2022-07-26 1:10 ` Mark Harris
2022-07-26 10:41 ` Jason A. Donenfeld
2022-07-26 11:06 ` Florian Weimer
2022-07-26 16:51 ` Mark Harris
2022-07-26 18:42 ` Jason A. Donenfeld
2022-07-26 19:18 ` Adhemerval Zanella Netto
2022-07-26 19:24 ` Jason A. Donenfeld
2022-07-26 9:55 ` Florian Weimer
2022-07-26 11:04 ` Jason A. Donenfeld
2022-07-26 11:07 ` [PATCH v3] " Jason A. Donenfeld
2022-07-26 11:11 ` Jason A. Donenfeld
2022-07-26 11:12 ` [PATCH v2] " Florian Weimer
2022-07-26 11:20 ` Jason A. Donenfeld
2022-07-26 11:35 ` Adhemerval Zanella Netto
2022-07-26 11:33 ` Adhemerval Zanella Netto
2022-07-26 11:54 ` Jason A. Donenfeld
2022-07-26 12:08 ` Jason A. Donenfeld
2022-07-26 12:20 ` Jason A. Donenfeld
2022-07-26 12:34 ` Adhemerval Zanella Netto
2022-07-26 12:47 ` Jason A. Donenfeld
2022-07-26 13:11 ` Adhemerval Zanella Netto
2022-07-26 13:30 ` [PATCH v4] " Jason A. Donenfeld
2022-07-26 15:21 ` Yann Droneaud
2022-07-26 16:20 ` Adhemerval Zanella Netto
2022-07-26 18:36 ` Jason A. Donenfeld
2022-07-26 19:08 ` [PATCH v5] " Jason A. Donenfeld
2022-07-26 19:58 ` [PATCH v6] " Jason A. Donenfeld
2022-07-26 20:17 ` Adhemerval Zanella Netto
2022-07-26 20:56 ` Adhemerval Zanella Netto
2022-07-28 10:29 ` Szabolcs Nagy
2022-07-28 10:36 ` Szabolcs Nagy
2022-07-28 11:01 ` Adhemerval Zanella
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