From: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Jann Horn <jannh@google.com>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Guenter Roeck <linux@roeck-us.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: [PATCH] random: allow writes to /dev/urandom to influence fast init
Date: Wed, 23 Mar 2022 00:30:14 -0400 [thread overview]
Message-ID: <1648009787.fah6dos6ya.none@localhost> (raw)
In-Reply-To: <20220322191436.110963-1-Jason@zx2c4.com>
I searched for users of RNDADDTOENTCNT using
(?s:ioctl.{1,500}RNDADDTOENTCNT) on Debian Code Search and
"/(?s)ioctl.{1,40},\s*RNDADDTOENTCNT/ -path:incfs_test.c" on GitHub Code
Search (beta).
Several programs use it for testing purposes, without writing any
entropy to /dev/random or /dev/urandom, including rauc, wireguard, and
openSUSE kdump. Several programs use it as intended, after writing
entropy to /dev/random or /dev/urandom. Of the latter group,
- kata-containers is a lightweight VM implementation. Its guest-side
agent offers a gRPC endpoint which will write the provided data to
/dev/random, then call RNDADDTOENTCNT with the length of the data,
then call RNDRESEEDRNG. As far as I can tell, this endpoint is
made available to users on the host, but is not used by
kata-containers itself.
- aws-nitro-enclaves-sdk-c is an SDK for building lightweight VMs to be
used with AWS Nitro Enclaves. kmstool-enclave is a sample application
provided, which writes "up to 256 bytes" (from where?) to /dev/random,
then calls RNDADDTOENTCNT, then repeats the process until it reaches
1024 bytes.
- sandy-harris/maxwell is a "jitter entropy" daemon, similar to haveged.
It writes 4 bytes of "generated entropy" to /dev/random, then calls
RNDADDTOENTCNT, then repeats.
- guix is, among other things, a "GNU/"Linux distribution. The provided
base services write the seed file to /dev/urandom, then call
RNDADDTOENTCNT, then write 512 bytes from /dev/hwrng to /dev/urandom,
then call RNDADDTOENTCNT, then "immediately" read 512 bytes from
/dev/urandom and write it to the seed file. On shutdown, 512 bytes are
read from /dev/urandom and written to the seed file.
I was unable to locate any other public non-archived usages of
RNDADDTOENTCNT on Debian or GitHub Code Search.
I don't have any particular expertise with the random subsystem or
conclusions to make from this data, but I hope this helps inform the
discussion.
Cheers,
Alex.
next prev parent reply other threads:[~2022-03-23 4:30 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 19:14 [PATCH] random: allow writes to /dev/urandom to influence fast init Jason A. Donenfeld
2022-03-22 20:42 ` Linus Torvalds
2022-03-22 23:54 ` Jason A. Donenfeld
2022-03-23 2:15 ` David Laight
2022-03-23 2:50 ` Jason A. Donenfeld
2022-03-23 8:43 ` Rasmus Villemoes
2022-03-24 14:12 ` Jason A. Donenfeld
2022-03-23 11:45 ` David Laight
2022-03-23 3:35 ` Theodore Ts'o
2022-03-23 4:00 ` Jason A. Donenfeld
2022-03-23 12:31 ` Theodore Ts'o
2022-05-23 17:59 ` Pavel Machek
2022-03-23 4:30 ` Alex Xu (Hello71) [this message]
2022-03-23 4:47 ` Jason A. Donenfeld
2022-03-23 14:01 ` David Laight
2022-03-23 19:53 ` Jason A. Donenfeld
2022-03-24 18:01 ` Eric Biggers
2022-03-24 3:18 ` Jason A. Donenfeld
2022-03-24 16:28 ` Alex Xu (Hello71)
2022-03-24 17:20 ` Jason A. Donenfeld
2022-03-24 19:03 ` Alex Xu (Hello71)
2022-03-24 18:26 ` Eric Biggers
2022-03-24 18:31 ` Jason A. Donenfeld
2022-06-19 16:44 ` Pavel Machek
2022-03-24 19:53 ` Eric Biggers
2022-03-24 20:25 ` Jason A. Donenfeld
2022-06-19 16:56 ` Pavel Machek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1648009787.fah6dos6ya.none@localhost \
--to=alex_y_xu@yahoo.ca \
--cc=Jason@zx2c4.com \
--cc=jannh@google.com \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@dominikbrodowski.net \
--cc=linux@roeck-us.net \
--cc=torvalds@linux-foundation.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).