linux-kernel - Re: Linux messages full of `random: get_random

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Date:   Sun, 29 Apr 2018 23:18:55 +0200
From:   Pavel Machek <pavel@....cz>
To:     Sultan Alsawaf <sultanxda@...il.com>
Cc:     "Theodore Y. Ts'o" <tytso@....edu>, linux-kernel@...r.kernel.org,
        Jann Horn <jannh@...gle.com>
Subject: Re: Linux messages full of `random: get_random_u32 called from`

On Sun 2018-04-29 13:20:33, Sultan Alsawaf wrote:
> On Sun, Apr 29, 2018 at 08:41:01PM +0200, Pavel Machek wrote:
> > Umm. No. https://www.youtube.com/watch?v=xneBjc8z0DE
> 
> Okay, but /dev/urandom isn't a solution to this problem because it isn't usable
> until crng init is complete, so it suffers from the same init lag as
> /dev/random.

So -- I'm pretty sure systemd and friends should be using
/dev/urandom. Maybe gpg wants to use /dev/random. _Maybe_.

[    2.948192] random: systemd: uninitialized urandom read (16 bytes
read)
[    2.953526] systemd[1]: systemd 215 running in system mode. (+PAM
+AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ
-SECCOMP -APPARMOR)
[    2.980278] systemd[1]: Detected architecture 'x86'.
[    3.115072] usb 5-2: New USB device found, idVendor=0483,
idProduct=2016, bcdDevice= 0.01
[    3.119633] usb 5-2: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
[    3.124147] usb 5-2: Product: Biometric Coprocessor
[    3.128621] usb 5-2: Manufacturer: STMicroelectronics
[    3.163839] systemd[1]: Failed to insert module 'ipv6'
[    3.181266] systemd[1]: Set hostname to <amd>.
[    3.267243] random: systemd-sysv-ge: uninitialized urandom read (16
bytes read)
[    3.669590] random: systemd-sysv-ge: uninitialized urandom read (16
bytes read)
[    3.696242] random: systemd: uninitialized urandom read (16 bytes
read)
[    3.700066] random: systemd: uninitialized urandom read (16 bytes
read)
[    3.703716] random: systemd: uninitialized urandom read (16 bytes
read)

Anyway, urandom should need to be seeded once, and then provide random
data forever... which is not impression I get from the dmesg output
above. Boot clearly proceeds... somehow. So now I'm confused.

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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