Fwd: Fwd: Linux entropy

From: Traian Teodorescu
Date: Sat Mar 25 2023 - 19:05:22 EST


Hello, can you please answer to my question below ? It's about the "/proc/sys/kernel/random/entropy_avail" variable which doesn't show anymore a credible value.
Thank you,
Traian

-------- Forwarded Message --------
Subject: Fwd: Linux entropy
Date: Wed, 22 Mar 2023 05:51:10 +0100
From: Traian Teodorescu <traian.teodorescu@xxxxxxxxxx>
To: linux-kernel@xxxxxxxxxxxxxxx



Hello,

I've been redirected by  the "friendly bot" to you (I've already looked into "kernelnewbies" but I didn't find a linked topic). I would want to know more about the subject below. Is there another possibility to read the value of current entropy in new versions of kernel ? Are the old services (as for instance haveged) still compatible ?

Thank you and have a nice evening,

Traian


-------- Forwarded Message --------
Subject:     Linux entropy
Date:     Tue, 21 Mar 2023 17:03:36 +0100
From:     Traian Teodorescu <traian.teodorescu@xxxxxxxxxx>
To:     gregkh@xxxxxxxxxxxxxxxxxxx


Mr Kroah-Hartmann,

I've recently discovered that the value containing the machine's entropy (in /proc/sys/kernel/random/entropy_avail ) isn't updated anymore on one of my machines. I found some articles on the Internet about this change, but nothing very "official".

There is also an explanation at "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.15.y&id=e7e196e1ae2603a2c5f1894f1868a7a5b5a2c5e0"; about keeping forward secrecy, etc, that I didn't really understood.

I began using Linux since less than 10 years and I am not what you can call an experienced user, but from my point of view this change doesn't make sense. If I understand well some basic principles, Linux kernel is the only one meant to be accessible to everybody wanting to understand deeply how a modern OS works, so what's the gain in this "obfuscation" ?  From my point of view, a sysadmin should know how much entropy they have on their machines.

So, please, can you please make some comments about this change ? (of eventually send me a link to an article that I can trust ?)

I really enjoyed Linux a lot those years and I learned to appreciate it, so from this point of view I am grateful to the teams maintaining free software, so ... thank you !

Thanks for an eventual answer and have a nice evening,

Traian