linux-kernel - Re: [PATCH] um: seed rng using host OS rng

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Message-ID: <9a028efb77ae662fe8eabcf2ffb5a64214f07418.camel@sipsolutions.net>
Date:   Wed, 13 Jul 2022 09:03:31 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org
Subject: Re: [PATCH] um: seed rng using host OS rng

On Wed, 2022-07-13 at 07:58 +0100, Anton Ivanov wrote:
> 
> IIRC UML RNG device reads directly from host.

Yes, but that's a /dev/hwrng device, so you still need some userspace to
feed entropy from that into /dev/random.

> If you are using UMLs own /dev/random you are effectively using the host 
> one.

> So unless I am mistaken, you need extra randomness only if you do not 
> have UMLs /dev/random compiled in.

No, neither of those is true.

johannes