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Date: Thu, 30 May 2013 00:13:28 -0700
From: David Schultz <das@FreeBSD.ORG>
To: Xin LI <delphij@freebsd.org>
Subject: Re: svn commit: r249035 - head/lib/libc/stdlib
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On Tue, Apr 02, 2013, Xin LI wrote:
> Author: delphij
> Date: Tue Apr  2 23:41:20 2013
> New Revision: 249035
> URL: http://svnweb.freebsd.org/changeset/base/249035
> 
> Log:
>   Replace access to /dev/random with the kernel pseudo-random number
>   source sysctl(KERN_ARND) and remove the fallback code.

Thanks. I wanted to do this several years ago.

Incidentally, the reason I didn't is that I had some concerns
about sysctl(KERN_ARND) not being sufficiently fail-safe.  There
were a couple of issues, but the main one was that if something in
the kernel asked for a random number before the random device was
loaded, the result was not-so-random numbers. Furthermore, since
the generator was seeded at that point, it continued to give out
not-so-random numbers for some time.  I added the following log
message in the problematic case:
    "random device not loaded; using insecure entropy"
According to a Google search, I'm not the only person to have
triggered it.  (I hit it because I dynamically link most drivers,
including random.ko. I'm not sure about the others.)  I think your
patch is good, but the kernel-side issues probably bear some investigation.