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From: Jung-uk Kim <jkim@FreeBSD.org>
To: Maxim Dounin <mdounin@mdounin.ru>
Date: Tue, 15 Mar 2011 15:55:43 -0400
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
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Subject: Re: svn commit: r219672 - in head: share/man/man9 sys/i386/include
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On Tuesday 15 March 2011 03:33 pm, Maxim Dounin wrote:
> Hello!
>
> On Tue, Mar 15, 2011 at 05:14:26PM +0000, Jung-uk Kim wrote:
> > Author: jkim
> > Date: Tue Mar 15 17:14:26 2011
> > New Revision: 219672
> > URL: http://svn.freebsd.org/changeset/base/219672
> >
> > Log:
> >   Unconditionally use binuptime(9) for get_cyclecount(9) on i386.
> >  Since this function is almost exclusively used for random
> > harvesting, there is no need for micro-optimization.  Adjust the
> > manual page accordingly.
>
> Note that on early boot only dummy timecounter available, and
> binuptime() has no entropy.
>
> As a result of this change random(9) won't have entropy on early
> boot on i386, and arc4random(9) as well.  While there are no known
> major security problems associated with it - it at least makes
> stack protector easily bypasseable as it now (again after r198295)
> uses well-known stack guard instead of random one.  And there may
> be other issues as well.
>
> Hope you thought well before moving i386 to a set of platforms
> which have no early boot randomness at all.  And you have good
> reason for doing it.

Hmm...  Is bintime(9) good enough for you then?

Jung-uk Kim