Proposed fix; stage 1 (Was: svn commit: r239569 - head/etc/rc.d)

[Pawel Jakub Dawidek]

On Sun, Sep 16, 2012 at 05:21:21PM +0100, Mark Murray wrote:
> Hi
> 
> Part 1 of the fix is enclosed; it involves drastically shortening the
> input into /dev/random (the "kickstart") at boot time. There are time
> implications that I'd like to hear any objections to.
> 
> Part 1a is going to be tweeks to stashing entropy at restart
> (and possibly during normal running). Also fixes to zero-entropy
> first-startup.
> 
> Part 2 will be a cheap shortening of files during reading so as not
> to clog up the harvest queue. The harvest queue will always be a bit
> intolerant of excess input via this route, so this should help a lot.
> 
> Part 3 will be the addition of another choice of software PRNG;
> Fortuna. Fortuna is MUCH more resilient to attack, at the expense
> of using more kernel memory. For modern machines, this is scarcely
> noticeable, but it could be bad for embedded units.
> 
> Tweeks along the way may include reverting to the original intent of
> starting the PRNG blocked, and only unblocking once reseeded.
> 
> M
> --
> Mark R V Murray
> Pi: 132511160

> Index: initrandom
> ===================================================================
> --- initrandom	(revision 240384)
> +++ initrandom	(working copy)
> @@ -23,15 +23,12 @@
>  
>  better_than_nothing()
>  {
> -	# XXX temporary until we can improve the entropy
> -	# harvesting rate.
>  	# Entropy below is not great, but better than nothing.
>  	# This unblocks the generator at startup
>  	# Note: commands are ordered to cause the most variance across reboots.
> -	( kenv; dmesg; df -ib; ps -fauxww; date; sysctl -a ) \
> -	    | dd of=/dev/random bs=8k 2>/dev/null
> -	/sbin/sha256 -q `sysctl -n kern.bootfile` \
> -	    | dd of=/dev/random bs=8k 2>/dev/null
> +	for cmd in "kenv" "dmesg" "df -ib" "ps -fauxww" "date" "sysctl -ao" "netstat -arn" "fstat" ; do
> +	    ${cmd}| sha256 > /dev/random
> +	done

I'd much prefer to just use sha512 here and also add -b to sysctl.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://tupytaj.pl
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