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Date:      Fri, 12 Jan 2001 00:46:37 -0800
From:      Doug Barton <DougB@FreeBSD.org>
To:        Matt Dillon <dillon@earth.backplane.com>
Cc:        Warner Losh <imp@harmony.village.org>, Mark Murray <mark@grondar.za>, Sheldon Hearn <sheldonh@uunet.co.za>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/etc crontab rc src/etc/defaults rc.conf  src/etc/mtree BSD.root.dist src/libexec Makefile  src/libexec/save-entropy Makefile save-entropy.sh
Message-ID:  <3A5EC46D.A912BC6F@FreeBSD.org>
References:  <200101120644.f0C6hvI12630@gratis.grondar.za>  <200101120534.f0C5YYH96390@earth.backplane.com>  <200101120652.f0C6qls78578@harmony.village.org> <200101120711.f0C7B4Y97991@earth.backplane.com>

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Matt Dillon wrote:

>     I think it's fairly obvious that we don't need cryptographic
>     randomness for early boot stages. 

	Since no one seems to actually be reading my posts, let me reiterate
something. /etc/rc does the following in the early stages right now:

1. rc.diskless
2. source the /*/rc.conf* files
3. try seeding from /entropy
   - This would be replaced by Warner's suggestion.
4. ccdconfig
5. vinum start
6. fsck
7. mount root RW (exit if this fails)
8. umount -a
9. mount -a -t nonfs

In case I haven't made it clear yet, I would really love to do away with
the "gross hacks" that make 3. work, and postpone reading in the "real"
entropy seeding till we get past 9. Up till we actually had offers of
help today, IT WAS NOT POSSIBLE TO MOUNT -A RELIABLY BECAUSE /DEV/RANDOM
WOULD BLOCK. Hopefully that will be the last time I have to say it. Now,
are you sure that ccdconfig, vinum, fsck, and mount* (other than nfs)
will work with a "weak" amount of randomness? In a previous post today I
asked this question and got no response. I welcome any help to get the
thing whipped into a shape that we will be proud to ship. But until that
happens can we seriously try and remember that this is -current?

>  All I'm hearing is paranoia (not
>     from Warner) and all I'm seeing are massive hacks being committed to
>     the system for no reason at all.  The system daemons that require
>     cryptographic randomness don't start until much, much later in the
>     boot sequence, long after the filesystems have been mounted.  It makes
>     no sense to construct massive hacks to make the random number generator
>     cryptographically secure so early in the boot process. 

	You know, your arguments would go across a lot easier without the
vitriol. You have been a great help to me in the past Matt, and I don't
get my feathers ruffled easily; but you would be well served to at least
give us credit for what we're actually trying to accomplish, misguided
or not. 

>     It makes even less sense to commit a cron job that runs every
>     3 *MINUTES*.  I don't care how much or how little it does... it makes
>     NO SENSE. 

	Apparently it makes sense to Schneier. For the initial commit Mark just
gave me something approximating the recommended values. I ran with the
stuff for a couple days and never even noticed it. I did start to think
however that the 8 seeds would probably really only be useful at boot
time, so it might make more sense to run it every 3 minutes for an hour
after boot, then every N minutes thereafter. However, I needed to do
some research on our new(ish) ability to schedule cron jobs for @boot,
or whatever the hell it is.

> How can anyone believe that that would fly in a release?

	How can anyone not pay attention to the first 427 messages saying that
our yarrow implementation is still under development and will be much
more polished way before 5.0-Release happens? 

>     Now I see two perfectly good solutions here. 

	As stated, Warner's suggestion is a good one, presuming that Mark is
satisfied regarding being able to provide sufficient entropy to
kickstart yarrow, AND that we're sure none of the things listed above in
4-9 need strong randomness to work. Assuming that all of that is true,
moving the reading of /var/db/entropy/* to right after the mount -a is
the logical next step. This should (better) put an end to the
complaints. As long as it's not needed, I don't think that special
casing mfs in mount is really a good idea, personally, but as I've said
several times today I'm not a fs expert.

	Finally, for those who have offered words of encouragement and/or
actual help in dealing with the issues involved in making this work,
please accept my thanks.

Doug


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