Date: Fri, 24 Jul 2015 23:20:12 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Mark R V Murray <markm@FreeBSD.org> Cc: src-committers <src-committers@FreeBSD.org>, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r284959 - in head: . share/man/man4 share/man/man9 sys/conf sys/dev/glxsb sys/dev/hifn sys/dev/random sys/dev/rndtest sys/dev/safe sys/dev/syscons sys/dev/ubsec sys/dev/virtio/random sy... Message-ID: <20150725062012.GT78154@funkthat.com> In-Reply-To: <BC734D25-375C-4C1C-BA8A-BD91158B6A39@FreeBSD.org> References: <201506301700.t5UH0jPq001498@svn.freebsd.org> <alpine.BSF.2.20.1507221138360.1071@desktop> <FFAED695-145A-45F5-988D-B843EF5F544B@FreeBSD.org> <alpine.BSF.2.20.1507221249120.1071@desktop> <FFFB06D7-164B-40B3-AFC3-A6630BCF074E@bsdimp.com> <E20B169F-4C8A-4D11-9853-5C2EFC116450@FreeBSD.org> <F54A96A8-D9AD-409A-814F-538B6AD3CD50@yahoo.com> <20150724012519.GE78154@funkthat.com> <BC734D25-375C-4C1C-BA8A-BD91158B6A39@FreeBSD.org>
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Mark R V Murray wrote this message on Fri, Jul 24, 2015 at 07:59 +0100:
> > On 24 Jul 2015, at 02:25, John-Mark Gurney <jmg@funkthat.com> wrote:
> >
> > I would like to point out that the goal of collecting large amounts
> > is starting to fall out of favor, and I happen to agree with the likes
> > of djb[1] that we don't need an infinite amount of entropy collected by
> > the system. If the attacker can read out our RNG state, then we are
> > already screwed due to many other vulns.
>
> I???m working on a premise of ???tools, not policy???. I???d like there to be
> enough harvesting points for the box owner to get the warm fuzzies.
> If they choose to use less, fine by me.
Except that we should set a sane default policy. Hashing 136 bytes
of the mbuf of every ethernet packet isn't a sane default policy. I'm
not saying don't have the hooks, but as Scott and others would like,
they need to be turned off by default...
> > Many of the issues that FreeBSD sees with lack of entropy at start up
> > is more of a problem on how systems are installed and provisioned. I
> > don't believe that we currently store any entropy from the install
> > process, yet this is one of the best places to get it, the user is
> > banging on keyboard selecting options, etc. If an image is designed
> > to be cloned (vm images or appliance images) we need to have a
> > mechanism to ensure that before we start, we get the entropy from
> > other sources, be it a hardware RNG or the console.
>
> Getting an initial entropy bundle for first boot is high up on my
> TODO list. :-) Patches welcome! We need the usual /entropy (or
> /var/db/entropy/??? or whatever) and crucially we need /boot/entropy
> and the correct invocation in /boot/loader.conf.
>
> > I would like to see us scale back the entropy collection, and replace
> > it with something like scan the zone once an hour or something
> > similar. Or do something dtrace style, where we nop/jmp the
> > collection after we feel that the system has collected enough.
>
> Most of the current entropy gathering is just about invisible
> anyway. I think the above goes too far, but may be a useful way
> of enabling/disabling (say) UMA gathering on the fly.
Well, just a random proposal to allow both, but these points should
be turned off by default, not enabled by default...
> > Heck, piping in mic data to /dev/random is a good way to seed the
> > rng on many machines.
>
> Well, sure, but what if you don???t have microphone? I want lots
> of choices, in anticipation of only a subset being usable.
I'm fine w/ more choices, but we need to make sure we have sane
defaults..
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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