From owner-freebsd-security@FreeBSD.ORG Wed Sep 5 04:41:20 2012 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx2.freebsd.org (mx2.freebsd.org [IPv6:2001:4f8:fff6::35]) by hub.freebsd.org (Postfix) with ESMTP id E7886106566B for ; Wed, 5 Sep 2012 04:41:20 +0000 (UTC) (envelope-from dougb@FreeBSD.org) Received: from [127.0.0.1] (hub.freebsd.org [IPv6:2001:4f8:fff6::36]) by mx2.freebsd.org (Postfix) with ESMTP id C09B814DAC5; Wed, 5 Sep 2012 04:41:20 +0000 (UTC) Message-ID: <5046D7F0.1000601@FreeBSD.org> Date: Tue, 04 Sep 2012 21:41:20 -0700 From: Doug Barton Organization: http://www.FreeBSD.org/ User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: RW References: <201208222337.q7MNbORo017642@svn.freebsd.org> <5043E449.8050005@FreeBSD.org> <20120904220126.GA85339@dragon.NUXI.org> <50468326.8070009@FreeBSD.org> <20120905021248.5a17ace9@gumby.homeunix.com> In-Reply-To: <20120905021248.5a17ace9@gumby.homeunix.com> X-Enigmail-Version: 1.4.4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-security@freebsd.org Subject: Re: svn commit: r239598 - head/etc/rc.d X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Security issues \[members-only posting\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Sep 2012 04:41:21 -0000 Can you point out where in the source you're seeing these things? Thanks, Doug On 09/04/2012 06:12 PM, RW wrote: > On Tue, 04 Sep 2012 15:39:34 -0700 > Doug Barton wrote: > >> and given what Yarrow does to >> obfuscate the internal entropy state I'm not confident that hashing >> the input is either necessary or desirable. > > All of the low-grade entropy should go through sha256. > > Anything written into /dev/random is passed by random_yarrow_write() 16 > Bytes at time into random_harvest_internal() which copies it into a > buffer and queues it up. If there are 256 buffers queued > random_harvest_internal() simply returns without doing anything. > > The yarrow kernel thread moves all of the entropy queues into a local > queue, processes that queue and then pauses for 100ms and loops. That > means that each time around the loop only a maximum of 4096 bytes can > be processed. Anything after that is discarded. > > It seems very likely that /entropy is completely discarded most of the > time, which means that the first 4096 bytes of " ps -fauxww ; sysctl -a" > is the only entropy that makes it through to yarrow, and that's > practically nothing. > > On a sufficiently fast system the entropy buffers may still be saturated > when rc.d/random runs, so in theory they could be lost too. And embedded > doesn't necessarily imply slow. > > I'm not overly concerned about this because anything that doesn't > generate enough entropy naturally, increasingly tends to have a hardware > generator, but it's easy to fix it, so it should be fixed. > > _______________________________________________ > freebsd-security@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscribe@freebsd.org" >