Date: Wed, 31 Jul 2013 10:46:14 -0700 From: "David O'Brien" <obrien@FreeBSD.org> To: Andrey Chernov <ache@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r253786 - in head/sys: dev/random modules/padlock_rng modules/rdrand_rng modules/yarrow_rng Message-ID: <20130731174614.GA76782@dragon.NUXI.org> In-Reply-To: <51F86F53.9020600@freebsd.org> References: <201307292058.r6TKwA56031193@svn.freebsd.org> <51F6E0AB.3010001@freebsd.org> <20130731000746.GA65806@dragon.NUXI.org> <51F86F53.9020600@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Jul 31, 2013 at 05:58:43AM +0400, Andrey Chernov wrote: > On 31.07.2013 4:07, David O'Brien wrote: > > I believe you're talking about this code in > > sys/libkern/arc4random.c:arc4rand() > > > > if (atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, > > ARC4_ENTR_SEED) || reseed || > > (arc4_numruns > ARC4_RESEED_BYTES) || > > (tv.tv_sec > arc4_t_reseed)) > > arc4_randomstir(); > > > > Without setting 'arc4rand_iniseed_state' from ARC4_ENTR_NONE -> > > ARC4_ENTR_HAVE, we would still call arc4_randomstir() periodically due > > to (tv.tv_sec > arc4_t_reseed) and (arc4_numruns > ARC4_RESEED_BYTES). > > The whole problem is that arc4 is poorly initialized right after boot, > but immediately used in many places like tcp. It reseeds again only > after 5 minutes after boot making vulnerability window at this interval. I realize the motivation for your r249631 change. But as it relates to the change I committed, there is no change in behavior in this. If one is using a hardware RNG, yarrow is not initialized and so the ARC4_ENTR_NONE -> ARC4_ENTR_HAVE transition does not happen. -- -- David (obrien@FreeBSD.org)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20130731174614.GA76782>