Date: Wed, 31 Jul 2013 05:58:43 +0400 From: Andrey Chernov <ache@freebsd.org> To: obrien@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: <51F86F53.9020600@freebsd.org> In-Reply-To: <20130731000746.GA65806@dragon.NUXI.org> References: <201307292058.r6TKwA56031193@svn.freebsd.org> <51F6E0AB.3010001@freebsd.org> <20130731000746.GA65806@dragon.NUXI.org>
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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. > But, this situation isn't the big issue. We have an existing bug where > if one is using a hardware RNG, read_random() never gets changed from > simply being read_random_phony() due to random_modevent() not calling > random_yarrow_init_harvester() thru '(*random_systat->init)()'. Thus > arc4random() has been weak for thus using the Intel RDRAND or Via > Padlock. I don't fix hardware RNG parts due to missing hardware for tests. They should have the same line as randomdev_soft.c somewhere. -- http://ache.vniz.net/ bitcoin:1G6ugdNY6e5jx1GVnAU2ntj2NEfmjKG85r
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