Date: Thu, 16 Mar 2017 15:19:46 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Dag-Erling Sm??rgrav <des@des.no> Cc: Andrey Chernov <ache@freebsd.org>, freebsd-security@freebsd.org, freebsd-hackers@freebsd.org, Steven Chamberlain <steven@pyro.eu.org> Subject: Re: arc4random weakness Message-ID: <20170316131946.GN16105@kib.kiev.ua> In-Reply-To: <86k27pz8sy.fsf@desk.des.no> References: <CAD2Ti28acbW%2BpGQR5UihECWvg9WduGmVzkVFug_2ZWRF2zyTBw@mail.gmail.com> <20170313220639.GB65190@pyro.eu.org> <20170315130615.GC25448@pyro.eu.org> <5160183b-9778-59aa-6cf9-118014a588eb@freebsd.org> <86k27pz8sy.fsf@desk.des.no>
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On Thu, Mar 16, 2017 at 01:48:45PM +0100, Dag-Erling Sm??rgrav wrote: > Andrey Chernov <ache@freebsd.org> writes: > > Steven Chamberlain <steven@pyro.eu.org> writes: > > > Also it is great to see INHERIT_ZERO was added to mmap(2)! > > It is not so great. For a program which forks very often zeroing even > > one page will be slowdown. > > Wouldn't it be possible to just set up the page entry but leave it > unmapped, so that it is paged in (and zeroed if necessary) on first > access? Thus, a process that uses arc4random() and fork()s would not > incur a penalty until (and unless) the child uses arc4random() too. This is how the forking code works, without any additional coding, for the INHERIT_ZERO regions as well. > > > It will be better and faster to implement it as fork syscall wrapper > > setting single variable, as it already done for threaded lib. > > fork() and vfork() and pdfork() and... From a security point of view, I > prefer to have it in a single place. > > DES > -- > Dag-Erling Sm??rgrav - des@des.no > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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