Date: Tue, 15 Nov 2011 02:11:03 +0100 From: Oliver Pinter <oliver.pntr@gmail.com> To: Andrey Chernov <ache@freebsd.org>, das@freebsd.org, current@freebsd.org, secteam@freebsd.org Subject: Re: Is fork() hook ever possible? Message-ID: <CAPjTQNFSbkiaDUzMh_WYffM9vF1-H3j-FA2FZJfHR-0uJyJ3eQ@mail.gmail.com> In-Reply-To: <20111115004443.GA50429@vniz.net> References: <20080916140319.GA34447@nagual.pp.ru> <20080916201932.GA59781@zim.MIT.EDU> <20111112102241.GA75396@vniz.net> <20111112154135.GA21512@zim.MIT.EDU> <20111112171531.GA83419@vniz.net> <20111114013004.GA53392@zim.MIT.EDU> <20111114192721.GA16834@vniz.net> <20111114205855.GB58790@zim.MIT.EDU> <20111114212926.GA28783@vniz.net> <20111114230855.GA59545@zim.MIT.EDU> <20111115004443.GA50429@vniz.net>
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On 11/15/11, Andrey Chernov <ache@freebsd.org> wrote:
> On Mon, Nov 14, 2011 at 06:08:55PM -0500, David Schultz wrote:
>> Not quite. OpenBSD's implementation is more careful. I just
>> noticed a funny thing about FreeBSD's KERN_ARND sysctl: If the
>> random device isn't (or can't be) loaded, KERN_ARND silently
>> decides to initialize itself with the output of random(). This
>> means that whatever minuscule amount of entropy it might have
>> picked up from the clock is reduced to a maximum of 31 bits.
>> That's a fantastic way to provide a false sense of security...
>
> I agree.
>
> Lets separate two things: "no /dev/random for jails" and "no random kernel
> module is loaded".
> IMHO kernel module should _not_ be optional anymore, it solves problem you
> describe and all similar problems at once.
>
> Adding KERN_ARND to arc4random() at this moment solves "no /dev/random for
> jails" problem alone and _not_ pretends to solve "no random kernel module
> is loaded" problem. When random kernel module will become non-optional,
> KERN_ARND automagically makes good security in that place too.
>
> P.S. Do I answer your doubts about &rdat key initialization in my prev.
> posting?
I think it's a much correct solution, rather than the original patch,
while it initializes the whole structure, not only the key array...
(&rdat.key vs &rdat; and uninitialized pid and tv):
fd = _open(RANDOMDEV, O_RDONLY, 0);
done = 0;
if (fd >= 0) {
- if (_read(fd, &rdat, KEYSIZE) == KEYSIZE)
+ if (_read(fd, &rdat, sizeof(rdat)) == sizeof(rdat))
done = 1;
(void)_close(fd);
- }
+ }
>
> --
> http://ache.vniz.net/
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