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bug#13768: --without-posix code uses scm_getpid() in libguile-2.0.2
From: |
Andy Wingo |
Subject: |
bug#13768: --without-posix code uses scm_getpid() in libguile-2.0.2 |
Date: |
Mon, 25 Feb 2013 10:06:38 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
On Mon 25 Feb 2013 02:17, Mark H Weaver <address@hidden> writes:
> Andy Wingo <address@hidden> writes:
>
>> On Wed 20 Feb 2013 00:38, Jan Schukat <address@hidden> writes:
>>
>>> What happens is, in random.c in random_state_of_last_resort on line 668
>>> scm_getpid is used to seed the random generator. So either a
>>> preprocessor switch or a hand constructed scm like in scm_getpid
>>> (scm_from_ulong(getpid())) should be used there.
>>
>> Fixed, thanks for the report.
>
> This has potential security implications. If the same program is run
> multiple times in the same second, then without something like a PID,
> there's a significant danger that two runs of the program will use the
> same random seed.
Our PRNG is not secure. We should not be making arguments from the
perspective of security. (I think including the PID is a good thing,
but not because of security.)
> Therefore, I think we ought to try hard to ensure that something like a
> PID will always be included in this seed. Perhaps 'scm_getpid' should
> be included even when building --without-posix.
Why don't we just add the result of getpid() without relying on the
scm_getpid() binding. All platforms have it.
> At the very least, the documentation (which currently claims that the
> PID is included in the random-state-of-last-resort) should be adjusted
> to reflect the new reality. I just took care of that.
Thanks for following up. TBH though I would prefer that if you already
know the solution, to go ahead and fix it instead of writing a mail and
fixing the docs. Much easier on users (and developers :) if Guile just
does the right thing.
Andy
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