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Date: Wed, 4 Jul 2018 13:36:00 +0200
From: Florian Weimer <fweimer@...hat.com>
To: Rich Felker <dalias@...c.org>
Cc: musl@...ts.openwall.com
Subject: Re: arc4random/csprng

On 07/03/2018 05:17 PM, Rich Felker wrote:

>> But it's still quite common to do things with direct system calls,
>> particularly for setting up containers.
>>
>> I have not yet found a case which I couldn't solve with plain fork
>> (with handlers) and unshare, but that's not what everyone does
>> unfortunately.
> 
> I agree you might need direct use of clone sometime for
> namespace/container stuff, but I don't think there's any way it can be
> made safe without careful consideration of what you do after the
> operation before a subsequent execve or _exit. I don't think it makes
> sense to design big machinery to support doing something that has
> deeper reasons it can't work, but this is probably partly a difference
> in philosophy between glibc and musl (see also: dlclose, lazy dtls,
> lazy tlsdesc, ...).

I would suggest to keep at least the fork detection bit, even if you do 
not reseed and deadlock or abort instead, because the duplicate stream 
of random bits could be very hard to detect otherwise.

Thanks,
Florian

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