Re: [RFC]: mm,power: introduce MADV_WIPEONSUSPEND

Pavel Machek
2020-07-04T11:48:27Z

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Hi!

> > > Cryptographic libraries carry pseudo random number generators to
> > > quickly provide randomness when needed. If such a random pool gets
> > > cloned, secrets may get revealed, as the same random number may get
> > > used multiple times. For fork, this was fixed using the WIPEONFORK
> > > madvise flag [1].
> >
> > > Unfortunately, the same problem surfaces when a virtual machine gets
> > > cloned. The existing flag does not help there. This patch introduces a
> > > new flag to automatically clear memory contents on VM suspend/resume,
> > > which will allow random number generators to reseed when virtual
> > > machines get cloned.
> >
> > Umm. If this is real problem, should kernel provide such rng in the
> > vsdo page using vsyscalls? Kernel can have special interface to its
> > vsyscalls, but we may not want to offer this functionality to rest of
> > userland...
>
> And then the kernel would just need to maintain a sequence
> number in the vDSO data page that gets bumped on suspen

Yes, something like that would work. Plus, we'd be free to change the
mechanism in future.

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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