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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