On Sat, Jul 4, 2020 at 12:44 AM Pavel Machek <pavel@xxxxxx> wrote: > > 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 suspend, right?
