Hi! > > Very much so, thanks again. What I take away from your results is: > > > > - RNDADDTOENTCNT is in active use in a safe way. Sure, RNDADDENTROPY > > is still much better, but RNDADDTOENTCNT isn't entirely broken in the > > above configurations either. > > - This patch would make RNDADDTOENTCNT unsafe for some of the above > > configurations in a way that it currently isn't unsafe. > > - Plenty of things are seeding the RNG correctly, and buildroot's > > shell script is just "doing it wrong". > > > > On that last point, I should reiterate that buildroot's shell script > > still isn't actually initializing the RNG, despite what it says in its > > echo; there's never been a way to initialize the RNG from a shell > > script, without calling out to various special purpose ioctl-aware > > binaries. > > Based on this, the fact that shell scripts cannot seed the RNG anyway, > and due to the hazards in trying to retrofit some heuristics onto an > interface that was never designed to work like this, I'm convinced at > this point that the right course of action here is to leave this > alone. There's no combination of /dev/urandom write hacks/heuristics > that do the right thing without creating some big problem elsewhere. > It just does not have the right semantics for it, and changing the > existing semantics will break existing users. > > In light of that conclusion, I'm going to work with every userspace > downstream I can find to help them fix their file-based seeding, if it > has bugs. I've started talking with the buildroot folks, and then I'll > speak with the OpenRC people (being a Gentoo dev, that should be easy > going). Systemd does the right thing already. > > I wrote a little utility for potential inclusion in > busybox/util-linux/whatever when it matures beyond its current age of > being half hour old: > - https://git.zx2c4.com/seedrng/about/ > - https://git.zx2c4.com/seedrng/tree/seedrng.c > So I'll see what the buildroot people think of this and take it from there. You could put it into the kernel into tools/ directory... Best regards, Pavel
