This series tackles a few issues that are intermingled with each other: - Using RDSEED when we can rather than using RDRAND. - Making sure RDRAND/RDSEED input always goes through the mixer rather than being xor'd into our state directly, in part in order to prevent ridiculous hypothetical cpu backdoors, and in part because it makes it easier to model RDRAND/RDSEED as just another entropy input. - Untangling the never ending headache that is kmalloc'd NUMA secondary CRNGs, and replacing these with leaner per-cpu ChaCha keys that don't have all the state troubles. There are other patches pending my review that take the current NUMA initialization code to yet another layer of complexity, sort of driving home the point to me that the current code is a can of worms. This patchset attempts a different direction there. - Enforcing "fast key erasure" expansion always, and not relying on having a shared block counter that is bound to lead to troubles sooner or later. - Nearly eliminating lock contention when several processes use the rng at the same time. WireGuard, for example, processes packets in parallel on all threads, and this packet processing requires frequent calls to get_random_bytes(). Because one design choice in here affects others, these issues are tackled by this same patchset. It's roughly divided into "things with RDSEED" and "things with struct crng", with the ordering of commits being important. Finally the series ends with a one-off patch removing an obsolete limit on /dev/urandom. Cc: Theodore Ts'o <tytso@xxxxxxx> Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> Jason A. Donenfeld (7): random: use RDSEED instead of RDRAND in entropy extraction random: get rid of secondary crngs random: inline leaves of rand_initialize() random: ensure early RDSEED goes through mixer on init random: do not xor RDRAND when writing into /dev/random random: use simpler fast key erasure flow on per-cpu keys random: remove outdated INT_MAX >> 6 check in urandom_read() drivers/char/random.c | 566 +++++++++++++++++------------------------- 1 file changed, 231 insertions(+), 335 deletions(-) -- 2.35.0
