From: Theodore Ts'o Date: Thu, 17 Jul 2014 09:27:30 +0000 (-0400) Subject: random: limit the contribution of the hw rng to at most half X-Git-Tag: omap-for-v3.17/fixes-against-rc2~150^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=48d6be955a7167b0d0e025ae6c39e795e3544499;p=pandora-kernel.git random: limit the contribution of the hw rng to at most half For people who don't trust a hardware RNG which can not be audited, the changes to add support for RDSEED can be troubling since 97% or more of the entropy will be contributed from the in-CPU hardware RNG. We now have a in-kernel khwrngd, so for those people who do want to implicitly trust the CPU-based system, we could create an arch-rng hw_random driver, and allow khwrng refill the entropy pool. This allows system administrator whether or not they trust the CPU (I assume the NSA will trust RDRAND/RDSEED implicitly :-), and if so, what level of entropy derating they want to use. The reason why this is a really good idea is that if different people use different levels of entropy derating, it will make it much more difficult to design a backdoor'ed hwrng that can be generally exploited in terms of the output of /dev/random when different attack targets are using differing levels of entropy derating. Signed-off-by: Theodore Ts'o --- Reading git-diff-tree failed