Decouple yarrow from random(4) device.

* Make Yarrow an optional kernel component -- enabled by "YARROW_RNG" option.
  The files sha2.c, hash.c, randomdev_soft.c and yarrow.c comprise yarrow.

* random(4) device doesn't really depend on rijndael-*.  Yarrow, however, does.

* Add random_adaptors.[ch] which is basically a store of random_adaptor's.
  random_adaptor is basically an adapter that plugs in to random(4).
  random_adaptor can only be plugged in to random(4) very early in bootup.
  Unplugging random_adaptor from random(4) is not supported, and is probably a
  bad idea anyway, due to potential loss of entropy pools.
  We currently have 3 random_adaptors:
  + yarrow
  + rdrand (ivy.c)
  + nehemeiah

* Remove platform dependent logic from probe.c, and move it into
  corresponding registration routines of each random_adaptor provider.
  probe.c doesn't do anything other than picking a specific random_adaptor
  from a list of registered ones.

* If the kernel doesn't have any random_adaptor adapters present then the
  creation of /dev/random is postponed until next random_adaptor is kldload'ed.

* Fix randomdev_soft.c to refer to its own random_adaptor, instead of a
  system wide one.

Submitted by: arthurmesh@gmail.com, obrien
Obtained from: Juniper Networks
Reviewed by: obrien

1 files changed, 13 insertions, 0 deletions

diff --git a/UPDATING b/UPDATING
index d3a6d569ebf3..39033064ecea 100644
--- a/UPDATING
+++ b/UPDATING
@@ -31,6 +31,19 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 10.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20130729:
+	random(4) and actual RNG implementations (aka, adaptors) have been
+	further decoupled.  If you are running a custom kernel, you may
+	need to explicitly enable at least one RNG adaptor in your kernel
+	config.  For example, to use Yarrow, add "options YARROW_RNG" to
+	your kernel config.  For hardware backed RNGs, use either
+	"RDRAND_RNG" or "PADLOCK_RNG" options.
+	If you use random.ko via 'random_load="YES"' in /boot/loader.conf
+	instead of "device random", you will need to change that to
+	'yarrow_rng_load="YES"', 'rdrand_rng_load="YES"', or
+	'padlock_rng_load="YES"'.  random.ko will be loaded automatically
+	as a dependency module.
+
 20130726:
 	Behavior of devfs rules path matching has been changed.
 	Pattern is now always matched against fully qualified devfs