Add DEV_RANDOM pseudo-option and use it to "include out" random(4)

if desired.

Retire randomdev_none.c and introduce random_infra.c for resident
infrastructure. Completely stub out random(4) calls in the "without
DEV_RANDOM" case.

Add RANDOM_LOADABLE option to allow loadable Yarrow/Fortuna/LocallyWritten
algorithm.  Add a skeleton "other" algorithm framework for folks
to add their own processing code. NIST, anyone?

Retire the RANDOM_DUMMY option.

Build modules for Yarrow, Fortuna and "other".

Use atomics for the live entropy rate-tracking.

Convert ints to bools for the 'seeded' logic.

Move _write() function from the algorithm-specific areas to randomdev.c

Get rid of reseed() function - it is unused.

Tidy up the opt_*.h includes.

Update documentation for random(4) modules.

Fix test program (reviewers, please leave this).

Differential Revision:    https://reviews.freebsd.org/D3354
Reviewed by:              wblock,delphij,jmg,bjk
Approved by:              so (/dev/random blanket)

1 files changed, 43 insertions, 8 deletions

diff --git a/share/man/man4/random.4 b/share/man/man4/random.4
index 133fb3b..75a7274 100644
--- a/share/man/man4/random.4
+++ b/share/man/man4/random.4
@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 30, 2015
+.Dd August 17, 2015
 .Dt RANDOM 4
 .Os
 .Sh NAME
@@ -31,6 +31,7 @@
 .Nd the entropy device
 .Sh SYNOPSIS
 .Cd "device random"
+.Cd "options RANDOM_LOADABLE"
 .Sh DESCRIPTION
 The
 .Nm
@@ -133,15 +134,49 @@ The
 .Va kern.random.harvest.mask_bin
 and
 .Va kern.random.harvest.mask_symbolic
-sysctl
-can be used confirm
-that your choices are correct.
+sysctls
+can be used to confirm
+that the choices are correct.
 Note that disabled items
 in the latter item
 are listed in square brackets.
 See
 .Xr random_harvest 9
 for more on the harvesting of entropy.
+.Pp
+When
+.Cd "options RANDOM_LOADABLE"
+is used,
+the
+.Pa /dev/random
+device is not created
+until an "algorithm module"
+is loaded.
+Two of these modules
+are built by default,
+.Em random_fortuna
+and
+.Em random_yarrow .
+The
+.Em random_yarrow
+module is deprecated,
+and will be removed in
+.Fx 12.
+Use of the Yarrow algorithm
+is not encouraged,
+but while still present
+in the kernel source,
+it can be selected with the
+.Cd "options RANDOM_YARROW"
+kernel option.
+Note that these loadable modules
+are slightly less efficient
+than their compiled-in equivalents.
+This is because some functions
+must be locked against
+load and unload events,
+and also must be indirect calls
+to allow for removal.
 .Sh RANDOMNESS
 The use of randomness in the field of computing
 is a rather subtle issue because randomness means
@@ -294,7 +329,7 @@ It replaces the previous
 implementation,
 introduced in
 .Fx 5.0 .
-The older
-.Em Yarrow
-algorithm remains available
-as a compile-time fallback.
+The Yarrow algorithm
+is no longer supported
+by its authors,
+and is therefore deprecated.