[PATCH v9] seedrng: import SeedRNG utility for kernel RNG seed files

[Steffen Nurpmeso]

Denys Vlasenko wrote in
 <CAK1hOcOZxXmiFVKqJQQBK5ZFaKHzQDkDqH8FO_e9C+yOR=2Z0w at mail.gmail.com>:
 ...
 |Even partial removal of these complicated error paths
 |cuts down the size by ~10%

A bit off topic but i personally am still thinking, really, that
people would rather be reenabled to do what they did for long.
ports/core/rc/rc

  ^e3afe2298e (Johannes Winkelmann 2006-02-23 15:26:10 +0000  80) # Load random seed
  ^e3afe2298e (Johannes Winkelmann 2006-02-23 15:26:10 +0000  81) /bin/cat /var/lib/urandom/seed > /dev/urandom

/ports/core/rc/rc.shutdown

  ^e3afe2298e (Johannes Winkelmann 2006-02-23 15:26:10 +0000 33) # Save random seed
  ^e3afe2298e (Johannes Winkelmann 2006-02-23 15:26:10 +0000 34) /bin/dd if=/dev/urandom of=/var/lib/urandom/seed count=1 2> /dev/null

It is a young Linux distribution.  Maybe they would consider to
use /dev/random instead of /dev/urandom, but fed in noise is fed
in noise in the end.
OpenBSD, just as an example, does in /etc/rc

  # Push the old seed into the kernel, create a future seed  and create a seed
  # file for the boot-loader.
  random_seed() {
          dd if=/var/db/host.random of=/dev/random bs=65536 count=1 status=none
          chmod 600 /var/db/host.random
          dd if=/dev/random of=/var/db/host.random bs=65536 count=1 status=none
          dd if=/dev/random of=/etc/random.seed bs=512 count=1 status=none
          chmod 600 /etc/random.seed
  }

Once i had to write entropy-saver.c (i later also had to install
haveged and this still do not understand why, rhetorically) it was
only to undo the mental displacement i encountered when the RNG no
longer became seeded upon system boot on my AlpineLinux VM,
resulting in boot hangs of up to half an hour (due to ssh iirc).

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)