openssh: remove RRECOMMENDS to rng-tools for sshd package

It appears that rngd is not needed as of linux-5.6 and later[1]
and should not be installed by default since the purpose of rngd
is to provide additional trusted sources of entropy.

We did some testing on real hardware, the result seems to support that
we no longer need rngd by default on kernel v5.6 and later.

Testing result as below:

1. observing the crng init stage.
 the "random: crng init done" always available before fs being mounted.

2. generating random number without rngd.
 testing command: dd if=/dev/random of=/dev/null status=progress
   on Marvell CN96xx RDB board, speed almost 20.4 MB/s without block
   on NXP i.mx6q board, speed almost 31.9 MB/s without block
   on qemu x86-64, speed almost 2.6MB/s without block

3. using rngtest command without rngd
 testing command: rngtest -c 1000 </dev/random
   on Marvell CN96xx RDB board:
      rngtest: input channel speed: (min=4.340; avg=135.364; max=146.719)Mibits/s
      rngtest: FIPS tests speed: (min=8.197; avg=69.020; max=72.800)Mibits/s
      rngtest: Program run time: 418771 microseconds

   on NXP i.mx6q board:
      rngtest: input channel speed: (min=96.820; avg=326.769; max=340.598)Mibits/s
      rngtest: FIPS tests speed: (min=15.090; avg=37.543; max=40.324)Mibits/s
      rngtest: Program run time: 570229 microseconds

   on qemu x86-64:
      rngtest: input channel speed: (min=37.769; avg=101.136; max=136.239)Mibits/s
      rngtest: FIPS tests speed: (min=10.288; avg=30.682; max=40.155)Mibits/s
      rngtest: Program run time: 836800 microseconds

4. observing sshd service.
  using "systemctl disable rng-tools" disable service and reboot system.
  system boot up normal, sshd service also start in normal time without
  block.

Reference:
[1] https://github.com/torvalds/linux/commit/30c08efec8884fb106b8e57094baa51bb4c44e32

Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit 868dfb46d96a27ec9041cb902fb769330277257d)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/recipes-connectivity/openssh/openssh_9.0p1.bb b/meta/recipes-connectivity/openssh/openssh_9.0p1.bb
index b63ea2b1373131d4204f3b3da24a6a7d45924cad..689952e8574cb7df23818e930e284185fa80d5a1 100644 (file)
--- a/meta/recipes-connectivity/openssh/openssh_9.0p1.bb
+++ b/meta/recipes-connectivity/openssh/openssh_9.0p1.bb
@@ -52,15 +52,12 @@ SYSTEMD_SERVICE:${PN}-sshd = "sshd.socket"
 
 inherit autotools-brokensep ptest
 
-PACKAGECONFIG ??= "rng-tools"
+PACKAGECONFIG ??= ""
 PACKAGECONFIG[kerberos] = "--with-kerberos5,--without-kerberos5,krb5"
 PACKAGECONFIG[ldns] = "--with-ldns,--without-ldns,ldns"
 PACKAGECONFIG[libedit] = "--with-libedit,--without-libedit,libedit"
 PACKAGECONFIG[manpages] = "--with-mantype=man,--with-mantype=cat"
 
-# Add RRECOMMENDS to rng-tools for sshd package
-PACKAGECONFIG[rng-tools] = ""
-
 EXTRA_AUTORECONF += "--exclude=aclocal"
 
 # login path is hardcoded in sshd
@@ -160,10 +157,6 @@ FILES:${PN}-keygen = "${bindir}/ssh-keygen"
 
 RDEPENDS:${PN} += "${PN}-scp ${PN}-ssh ${PN}-sshd ${PN}-keygen ${PN}-sftp-server"
 RDEPENDS:${PN}-sshd += "${PN}-keygen ${@bb.utils.contains('DISTRO_FEATURES', 'pam', 'pam-plugin-keyinit pam-plugin-loginuid', '', d)}"
-RRECOMMENDS:${PN}-sshd:append:class-target = "\
-    ${@bb.utils.filter('PACKAGECONFIG', 'rng-tools', d)} \
-"
-
 # gdb would make attach-ptrace test pass rather than skip but not worth the build dependencies
 RDEPENDS:${PN}-ptest += "${PN}-sftp ${PN}-misc ${PN}-sftp-server make sed sudo coreutils"