package/urandom-scripts: new package

The init script S20urandom is used to preserve the kernel's RNG
seed between reboots. This functionality is not required for the
package "initscripts". Further there are use-cases where this script
should not be installed at all (e.g. systems that only have read-only
partitions), but that's currently not possible as the script is
a mandatory part of the package "initscripts".

Let's move the script into its own package "urandom-scripts" and select it,
if the default skeleton is enabled. This maintains backward-compatibility
and allows to deselect it.

Signed-off-by: Christoph Müllner <christoph.muellner@theobroma-systems.com>
[yann.morin.1998@free.fr:
  - extend help text
  - default y if initscripts (instead of skeleton default)
  - allow use with openRC, but not systemd
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

diff --git a/package/Config.in b/package/Config.in
index 7ab11126445c4431060cbd54a00f41d4e9bc810c..e6500123f606a2a6385fa3101279b5b9ee3666c2 100644 (file)
--- a/package/Config.in
+++ b/package/Config.in
@@ -2291,6 +2291,7 @@ menu "Security"
        source "package/selinux-python/Config.in"
        source "package/semodule-utils/Config.in"
        source "package/setools/Config.in"
+       source "package/urandom-scripts/Config.in"
 endmenu
 
 menu "Shell and utilities"

diff --git a/package/initscripts/init.d/S20urandom b/package/initscripts/init.d/S20urandom
deleted file mode 100644 (file)
index e4fd125..0000000
--- a/package/initscripts/init.d/S20urandom
+++ /dev/null
@@ -1,74 +0,0 @@
-#! /bin/sh
-#
-# Preserve the random seed between reboots. See urandom(4).
-#
-
-# Quietly do nothing if /dev/urandom does not exist
-[ -c /dev/urandom ] || exit 0
-
-URANDOM_SEED="/var/lib/random-seed"
-
-# shellcheck source=/dev/null
-[ -r "/etc/default/urandom" ] && . "/etc/default/urandom"
-
-if pool_bits=$(cat /proc/sys/kernel/random/poolsize 2> /dev/null); then
-       pool_size=$((pool_bits/8))
-else
-       pool_size=512
-fi
-
-check_file_size() {
-       [ -f "$URANDOM_SEED" ] || return 1
-       # Try to read two blocks but exactly one will be read if the file has
-       # the correct size.
-       size=$(dd if="$URANDOM_SEED" bs="$pool_size" count=2 2> /dev/null | wc -c)
-       test "$size" -eq "$pool_size"
-}
-
-init_rng() {
-       if check_file_size; then
-               printf 'Initializing random number generator: '
-               dd if="$URANDOM_SEED" bs="$pool_size" of=/dev/urandom count=1 2> /dev/null
-               status=$?
-               if [ "$status" -eq 0 ]; then
-                       echo "OK"
-               else
-                       echo "FAIL"
-               fi
-               return "$status"
-       fi
-}
-
-save_random_seed() {
-       printf 'Saving random seed: '
-       if touch "$URANDOM_SEED" 2> /dev/null; then
-               old_umask=$(umask)
-               umask 077
-               dd if=/dev/urandom of="$URANDOM_SEED" bs="$pool_size" count=1 2> /dev/null
-               status=$?
-               umask "$old_umask"
-               if [ "$status" -eq 0 ]; then
-                       echo "OK"
-               else
-                       echo "FAIL"
-               fi
-       else
-               status=$?
-               echo "SKIP (read-only file system detected)"
-       fi
-       return "$status"
-}
-
-case "$1" in
-       start|restart|reload)
-               # Carry a random seed from start-up to start-up
-               # Load and then save the whole entropy pool
-               init_rng && save_random_seed;;
-       stop)
-               # Carry a random seed from shut-down to start-up
-               # Save the whole entropy pool
-               save_random_seed;;
-       *)
-               echo "Usage: $0 {start|stop|restart|reload}"
-               exit 1
-esac

diff --git a/package/urandom-scripts/Config.in b/package/urandom-scripts/Config.in
new file mode 100644 (file)
index 0000000..987e442
--- /dev/null
+++ b/package/urandom-scripts/Config.in
@@ -0,0 +1,10 @@
+config BR2_PACKAGE_URANDOM_SCRIPTS
+       bool "urandom-initscripts"
+       default y if BR2_PACKAGE_INITSCRIPTS
+       depends on !BR2_PACKAGE_SYSTEMD
+       help
+         Initscript to preserve the random seed between reboots.
+
+         WARNING: this is a poor fit to try and get high-quality
+         entropy at boot. There are better ways, like haveged, or
+         rng-tools.

diff --git a/package/urandom-scripts/S20urandom b/package/urandom-scripts/S20urandom
new file mode 100644 (file)
index 0000000..e4fd125
--- /dev/null
+++ b/package/urandom-scripts/S20urandom
@@ -0,0 +1,74 @@
+#! /bin/sh
+#
+# Preserve the random seed between reboots. See urandom(4).
+#
+
+# Quietly do nothing if /dev/urandom does not exist
+[ -c /dev/urandom ] || exit 0
+
+URANDOM_SEED="/var/lib/random-seed"
+
+# shellcheck source=/dev/null
+[ -r "/etc/default/urandom" ] && . "/etc/default/urandom"
+
+if pool_bits=$(cat /proc/sys/kernel/random/poolsize 2> /dev/null); then
+       pool_size=$((pool_bits/8))
+else
+       pool_size=512
+fi
+
+check_file_size() {
+       [ -f "$URANDOM_SEED" ] || return 1
+       # Try to read two blocks but exactly one will be read if the file has
+       # the correct size.
+       size=$(dd if="$URANDOM_SEED" bs="$pool_size" count=2 2> /dev/null | wc -c)
+       test "$size" -eq "$pool_size"
+}
+
+init_rng() {
+       if check_file_size; then
+               printf 'Initializing random number generator: '
+               dd if="$URANDOM_SEED" bs="$pool_size" of=/dev/urandom count=1 2> /dev/null
+               status=$?
+               if [ "$status" -eq 0 ]; then
+                       echo "OK"
+               else
+                       echo "FAIL"
+               fi
+               return "$status"
+       fi
+}
+
+save_random_seed() {
+       printf 'Saving random seed: '
+       if touch "$URANDOM_SEED" 2> /dev/null; then
+               old_umask=$(umask)
+               umask 077
+               dd if=/dev/urandom of="$URANDOM_SEED" bs="$pool_size" count=1 2> /dev/null
+               status=$?
+               umask "$old_umask"
+               if [ "$status" -eq 0 ]; then
+                       echo "OK"
+               else
+                       echo "FAIL"
+               fi
+       else
+               status=$?
+               echo "SKIP (read-only file system detected)"
+       fi
+       return "$status"
+}
+
+case "$1" in
+       start|restart|reload)
+               # Carry a random seed from start-up to start-up
+               # Load and then save the whole entropy pool
+               init_rng && save_random_seed;;
+       stop)
+               # Carry a random seed from shut-down to start-up
+               # Save the whole entropy pool
+               save_random_seed;;
+       *)
+               echo "Usage: $0 {start|stop|restart|reload}"
+               exit 1
+esac

diff --git a/package/urandom-scripts/urandom-scripts.mk b/package/urandom-scripts/urandom-scripts.mk
new file mode 100644 (file)
index 0000000..2c09728
--- /dev/null
+++ b/package/urandom-scripts/urandom-scripts.mk
@@ -0,0 +1,12 @@
+################################################################################
+#
+# urandom-scripts
+#
+################################################################################
+
+define URANDOM_SCRIPTS_INSTALL_INIT_SYSV
+       $(INSTALL) -D -m 0755 $(URANDOM_SCRIPTS_PKGDIR)/S20urandom \
+               $(TARGET_DIR)/etc/init.d/S20urandom
+endef
+
+$(eval $(generic-package))