[PATCH v3] meta: add isar-cfg-rootpw recipe for setting root password

[claudius.heine.ext@siemens.com]

From: Claudius Heine <ch@denx.de>

The isar-cfg-rootpw recipe is a central point to set the root password
for images. It provides the `CFG_ROOT_PW` and `CFG_ROOT_LOCKED`
variables, that can be set from any `.conf` file or via
`isar-cfg-rootpw.bbappend`.

This package is installed as a transient package to avoid leaking
passwords set by it via the scripts in `/var/lib/dpkg/info/`.

The `CFG_ROOT_PW` variable contain the root password as crypt(3)
encrypted string. If this variable is empty root login without password
is possible possible.

The `CFG_ROOT_LOCKED` variable that can be set to "1" in order to lock
the root account, other values leave the account unlocked. Unlocking the
account at a later point will restore the password set by `CFG_ROOT_PW`.

Signed-off-by: Claudius Heine <ch@denx.de>
---
 RECIPE-API-CHANGELOG.md                       |  9 +++++++++
 doc/user_manual.md                            |  2 ++
 meta-isar/conf/local.conf.sample              |  6 ++++++
 .../recipes-app/example-raw/files/postinst    |  4 ----
 meta/classes/isar-image.bbclass               |  2 +-
 .../isar-cfg-rootpw/files/postinst.tmpl       | 19 +++++++++++++++++++
 .../isar-cfg-rootpw/isar-cfg-rootpw.bb        | 19 +++++++++++++++++++
 7 files changed, 56 insertions(+), 5 deletions(-)
 create mode 100644 meta/recipes-support/isar-cfg-rootpw/files/postinst.tmpl
 create mode 100644 meta/recipes-support/isar-cfg-rootpw/isar-cfg-rootpw.bb

diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
index dcfbbee..197ce99 100644
--- a/RECIPE-API-CHANGELOG.md
+++ b/RECIPE-API-CHANGELOG.md
@@ -136,3 +136,12 @@ files). Otherwise, default permissions are used.
 
 It's now sufficient to provide only kbuild rules. Makefile targets like modules
 or modules_install as well as KDIR and DESTDIR evaluation are no longer needed.
+
+### Remove setting of root passwords in custom packages
+
+Custom packages that are not installed via the IMAGE_TRANSIENT_PACKAGES and set
+a root password, leak that password via its script in /var/lib/dpkg/info.
+
+Instead set the CFG_ROOT_PW variable to the encrypted password and use the
+transient 'isar-cfg-rootpw' package (now installed as transient package per
+default).
diff --git a/doc/user_manual.md b/doc/user_manual.md
index eebcaa9..dfd46ce 100644
--- a/doc/user_manual.md
+++ b/doc/user_manual.md
@@ -313,6 +313,8 @@ Some other variables include:
  - `HOST_ARCH` - The Debian architecture of SDK root filesystem (e.g., `amd64`). By default set to current Debian host architecture. This variable is optional.
  - `HOST_DISTRO_APT_SOURCES` - List of apt source files for SDK root filesystem. This variable is optional.
  - `HOST_DISTRO_APT_PREFERENCES` - List of apt preference files for SDK root filesystem. This variable is optional.
+ - `CFG_ROOT_PW` - The encrypted root password to be set. To encrypt password use `mkpasswd`. You find `mkpasswd` in the `whois` package of Debian. If the variable is empty, root login requires not password
+ - `CFG_ROOT_LOCKED` - If set to `1` the root account will be locked.
 
 ---
 
diff --git a/meta-isar/conf/local.conf.sample b/meta-isar/conf/local.conf.sample
index a671b20..9bdfe10 100644
--- a/meta-isar/conf/local.conf.sample
+++ b/meta-isar/conf/local.conf.sample
@@ -171,3 +171,9 @@ ISAR_CROSS_COMPILE ?= "0"
 #
 # Uncomment this to enable use of cached base repository
 #ISAR_USE_CACHED_BASE_REPO ?= "1"
+
+# Set root password to 'root'
+# Password was encrypted using following command:
+#   mkpasswd -m sha512crypt -R 10000
+# mkpasswd is part of the 'whois' package of Debian
+CFG_ROOT_PW ?= "$6$rounds=10000$RXeWrnFmkY$DtuS/OmsAS2cCEDo0BF5qQsizIrq6jPgXnwv3PHqREJeKd1sXdHX/ayQtuQWVDHe0KIO0/sVH8dvQm1KthF0d/"
diff --git a/meta-isar/recipes-app/example-raw/files/postinst b/meta-isar/recipes-app/example-raw/files/postinst
index f60be8c..f48d993 100644
--- a/meta-isar/recipes-app/example-raw/files/postinst
+++ b/meta-isar/recipes-app/example-raw/files/postinst
@@ -15,8 +15,4 @@ fi
 
 chown -R isar:isar /var/lib/isar
 
-# this wins over meta-isar/recipes-core/images/files/*configscript.sh
-# but we take the same password for this example
-echo "root:root" | chpasswd
-
 echo "isar" > /etc/hostname
diff --git a/meta/classes/isar-image.bbclass b/meta/classes/isar-image.bbclass
index e2bae58..cdd1651 100644
--- a/meta/classes/isar-image.bbclass
+++ b/meta/classes/isar-image.bbclass
@@ -17,7 +17,7 @@ SRC_URI += "${@ cfg_script(d) }"
 
 DEPENDS += "${IMAGE_INSTALL} ${IMAGE_TRANSIENT_PACKAGES}"
 
-IMAGE_TRANSIENT_PACKAGES += "isar-cfg-localepurge"
+IMAGE_TRANSIENT_PACKAGES += "isar-cfg-localepurge isar-cfg-rootpw"
 
 WORKDIR = "${TMPDIR}/work/${DISTRO}-${DISTRO_ARCH}/${PN}"
 
diff --git a/meta/recipes-support/isar-cfg-rootpw/files/postinst.tmpl b/meta/recipes-support/isar-cfg-rootpw/files/postinst.tmpl
new file mode 100644
index 0000000..ca08a41
--- /dev/null
+++ b/meta/recipes-support/isar-cfg-rootpw/files/postinst.tmpl
@@ -0,0 +1,19 @@
+#!/bin/sh
+set -e
+
+if ! grep -q 'root:\*:' /etc/shadow; then
+    echo "ERROR:isar-cfg-rootpw: root password was set by a different package" >&2
+    exit -1
+fi
+
+if [ -n '${CFG_ROOT_PW}' ]; then
+    echo 'root:${CFG_ROOT_PW}' | chpasswd -e
+else
+    passwd -d root
+fi
+
+if [ '${CFG_ROOT_LOCKED}' = "1" ]; then
+    # Lock the account after setting the password, since unlocking it at some
+    # point later would set it to the back to the previous one.
+    passwd -l root
+fi
diff --git a/meta/recipes-support/isar-cfg-rootpw/isar-cfg-rootpw.bb b/meta/recipes-support/isar-cfg-rootpw/isar-cfg-rootpw.bb
new file mode 100644
index 0000000..adee3b5
--- /dev/null
+++ b/meta/recipes-support/isar-cfg-rootpw/isar-cfg-rootpw.bb
@@ -0,0 +1,19 @@
+# This software is a part of ISAR.
+
+DESCRIPTION = "Isar configuration package for root password"
+MAINTAINER = "isar-users <isar-users@googlegroups.com>"
+DEBIAN_DEPENDS = "passwd"
+
+SRC_URI = "file://postinst.tmpl"
+
+TEMPLATE_FILES = "postinst.tmpl"
+TEMPLATE_VARS = "CFG_ROOT_PW CFG_ROOT_LOCKED"
+
+CFG_ROOT_PW ??= ""
+CFG_ROOT_LOCKED ??= "0"
+
+inherit dpkg-raw
+
+do_install() {
+    echo "intentionally left blank"
+}
-- 
2.20.1