Patchwork [1/2] target: add option to set the root password

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Submitter Yann E. MORIN
Date Dec. 29, 2012, 12:07 a.m.
Message ID <0e6cac687daa80382f614d38c6394947eab5d892.1356739565.git.yann.morin.1998@free.fr>
Download mbox | patch
Permalink /patch/208607/
State Accepted
Headers show

Comments

Yann E. MORIN - Dec. 29, 2012, 12:07 a.m.
Add an option in the menuconfig to specify a root password.

If set to empty, no root password is created; otherwise, the password is
encrypted using MD5 (MD5 is not the default for crypt(3), DES-56 is, but
MD5 is widely available, not-so-strong, but not-so-weak either).

Add a check for 'mkpasswd' as a new dependency.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
Switched to using MD5 as per Arnout's suggestion:
    http://lists.busybox.net/pipermail/buildroot/2012-September/058712.html
---
 support/dependencies/dependencies.sh |    9 +++++++++
 system/Config.in                     |   21 +++++++++++++++++++++
 system/system.mk                     |   14 ++++++++++++++
 3 files changed, 44 insertions(+), 0 deletions(-)
Peter Korsgaard - Dec. 30, 2012, 5:01 p.m.
>>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes:

 Yann> Add an option in the menuconfig to specify a root password.
 Yann> If set to empty, no root password is created; otherwise, the password is
 Yann> encrypted using MD5 (MD5 is not the default for crypt(3), DES-56 is, but
 Yann> MD5 is widely available, not-so-strong, but not-so-weak either).

 Yann> Add a check for 'mkpasswd' as a new dependency.

 Yann> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
 Yann> Cc: Arnout Vandecappelle <arnout@mind.be>
 Yann> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
 
 Yann> +config BR2_TARGET_GENERIC_ROOT_PASSWD
 Yann> +	string "root password"

The rest of the options here are capitilized, so I've done that as well
here.

 Yann> +	default ""
 Yann> +	help
 Yann> +	  Set the initial root password (in clear). It will be md5-encrypted.
 Yann> +	  
 Yann> +	  If set to empty (the default), then no root password will be set,
 Yann> +	  and root will need no password to log in.
 Yann> +	  
 Yann> +	  WARNING! WARNING!
 Yann> +	  Although pretty strong, MD5 is now an old hash function, and
 Yann> +	  suffers from som weaknesses, which makes it susceptible to attacks.

s/som/some/

 Yann> +target-no-root-passwd:
 Yann> +	$(SED) "s/^root:[^:]*:/root::/" $(TARGET_DIR)/etc/shadow
 Yann> +
 Yann> +target-root-passwd:
 Yann> +	root_passwd="$$( mkpasswd -m md5 "$(TARGET_GENERIC_ROOT_PASSWD)" )"; \
 Yann> +	$(SED) "s,^root::,root:$${root_passwd}:," $(TARGET_DIR)/etc/shadow
 Yann> +

The 2nd sed only applies if the root passwd isn't set (E.G. running make
menuconfig and changing password + make doesn't work), so I've
simplified the two cases together to simply replace root:[^:]*: with
root:$(TARGET_GENERIC_ROOT_PASSWD_HASH): which is either the empty
string or the mkpasswd -m md5 output.

Patch

diff --git a/support/dependencies/dependencies.sh b/support/dependencies/dependencies.sh
index 7a02512..eb5a481 100755
--- a/support/dependencies/dependencies.sh
+++ b/support/dependencies/dependencies.sh
@@ -158,6 +158,7 @@  if grep ^BR2_TOOLCHAIN_BUILDROOT=y $CONFIG_FILE > /dev/null && \
        exit 1 ;
    fi
 fi
+
 if grep -q ^BR2_PACKAGE_CLASSPATH=y $CONFIG_FILE ; then
     for prog in javac jar; do
 	if ! which $prog > /dev/null ; then
@@ -166,3 +167,11 @@  if grep -q ^BR2_PACKAGE_CLASSPATH=y $CONFIG_FILE ; then
 	fi
     done
 fi
+
+if grep -E '^BR2_TARGET_GENERIC_ROOT_PASSWD=".+"$' $CONFIG_FILE > /dev/null 2>&1; then
+    if ! which mkpasswd > /dev/null 2>&1; then
+        /bin/echo -e "\nYou need the 'mkpasswd' utility to set the root password\n"
+        /bin/echo -e "(in Debian/ubuntu, 'mkpasswd' provided by the whois package)\n"
+        exit 1
+    fi
+fi
diff --git a/system/Config.in b/system/Config.in
index a557ea0..deead86 100644
--- a/system/Config.in
+++ b/system/Config.in
@@ -12,6 +12,27 @@  config BR2_TARGET_GENERIC_ISSUE
        help
          Select system banner (/etc/issue) to be displayed at login.
 
+config BR2_TARGET_GENERIC_ROOT_PASSWD
+	string "root password"
+	default ""
+	help
+	  Set the initial root password (in clear). It will be md5-encrypted.
+	  
+	  If set to empty (the default), then no root password will be set,
+	  and root will need no password to log in.
+	  
+	  WARNING! WARNING!
+	  Although pretty strong, MD5 is now an old hash function, and
+	  suffers from som weaknesses, which makes it susceptible to attacks.
+	  It is showing its age, so this root password should not be trusted
+	  to properly secure any product that can be shipped to the wide,
+	  hostile world.
+	  
+	  WARNING! WARNING!
+	  The password appears in clear in the .config file, and may appear
+	  in the build log! Avoid using a valuable password if either the
+	  .config file or the build log may be distributed!
+
 choice
 	prompt "/dev management"
 	default BR2_ROOTFS_DEVICE_CREATION_STATIC
diff --git a/system/system.mk b/system/system.mk
index 353d0ba..a23feef 100644
--- a/system/system.mk
+++ b/system/system.mk
@@ -1,5 +1,6 @@ 
 TARGET_GENERIC_HOSTNAME:=$(call qstrip,$(BR2_TARGET_GENERIC_HOSTNAME))
 TARGET_GENERIC_ISSUE:=$(call qstrip,$(BR2_TARGET_GENERIC_ISSUE))
+TARGET_GENERIC_ROOT_PASSWD:=$(call qstrip,$(BR2_TARGET_GENERIC_ROOT_PASSWD))
 TARGET_GENERIC_GETTY:=$(call qstrip,$(BR2_TARGET_GENERIC_GETTY_PORT))
 TARGET_GENERIC_GETTY_BAUDRATE:=$(call qstrip,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE))
 TARGET_GENERIC_GETTY_TERM:=$(call qstrip,$(BR2_TARGET_GENERIC_GETTY_TERM))
@@ -14,6 +15,13 @@  target-generic-issue:
 	mkdir -p $(TARGET_DIR)/etc
 	echo "$(TARGET_GENERIC_ISSUE)" > $(TARGET_DIR)/etc/issue
 
+target-no-root-passwd:
+	$(SED) "s/^root:[^:]*:/root::/" $(TARGET_DIR)/etc/shadow
+
+target-root-passwd:
+	root_passwd="$$( mkpasswd -m md5 "$(TARGET_GENERIC_ROOT_PASSWD)" )"; \
+	$(SED) "s,^root::,root:$${root_passwd}:," $(TARGET_DIR)/etc/shadow
+
 target-generic-getty-busybox:
 	$(SED) '/# GENERIC_SERIAL$$/s~^.*#~$(TARGET_GENERIC_GETTY)::respawn:/sbin/getty -L $(TARGET_GENERIC_GETTY) $(TARGET_GENERIC_GETTY_BAUDRATE) $(TARGET_GENERIC_GETTY_TERM) #~' \
 		$(TARGET_DIR)/etc/inittab
@@ -40,6 +48,12 @@  ifneq ($(TARGET_GENERIC_ISSUE),)
 TARGETS += target-generic-issue
 endif
 
+ifneq ($(TARGET_GENERIC_ROOT_PASSWD),)
+TARGETS += target-root-passwd
+else
+TARGETS += target-no-root-passwd
+endif
+
 ifeq ($(BR2_ROOTFS_SKELETON_DEFAULT),y)
 ifeq ($(BR2_PACKAGE_SYSVINIT),y)
 TARGETS += target-generic-getty-sysvinit