[Buildroot] [PATCH 4/4] busybox: applets as individual binaries

[Thomas Petazzoni]

From: Clayton Shotwell <clayton.shotwell at rockwellcollins.com>

The individual binaries option of busybox allows for the applets that
would usually be symlinks to be built as individual applications that
link against a shared library.

This feature is needed for SELinux to allow the applications to run
under the correct SELinux context.

The patch being added allows the individual applications to be installed
and will be upstreamed to the busybox developers.

The initial work for this change was done by Thomas Petazzoni
<thomas.petazzoni at free-electrons.com>.

The implementation of the BUSYBOX_PERMISSIONS_FILE generation has been
provided by Yann E. Morin.

Signed-off-by: Clayton Shotwell <clayton.shotwell at rockwellcollins.com>
Signed-off-by: Matthew Weber <matthew.weber at rockwellcollins.com>
Reviewed-by: Samuel Martin <s.martin49 at gmail.com>
Signed-off-by: Niranjan Reddy <niranjan.reddy at rockwellcollins.com>
Signed-off-by: Bryce Ferguson <bryce.ferguson at rockwellcollins.com>
[Thomas:
 - add help text in Config.in option.
 - remove change to BUSYBOX_PERMISSIONS, for now the permissions of the
   individual binaries are not correct. A follow-up patch will fix
   that. Therefore, the change to makedevs.c was removed.
 - rename BUSYBOX_CONFIGURE_INDIVIDUAL_BINARIES to
   BUSYBOX_SET_INDIVIDUAL_BINARIES to be consistent with other
   variables.
 - call BUSYBOX_INSTALL_INDIVIDUAL_BINARIES in
   BUSYBOX_INSTALL_TARGET_CMDS, not in BUSYBOX_INSTALL_INIT_SYSV.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 package/busybox/Config.in  | 16 ++++++++++++++++
 package/busybox/busybox.mk | 28 ++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/package/busybox/Config.in b/package/busybox/Config.in
index 504cd8a..9a2f411 100644
--- a/package/busybox/Config.in
+++ b/package/busybox/Config.in
@@ -54,6 +54,22 @@ config BR2_PACKAGE_BUSYBOX_SELINUX
 	  crond, then individual binaries have to be enabled for the
 	  SELinux type transitions to occur properly.
 
+config BR2_PACKAGE_BUSYBOX_INDIVIDUAL_BINARIES
+	bool "Individual binaries"
+	depends on !BR2_STATIC_LIBS
+	depends on !BR2_bfin # libbusybox.so link issue
+	help
+	  By default (i.e with this option disabled), Busybox is
+	  installed as a single binary in /bin/busybox and all applets
+	  are a symbolic link to /bin/busybox.
+
+	  With this option enabled, each applet is a separate binary,
+	  which is needed for proper operation with SELinux.
+
+comment "Busybox individual binaries depends on dynamic libraries"
+	depends on BR2_STATIC_LIBS
+	depends on !BR2_bfin
+
 config BR2_PACKAGE_BUSYBOX_WATCHDOG
 	bool "Install the watchdog daemon startup script"
 	help
diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
index 577f2f2..205b45a 100644
--- a/package/busybox/busybox.mk
+++ b/package/busybox/busybox.mk
@@ -60,9 +60,24 @@ BUSYBOX_KCONFIG_FRAGMENT_FILES = $(call qstrip,$(BR2_PACKAGE_BUSYBOX_CONFIG_FRAG
 BUSYBOX_KCONFIG_EDITORS = menuconfig xconfig gconfig
 BUSYBOX_KCONFIG_OPTS = $(BUSYBOX_MAKE_OPTS)
 
+ifeq ($(BR2_PACKAGE_BUSYBOX_INDIVIDUAL_BINARIES),y)
+BUSYBOX_PERMISSIONS_FILE = $(BUSYBOX_DIR)/busybox.permissions
+define BUSYBOX_GEN_PERMISSIONS
+	for app in `grep -r -e "APPLET.*BB_SUID_REQUIRE\|APPLET.*BB_SUID_MAYBE" $(@D)/include/applets.h \
+		| sed -e 's/,.*//' -e 's/.*(//'`; \
+	do \
+		temp=`grep -w $${app} $(@D)/busybox.links`; \
+		if [ -n "$${temp}" ]; then \
+			echo "$${temp} f 4755 0  0 - - - - -"; \
+		fi; \
+	done >$(BUSYBOX_PERMISSIONS_FILE)
+endef
+BUSYBOX_POST_INSTALL_TARGET_HOOKS += BUSYBOX_GEN_PERMISSIONS
+else
 define BUSYBOX_PERMISSIONS
 	/bin/busybox                     f 4755 0  0 - - - - -
 endef
+endif
 
 # If mdev will be used for device creation enable it and copy S10mdev to /etc/init.d
 ifeq ($(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),y)
@@ -171,6 +186,17 @@ define BUSYBOX_SET_SELINUX
 endef
 endif
 
+ifeq ($(BR2_PACKAGE_BUSYBOX_INDIVIDUAL_BINARIES),y)
+define BUSYBOX_SET_INDIVIDUAL_BINARIES
+	$(call KCONFIG_ENABLE_OPT,CONFIG_BUILD_LIBBUSYBOX,$(BUSYBOX_BUILD_CONFIG))
+	$(call KCONFIG_ENABLE_OPT,CONFIG_FEATURE_INDIVIDUAL,$(BUSYBOX_BUILD_CONFIG))
+endef
+
+define BUSYBOX_INSTALL_INDIVIDUAL_BINARIES
+	rm -f $(TARGET_DIR)/bin/busybox
+endef
+endif
+
 define BUSYBOX_INSTALL_LOGGING_SCRIPT
 	if grep -q CONFIG_SYSLOGD=y $(@D)/.config; then \
 		$(INSTALL) -m 0755 -D package/busybox/S01logging \
@@ -228,6 +254,7 @@ define BUSYBOX_KCONFIG_FIXUP_CMDS
 	$(BUSYBOX_SET_INIT)
 	$(BUSYBOX_SET_WATCHDOG)
 	$(BUSYBOX_SET_SELINUX)
+	$(BUSYBOX_SET_INDIVIDUAL_BINARIES)
 	$(BUSYBOX_MUSL_TWEAKS)
 endef
 
@@ -244,6 +271,7 @@ define BUSYBOX_INSTALL_TARGET_CMDS
 	$(BUSYBOX_INSTALL_INITTAB)
 	$(BUSYBOX_INSTALL_UDHCPC_SCRIPT)
 	$(BUSYBOX_INSTALL_MDEV_CONF)
+	$(BUSYBOX_INSTALL_INDIVIDUAL_BINARIES)
 endef
 
 define BUSYBOX_INSTALL_INIT_SYSV
-- 
2.7.4