[PATCH] kbuild: Don't source kernel config

[PATCH] kbuild: Don't source kernel config

[Richard Weinberger]

Don't source the kernel config file in shell scripts.
The config file is not a shell script and often imported from untrusted
sources.
What could possible go wrong? ;-)

Instead, read config file line by line and access config entries using a bash
array.

Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Arnaud Lacombe <lacombar@gmail.com>
Cc: Nick Bowler <nbowler@elliptictech.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Fixes: 23121ca2b56b ("kbuild: create/adjust generated/autoksyms.h")
Fixes: 1f2bfbd00e46 ("kbuild: link of vmlinux moved to a script")
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 scripts/adjust_autoksyms.sh | 13 +++----------
 scripts/importkconf.sh      | 14 ++++++++++++++
 scripts/link-vmlinux.sh     | 23 ++++++++---------------
 3 files changed, 25 insertions(+), 25 deletions(-)
 create mode 100755 scripts/importkconf.sh

diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
index 513da1a4a2da..632abcd0dc69 100755
--- a/scripts/adjust_autoksyms.sh
+++ b/scripts/adjust_autoksyms.sh
@@ -39,14 +39,7 @@ case "$KBUILD_VERBOSE" in
 esac
 
 # We need access to CONFIG_ symbols
-case "${KCONFIG_CONFIG}" in
-*/*)
-	. "${KCONFIG_CONFIG}"
-	;;
-*)
-	# Force using a file from the current directory
-	. "./${KCONFIG_CONFIG}"
-esac
+. scripts/importkconf.sh
 
 # In case it doesn't exist yet...
 if [ -e "$cur_ksyms_file" ]; then touch "$cur_ksyms_file"; fi
@@ -62,14 +55,14 @@ EOT
 [ "$(ls -A "$MODVERDIR")" ] &&
 sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u |
 while read sym; do
-	if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
+	if [ -n "${KERNEL_CONFIG[CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX]}" ]; then
 		sym="${sym#_}"
 	fi
 	echo "#define __KSYM_${sym} 1"
 done >> "$new_ksyms_file"
 
 # Special case for modversions (see modpost.c)
-if [ -n "$CONFIG_MODVERSIONS" ]; then
+if [ -n "${KERNEL_CONFIG[CONFIG_MODVERSIONS]}" ]; then
 	echo "#define __KSYM_module_layout 1" >> "$new_ksyms_file"
 fi
 
diff --git a/scripts/importkconf.sh b/scripts/importkconf.sh
new file mode 100755
index 000000000000..755a9a2e9c65
--- /dev/null
+++ b/scripts/importkconf.sh
@@ -0,0 +1,14 @@
+#!/bin/bash
+#
+# helper script which reads all kconfig keys from the kernel .config file into
+# a bash associative array.
+# By testing ${KERNEL_CONFIG[CONFIG_FOO_BAR]} shell scripts can check whether
+# CONFIG_FOO_BAR is set in .config or not.
+#
+
+declare -A KERNEL_CONFIG
+
+for cfg_ent in $(awk -F= '/^CONFIG_[A-Z0-9_]+=/{print $1}' < ${KCONFIG_CONFIG})
+do
+	KERNEL_CONFIG[${cfg_ent}]="$cfg_ent"
+done
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index c0d129d7f430..c094dd8f19a2 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -55,7 +55,7 @@ info()
 #
 archive_builtin()
 {
-	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
+	if [ -n "${KERNEL_CONFIG[CONFIG_THIN_ARCHIVES]}" ]; then
 		info AR built-in.o
 		rm -f built-in.o;
 		${AR} rcsTP${KBUILD_ARFLAGS} built-in.o			\
@@ -70,7 +70,7 @@ modpost_link()
 {
 	local objects
 
-	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
+	if [ -n "${KERNEL_CONFIG[CONFIG_THIN_ARCHIVES]}" ]; then
 		objects="--whole-archive				\
 			built-in.o					\
 			--no-whole-archive				\
@@ -96,7 +96,7 @@ vmlinux_link()
 	local objects
 
 	if [ "${SRCARCH}" != "um" ]; then
-		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
+		if [ -n "${KERNEL_CONFIG[CONFIG_THIN_ARCHIVES]}" ]; then
 			objects="--whole-archive			\
 				built-in.o				\
 				--no-whole-archive			\
@@ -116,7 +116,7 @@ vmlinux_link()
 		${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}		\
 			-T ${lds} ${objects}
 	else
-		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
+		if [ -n "${KERNEL_CONFIG[CONFIG_THIN_ARCHIVES]}" ]; then
 			objects="-Wl,--whole-archive			\
 				built-in.o				\
 				-Wl,--no-whole-archive			\
@@ -226,14 +226,7 @@ if [ "$1" = "clean" ]; then
 fi
 
 # We need access to CONFIG_ symbols
-case "${KCONFIG_CONFIG}" in
-*/*)
-	. "${KCONFIG_CONFIG}"
-	;;
-*)
-	# Force using a file from the current directory
-	. "./${KCONFIG_CONFIG}"
-esac
+. scripts/importkconf.sh
 
 # Update version
 info GEN .version
@@ -259,7 +252,7 @@ ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 
 kallsymso=""
 kallsyms_vmlinux=""
-if [ -n "${CONFIG_KALLSYMS}" ]; then
+if [ -n "${KERNEL_CONFIG[CONFIG_KALLSYMS]}" ]; then
 
 	# kallsyms support
 	# Generate section listing all symbols and add it into vmlinux
@@ -312,7 +305,7 @@ fi
 info LD vmlinux
 vmlinux_link "${kallsymso}" vmlinux
 
-if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
+if [ -n "${KERNEL_CONFIG[CONFIG_BUILDTIME_EXTABLE_SORT]}" ]; then
 	info SORTEX vmlinux
 	sortextable vmlinux
 fi
@@ -321,7 +314,7 @@ info SYSMAP System.map
 mksysmap vmlinux System.map
 
 # step a (see comment above)
-if [ -n "${CONFIG_KALLSYMS}" ]; then
+if [ -n "${KERNEL_CONFIG[CONFIG_KALLSYMS]}" ]; then
 	mksysmap ${kallsyms_vmlinux} .tmp_System.map
 
 	if ! cmp -s System.map .tmp_System.map; then
-- 
2.13.6

Re: [PATCH] kbuild: Don't source kernel config

[kbuild test robot]

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Hi Richard,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc1 next-20180216]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Richard-Weinberger/kbuild-Don-t-source-kernel-config/20180219-082820
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

>> scripts/link-vmlinux.sh: line 229: scripts/importkconf.sh: No such file or directory

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH] kbuild: Don't source kernel config

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1011 bytes --]

Hi Richard,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc2 next-20180216]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Richard-Weinberger/kbuild-Don-t-source-kernel-config/20180219-082820
config: mips-64r6el_defconfig (attached as .config)
compiler: mips64el-linux-gnuabi64-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mips 

All errors (new ones prefixed by >>):

>> scripts/adjust_autoksyms.sh: line 42: scripts/importkconf.sh: No such file or directory

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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