fix MSR reading, need rdmsr for now

README.md

@@ -5,28 +5,34 @@ A simple shell script to tell if your Linux installation is vulnerable
 against the 3 "speculative execution" CVEs:
 
 CVE-2017-5753 bounds check bypass (Spectre Variant 1)
-   Impact: Kernel & all software
+
-   Mitigation: recompile software *and* kernel with a modified compiler that introduces the LFENCE opcode at the proper positions in the resulting code
+   - Impact: Kernel & all software
-   Performance impact of the mitigation: negligible
+   - Mitigation: recompile software *and* kernel with a modified compiler that introduces the LFENCE opcode at the proper positions in the resulting code
+   - Performance impact of the mitigation: negligible
 
 CVE-2017-5715: branch target injection (Spectre Variant 2)
-   Impact: Kernel
+
-   Mitigation 1: new opcode via microcode update that should be used by up to date compilers to protect the BTB (by flushing indirect branch predictors)
+   - Impact: Kernel
-   Mitigation 2: introducing "retpoline" into compilers, and recompile software/OS with it
+   - Mitigation 1: new opcode via microcode update that should be used by up to date compilers to protect the BTB (by flushing indirect branch predictors)
-   Performance impact of the mitigation: high for mitigation 1, medium for mitigation 2, depending on your CPU
+   - Mitigation 2: introducing "retpoline" into compilers, and recompile software/OS with it
+   - Performance impact of the mitigation: high for mitigation 1, medium for mitigation 2, depending on your CPU
 
 CVE-2017-5754: rogue data cache load (Meltdown)
-   Impact: Kernel
+
-   Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
+   - Impact: Kernel
-   Performance impact of the mitigation: low to medium
+   - Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
+   - Performance impact of the mitigation: low to medium
 
 Example of the output of the script:
 
-Spectre and Meltdown mitigation detection tool v0.01
+
+```
+$ sudo ./spectre-meltdown-checker.sh
+Spectre and Meltdown mitigation detection tool v0.02
 
 CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
-* Kernel recompiled with LFENCE opcode insertion: UNKNOWN (check not yet implemented)
+* Kernel compiled with LFENCE opcode inserted at the proper places: NO (only 38 opcodes found, should be >= 60)
-> STATUS: UNKNOWN (not implemented, but real answer is most probably VULNERABLE at this stage)
+> STATUS: VULNERABLE
 
 CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
 * Mitigation 1
@@ -35,10 +41,11 @@ CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
 *   IBRS enabled for Kernel space: NO
 *   IBRS enabled for User space: NO
 * Mitigation 2
-*   Kernel recompiled with retpoline: UNKNOWN (check not yet implemented)
+*   Kernel recompiled with retpolines: UNKNOWN (check not yet implemented)
-> STATUS: VULNERABLE (IBRS hardware + kernel support OR retpoline-compiled kernel are needed to mitigate the vulnerability)
+> STATUS: VULNERABLE (IBRS hardware + kernel support OR retpolines-compiled kernel are needed to mitigate the vulnerability)
 
 CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
 * Kernel supports Page Table Isolation (PTI): YES
 * PTI enabled and active: YES
 > STATUS: NOT VULNERABLE (PTI mitigates the vulnerability)
+```

spectre-meltdown-checker.sh

@@ -1,7 +1,7 @@
 #! /bin/sh
 # Spectre & Meltdown checker
-# Stephane Lesimple, v0.00.01
+# Stephane Lesimple
-VERSION=0.01
+VERSION=0.05
 
 pstatus()
 {
@@ -11,48 +11,135 @@ pstatus()
 		yellow) col="\033[103m\033[30m";;
 		*)      col="";;
 	esac
-	echo -n "$col$2\033[0m"
+	/bin/echo -ne "$col $2 \033[0m"
-	[ -n "$3" ] && echo -n " ($3)"
+	[ -n "$3" ] && /bin/echo -n " ($3)"
-	echo
+	/bin/echo
 }
 
-echo "Spectre and Meltdown mitigation detection tool v$VERSION"
+# ----------------------------------------------------------------------
-echo
+# extract-vmlinux - Extract uncompressed vmlinux from a kernel image
+#
+# Inspired from extract-ikconfig
+# (c) 2009,2010 Dick Streefland <dick@streefland.net>
+#
+# (c) 2011      Corentin Chary <corentin.chary@gmail.com>
+#
+# Licensed under the GNU General Public License, version 2 (GPLv2).
+# ----------------------------------------------------------------------
+
+check_vmlinux()
+{
+	file "$1" 2>/dev/null | grep -q ELF || return 1
+	return 0
+}
+
+try_decompress()
+{
+        # The obscure use of the "tr" filter is to work around older versions of
+        # "grep" that report the byte offset of the line instead of the pattern.
+
+        # Try to find the header ($1) and decompress from here
+        for     pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"`
+        do
+                pos=${pos%%:*}
+                tail -c+$pos "$img" | $3 > $vmlinuxtmp 2> /dev/null
+                check_vmlinux $vmlinuxtmp && echo $vmlinuxtmp || rm -f $vmlinuxtmp
+        done
+}
+
+extract_vmlinux()
+{
+	img="$1"
+
+	# Prepare temp files:
+	vmlinuxtmp=$(mktemp /tmp/vmlinux-XXX)
+
+	# Initial attempt for uncompressed images or objects:
+	check_vmlinux $img
+
+	# That didn't work, so retry after decompression.
+	try_decompress '\037\213\010' xy    gunzip     || \
+	try_decompress '\3757zXZ\000' abcde unxz       || \
+	try_decompress 'BZh'          xy    bunzip2    || \
+	try_decompress '\135\0\0\0'   xxx   unlzma     || \
+	try_decompress '\211\114\132' xy    'lzop -d'
+}
+
+
+/bin/echo "Spectre and Meltdown mitigation detection tool v$VERSION"
+/bin/echo
 
 # SPECTRE 1
-echo "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
+/bin/echo -e "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
-echo -n "* Kernel recompiled with LFENCE opcode insertion: "
+/bin/echo -n "* Kernel compiled with LFENCE opcode inserted at the proper places: "
-pstatus yellow UNKNOWN "check not yet implemented"
+
-echo -n "> \033[46m\033[30mSTATUS:\033[0m "
+status=0
-pstatus yellow UNKNOWN "not implemented, but real answer is most probably VULNERABLE at this stage"
+img=''
+[ -e /boot/vmlinuz-$(uname -r) ] && img=/boot/vmlinuz-$(uname -r)
+[ -e /boot/vmlinux-$(uname -r) ] && img=/boot/vmlinux-$(uname -r)
+[ -e /boot/bzImage-$(uname -r) ] && img=/boot/bzImage-$(uname -r)
+if [ -z "$img" ]; then
+	pstatus yellow UNKNOWN "couldn't find your kernel image in /boot"
+else
+	vmlinux=$(extract_vmlinux $img)
+	if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
+		pstatus yellow UNKNOWN "couldn't extract your kernel"
+	elif ! which objdump >/dev/null 2>&1; then
+		pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
+	else
+		nb_lfence=$(objdump -D "$vmlinux" | grep -wc lfence)
+		if [ "$nb_lfence" -lt 60 ]; then
+			pstatus red NO "only $nb_lfence opcodes found, should be >= 60"
+			status=1
+		else
+			pstatus green YES "$nb_lfence opcodes found, which is >= 60"
+			status=2
+		fi
+		rm -f $vmlinux
+	fi
+fi
+
+/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
+[ "$status" = 0 ] && pstatus yellow UNKNOWN
+[ "$status" = 1 ] && pstatus red VULNERABLE
+[ "$status" = 2 ] && pstatus green 'NOT VULNERABLE'
 
 
 # VARIANT 2
-echo
+/bin/echo
-echo "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
+/bin/echo -e "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
-echo "* Mitigation 1"
+/bin/echo "* Mitigation 1"
-echo -n "*   Hardware (CPU microcode) support for mitigation: "
+/bin/echo -n "*   Hardware (CPU microcode) support for mitigation: "
 if [ ! -e /dev/cpu/0/msr ]; then
 	modprobe msr 2>/dev/null && insmod_msr=1
 fi
 if [ ! -e /dev/cpu/0/msr ]; then
 	pstatus yellow UNKNOWN "couldn't read /dev/cpu/0/msr, is msr support enabled in your kernel?"
 else
-	dd if=/dev/cpu/0/msr of=/dev/null bs=1 count=8 skip=72 2>/dev/null
+	if which rdmsr >/dev/null 2>&1; then
+		rdmsr 0x48 >/dev/null 2>&1
 		if [ $? -eq 0 ]; then
 			pstatus green YES
 		else
 			pstatus red NO
 		fi
-	#dd if=/dev/cpu/0/msr of=/dev/null bs=1 count=8 skip=73 2>/dev/null
+	else
-	#echo $?
+		pstatus yellow UNKNOWN "missing 'rdmsr' tool, please install it, usually it's in the msr-tools package"
+		# doesn't work:
+		#dd if=/dev/cpu/0/msr of=/dev/null bs=1 count=8 skip=72 2>/dev/null
+		#if [ $? -eq 0 ]; then
+		#	pstatus green YES
+		#else
+		#	pstatus red NO
+		#fi
+	fi
 fi
 
 if [ "$insmod_msr" = 1 ]; then
 	rmmod msr 2>/dev/null
 fi
 
-echo -n "*   Kernel support for IBRS: "
+/bin/echo -n "*   Kernel support for IBRS: "
 if [ -e /sys/kernel/debug/sched_features ]; then
 	mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
 fi
@@ -64,7 +151,7 @@ else
 fi
 
 ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
-echo -n "*   IBRS enabled for Kernel space: "
+/bin/echo -n "*   IBRS enabled for Kernel space: "
 case "$ibrs_enabled" in
 	"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
 	0)     pstatus red NO;;
@@ -72,7 +159,7 @@ case "$ibrs_enabled" in
 	*)     pstatus yellow UNKNOWN;;
 esac
 
-echo -n "*   IBRS enabled for User space: "
+/bin/echo -n "*   IBRS enabled for User space: "
 case "$ibrs_enabled" in
 	"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
 	0 | 1) pstatus red NO;;
@@ -84,23 +171,40 @@ if [ "$mounted_debugfs" = 1 ]; then
 	umount /sys/kernel/debug
 fi
 
-echo "* Mitigation 2"
+/bin/echo "* Mitigation 2"
-echo -n "*   Kernel recompiled with retpoline: "
+/bin/echo -n "*   Kernel recompiled with retpolines: "
-pstatus yellow UNKNOWN "check not yet implemented"
+# XXX this doesn't mean the kernel has been compiled with a retpoline-aware gcc
+if [ -e /proc/config.gz ]; then
+	if zgrep -q '^CONFIG_RETPOLINE=y' /proc/config.gz; then
+		pstatus green YES
+		retpoline=1
+	else
+		pstatus red NO
+	fi
+elif [ -e /boot/config-$(uname -r) ]; then
+	if grep  -q '^CONFIG_RETPOLINE=y' /boot/config-$(uname -r); then
+		pstatus green YES
+		retpoline=1
+	else
+		pstatus red NO
+	fi
+fi
 
-echo -n "> \033[46m\033[30mSTATUS:\033[0m "
+/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
 if grep -q AMD /proc/cpuinfo; then
 	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
 elif [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
 	pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
+elif [ "$retpoline" = 1 ]; then
+	pstatus green "NOT VULNERABLE" "retpolines mitigate the vulnerability"
 else
-	pstatus red VULNERABLE "IBRS hardware + kernel support OR retpoline-compiled kernel are needed to mitigate the vulnerability"
+	pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpolines are needed to mitigate the vulnerability"
 fi
 
 # MELTDOWN
-echo
+/bin/echo
-echo "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
+/bin/echo -e "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
-echo -n "* Kernel supports Page Table Isolation (PTI): "
+/bin/echo -n "* Kernel supports Page Table Isolation (PTI): "
 if [ -e /proc/config.gz ]; then
 	if zgrep -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /proc/config.gz; then
 		pstatus green YES
@@ -115,11 +219,18 @@ elif [ -e /boot/config-$(uname -r) ]; then
 	else
 		pstatus red NO
 	fi
+elif [ -e /boot/System.map-$(uname -r) ]; then
+	if grep -qw kpti_force_enabled /boot/System.map-$(uname -r); then
+		pstatus green YES
+		kpti_support=1
+	else
+		pstatus red NO
+	fi
 else
 	pstatus yellow UNKNOWN
 fi
 
-echo -n "* PTI enabled and active: "
+/bin/echo -n "* PTI enabled and active: "
 if grep ^flags /proc/cpuinfo | grep -qw pti; then
 	pstatus green YES
 	kpti_enabled=1
@@ -130,7 +241,7 @@ else
 	pstatus red NO
 fi
 
-echo -n "> \033[46m\033[30mSTATUS:\033[0m "
+/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
 if grep -q AMD /proc/cpuinfo; then
 	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
 elif [ "$kpti_enabled" = 1 ]; then
@@ -140,10 +251,9 @@ else
 fi
 
 
-echo
+/bin/echo
 if [ "$USER" != root ]; then
-	echo "Note that you should launch this script with root privileges to get accurate information"
+	/bin/echo "Note that you should launch this script with root privileges to get accurate information"
-	echo "You can try the following command: sudo $0"
+	/bin/echo "You can try the following command: sudo $0"
 fi
 
-