#! /bin/sh # Spectre & Meltdown checker # Stephane Lesimple VERSION=0.16 # print status function pstatus() { case "$1" in red) col="\033[101m\033[30m";; green) col="\033[102m\033[30m";; yellow) col="\033[103m\033[30m";; *) col="";; esac /bin/echo -ne "$col $2 \033[0m" [ -n "$3" ] && /bin/echo -n " ($3)" /bin/echo } # The 3 below functions are taken from the extract-linux script, available here: # https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux # The functions have been modified for better integration to this script # The original header of the file has been retained below # ---------------------------------------------------------------------- # extract-vmlinux - Extract uncompressed vmlinux from a kernel image # # Inspired from extract-ikconfig # (c) 2009,2010 Dick Streefland # # (c) 2011 Corentin Chary # # Licensed under the GNU General Public License, version 2 (GPLv2). # ---------------------------------------------------------------------- vmlinux='' vmlinux_err='' check_vmlinux() { readelf -h $1 > /dev/null 2>&1 || 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=" < "$5" | grep -abo "^$2"` do if ! which $3 >/dev/null 2>&1; then vmlinux_err="missing '$3' tool, please install it, usually it's in the '$4' package" return 0 fi pos=${pos%%:*} tail -c+$pos "$5" | $3 > $vmlinuxtmp 2> /dev/null check_vmlinux "$vmlinuxtmp" && vmlinux=$vmlinuxtmp && return 0 done return 1 } extract_vmlinux() { [ -n "$1" ] || return 1 # Prepare temp files: vmlinuxtmp="$(mktemp /tmp/vmlinux-XXX)" # Initial attempt for uncompressed images or objects: if check_vmlinux "$1"; then cat "$1" > "$vmlinuxtmp" echo "$vmlinuxtmp" return 0 fi # That didn't work, so retry after decompression. try_decompress '\037\213\010' xy gunzip gunzip "$1" && return 0 try_decompress '\3757zXZ\000' abcde unxz xz-utils "$1" && return 0 try_decompress 'BZh' xy bunzip2 bzip2 "$1" && return 0 try_decompress '\135\0\0\0' xxx unlzma xz-utils "$1" && return 0 try_decompress '\211\114\132' xy 'lzop -d' lzop "$1" && return 0 return 1 } # end of extract-vmlinux functions /bin/echo -e "\033[1;34mSpectre and Meltdown mitigation detection tool v$VERSION\033[0m" /bin/echo # root check if [ "$(id -u)" -ne 0 ]; then /bin/echo -e "\033[31mNote that you should launch this script with root privileges to get accurate information.\033[0m" /bin/echo -e "\033[31mWe'll proceed but you might see permission denied errors.\033[0m" /bin/echo -e "\033[31mTo run it as root, you can try the following command: sudo $0\033[0m" /bin/echo fi /bin/echo -e "Checking vulnerabilities against \033[35m"$(uname -s) $(uname -r) $(uname -v) $(uname -m)"\033[0m" /bin/echo ########### # SPECTRE 1 /bin/echo -e "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m" /bin/echo -n "* Kernel compiled with LFENCE opcode inserted at the proper places: " status=0 img='' # try to find the image of the current running kernel [ -e /boot/vmlinuz-linux ] && img=/boot/vmlinuz-linux [ -e /boot/vmlinuz-linux-libre ] && img=/boot/vmlinuz-linux-libre [ -e /boot/vmlinuz-$(uname -r) ] && img=/boot/vmlinuz-$(uname -r) [ -e /boot/kernel-$( uname -r) ] && img=/boot/kernel-$( uname -r) [ -e /boot/bzImage-$(uname -r) ] && img=/boot/bzImage-$(uname -r) [ -e /boot/kernel-genkernel-$(uname -m)-$(uname -r) ] && img=/boot/kernel-genkernel-$(uname -m)-$(uname -r) if [ -z "$img" ]; then pstatus yellow UNKNOWN "couldn't find your kernel image in /boot, if you used netboot, this is normal" else if ! which readelf >/dev/null 2>&1; then pstatus yellow UNKNOWN "missing 'readelf' tool, please install it, usually it's in the 'binutils' package" else extract_vmlinux $img if [ "$vmlinux_err" != "" ]; then pstatus yellow UNKNOWN "couldn't extract your kernel from $img: $vmlinux_err" elif [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then pstatus yellow UNKNOWN "couldn't extract your kernel from $img" elif ! which objdump >/dev/null 2>&1; then pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package" else # here we disassemble the kernel and count the number of occurences of the LFENCE opcode # in non-patched kernels, this has been empirically determined as being around 40-50 # in patched kernels, this is more around 70-80, sometimes way higher (100+) # v0.13: 68 found in a 3.10.23-xxxx-std-ipv6-64 (with lots of modules compiled-in directly), which doesn't have the LFENCE patches, # so let's push the threshold to 70. # TODO LKML patch is starting to dump LFENCE in favor of the PAUSE opcode, we might need to check that (patch not stabilized yet) nb_lfence=$(objdump -D "$vmlinux" | grep -wc lfence) if [ "$nb_lfence" -lt 70 ]; then pstatus red NO "only $nb_lfence opcodes found, should be >= 70" status=1 else pstatus green YES "$nb_lfence opcodes found, which is >= 70" status=2 fi fi 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 /bin/echo /bin/echo -e "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m" /bin/echo "* Mitigation 1" /bin/echo -n "* Hardware (CPU microcode) support for mitigation: " if [ ! -e /dev/cpu/0/msr ]; then # try to load the module ourselves (and remember it so we can rmmod it afterwards) 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 # the new MSR 'SPEC_CTRL' is at offset 0x48 # here we use dd, it's the same as using 'rdmsr 0x48' but without needing the rdmsr tool # if we get a read error, the MSR is not there dd if=/dev/cpu/0/msr of=/dev/null bs=8 count=1 skip=9 2>/dev/null if [ $? -eq 0 ]; then pstatus green YES else pstatus red NO fi fi if [ "$insmod_msr" = 1 ]; then # if we used modprobe ourselves, rmmod the module rmmod msr 2>/dev/null fi /bin/echo -n "* Kernel support for IBRS: " if [ ! -e /sys/kernel/debug/sched_features ]; then # try to mount the debugfs hierarchy ourselves and remember it to umount afterwards mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1 fi if [ -e /sys/kernel/debug/ibrs_enabled ]; then # if the file is there, we have IBRS compiled-in pstatus green YES ibrs_supported=1 ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null) elif [ -e /sys/kernel/debug/x86/ibrs_enabled ]; then # RedHat uses a different path (see https://access.redhat.com/articles/3311301) pstatus green YES ibrs_supported=1 ibrs_enabled=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null) else pstatus red NO fi /bin/echo -n "* IBRS enabled for Kernel space: " # 0 means disabled # 1 is enabled only for kernel space # 2 is enabled for kernel and user space case "$ibrs_enabled" in "") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;; 0) pstatus red NO;; 1 | 2) pstatus green YES;; *) pstatus yellow UNKNOWN;; esac /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;; 2) pstatus green YES;; *) pstatus yellow UNKNOWN;; esac /bin/echo "* Mitigation 2" /bin/echo -n "* Kernel compiled with retpoline option: " # We check the RETPOLINE kernel options if [ -e /proc/config.gz ]; then # either the running kernel exports his own config if zgrep -q '^CONFIG_RETPOLINE=y' /proc/config.gz; then pstatus green YES retpoline=1 else pstatus red NO fi elif [ -e /boot/config-$(uname -r) ]; then # or we can find a config file in /root with the kernel release name if grep -q '^CONFIG_RETPOLINE=y' /boot/config-$(uname -r); then pstatus green YES retpoline=1 else pstatus red NO fi else pstatus yellow UNKNOWN "couldn't read your kernel configuration" fi /bin/echo -n "* Kernel compiled with a retpoline-aware compiler: " # Now check if the compiler used to compile the kernel knows how to insert retpolines in generated asm # For gcc, this is -mindirect-branch=thunk-extern (detected by the kernel makefiles) # See gcc commit https://github.com/hjl-tools/gcc/commit/23b517d4a67c02d3ef80b6109218f2aadad7bd79 # In latest retpoline LKML patches, the noretpoline_setup symbol exists only if CONFIG_RETPOLINE is set # *AND* if the compiler is retpoline-compliant, so look for that symbol if [ -n "$vmlinux" ]; then # look for the symbol if [ -e /boot/System.map-$(uname -r) ]; then if grep -qw noretpoline_setup /boot/System.map-$(uname -r); then retpoline_compiler=1 pstatus green YES "noretpoline_setup symbol found in System.map" fi elif which nm >/dev/null 2>&1; then # the proper way: use nm and look for the symbol if nm "$vmlinux" 2>/dev/null | grep -qw 'noretpoline_setup'; then retpoline_compiler=1 pstatus green YES "noretpoline_setup symbol found in vmlinux" fi elif grep -q noretpoline_setup "$vmlinux"; then # if we don't have nm, nevermind, the symbol name is long enough to not have # any false positive using good old grep directly on the binary retpoline_compiler=1 pstatus green YES "noretpoline_setup symbol found in vmlinux" fi if [ "$retpoline_compiler" != 1 ]; then pstatus red NO fi else pstatus yellow UNKNOWN "couldn't find your kernel image" fi /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 [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then pstatus green "NOT VULNERABLE" "retpoline mitigate the vulnerability" else pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability" fi ########## # MELTDOWN /bin/echo /bin/echo -e "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m" /bin/echo -n "* Kernel supports Page Table Isolation (PTI): " kpti_support=0 kpti_can_tell=0 if [ -e /proc/config.gz ]; then # either the running kernel exports his own config kpti_can_tell=1 if zgrep -q '^\(CONFIG_PAGE_TABLE_ISOLATION=y\|CONFIG_KAISER=y\)' /proc/config.gz; then kpti_support=1 fi elif [ -e /boot/config-$(uname -r) ]; then # or we can find a config file in /root with the kernel release name kpti_can_tell=1 if grep -q '^\(CONFIG_PAGE_TABLE_ISOLATION=y\|CONFIG_KAISER=y\)' /boot/config-$(uname -r); then kpti_support=1 fi fi if [ "$kpti_support" = 0 -a -e /boot/System.map-$(uname -r) ]; then # it's not an elif: some backports don't have the PTI config but still include the patch # so we try to find an exported symbol that is part of the PTI patch in System.map kpti_can_tell=1 if grep -qw kpti_force_enabled /boot/System.map-$(uname -r); then kpti_support=1 fi fi if [ "$kpti_support" = 0 -a -n "$vmlinux" ]; then # same as above but in case we don't have System.map and only vmlinux, look for the # nopti option that is part of the patch (kernel command line option) kpti_can_tell=1 if ! which strings >/dev/null 2>&1; then pstatus yellow UNKNOWN "missing 'strings' tool, please install it, usually it's in the binutils package" else if strings "$vmlinux" | grep -qw nopti; then kpti_support=1 fi fi fi if [ "$kpti_support" = 1 ]; then pstatus green YES elif [ "$kpti_can_tell" = 1 ]; then pstatus red NO else pstatus yellow UNKNOWN "couldn't read your kernel configuration" fi /bin/echo -n "* PTI enabled and active: " if grep ^flags /proc/cpuinfo | grep -qw pti; then # vanilla PTI patch sets the 'pti' flag in cpuinfo kpti_enabled=1 elif grep ^flags /proc/cpuinfo | grep -qw kaiser; then # kernel line 4.9 sets the 'kaiser' flag in cpuinfo kpti_enabled=1 elif [ -e /sys/kernel/debug/x86/pti_enabled ]; then # RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301 kpti_enabled=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null) elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then # if we can't find the flag, grep in dmesg kpti_enabled=1 else kpti_enabled=0 fi if [ "$kpti_enabled" = 1 ]; then pstatus green YES else pstatus red NO fi if [ "$mounted_debugfs" = 1 ]; then # umount debugfs if we did mount it ourselves umount /sys/kernel/debug fi /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 [ "$kpti_enabled" = 1 ]; then pstatus green "NOT VULNERABLE" "PTI mitigates the vulnerability" else pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability" fi /bin/echo [ -n "$vmlinux" -a -f "$vmlinux" ] && rm -f "$vmlinux"