mirror of
https://github.com/speed47/spectre-meltdown-checker
synced 2024-12-22 20:33:56 +01:00
add some comments, enhance pti detection
This commit is contained in:
Stéphane Lesimple
parent
5c14384e15
commit
fa0850466e
@ -3,6 +3,7 @@
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# Stephane Lesimple
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VERSION=0.09
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# print status function
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pstatus()
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{
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case "$1" in
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@ -16,6 +17,11 @@ pstatus()
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/bin/echo
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}
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# The 3 below functions are taken from the extract-linux script, available here:
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# https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux
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# The functions have been modified for better integration to this script
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# The original header of the file has been retained below
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# ----------------------------------------------------------------------
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# extract-vmlinux - Extract uncompressed vmlinux from a kernel image
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#
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@ -69,29 +75,35 @@ extract_vmlinux()
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try_decompress '\211\114\132' xy 'lzop -d'
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}
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# end of extract-vmlinux functions
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/bin/echo "Spectre and Meltdown mitigation detection tool v$VERSION"
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/bin/echo
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###########
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# SPECTRE 1
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/bin/echo -e "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
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/bin/echo -n "* Kernel compiled with LFENCE opcode inserted at the proper places: "
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status=0
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img=''
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# try to find the image of the current running kernel
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[ -e /boot/vmlinuz-$(uname -r) ] && img=/boot/vmlinuz-$(uname -r)
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[ -e /boot/vmlinux-$(uname -r) ] && img=/boot/vmlinux-$(uname -r)
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[ -e /boot/kernel-$( uname -r) ] && img=/boot/kernel-$( uname -r)
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[ -e /boot/bzImage-$(uname -r) ] && img=/boot/bzImage-$(uname -r)
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if [ -z "$img" ]; then
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pstatus yellow UNKNOWN "couldn't find your kernel image in /boot"
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pstatus yellow UNKNOWN "couldn't find your kernel image in /boot, if you used netboot, this is normal"
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else
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vmlinux=$(extract_vmlinux $img)
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if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
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pstatus yellow UNKNOWN "couldn't extract your kernel"
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pstatus yellow UNKNOWN "couldn't extract your kernel from $img"
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elif ! which objdump >/dev/null 2>&1; then
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pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
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else
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# here we disassemble the kernel and count the number of occurences of the LFENCE opcode
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# in non-patched kernels, this has been empirically determined as being around 40-50
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# in patched kernels, this is more around 70-80
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nb_lfence=$(objdump -D "$vmlinux" | grep -wc lfence)
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if [ "$nb_lfence" -lt 60 ]; then
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pstatus red NO "only $nb_lfence opcodes found, should be >= 60"
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@ -108,19 +120,22 @@ fi
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[ "$status" = 1 ] && pstatus red VULNERABLE
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[ "$status" = 2 ] && pstatus green 'NOT VULNERABLE'
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###########
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# VARIANT 2
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/bin/echo
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/bin/echo -e "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
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/bin/echo "* Mitigation 1"
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/bin/echo -n "* Hardware (CPU microcode) support for mitigation: "
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if [ ! -e /dev/cpu/0/msr ]; then
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# try to load the module ourselves (and remember it so we can rmmod it afterwards)
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modprobe msr 2>/dev/null && insmod_msr=1
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fi
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if [ ! -e /dev/cpu/0/msr ]; then
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pstatus yellow UNKNOWN "couldn't read /dev/cpu/0/msr, is msr support enabled in your kernel?"
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else
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# same that rdmsr 0x48 but without needing the rdmsr tool
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# the new MSR 'SPEC_CTRL' is at offset 0x48
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# here we use dd, it's the same as using 'rdmsr 0x48' but without needing the rdmsr tool
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# if we get a read error, the MSR is not there
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dd if=/dev/cpu/0/msr of=/dev/null bs=8 count=1 skip=9 2>/dev/null
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if [ $? -eq 0 ]; then
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pstatus green YES
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@ -130,14 +145,17 @@ else
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fi
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if [ "$insmod_msr" = 1 ]; then
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# if we used modprobe ourselves, rmmod the module
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rmmod msr 2>/dev/null
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fi
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/bin/echo -n "* Kernel support for IBRS: "
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if [ -e /sys/kernel/debug/sched_features ]; then
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# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
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mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
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fi
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if [ -e /sys/kernel/debug/ibrs_enabled ]; then
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# if the file is there, we have IBRS compiled-in
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pstatus green YES
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ibrs_supported=1
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else
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@ -146,6 +164,9 @@ fi
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ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
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/bin/echo -n "* IBRS enabled for Kernel space: "
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# 0 means disabled
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# 1 is enabled only for kernel space
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# 2 is enabled for kernel and user space
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case "$ibrs_enabled" in
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"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
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0) pstatus red NO;;
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@ -162,13 +183,17 @@ case "$ibrs_enabled" in
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esac
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if [ "$mounted_debugfs" = 1 ]; then
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# umount debugfs if we did mount it ourselves
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umount /sys/kernel/debug
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fi
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/bin/echo "* Mitigation 2"
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/bin/echo -n "* Kernel compiled with retpolines: "
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# We check the RETPOLINE kernel options
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# XXX this doesn't mean the kernel has been compiled with a retpoline-aware gcc
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# still looking for a way do detect that ...
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if [ -e /proc/config.gz ]; then
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# either the running kernel exports his own config
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if zgrep -q '^CONFIG_RETPOLINE=y' /proc/config.gz; then
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pstatus green YES
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retpoline=1
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@ -176,6 +201,7 @@ if [ -e /proc/config.gz ]; then
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pstatus red NO
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fi
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elif [ -e /boot/config-$(uname -r) ]; then
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# or we can find a config file in /root with the kernel release name
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if grep -q '^CONFIG_RETPOLINE=y' /boot/config-$(uname -r); then
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pstatus green YES
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retpoline=1
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@ -197,48 +223,58 @@ else
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pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpolines are needed to mitigate the vulnerability"
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fi
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##########
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# MELTDOWN
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/bin/echo
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/bin/echo -e "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
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/bin/echo -n "* Kernel supports Page Table Isolation (PTI): "
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kpti_support=0
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kpti_can_tell=0
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if [ -e /proc/config.gz ]; then
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# either the running kernel exports his own config
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kpti_can_tell=1
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if zgrep -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /proc/config.gz; then
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pstatus green YES
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kpti_support=1
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else
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pstatus red NO
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fi
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elif [ -e /boot/config-$(uname -r) ]; then
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# or we can find a config file in /root with the kernel release name
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kpti_can_tell=1
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if grep -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /boot/config-$(uname -r); then
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pstatus green YES
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kpti_support=1
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else
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pstatus red NO
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fi
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elif [ -e /boot/System.map-$(uname -r) ]; then
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fi
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if [ -e /boot/System.map-$(uname -r) ]; then
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# it's not an elif: some backports don't have the PTI config but still include the patch
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# so we try to find an exported symbol that is part of the PTI patch in System.map
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kpti_can_tell=1
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if grep -qw kpti_force_enabled /boot/System.map-$(uname -r); then
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pstatus green YES
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kpti_support=1
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else
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pstatus red NO
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fi
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elif [ -n "$vmlinux" ]; then
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# some backports don't have the option but still have the patch, try to find out
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fi
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if [ -n "$vmlinux" ]; then
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# same as above but in case we don't have System.map and only vmlinux, look for the
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# nopti option that is part of the patch (kernel command line option)
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kpti_can_tell=1
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if strings "$vmlinux" | grep -qw nopti; then
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pstatus green YES
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kpti_support=1
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else
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pstatus red NO
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fi
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fi
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if [ "$kpti_support" = 1 ]; then
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pstatus green YES
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elif [ "$kpti_can_tell" = 1 ]; then
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pstatus red NO
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else
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pstatus yellow UNKNOWN "couldn't read your kernel configuration"
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fi
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/bin/echo -n "* PTI enabled and active: "
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if grep ^flags /proc/cpuinfo | grep -qw pti; then
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# vanilla PTI patch sets the 'pti' flag in cpuinfo
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pstatus green YES
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kpti_enabled=1
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elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then
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# if we can't find the flag, grep in dmesg
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pstatus green YES
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kpti_enabled=1
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else
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@ -254,7 +290,6 @@ else
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pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability"
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fi
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/bin/echo
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if [ "$(id -u)" -ne 0 ]; then
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/bin/echo "Note that you should launch this script with root privileges to get accurate information"
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@ -262,4 +297,3 @@ if [ "$(id -u)" -ne 0 ]; then
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fi
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[ -n "$vmlinux" -a -f "$vmlinux" ] && rm -f "$vmlinux"
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