spectre-meltdown-checker/spectre-meltdown-checker.sh

#! /bin/sh
# Spectre & Meltdown checker
#
# Check for the latest version at:
# https://github.com/speed47/spectre-meltdown-checker
# git clone https://github.com/speed47/spectre-meltdown-checker.git
# or wget https://raw.githubusercontent.com/speed47/spectre-meltdown-checker/master/spectre-meltdown-checker.sh
#
# Stephane Lesimple
#
VERSION=0.24

# Script configuration
show_usage()
{
	cat <<EOF
	Usage:
		Live mode:    $0 [options] [--live]
		Offline mode: $0 [options] [--kernel <vmlinux_file>] [--config <kernel_config>] [--map <kernel_map_file>]

	Modes:
		Two modes are available.

		First mode is the "live" mode (default), it does its best to find information about the currently running kernel.
		To run under this mode, just start the script without any option (you can also use --live explicitely)

		Second mode is the "offline" mode, where you can inspect a non-running kernel.
		You'll need to specify the location of the vmlinux file, and if possible, the corresponding config and System.map files:

		--kernel vmlinux_file		Specify a (possibly compressed) vmlinux file
		--config kernel_config		Specify a kernel config file
		--map	 kernel_map_file	Specify a kernel System.map file

	Options:
		--no-color			Don't use color codes
		-v, --verbose			Increase verbosity level
		--batch text			Produce machine readable output, this is the default if --batch is specified alone
		--batch json			Produce JSON output formatted for Puppet, Ansible, Chef...
		--batch nrpe			Produce machine readable output formatted for NRPE
		--variant [1,2,3]		Specify which variant you'd like to check, by default all variants are checked
						Can be specified multiple times (e.g. --variant 2 --variant 3)

	IMPORTANT:
	A false sense of security is worse than no security at all.
	Please use the --disclaimer option to understand exactly what this script does.

EOF
}

show_disclaimer()
{
	cat <<EOF
Disclaimer:

This tool does its best to determine whether your system is immune (or has proper mitigations in place) for the
collectively named "speculative execution" vulnerabilities. It doesn't attempt to run any kind of exploit, and can't guarantee
that your system is secure, but rather helps you verifying whether your system has the known correct mitigations in place.
However, some mitigations could also exist in your kernel that this script doesn't know (yet) how to detect, or it might
falsely detect mitigations that in the end don't work as expected (for example, on backported or modified kernels).

Your system exposure also depends on your CPU. As of now, AMD and ARM processors are marked as immune to some or all of these
vulnerabilities (except some specific ARM models). All Intel processors manufactured since circa 1995 are thought to be vulnerable.
Whatever processor one uses, one might seek more information from the manufacturer of that processor and/or of the device
in which it runs.

The nature of the discovered vulnerabilities being quite new, the landscape of vulnerable processors can be expected
to change over time, which is why this script makes the assumption that all CPUs are vulnerable, except if the manufacturer
explicitely stated otherwise in a verifiable public announcement.

This tool has been released in the hope that it'll be useful, but don't use it to jump to conclusions about your security.

EOF
}

# parse options
opt_kernel=''
opt_config=''
opt_map=''
opt_live_explicit=0
opt_live=1
opt_no_color=0
opt_batch=0
opt_batch_format="text"
opt_verbose=1
opt_variant1=0
opt_variant2=0
opt_variant3=0
opt_allvariants=1

nrpe_critical=0
nrpe_unknown=0
nrpe_vuln=""

__echo()
{
	opt="$1"
	shift
	msg="$@"
	if [ "$opt_no_color" = 1 ] ; then
		# strip ANSI color codes
		msg=$(/bin/echo -e  "$msg" | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g")
	fi
	# explicitely call /bin/echo to avoid shell builtins that might not take options
	/bin/echo $opt -e "$msg"
}

_echo()
{
	if [ $opt_verbose -ge $1 ]; then
		shift
		__echo '' "$@"
	fi
}

_echo_nol()
{
	if [ $opt_verbose -ge $1 ]; then
		shift
		__echo -n "$@"
	fi
}

_warn()
{
	_echo 0 "\033[31m${@}\033[0m"
}

_info()
{
	_echo 1 "$@"
}

_info_nol()
{
	_echo_nol 1 "$@"
}

_verbose()
{
	_echo 2 "$@"
}

_debug()
{
	_echo 3 "(debug) $@"
}

is_cpu_vulnerable()
{
	# param: 1, 2 or 3 (variant)
	# returns 1 if vulnerable, 0 if not vulnerable, 255 on error
	# by default, everything is vulnerable, we work in a "whitelist" logic here.
	# usage: is_cpu_vulnerable 2 && do something if vulnerable
	variant1=0
	variant2=0
	variant3=0
	if grep -q AMD /proc/cpuinfo; then
		variant1=0
		variant2=1
		variant3=1
	elif grep -qi 'CPU implementer\s*:\s*0x41' /proc/cpuinfo; then
		# ARM
		# reference: https://developer.arm.com/support/security-update
		cpupart=$(awk '/CPU part/         {print $4;exit}' /proc/cpuinfo)
		cpuarch=$(awk '/CPU architecture/ {print $3;exit}' /proc/cpuinfo)
		if [ -n "$cpupart" -a -n "$cpuarch" ]; then
			# Cortex-R7 and Cortex-R8 are real-time and only used in medical devices or such
			# I can't find their CPU part number, but it's probably not that useful anyway
			# model R7 R8 A9    A15   A17   A57   A72    A73    A75
			# part   ?  ? 0xc09 0xc0f 0xc0e 0xd07 0xd08  0xd09  0xd0a
			# arch  7? 7? 7     7     7     8     8      8      8
			if [ "$cpuarch" = 7 ] && echo "$cpupart" | grep -Eq '^0x(c09|c0f|c0e)$'; then
				# armv7 vulnerable chips
				variant1=0
				variant2=0
			elif [ "$cpuarch" = 8 ] && echo "$cpupart" | grep -Eq '^0x(d07|d08|d09|d0a)$'; then
				# armv8 vulnerable chips
				variant1=0
				variant2=0
			else
				variant1=1
				variant2=1
			fi
			# for variant3, only A75 is vulnerable
			if [ "$cpuarch" = 8 -a "$cpupart" = 0xd0a ]; then
				variant3=0
			else
				variant3=1
			fi
		fi
	fi
	[ "$1" = 1 ] && return $variant1
	[ "$1" = 2 ] && return $variant2
	[ "$1" = 3 ] && return $variant3
	return 255
}

show_header()
{
	_info "\033[1;34mSpectre and Meltdown mitigation detection tool v$VERSION\033[0m"
	_info
}

parse_opt_file()
{
	# parse_opt_file option_name option_value
	option_name="$1"
	option_value="$2"
	if [ -z "$option_value" ]; then
		show_header
		show_usage
		echo "$0: error: --$option_name expects one parameter (a file)" >&2
		exit 1
	elif [ ! -e "$option_value" ]; then
		show_header
		echo "$0: error: couldn't find file $option_value" >&2
		exit 1
	elif [ ! -f "$option_value" ]; then
		show_header
		echo "$0: error: $option_value is not a file" >&2
		exit 1
	elif [ ! -r "$option_value" ]; then
		show_header
		echo "$0: error: couldn't read $option_value (are you root?)" >&2
		exit 1
	fi
	echo "$option_value"
	exit 0
}

while [ -n "$1" ]; do
	if [ "$1" = "--kernel" ]; then
		opt_kernel=$(parse_opt_file kernel "$2")
		[ $? -ne 0 ] && exit $?
		shift 2
		opt_live=0
	elif [ "$1" = "--config" ]; then
		opt_config=$(parse_opt_file config "$2")
		[ $? -ne 0 ] && exit $?
		shift 2
		opt_live=0
	elif [ "$1" = "--map" ]; then
		opt_map=$(parse_opt_file map "$2")
		[ $? -ne 0 ] && exit $?
		shift 2
		opt_live=0
	elif [ "$1" = "--live" ]; then
		opt_live_explicit=1
		shift
	elif [ "$1" = "--no-color" ]; then
		opt_no_color=1
		shift
	elif [ "$1" = "--batch" ]; then
		opt_batch=1
		opt_verbose=0
		shift
		case "$1" in
			text|nrpe|json) opt_batch_format="$1"; shift;;
			--*) ;;    # allow subsequent flags
			'') ;;     # allow nothing at all
			*)
				echo "$0: error: unknown batch format '$1'"
				echo "$0: error: --batch expects a format from: text, nrpe, json"
				exit 1 >&2
				;;
		esac
	elif [ "$1" = "-v" -o "$1" = "--verbose" ]; then
		opt_verbose=$(expr $opt_verbose + 1)
		shift
	elif [ "$1" = "--variant" ]; then
		if [ -z "$2" ]; then
			echo "$0: error: option --variant expects a parameter (1, 2 or 3)" >&2
			exit 1
		fi
		case "$2" in
			1) opt_variant1=1; opt_allvariants=0;;
			2) opt_variant2=1; opt_allvariants=0;;
			3) opt_variant3=1; opt_allvariants=0;;
			*)
				echo "$0: error: invalid parameter '$2' for --variant, expected either 1, 2 or 3" >&2;
				exit 1;;
		esac
		shift 2
	elif [ "$1" = "-h" -o "$1" = "--help" ]; then
		show_header
		show_usage
		exit 0
	elif [ "$1" = "--disclaimer" ]; then
		show_header
		show_disclaimer
		exit 0
	else
		show_header
		show_usage
		echo "$0: error: unknown option '$1'"
		exit 1
	fi
done

show_header

# print status function
pstatus()
{
	if [ "$opt_no_color" = 1 ]; then
		_info_nol "$2"
	else
		case "$1" in
			red)    col="\033[101m\033[30m";;
			green)  col="\033[102m\033[30m";;
			yellow) col="\033[103m\033[30m";;
			blue)   col="\033[104m\033[30m";;
			*)      col="";;
		esac
		_info_nol "$col $2 \033[0m"
	fi
	[ -n "$3" ] && _info_nol " ($3)"
	_info
}

# Print the final status of a vulnerability (incl. batch mode)
# Arguments are: CVE UNK/OK/VULN description
pvulnstatus()
{
	if [ "$opt_batch" = 1 ]; then
                case "$opt_batch_format" in
                        text) _echo 0 "$1: $2 ($3)";;
                        nrpe)
                              case "$2" in
                                       UKN) nrpe_unknown="1";;
                                       VULN) nrpe_critical="1"; nrpe_vuln="$nrpe_vuln $1";;
                              esac
                              ;;
                        json)
                              case "$1" in
                                       CVE-2017-5753) aka="SPECTRE VARIANT 1";;
                                       CVE-2017-5715) aka="SPECTRE VARIANT 2";;
                                       CVE-2017-5754) aka="MELTDOWN";;
                              esac
                              case "$2" in
                                       UKN)  is_vuln="unknown";;
                                       VULN) is_vuln="true";;
                                       OK)   is_vuln="false";;
                              esac
                              json_output="${json_output:-[}{\"NAME\":\""$aka"\",\"CVE\":\""$1"\",\"VULNERABLE\":$is_vuln,\"INFOS\":\""$3"\"},"
                              ;;
		esac
	fi

	_info_nol "> \033[46m\033[30mSTATUS:\033[0m "
	vulnstatus="$2"
	shift 2
	case "$vulnstatus" in
		UNK) pstatus yellow UNKNOWN "$@";;
		VULN) pstatus red 'VULNERABLE' "$@";;
		OK) pstatus green 'NOT VULNERABLE' "$@";;
	esac
}


# 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 <dick@streefland.net>
#
# (c) 2011      Corentin Chary <corentin.chary@gmail.com>
#
# 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=" < "$6" | grep -abo "^$2"`
	do
		_debug "try_decompress: magic for $3 found at offset $pos"
		if ! which "$3" >/dev/null 2>&1; then
			vmlinux_err="missing '$3' tool, please install it, usually it's in the '$5' package"
			return 0
		fi
		pos=${pos%%:*}
		tail -c+$pos "$6" 2>/dev/null | $3 $4 > $vmlinuxtmp 2>/dev/null
		if check_vmlinux "$vmlinuxtmp"; then
			vmlinux="$vmlinuxtmp"
			_debug "try_decompress: decompressed with $3 successfully!"
			return 0
		else
			_debug "try_decompress: decompression with $3 did not work"
		fi
	done
	return 1
}

extract_vmlinux()
{
	[ -n "$1" ] || return 1
	# Prepare temp files:
	vmlinuxtmp="$(mktemp /tmp/vmlinux-XXXXXX)"
	trap "rm -f $vmlinuxtmp" EXIT

	# Initial attempt for uncompressed images or objects:
	if check_vmlinux "$1"; then
		cat "$1" > "$vmlinuxtmp"
		vmlinux=$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
	try_decompress '\002\041\114\030' xyy   'lz4'   '-d -l' liblz4-tool "$1" && return 0
	return 1
}

# end of extract-vmlinux functions

# check for mode selection inconsistency
if [ "$opt_live_explicit" = 1 ]; then
	if [ -n "$opt_kernel" -o -n "$opt_config" -o -n "$opt_map" ]; then
		show_usage
		echo "$0: error: incompatible modes specified, use either --live or --kernel/--config/--map"
		exit 1
	fi
fi

# root check (only for live mode, for offline mode, we already checked if we could read the files)

if [ "$opt_live" = 1 ]; then
	if [ "$(id -u)" -ne 0 ]; then
		_warn "Note that you should launch this script with root privileges to get accurate information."
		_warn "We'll proceed but you might see permission denied errors."
		_warn "To run it as root, you can try the following command: sudo $0"
		_warn
	fi
	_info "Checking for vulnerabilities against live running kernel \033[35m"$(uname -s) $(uname -r) $(uname -v) $(uname -m)"\033[0m"

	# try to find the image of the current running kernel
	# first, look for the BOOT_IMAGE hint in the kernel cmdline
	if [ -r /proc/cmdline ] && grep -q 'BOOT_IMAGE=' /proc/cmdline; then
		opt_kernel=$(grep -Eo 'BOOT_IMAGE=[^ ]+' /proc/cmdline | cut -d= -f2)
		_debug "found opt_kernel=$opt_kernel in /proc/cmdline"
		# if we have a dedicated /boot partition, our bootloader might have just called it /
		# so try to prepend /boot and see if we find anything
		[ -e "/boot/$opt_kernel" ] && opt_kernel="/boot/$opt_kernel"
		_debug "opt_kernel is now $opt_kernel"
		# else, the full path is already there (most probably /boot/something)
	fi
	# if we didn't find a kernel, default to guessing
	if [ ! -e "$opt_kernel" ]; then
		[ -e /boot/vmlinuz-linux       ] && opt_kernel=/boot/vmlinuz-linux
		[ -e /boot/vmlinuz-linux-libre ] && opt_kernel=/boot/vmlinuz-linux-libre
		[ -e /boot/vmlinuz-$(uname -r) ] && opt_kernel=/boot/vmlinuz-$(uname -r)
		[ -e /boot/kernel-$( uname -r) ] && opt_kernel=/boot/kernel-$( uname -r)
		[ -e /boot/bzImage-$(uname -r) ] && opt_kernel=/boot/bzImage-$(uname -r)
		[ -e /boot/kernel-genkernel-$(uname -m)-$(uname -r) ] && opt_kernel=/boot/kernel-genkernel-$(uname -m)-$(uname -r)
	fi

	# system.map
	if [ -e /proc/kallsyms ] ; then
		opt_map="/proc/kallsyms"
	elif [ -e /boot/System.map-$(uname -r) ] ; then
		opt_map=/boot/System.map-$(uname -r)
	fi

	# config
	if [ -e /proc/config.gz ] ; then
		dumped_config="$(mktemp /tmp/config-XXXXXX)"
		gunzip -c /proc/config.gz > $dumped_config
		# dumped_config will be deleted at the end of the script
		opt_config=$dumped_config
	elif [ -e /boot/config-$(uname -r) ]; then
		opt_config=/boot/config-$(uname -r)
	fi
else
	_info "Checking for vulnerabilities against specified kernel"
fi
if [ -n "$opt_kernel" ]; then
	_verbose "Will use vmlinux image \033[35m$opt_kernel\033[0m"
else
	_verbose "Will use no vmlinux image (accuracy might be reduced)"
fi
if [ -n "$dumped_config" ]; then
	_verbose "Will use kconfig \033[35m/proc/config.gz\033[0m"
elif [ -n "$opt_config" ]; then
	_verbose "Will use kconfig \033[35m$opt_config\033[0m"
else
	_verbose "Will use no kconfig (accuracy might be reduced)"
fi
if [ -n "$opt_map" ]; then
	_verbose "Will use System.map file \033[35m$opt_map\033[0m"
else
	_verbose "Will use no System.map file (accuracy might be reduced)"
fi

if [ -e "$opt_kernel" ]; then
	if ! which readelf >/dev/null 2>&1; then
		vmlinux_err="missing 'readelf' tool, please install it, usually it's in the 'binutils' package"
	else
		extract_vmlinux "$opt_kernel"
	fi
else
	vmlinux_err="couldn't find your kernel image in /boot, if you used netboot, this is normal"
fi
if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
	[ -z "$vmlinux_err" ] && vmlinux_err="couldn't extract your kernel from $opt_kernel"
fi

_info

# end of header stuff

# now we define some util functions and the check_*() funcs, as
# the user can choose to execute only some of those

mount_debugfs()
{
	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
}

umount_debugfs()
{
	if [ "$mounted_debugfs" = 1 ]; then
		# umount debugfs if we did mount it ourselves
		umount /sys/kernel/debug
	fi
}

###################
# SPECTRE VARIANT 1
check_variant1()
{
	_info "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
	_info_nol "* Checking count of LFENCE opcodes in kernel: "

	status=0
	if [ -n "$vmlinux_err" ]; then
		pstatus yellow UNKNOWN "$vmlinux_err"
	else
		if ! 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

	if ! is_cpu_vulnerable 1; then
		pvulnstatus CVE-2017-5753 OK "your CPU vendor reported your CPU model as not vulnerable"
	else
		case "$status" in
			0) pvulnstatus CVE-2017-5753 UNK "impossible to check ${vmlinux}";;
			1) pvulnstatus CVE-2017-5753 VULN 'heuristic to be improved when official patches become available';;
			2) pvulnstatus CVE-2017-5753 OK 'heuristic to be improved when official patches become available';;
		esac
	fi
}

###################
# SPECTRE VARIANT 2
check_variant2()
{
	_info "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
	_info "* Mitigation 1"
	_info_nol "*   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

	_info_nol "*   Kernel support for IBRS: "
	if [ "$opt_live" = 1 ]; then
		mount_debugfs
		for ibrs_file in \
			/sys/kernel/debug/ibrs_enabled \
			/sys/kernel/debug/x86/ibrs_enabled \
			/proc/sys/kernel/ibrs_enabled; do
			if [ -e "$ibrs_file" ]; then
				# if the file is there, we have IBRS compiled-in
				# /sys/kernel/debug/ibrs_enabled: vanilla
				# /sys/kernel/debug/x86/ibrs_enabled: RedHat (see https://access.redhat.com/articles/3311301)
				# /proc/sys/kernel/ibrs_enabled: OpenSUSE tumbleweed
				pstatus green YES
				ibrs_supported=1
				ibrs_enabled=$(cat "$ibrs_file" 2>/dev/null)
				break
			fi
		done
	fi
	if [ "$ibrs_supported" != 1 -a -n "$opt_map" ]; then
		if grep -q spec_ctrl "$opt_map"; then
			pstatus green YES
			ibrs_supported=1
		fi
	fi
	if [ "$ibrs_supported" != 1 ]; then
		pstatus red NO
	fi

	_info_nol "*   IBRS enabled for Kernel space: "
	if [ "$opt_live" = 1 ]; then
		# 0 means disabled
		# 1 is enabled only for kernel space
		# 2 is enabled for kernel and user space
		case "$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
	else
		pstatus blue N/A "not testable in offline mode"
	fi

	_info_nol "*   IBRS enabled for User space: "
	if [ "$opt_live" = 1 ]; then
		case "$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
	else
		pstatus blue N/A "not testable in offline mode"
	fi

	_info "* Mitigation 2"
	_info_nol "*   Kernel compiled with retpoline option: "
	# We check the RETPOLINE kernel options
	if [ -r "$opt_config" ]; then
		if grep -q '^CONFIG_RETPOLINE=y' "$opt_config"; then
			pstatus green YES
			retpoline=1
		else
			pstatus red NO
		fi
	else
		pstatus yellow UNKNOWN "couldn't read your kernel configuration"
	fi

	_info_nol "*   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 "$opt_map" ]; then
		# look for the symbol
		if grep -qw noretpoline_setup "$opt_map"; then
			retpoline_compiler=1
			pstatus green YES "noretpoline_setup symbol found in System.map"
		else
			pstatus red NO
		fi
	elif [ -n "$vmlinux" ]; then
		# look for the symbol
		if which nm >/dev/null 2>&1; then
			# the proper way: use nm and look for the symbol
			if nm "$vmlinux" 2>/dev/null | grep -qw 'noretpoline_setup'; then
				retpoline_compiler=1
				pstatus green YES "noretpoline_setup found in vmlinux symbols"
			else
				pstatus red NO
			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 found in vmlinux"
		else
			pstatus red NO
		fi
	else
		pstatus yellow UNKNOWN "couldn't find your kernel image or System.map"
	fi

	if ! is_cpu_vulnerable 2; then
		pvulnstatus CVE-2017-5715 OK "your CPU vendor reported your CPU model as not vulnerable"
	elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
		pvulnstatus CVE-2017-5715 OK "retpoline mitigate the vulnerability"
	elif [ "$opt_live" = 1 ]; then
		if [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
			pvulnstatus CVE-2017-5715 OK "IBRS mitigates the vulnerability"
		else
			pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
		fi
	else
		if [ "$ibrs_supported" = 1 ]; then
			pvulnstatus CVE-2017-5715 OK "offline mode: IBRS will mitigate the vulnerability if enabled at runtime"
		else
			pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
		fi
	fi
}

########################
# MELTDOWN aka VARIANT 3
check_variant3()
{
	_info "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
	_info_nol "* Kernel supports Page Table Isolation (PTI): "
	kpti_support=0
	kpti_can_tell=0
	if [ -n "$opt_config" ]; then
		kpti_can_tell=1
		if grep -Eq '^(CONFIG_PAGE_TABLE_ISOLATION|CONFIG_KAISER)=y' "$opt_config"; then
			kpti_support=1
		fi
	fi
	if [ "$kpti_support" = 0 -a -n "$opt_map" ]; 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 "$opt_map"; then
			kpti_support=1
		fi
	fi
	if [ "$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 nor System.map file"
	fi

	mount_debugfs
	_info_nol "* PTI enabled and active: "
	if [ "$opt_live" = 1 ]; then
		if grep ^flags /proc/cpuinfo | grep -qw pti; then
			# vanilla PTI patch sets the 'pti' flag in cpuinfo
			kpti_enabled=1
		elif grep ^flags /proc/cpuinfo | grep -qw kaiser; then
			# kernel line 4.9 sets the 'kaiser' flag in cpuinfo
			kpti_enabled=1
		elif [ -e /sys/kernel/debug/x86/pti_enabled ]; then
			# RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301
			kpti_enabled=$(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 dmesg output
			kpti_enabled=1
		elif [ -r /var/log/dmesg ] && grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled' /var/log/dmesg; then
			# if we can't find the flag in dmesg output, grep in /var/log/dmesg when readable
			kpti_enabled=1
		else
			kpti_enabled=0
		fi
		if [ "$kpti_enabled" = 1 ]; then
			pstatus green YES
		else
			pstatus red NO
		fi
	else
		pstatus blue N/A "can't verify if PTI is enabled in offline mode"
	fi

	if ! is_cpu_vulnerable 3; then
		pvulnstatus CVE-2017-5754 OK "your CPU vendor reported your CPU model as not vulnerable"
	elif [ "$opt_live" = 1 ]; then
		if [ "$kpti_enabled" = 1 ]; then
			pvulnstatus CVE-2017-5754 OK "PTI mitigates the vulnerability"
		else
			pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
		fi
	else
		if [ "$kpti_support" = 1 ]; then
			pvulnstatus CVE-2017-5754 OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
		else
			pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
		fi
	fi
}

# now run the checks the user asked for
if [ "$opt_variant1" = 1 -o "$opt_allvariants" = 1 ]; then
	check_variant1
	_info
fi
if [ "$opt_variant2" = 1 -o "$opt_allvariants" = 1 ]; then
	check_variant2
	_info
fi
if [ "$opt_variant3" = 1 -o "$opt_allvariants" = 1 ]; then
	check_variant3
	_info
fi

_info "A false sense of security is worse than no security at all, see --disclaimer"

# this'll umount only if we mounted debugfs ourselves
umount_debugfs

# cleanup the temp decompressed config
[ -n "$dumped_config" ] && rm -f "$dumped_config"

if [ "$opt_batch" = 1 -a "$opt_batch_format" = "nrpe" ]; then
	if [ ! -z "$nrpe_vuln" ]; then
		echo "Vulnerable:$nrpe_vuln"
	else
		echo "OK"
	fi
	[ "$nrpe_critical" = 1 ] && exit 2  # critical
	[ "$nrpe_unknown" = 1 ] && exit 3  # unknown
	exit 0  # ok
fi

if [ "$opt_batch" = 1 -a "$opt_batch_format" = "json" ]; then
	_echo 0 ${json_output%?}]
fi