bump to v0.25 to reflect changes

Produce JSON output formatted for Puppet, Ansible, Chef...

README.md

@@ -1,44 +1,45 @@
 Spectre & Meltdown Checker
 ==========================
 
-A simple shell script to tell if your Linux installation is vulnerable
-against the 3 "speculative execution" CVEs:
+A simple shell script to tell if your Linux installation is vulnerable against the 3 "speculative execution" CVEs that were made public early 2018.
 
-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
-   Performance impact of the mitigation: negligible
+Without options, it'll inspect you currently running kernel. 
+You can also specify a kernel image on the command line, if you'd like to inspect a kernel you're not running.
 
-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)
-   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
+The script will do its best to detect mitigations, including backported non-vanilla patches, regardless of the advertised kernel version number.
 
-CVE-2017-5754: rogue data cache load (Meltdown)
-   Impact: Kernel
-   Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
-   Performance impact of the mitigation: low to medium
+## Example of script output
 
-Example of the output of the script:
+![checker](https://framapic.org/6O4v4AAwMenv/M6J4CFWwsB3z.png)
 
-Spectre and Meltdown mitigation detection tool v0.01
+## Quick summary of the CVEs
 
-CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
-* Kernel recompiled with LFENCE opcode insertion: UNKNOWN (check not yet implemented)
-> STATUS: UNKNOWN (not implemented, but real answer is most probably VULNERABLE at this stage)
+**CVE-2017-5753** bounds check bypass (Spectre Variant 1)
 
-CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
-* Mitigation 1
-*   Hardware (CPU microcode) support for mitigation: NO
-*   Kernel support for IBRS: NO
-*   IBRS enabled for Kernel space: NO
-*   IBRS enabled for User space: NO
-* Mitigation 2
-*   Kernel recompiled with retpoline: UNKNOWN (check not yet implemented)
-> STATUS: VULNERABLE (IBRS hardware + kernel support OR retpoline-compiled kernel are needed to mitigate the vulnerability)
+   - 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
+   - Performance impact of the mitigation: negligible
 
-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)
+**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)
+   - 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
+   - Performance impact of the mitigation: low to medium
+
+## 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.

spectre-meltdown-checker.sh

@@ -1,149 +1,873 @@
 #! /bin/sh
 # Spectre & Meltdown checker
-# Stephane Lesimple, v0.00.01
-VERSION=0.01
+#
+# 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=0.25
 
+# 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 "$1" in
 			red)    col="\033[101m\033[30m";;
 			green)  col="\033[102m\033[30m";;
 			yellow) col="\033[103m\033[30m";;
+			blue)   col="\033[104m\033[30m";;
 			*)      col="";;
 		esac
-	echo -n "$col$2\033[0m"
-	[ -n "$3" ] && echo -n " ($3)"
-	echo
+		_info_nol "$col $2 \033[0m"
+	fi
+	[ -n "$3" ] && _info_nol " ($3)"
+	_info
 }
 
-echo "Spectre and Meltdown mitigation detection tool v$VERSION"
-echo
+# Print the final status of a vulnerability (incl. batch mode)
+# Arguments are: CVE UNK/OK/VULN description
+pvulnstatus()
+{
+	if [ "$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
 
-# SPECTRE 1
-echo "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
-echo -n "* Kernel recompiled with LFENCE opcode insertion: "
-pstatus yellow UNKNOWN "check not yet implemented"
-echo -n "> \033[46m\033[30mSTATUS:\033[0m "
-pstatus yellow UNKNOWN "not implemented, but real answer is most probably VULNERABLE at this stage"
+	_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
+}
 
 
-# VARIANT 2
-echo
-echo "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
-echo "* Mitigation 1"
-echo -n "*   Hardware (CPU microcode) support for mitigation: "
-if [ ! -e /dev/cpu/0/msr ]; then
-	modprobe msr 2>/dev/null && insmod_msr=1
+# 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 "$0: error: incompatible modes specified, use either --live or --kernel/--config/--map"
+		exit 1
+	fi
 fi
-if [ ! -e /dev/cpu/0/msr ]; then
-	pstatus yellow UNKNOWN "couldn't read /dev/cpu/0/msr, is msr support enabled in your kernel?"
+
+# root check (only for live mode, for offline mode, we already checked if we could read the files)
+
+if [ "$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
-	dd if=/dev/cpu/0/msr of=/dev/null bs=1 count=8 skip=72 2>/dev/null
+	_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
-	#dd if=/dev/cpu/0/msr of=/dev/null bs=1 count=8 skip=73 2>/dev/null
-	#echo $?
-fi
+	fi
 
-if [ "$insmod_msr" = 1 ]; then
+	if [ "$insmod_msr" = 1 ]; then
+		# if we used modprobe ourselves, rmmod the module
 		rmmod msr 2>/dev/null
-fi
+	fi
 
-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
-if [ -e /sys/kernel/debug/ibrs_enabled ]; then
+	_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
-else
+				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
+	fi
 
-ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
-echo -n "*   IBRS enabled for Kernel space: "
-case "$ibrs_enabled" in
+	_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
+		esac
+	else
+		pstatus blue N/A "not testable in offline mode"
+	fi
 
-echo -n "*   IBRS enabled for User space: "
-case "$ibrs_enabled" in
+	_info_nol "*   IBRS enabled for User space: "
+	if [ "$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
+			*) pstatus yellow UNKNOWN;;
+		esac
+	else
+		pstatus blue N/A "not testable in offline mode"
+	fi
 
-if [ "$mounted_debugfs" = 1 ]; then
-	umount /sys/kernel/debug
-fi
-
-echo "* Mitigation 2"
-echo -n "*   Kernel recompiled with retpoline: "
-pstatus yellow UNKNOWN "check not yet implemented"
-
-echo -n "> \033[46m\033[30mSTATUS:\033[0m "
-if grep -q AMD /proc/cpuinfo; then
-	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
-elif [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
-	pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
-else
-	pstatus red VULNERABLE "IBRS hardware + kernel support OR retpoline-compiled kernel are needed to mitigate the vulnerability"
-fi
-
-# MELTDOWN
-echo
-echo "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
-echo -n "* Kernel supports Page Table Isolation (PTI): "
-if [ -e /proc/config.gz ]; then
-	if zgrep -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /proc/config.gz; then
+	_info "* Mitigation 2"
+	_info_nol "*   Kernel compiled with retpoline option: "
+	# We check the RETPOLINE kernel options
+	if [ -r "$opt_config" ]; then
+		if grep -q '^CONFIG_RETPOLINE=y' "$opt_config"; then
 			pstatus green YES
-		kpti_support=1
+			retpoline=1
 		else
 			pstatus red NO
 		fi
-elif [ -e /boot/config-$(uname -r) ]; then
-	if grep  -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /boot/config-$(uname -r); then
-		pstatus green YES
-		kpti_support=1
+	else
+		pstatus yellow UNKNOWN "couldn't read your kernel configuration"
+	fi
+
+	_info_nol "*   Kernel compiled with a retpoline-aware compiler: "
+	# Now check if the compiler used to compile the kernel knows how to insert retpolines in generated asm
+	# For gcc, this is -mindirect-branch=thunk-extern (detected by the kernel makefiles)
+	# See gcc commit https://github.com/hjl-tools/gcc/commit/23b517d4a67c02d3ef80b6109218f2aadad7bd79
+	# In latest retpoline LKML patches, the noretpoline_setup symbol exists only if CONFIG_RETPOLINE is set
+	# *AND* if the compiler is retpoline-compliant, so look for that symbol
+	if [ -n "$opt_map" ]; then
+		# look for the symbol
+		if grep -qw noretpoline_setup "$opt_map"; then
+			retpoline_compiler=1
+			pstatus green YES "noretpoline_setup symbol found in System.map"
 		else
 			pstatus red NO
 		fi
-else
-	pstatus yellow UNKNOWN
-fi
-
-echo -n "* PTI enabled and active: "
-if grep ^flags /proc/cpuinfo | grep -qw pti; then
-	pstatus green YES
-	kpti_enabled=1
-elif dmesg | grep -q 'Kernel/User page tables isolation: enabled'; then
-	pstatus green YES
-	kpti_enabled=1
-else
+	elif [ -n "$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
 
-echo -n "> \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 [ "$kpti_enabled" = 1 ]; then
-	pstatus green "NOT VULNERABLE" "PTI mitigates the vulnerability"
-else
-	pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability"
+_info "A false sense of security is worse than no security at all, see --disclaimer"
+
+# this'll umount only if we mounted debugfs ourselves
+umount_debugfs
+
+# cleanup the temp decompressed config
+[ -n "$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
 
-
-echo
-if [ "$USER" != root ]; then
-	echo "Note that you should launch this script with root privileges to get accurate information"
-	echo "You can try the following command: sudo $0"
+if [ "$opt_batch" = 1 -a "$opt_batch_format" = "json" ]; then
+	_echo 0 ${json_output%?}]
 fi
-
-