adding support for new /sys interface (#55)

* adding support for new /sys interface
* fix(objdump): prefer -d instead of -D, some kernels crash objdump otherwise

README.md

@@ -1,13 +1,17 @@
 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.
 
-Without options, it'll inspect you currently running kernel. 
+Without options, it'll inspect your 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.
 
 The script will do its best to detect mitigations, including backported non-vanilla patches, regardless of the advertised kernel version number.
 
+## Example of script output
+
+![checker](https://framapic.org/6O4v4AAwMenv/M6J4CFWwsB3z.png)
+
 ## Quick summary of the CVEs
 
 **CVE-2017-5753** bounds check bypass (Spectre Variant 1)
@@ -29,68 +33,13 @@ The script will do its best to detect mitigations, including backported non-vani
    - Mitigation: updated kernel (with PTI/KPTI patches), updating the kernel is enough
    - Performance impact of the mitigation: low to medium
 
-## Example of script output
+## Disclaimer
 
-### Ubuntu LTS (before official patches)
+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.
-$ sudo ./spectre-and-meltdown.sh
-Spectre and Meltdown mitigation detection tool v0.16
 
-Checking for vulnerabilities against live running kernel Linux 4.4.0-104-generic #127-Ubuntu SMP Mon Dec 11 12:16:42 UTC 2017 x86_64
+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.
-Will use vmlinux image /boot/vmlinuz-4.4.0-104-generic
-Will use kconfig /boot/config-4.4.0-104-generic
-Will use System.map file /boot/System.map-4.4.0-104-generic
 
-CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
+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.
-* Kernel compiled with LFENCE opcode inserted at the proper places:  NO  (only 38 opcodes found, should be >= 70)
-> STATUS:  VULNERABLE 
-
-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 compiled with retpoline option:  NO 
-*   Kernel compiled with a retpoline-aware compiler:  NO 
-> STATUS:  VULNERABLE  (IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability)
-
-CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
-* Kernel supports Page Table Isolation (PTI):  NO 
-* PTI enabled and active:  NO 
-> STATUS:  VULNERABLE  (PTI is needed to mitigate the vulnerability)
-```
-
-### First patched kernel of RHEL6
-
-```
-$ sudo ./spectre-meltdown-checker.sh --kernel /tmp/vmlinuz-2.6.32-696.18.7.el6.x86_64 --config /tmp/config-2.6.32-696.18.7.el6.x86_64 --map /tmp/System.map-2.6.32-696.18.7.el6.x86_64
-Spectre and Meltdown mitigation detection tool v0.16
-
-Checking for vulnerabilities against specified kernel
-Will use vmlinux image /tmp/vmlinuz-2.6.32-696.18.7.el6.x86_64
-Will use kconfig /tmp/config-2.6.32-696.18.7.el6.x86_64
-Will use System.map file /tmp/System.map-2.6.32-696.18.7.el6.x86_64
-
-CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
-* Kernel compiled with LFENCE opcode inserted at the proper places:  YES  (84 opcodes found, which is >= 70)
-> STATUS:  NOT VULNERABLE 
-
-CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
-* Mitigation 1
-*   Hardware (CPU microcode) support for mitigation:  NO 
-*   Kernel support for IBRS:  YES 
-*   IBRS enabled for Kernel space:  N/A  (not testable in offline mode)
-*   IBRS enabled for User space:  N/A  (not testable in offline mode)
-* Mitigation 2
-*   Kernel compiled with retpoline option:  NO 
-*   Kernel compiled with a retpoline-aware compiler:  NO 
-> STATUS:  NOT VULNERABLE  (offline mode: IBRS will mitigate the vulnerability if enabled at runtime)
-
-CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
-* Kernel supports Page Table Isolation (PTI):  YES 
-* PTI enabled and active:  N/A  (can't verify if PTI is enabled in offline mode)
-> STATUS:  NOT VULNERABLE  (offline mode: PTI will mitigate the vulnerability if enabled at runtime)
-```

spectre-meltdown-checker.sh

@@ -8,102 +8,21 @@
 #
 # Stephane Lesimple
 #
-VERSION=0.18
+VERSION=0.26
-
-# print status function
-pstatus()
-{
-	case "$1" in
-		red)    col="\033[101m\033[30m";;
-		green)  col="\033[102m\033[30m";;
-		yellow) col="\033[103m\033[30m";;
-		blue)   col="\033[104m\033[30m";;
-		*)      col="";;
-	esac
-	/bin/echo -ne "$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 <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=" < "$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-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
-	return 1
-}
-
-# end of extract-vmlinux functions
 
+# Script configuration
 show_usage()
 {
 	cat <<EOF
 	Usage:
-		Live mode:    $0
+		Live mode:    $0 [options] [--live]
-		Offline mode: $0 [--kernel <vmlinux_file>] [--config <kernel_config>] [--map <kernel_map_file>]
+		Offline mode: $0 [options] [--kernel <vmlinux_file>] [--config <kernel_config>] [--map <kernel_map_file>]
-	Options:
+
+	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.
+		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:
@@ -112,17 +31,177 @@ show_usage()
 		--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
+		--verbose, -v			Increase verbosity level
+		--no-sysfs			Don't use the /sys interface even if present
+		--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
 }
 
-/bin/echo -e "\033[1;34mSpectre and Meltdown mitigation detection tool v$VERSION\033[0m"
+show_disclaimer()
-/bin/echo
+{
+	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
+opt_no_sysfs=0
+
+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${@}\033[0m" >&2
+}
+
+_info()
+{
+	_echo 1 "$@"
+}
+
+_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()
 {
@@ -130,16 +209,20 @@ parse_opt_file()
 	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: $option_value is not a file" >&2
 		exit 1
-	elif [ ! -e "$option_value" ]; then
+	elif [ ! -r "$option_value" ]; then
+		show_header
 		echo "$0: error: couldn't read $option_value (are you root?)" >&2
 		exit 1
 	fi
@@ -163,34 +246,239 @@ while [ -n "$1" ]; do
 		[ $? -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" = "--no-sysfs" ]; then
+		opt_no_sysfs=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
-		/bin/echo -e "\033[31mNote that you should launch this script with root privileges to get accurate information.\033[0m"
+		_warn "Note that you should launch this script with root privileges to get accurate information."
-		/bin/echo -e "\033[31mWe'll proceed but you might see permission denied errors.\033[0m"
+		_warn "We'll proceed but you might see permission denied errors."
-		/bin/echo -e "\033[31mTo run it as root, you can try the following command: sudo $0\033[0m"
+		_warn "To run it as root, you can try the following command: sudo $0"
-		/bin/echo
+		_warn
 	fi
-	/bin/echo -e "Checking for vulnerabilities against live running kernel \033[35m"$(uname -s) $(uname -r) $(uname -v) $(uname -m)"\033[0m"
+	_info "Checking for vulnerabilities against live running kernel \033[35m"$(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
@@ -209,24 +497,24 @@ if [ "$opt_live" = 1 ]; then
 		opt_config=/boot/config-$(uname -r)
 	fi
 else
-	/bin/echo "Checking for vulnerabilities against specified kernel"
+	_info "Checking for vulnerabilities against specified kernel"
 fi
 if [ -n "$opt_kernel" ]; then
-	/bin/echo -e "Will use vmlinux image \033[35m$opt_kernel\033[0m"
+	_verbose "Will use vmlinux image \033[35m$opt_kernel\033[0m"
 else
-	/bin/echo "Will use no vmlinux image (accuracy might be reduced)"
+	_verbose "Will use no vmlinux image (accuracy might be reduced)"
 fi
 if [ -n "$dumped_config" ]; then
-	/bin/echo -e "Will use kconfig \033[35m/proc/config.gz\033[0m"
+	_verbose "Will use kconfig \033[35m/proc/config.gz\033[0m"
 elif [ -n "$opt_config" ]; then
-	/bin/echo -e "Will use kconfig \033[35m$opt_config\033[0m"
+	_verbose "Will use kconfig \033[35m$opt_config\033[0m"
 else
-	/bin/echo "Will use no kconfig (accuracy might be reduced)"
+	_verbose "Will use no kconfig (accuracy might be reduced)"
 fi
 if [ -n "$opt_map" ]; then
-	/bin/echo -e "Will use System.map file \033[35m$opt_map\033[0m"
+	_verbose "Will use System.map file \033[35m$opt_map\033[0m"
 else
-	/bin/echo "Will use no System.map file (accuracy might be reduced)"
+	_verbose "Will use no System.map file (accuracy might be reduced)"
 fi
 
 if [ -e "$opt_kernel" ]; then
@@ -236,54 +524,129 @@ if [ -e "$opt_kernel" ]; then
 		extract_vmlinux "$opt_kernel"
 	fi
 else
-	vmlinux_err="couldn't find your kernel image in /boot, if you used neboot, this is normal"
+	vmlinux_err="couldn't find your kernel image in /boot, if you used netboot, this is normal"
 fi
 if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
 	[ -z "$vmlinux_err" ] && vmlinux_err="couldn't extract your kernel from $opt_kernel"
 fi
 
-/bin/echo
+_info
 
-###########
+# end of header stuff
-# SPECTRE 1
-/bin/echo -e "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
-/bin/echo -n "* Checking count of LFENCE opcodes in kernel: "
 
-status=0
+# 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 [ "$mounted_debugfs" = 1 ]; then
+		# umount debugfs if we did mount it ourselves
+		umount /sys/kernel/debug
+	fi
+}
+
+sys_interface_check()
+{
+	[ "$opt_live" = 1 -a "$opt_no_sysfs" = 0 -a -r "$1" ] || return 1
+	_info_nol "* Checking wheter we're safe according to the /sys interface: "
+	if grep -qi '^not affected' "$1"; then
+		# Not affected
+		status=OK
+		pstatus green YES "kernel confirms that your CPU is unaffected"
+	elif grep -qi '^mitigation' "$1"; then
+		# Mitigation: PTI
+		status=OK
+		pstatus green YES "kernel confirms that the mitigation is active"
+	elif grep -qi '^vulnerable' "$1"; then
+		# Vulnerable
+		status=VULN
+		pstatus red NO "kernel confirms your system is vulnerable"
+	else
+		status=UNK
+		pstatus yellow UNKNOWN "unknown value reported by kernel"
+	fi
+	msg=$(cat "$1")
+	return 0
+}
+
+###################
+# SPECTRE VARIANT 1
+check_variant1()
+{
+	_info "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
+
+	status=UNK
+	sys_interface_available=0
+	msg=''
+	if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/spectre_v1"; then
+		# this kernel has the /sys interface, trust it over everything
+		sys_interface_available=1
+	else
+		# no /sys interface (or offline mode), fallback to our own ways
+		_info_nol "* Checking count of LFENCE opcodes in kernel: "
 		if [ -n "$vmlinux_err" ]; then
-	pstatus yellow UNKNOWN "$vmlinux_err"
+			msg="couldn't check ($vmlinux_err)"
+			status=UNK
+			pstatus yellow UNKNOWN
 		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"
+				msg="missing 'objdump' tool, please install it, usually it's in the binutils package"
+				status=UNK
+				pstatus yellow UNKNOWN
 			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)
-		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"
+					msg="only $nb_lfence opcodes found, should be >= 70, heuristic to be improved when official patches become available"
-			status=1
+					status=VULN
+					pstatus yellow UNKNOWN
 				else
-			pstatus green YES "$nb_lfence opcodes found, which is >= 70"
+					msg="$nb_lfence opcodes found, which is >= 70, heuristic to be improved when official patches become available"
-			status=2
+					status=OK
+					pstatus green YES
+				fi
 			fi
 		fi
 	fi
 
-/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
+	# if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
-[ "$status" = 0 ] && pstatus yellow UNKNOWN
+	if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 1; then
-[ "$status" = 1 ] && pstatus red   'VULNERABLE'     'heuristic to be improved when official patches become available'
+		# override status & msg in case CPU is not vulnerable after all
-[ "$status" = 2 ] && pstatus green 'NOT VULNERABLE' 'heuristic to be improved when official patches become available'
+		msg="your CPU vendor reported your CPU model as not vulnerable"
+		status=OK
+	fi
 
-###########
+	# report status
-# VARIANT 2
+	pvulnstatus CVE-2017-5753 "$status" "$msg"
-/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: "
+# SPECTRE VARIANT 2
+check_variant2()
+{
+	_info "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
+
+	status=UNK
+	sys_interface_available=0
+	msg=''
+	if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
+		# this kernel has the /sys interface, trust it over everything
+		sys_interface_available=1
+	else
+		_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
@@ -307,23 +670,24 @@ if [ "$insmod_msr" = 1 ]; then
 			rmmod msr 2>/dev/null
 		fi
 
-/bin/echo -n "*   Kernel support for IBRS: "
+		_info_nol "*   Kernel support for IBRS: "
 		if [ "$opt_live" = 1 ]; then
-	if [ ! -e /sys/kernel/debug/sched_features ]; then
+			mount_debugfs
-		# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
+			for ibrs_file in \
-		mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
+				/sys/kernel/debug/ibrs_enabled \
-	fi
+				/sys/kernel/debug/x86/ibrs_enabled \
-	if [ -e /sys/kernel/debug/ibrs_enabled ]; then
+				/proc/sys/kernel/ibrs_enabled; do
+				if [ -e "$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=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
+					ibrs_enabled=$(cat "$ibrs_file" 2>/dev/null)
-	elif [ -e /sys/kernel/debug/x86/ibrs_enabled ]; then
+					break
-		# RedHat uses a different path (see https://access.redhat.com/articles/3311301)
-		pstatus green YES
-		ibrs_supported=1
-		ibrs_enabled=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null)
 				fi
+			done
 		fi
 		if [ "$ibrs_supported" != 1 -a -n "$opt_map" ]; then
 			if grep -q spec_ctrl "$opt_map"; then
@@ -335,7 +699,7 @@ if [ "$ibrs_supported" != 1 ]; then
 			pstatus red NO
 		fi
 
-/bin/echo -n "*   IBRS enabled for Kernel space: "
+		_info_nol "*   IBRS enabled for Kernel space: "
 		if [ "$opt_live" = 1 ]; then
 			# 0 means disabled
 			# 1 is enabled only for kernel space
@@ -350,7 +714,7 @@ else
 			pstatus blue N/A "not testable in offline mode"
 		fi
 
-/bin/echo -n "*   IBRS enabled for User space: "
+		_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;;
@@ -362,8 +726,8 @@ else
 			pstatus blue N/A "not testable in offline mode"
 		fi
 
-/bin/echo "* Mitigation 2"
+		_info "* Mitigation 2"
-/bin/echo -n "*   Kernel compiled with retpoline option: "
+		_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
@@ -376,7 +740,7 @@ else
 			pstatus yellow UNKNOWN "couldn't read your kernel configuration"
 		fi
 
-/bin/echo -n "*   Kernel compiled with a retpoline-aware compiler: "
+		_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
@@ -411,36 +775,53 @@ elif [ -n "$vmlinux" ]; then
 		else
 			pstatus yellow UNKNOWN "couldn't find your kernel image or System.map"
 		fi
+	fi
 
-/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
+	# if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
-if grep -q AMD /proc/cpuinfo; then
+	if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 2; then
-	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
+		# override status & msg in case CPU is not vulnerable after all
-elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
+		pvulnstatus CVE-2017-5715 OK "your CPU vendor reported your CPU model as not vulnerable"
-	pstatus green "NOT VULNERABLE" "retpoline mitigate the vulnerability"
+	elif [ -z "$msg" ]; then
+		# if msg is empty, sysfs check didn't fill it, rely on our own test
+		if [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
+			pvulnstatus CVE-2017-5715 OK "retpoline mitigate the vulnerability"
 		elif [ "$opt_live" = 1 ]; then
 			if [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
-		pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
+				pvulnstatus CVE-2017-5715 OK "IBRS mitigates the vulnerability"
 			else
-		pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+				pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
 			fi
 		else
 			if [ "$ibrs_supported" = 1 ]; then
-		pstatus green "NOT VULNERABLE" "offline mode: IBRS will mitigate the vulnerability if enabled at runtime"
+				pvulnstatus CVE-2017-5715 OK "offline mode: IBRS will mitigate the vulnerability if enabled at runtime"
 			else
-		pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+				pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
 			fi
 		fi
+	else
+		pvulnstatus CVE-2017-5715 "$status" "$msg"
+	fi
+}
 
-##########
+########################
-# MELTDOWN
+# MELTDOWN aka VARIANT 3
-/bin/echo
+check_variant3()
-/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): "
+	_info "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
+
+	status=UNK
+	sys_interface_available=0
+	msg=''
+	if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/meltdown"; then
+		# this kernel has the /sys interface, trust it over everything
+		sys_interface_available=1
+	else
+		_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' "$opt_config"; then
+			if grep -Eq '^(CONFIG_PAGE_TABLE_ISOLATION|CONFIG_KAISER)=y' "$opt_config"; then
 				kpti_support=1
 			fi
 		fi
@@ -473,7 +854,8 @@ else
 			pstatus yellow UNKNOWN "couldn't read your kernel configuration nor System.map file"
 		fi
 
-/bin/echo -n "* PTI enabled and active: "
+		mount_debugfs
+		_info_nol "* PTI enabled and active: "
 		if [ "$opt_live" = 1 ]; then
 			if grep ^flags /proc/cpuinfo | grep -qw pti; then
 				# vanilla PTI patch sets the 'pti' flag in cpuinfo
@@ -485,7 +867,10 @@ if [ "$opt_live" = 1 ]; then
 				# RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301
 				kpti_enabled=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)
 			elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then
-		# if we can't find the flag, grep in dmesg
+				# if we can't find the flag, grep dmesg output
+				kpti_enabled=1
+			elif [ -r /var/log/dmesg ] && grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled' /var/log/dmesg; then
+				# if we can't find the flag in dmesg output, grep in /var/log/dmesg when readable
 				kpti_enabled=1
 			else
 				kpti_enabled=0
@@ -498,29 +883,66 @@ if [ "$opt_live" = 1 ]; then
 		else
 			pstatus blue N/A "can't verify if PTI is enabled in offline mode"
 		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 we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
-if grep -q AMD /proc/cpuinfo; then
+	cve='CVE-2017-5754'
-	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
+	if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 3; then
-elif [ "$opt_live" = 1 ]; then
+		# override status & msg in case CPU is not vulnerable after all
+		pvulnstatus $cve OK "your CPU vendor reported your CPU model as not vulnerable"
+	elif [ -z "$msg" ]; then
+		# if msg is empty, sysfs check didn't fill it, rely on our own test
+		if [ "$opt_live" = 1 ]; then
 			if [ "$kpti_enabled" = 1 ]; then
-		pstatus green "NOT VULNERABLE" "PTI mitigates the vulnerability"
+				pvulnstatus $cve OK "PTI mitigates the vulnerability"
 			else
-		pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability"
+				pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
 			fi
 		else
 			if [ "$kpti_support" = 1 ]; then
-		pstatus green "NOT VULNERABLE" "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
+				pvulnstatus $cve OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
 			else
-		pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability"
+				pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
 			fi
 		fi
+	else
+		pvulnstatus $cve "$status" "$msg"
+	fi
+}
 
-/bin/echo
+# 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