v0.19: introduce --no-color

When using /proc/config.gz, indicate it more clearly

README.md

@@ -1,37 +1,49 @@
 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.
 
-CVE-2017-5753 bounds check bypass (Spectre Variant 1)
+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.
+
+The script will do its best to detect mitigations, including backported non-vanilla patches, regardless of the advertised kernel version number.
+
+## Quick summary of the CVEs
+
+**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
 
-CVE-2017-5715: branch target injection (Spectre Variant 2)
+**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)
+**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 the output of the script:
+## Example of script output
 
+### Ubuntu LTS (before official patches)
 
 ```
-$ sudo ./spectre-meltdown-checker.sh
-Spectre and Meltdown mitigation detection tool v0.02
+$ 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
+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'
-* Kernel compiled with LFENCE opcode inserted at the proper places: NO (only 38 opcodes found, should be >= 60)
+* 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'
@@ -41,11 +53,44 @@ CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
 *   IBRS enabled for Kernel space:  NO 
 *   IBRS enabled for User space:  NO 
 * Mitigation 2
-*   Kernel recompiled with retpolines: UNKNOWN (check not yet implemented)
-> STATUS: VULNERABLE (IBRS hardware + kernel support OR retpolines-compiled kernel are needed to mitigate the vulnerability)
+*   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: YES
-> STATUS: NOT VULNERABLE (PTI mitigates the vulnerability)
+* 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

@@ -1,21 +1,39 @@
 #! /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=0.06
+#
+VERSION=0.19
 
+# print status function
 pstatus()
 {
+	if [ "$opt_no_color" = 1 ]; then
+		_echo_nol "$2"
+	else
 		case "$1" in
 			red)    col="\033[101m\033[30m";;
 			green)  col="\033[102m\033[30m";;
 			yellow) col="\033[103m\033[30m";;
+			blue)   col="\033[104m\033[30m";;
 			*)      col="";;
 		esac
-	/bin/echo -ne "$col $2 \033[0m"
-	[ -n "$3" ] && /bin/echo -n " ($3)"
-	/bin/echo
+		_echo_nol "$col $2 \033[0m"
+	fi
+	[ -n "$3" ] && _echo_nol " ($3)"
+	_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
 #
@@ -27,9 +45,11 @@ pstatus()
 # Licensed under the GNU General Public License, version 2 (GPLv2).
 # ----------------------------------------------------------------------
 
+vmlinux=''
+vmlinux_err=''
 check_vmlinux()
 {
-	file "$1" 2>/dev/null | grep -q ELF || return 1
+	readelf -h $1 > /dev/null 2>&1 || return 1
 	return 0
 }
 
@@ -39,84 +59,289 @@ try_decompress()
 	# "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$2=" < "$img" | grep -abo "^$2"`
+	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+$pos "$img" | $3 > $vmlinuxtmp 2> /dev/null
-                check_vmlinux $vmlinuxtmp && echo $vmlinuxtmp || rm -f $vmlinuxtmp
+		tail -c+$pos "$5" | $3 > $vmlinuxtmp 2> /dev/null
+		check_vmlinux "$vmlinuxtmp" && vmlinux=$vmlinuxtmp && return 0
 	done
+	return 1
 }
 
 extract_vmlinux()
 {
-	img="$1"
-
+	[ -n "$1" ] || return 1
 	# Prepare temp files:
-	vmlinuxtmp=$(mktemp /tmp/vmlinux-XXX)
+	vmlinuxtmp="$(mktemp /tmp/vmlinux-XXXXXX)"
+	trap "rm -f $vmlinuxtmp" EXIT
 
 	# Initial attempt for uncompressed images or objects:
-	check_vmlinux $img
+	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     || \
-	try_decompress '\3757zXZ\000' abcde unxz       || \
-	try_decompress 'BZh'          xy    bunzip2    || \
-	try_decompress '\135\0\0\0'   xxx   unlzma     || \
-	try_decompress '\211\114\132' xy    'lzop -d'
+	try_decompress '\037\213\010' xy    gunzip     gunzip	"$1" && return 0
+	try_decompress '\3757zXZ\000' abcde unxz       xz-utils	"$1" && return 0
+	try_decompress 'BZh'          xy    bunzip2    bzip2	"$1" && return 0
+	try_decompress '\135\0\0\0'   xxx   unlzma     xz-utils	"$1" && return 0
+	try_decompress '\211\114\132' xy    'lzop -d'  lzop	"$1" && return 0
+	return 1
 }
 
+# end of extract-vmlinux functions
 
-/bin/echo "Spectre and Meltdown mitigation detection tool v$VERSION"
-/bin/echo
+show_usage()
+{
+	cat <<EOF
+	Usage:
+		Live mode:    $0 [options] [--live]
+		Offline mode: $0 [options] [--kernel <vmlinux_file>] [--config <kernel_config>] [--map <kernel_map_file>]
 
-# SPECTRE 1
-/bin/echo -e "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
-/bin/echo -n "* Kernel compiled with LFENCE opcode inserted at the proper places: "
+	Modes:
+		Two modes are available.
 
-status=0
-img=''
-[ -e /boot/vmlinuz-$(uname -r) ] && img=/boot/vmlinuz-$(uname -r)
-[ -e /boot/vmlinux-$(uname -r) ] && img=/boot/vmlinux-$(uname -r)
-[ -e /boot/bzImage-$(uname -r) ] && img=/boot/bzImage-$(uname -r)
-if [ -z "$img" ]; then
-	pstatus yellow UNKNOWN "couldn't find your kernel image in /boot"
-else
-	vmlinux=$(extract_vmlinux $img)
-	if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
-		pstatus yellow UNKNOWN "couldn't extract your kernel"
-	elif ! which objdump >/dev/null 2>&1; then
-		pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
-	else
-		nb_lfence=$(objdump -D "$vmlinux" | grep -wc lfence)
-		if [ "$nb_lfence" -lt 60 ]; then
-			pstatus red NO "only $nb_lfence opcodes found, should be >= 60"
-			status=1
-		else
-			pstatus green YES "$nb_lfence opcodes found, which is >= 60"
-			status=2
+		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
+
+EOF
+}
+
+__echo()
+{
+	opt="$1"
+	shift
+	msg="$@"
+	if [ "$opt_no_color" = 1 ] ; then
+		# strip ANSI color codes
+		msg=$(echo "$msg" | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g")
 	fi
-		rm -f $vmlinux
+	# explicitely call /bin/echo to avoid shell builtins that might not take options
+	/bin/echo $opt -e "$msg"
+}
+
+_echo()
+{
+	__echo '' "$@"
+}
+
+_echo_nol()
+{
+	__echo -n "$@"
+}
+
+_echo "\033[1;34mSpectre and Meltdown mitigation detection tool v$VERSION\033[0m"
+_echo
+
+# parse options
+opt_kernel=''
+opt_config=''
+opt_map=''
+opt_live_explicit=0
+opt_live=1
+opt_no_color=0
+
+parse_opt_file()
+{
+	# parse_opt_file option_name option_value
+	option_name="$1"
+	option_value="$2"
+	if [ -z "$option_value" ]; then
+		show_usage
+		echo "$0: error: --$option_name expects one parameter (a file)" >&2
+		exit 1
+	elif [ ! -e "$option_value" ]; then
+		echo "$0: error: couldn't find file $option_value" >&2
+		exit 1
+	elif [ ! -f "$option_value" ]; then
+		echo "$0: error: $option_value is not a file" >&2
+		exit 1
+	elif [ ! -e "$option_value" ]; then
+		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" = "-h" -o "$1" = "--help" ]; then
+		show_usage
+		exit 0
+	else
+		show_usage
+		echo "$0: error: unknown option '$1'"
+		exit 1
+	fi
+done
+
+# check for mode selection inconsistency
+if [ "$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
 
-/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
+# 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
+		_echo "\033[31mNote that you should launch this script with root privileges to get accurate information.\033[0m"
+		_echo "\033[31mWe'll proceed but you might see permission denied errors.\033[0m"
+		_echo "\033[31mTo run it as root, you can try the following command: sudo $0\033[0m"
+		_echo
+	fi
+	_echo "Checking for vulnerabilities against live running kernel \033[35m"$(uname -s) $(uname -r) $(uname -v) $(uname -m)"\033[0m"
+
+	# try to find the image of the current running kernel
+	[ -e /boot/vmlinuz-linux       ] && opt_kernel=/boot/vmlinuz-linux
+	[ -e /boot/vmlinuz-linux-libre ] && opt_kernel=/boot/vmlinuz-linux-libre
+	[ -e /boot/vmlinuz-$(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)-$(uname -r)
+
+	# system.map
+	if [ -e /proc/kallsyms ] ; then
+		opt_map="/proc/kallsyms"
+	elif [ -e /boot/System.map-$(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
+	_echo "Checking for vulnerabilities against specified kernel"
+fi
+if [ -n "$opt_kernel" ]; then
+	_echo "Will use vmlinux image \033[35m$opt_kernel\033[0m"
+else
+	_echo "Will use no vmlinux image (accuracy might be reduced)"
+fi
+if [ -n "$dumped_config" ]; then
+	_echo "Will use kconfig \033[35m/proc/config.gz\033[0m"
+elif [ -n "$opt_config" ]; then
+	_echo "Will use kconfig \033[35m$opt_config\033[0m"
+else
+	_echo "Will use no kconfig (accuracy might be reduced)"
+fi
+if [ -n "$opt_map" ]; then
+	_echo "Will use System.map file \033[35m$opt_map\033[0m"
+else
+	_echo "Will use no System.map file (accuracy might be reduced)"
+fi
+
+if [ -e "$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 "$opt_kernel"
+	fi
+else
+	vmlinux_err="couldn't find your kernel image in /boot, if you used neboot, this is normal"
+fi
+if [ -z "$vmlinux" -o ! -r "$vmlinux" ]; then
+	[ -z "$vmlinux_err" ] && vmlinux_err="couldn't extract your kernel from $opt_kernel"
+fi
+
+_echo
+
+###########
+# SPECTRE 1
+_echo "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
+_echo_nol "* Checking count of LFENCE opcodes in kernel: "
+
+status=0
+if [ -n "$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
+
+_echo_nol "> \033[46m\033[30mSTATUS:\033[0m "
 [ "$status" = 0 ] && pstatus yellow UNKNOWN
-[ "$status" = 1 ] && pstatus red VULNERABLE
-[ "$status" = 2 ] && pstatus green 'NOT VULNERABLE'
-
+[ "$status" = 1 ] && pstatus red   'VULNERABLE'     'heuristic to be improved when official patches become available'
+[ "$status" = 2 ] && pstatus green 'NOT VULNERABLE' 'heuristic to be improved when official patches become available'
 
+###########
 # VARIANT 2
-/bin/echo
-/bin/echo -e "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
-/bin/echo "* Mitigation 1"
-/bin/echo -n "*   Hardware (CPU microcode) support for mitigation: "
+_echo
+_echo "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
+_echo "* Mitigation 1"
+_echo_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
-	# same that rdmsr 0x48 but without needing the rdmsr tool
+	# 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
@@ -126,124 +351,224 @@ else
 fi
 
 if [ "$insmod_msr" = 1 ]; then
+	# if we used modprobe ourselves, rmmod the module
 	rmmod msr 2>/dev/null
 fi
 
-/bin/echo -n "*   Kernel support for IBRS: "
-if [ -e /sys/kernel/debug/sched_features ]; then
+_echo_nol "*   Kernel support for IBRS: "
+if [ "$opt_live" = 1 ]; then
+	if [ ! -e /sys/kernel/debug/sched_features ]; then
+		# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
 		mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
-fi
-if [ -e /sys/kernel/debug/ibrs_enabled ]; then
+	fi
+	if [ -e /sys/kernel/debug/ibrs_enabled ]; then
+		# if the file is there, we have IBRS compiled-in
 		pstatus green YES
 		ibrs_supported=1
-else
+		ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
+	elif [ -e /sys/kernel/debug/x86/ibrs_enabled ]; then
+		# RedHat uses a different path (see https://access.redhat.com/articles/3311301)
+		pstatus green YES
+		ibrs_supported=1
+		ibrs_enabled=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null)
+	fi
+fi
+if [ "$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
 
-ibrs_enabled=$(cat /sys/kernel/debug/ibrs_enabled 2>/dev/null)
-/bin/echo -n "*   IBRS enabled for Kernel space: "
-case "$ibrs_enabled" in
+_echo_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
 
-/bin/echo -n "*   IBRS enabled for User space: "
-case "$ibrs_enabled" in
+_echo_nol "*   IBRS enabled for User space: "
+if [ "$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
+
+_echo "* Mitigation 2"
+_echo_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
+
+_echo_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 "$vmlinux"; then
+		# if we don't have nm, nevermind, the symbol name is long enough to not have
+		# any false positive using good old grep directly on the binary
+		retpoline_compiler=1
+		pstatus green YES "noretpoline_setup found in vmlinux"
+	else
+		pstatus red NO
+	fi
+else
+	pstatus yellow UNKNOWN "couldn't find your kernel image or System.map"
+fi
+
+_echo_nol "> \033[46m\033[30mSTATUS:\033[0m "
+if grep -q AMD /proc/cpuinfo; then
+	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
+elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
+	pstatus green "NOT VULNERABLE" "retpoline mitigate the vulnerability"
+elif [ "$opt_live" = 1 ]; then
+	if [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
+		pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
+	else
+		pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+	fi
+else
+	if [ "$ibrs_supported" = 1 ]; then
+		pstatus green "NOT VULNERABLE" "offline mode: IBRS will mitigate the vulnerability if enabled at runtime"
+	else
+		pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+	fi
+fi
+
+##########
+# MELTDOWN
+_echo
+_echo "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
+_echo_nol "* Kernel supports Page Table Isolation (PTI): "
+kpti_support=0
+kpti_can_tell=0
+if [ -n "$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 [ "$kpti_can_tell" = 1 ]; then
+	pstatus red NO
+else
+	pstatus yellow UNKNOWN "couldn't read your kernel configuration nor System.map file"
+fi
+
+_echo_nol "* PTI enabled and active: "
+if [ "$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=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)
+	elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then
+		# if we can't find the flag, grep in dmesg
+		kpti_enabled=1
+	else
+		kpti_enabled=0
+	fi
+	if [ "$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 [ "$mounted_debugfs" = 1 ]; then
+	# umount debugfs if we did mount it ourselves
 	umount /sys/kernel/debug
 fi
 
-/bin/echo "* Mitigation 2"
-/bin/echo -n "*   Kernel compiled with retpolines: "
-# XXX this doesn't mean the kernel has been compiled with a retpoline-aware gcc
-if [ -e /proc/config.gz ]; then
-	if zgrep -q '^CONFIG_RETPOLINE=y' /proc/config.gz; then
-		pstatus green YES
-		retpoline=1
-	else
-		pstatus red NO
-	fi
-elif [ -e /boot/config-$(uname -r) ]; then
-	if grep  -q '^CONFIG_RETPOLINE=y' /boot/config-$(uname -r); then
-		pstatus green YES
-		retpoline=1
-	else
-		pstatus red NO
-	fi
-fi
-
-/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
+_echo_nol "> \033[46m\033[30mSTATUS:\033[0m "
 if grep -q AMD /proc/cpuinfo; then
 	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
-elif [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
-	pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
-elif [ "$retpoline" = 1 ]; then
-	pstatus green "NOT VULNERABLE" "retpolines mitigate the vulnerability"
-else
-	pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpolines are needed to mitigate the vulnerability"
-fi
-
-# MELTDOWN
-/bin/echo
-/bin/echo -e "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
-/bin/echo -n "* Kernel supports Page Table Isolation (PTI): "
-if [ -e /proc/config.gz ]; then
-	if zgrep -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /proc/config.gz; then
-		pstatus green YES
-		kpti_support=1
-	else
-		pstatus red NO
-	fi
-elif [ -e /boot/config-$(uname -r) ]; then
-	if grep  -q '^CONFIG_PAGE_TABLE_ISOLATION=y' /boot/config-$(uname -r); then
-		pstatus green YES
-		kpti_support=1
-	else
-		pstatus red NO
-	fi
-elif [ -e /boot/System.map-$(uname -r) ]; then
-	if grep -qw kpti_force_enabled /boot/System.map-$(uname -r); then
-		pstatus green YES
-		kpti_support=1
-	else
-		pstatus red NO
-	fi
-else
-	pstatus yellow UNKNOWN
-fi
-
-/bin/echo -n "* PTI enabled and active: "
-if grep ^flags /proc/cpuinfo | grep -qw pti; then
-	pstatus green YES
-	kpti_enabled=1
-elif dmesg | grep -q 'Kernel/User page tables isolation: enabled'; then
-	pstatus green YES
-	kpti_enabled=1
-else
-	pstatus red NO
-fi
-
-/bin/echo -ne "> \033[46m\033[30mSTATUS:\033[0m "
-if grep -q AMD /proc/cpuinfo; then
-	pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
-elif [ "$kpti_enabled" = 1 ]; then
+elif [ "$opt_live" = 1 ]; then
+	if [ "$kpti_enabled" = 1 ]; then
 		pstatus green "NOT VULNERABLE" "PTI mitigates the vulnerability"
-else
+	else
 		pstatus red "VULNERABLE" "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"
+	else
+		pstatus red "VULNERABLE" "PTI is needed to mitigate the vulnerability"
+	fi
 fi
 
+_echo
 
-/bin/echo
-if [ "$USER" != root ]; then
-	/bin/echo "Note that you should launch this script with root privileges to get accurate information"
-	/bin/echo "You can try the following command: sudo $0"
-fi
-
+[ -n "$dumped_config" ] && rm -f "$dumped_config"