bump to v0.23 to reflect changes

NRPE mode

README.md

@@ -8,6 +8,10 @@ You can also specify a kernel image on the command line, if you'd like to inspec
 
 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/FjroIZximyoM/EO5msoSMKb6L.png)
+
 ## Quick summary of the CVEs
 
 **CVE-2017-5753** bounds check bypass (Spectre Variant 1)
@@ -28,69 +32,3 @@ The script will do its best to detect mitigations, including backported non-vani
    - 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
-
-### Ubuntu LTS (before official patches)
-
-```
-$ 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 >= 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

@@ -8,7 +8,7 @@
 #
 # Stephane Lesimple
 #
-VERSION=0.21
+VERSION=0.23
 
 # Script configuration
 show_usage()
@@ -34,7 +34,10 @@ show_usage()
 	Options:
 		--no-color			Don't use color codes
 		-v, --verbose			Increase verbosity level
-		--batch				Produce machine readable output
+		--batch text			Produce machine readable output, this is the default if --batch is specified alone
+		--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.
@@ -76,7 +79,16 @@ 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()
 {
@@ -236,9 +248,33 @@ while [ -n "$1" ]; do
 		opt_batch=1
 		opt_verbose=0
 		shift
+		case "$1" in
+			text|nrpe) 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"
+				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 "$1" = "--help" ]; then
 		show_header
 		show_usage
@@ -280,7 +316,18 @@ pstatus()
 # Arguments are: CVE UNK/OK/VULN description
 pvulnstatus()
 {
-	[ "$opt_batch" = 1 ] && _echo 0 "$1: $2 ($3)"
+	if [ "$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
+				;;
+		esac
+	fi
+
 	_info_nol "> \033[46m\033[30mSTATUS:\033[0m "
 	vulnstatus="$2"
 	shift 2
@@ -440,288 +487,339 @@ fi
 
 _info
 
-###########
-# SPECTRE 1
-_info "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
-_info_nol "* Checking count of LFENCE opcodes in kernel: "
+# end of header stuff
 
-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
+# now we define some util functions and the check_*() funcs, as
+# the user can choose to execute only some of those
 
-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
-
-###########
-# VARIANT 2
-_info
-_info "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
-_info "* Mitigation 1"
-_info_nol "*   Hardware (CPU microcode) support for mitigation: "
-if [ ! -e /dev/cpu/0/msr ]; then
-	# try to load the module ourselves (and remember it so we can rmmod it afterwards)
-	modprobe msr 2>/dev/null && insmod_msr=1
-fi
-if [ ! -e /dev/cpu/0/msr ]; then
-	pstatus yellow UNKNOWN "couldn't read /dev/cpu/0/msr, is msr support enabled in your kernel?"
-else
-	# the new MSR 'SPEC_CTRL' is at offset 0x48
-	# here we use dd, it's the same as using 'rdmsr 0x48' but without needing the rdmsr tool
-	# if we get a read error, the MSR is not there
-	dd if=/dev/cpu/0/msr of=/dev/null bs=8 count=1 skip=9 2>/dev/null
-	if [ $? -eq 0 ]; then
-		pstatus green YES
-	else
-		pstatus red NO
-	fi
-fi
-
-if [ "$insmod_msr" = 1 ]; then
-	# if we used modprobe ourselves, rmmod the module
-	rmmod msr 2>/dev/null
-fi
-
-_info_nol "*   Kernel support for IBRS: "
-if [ "$opt_live" = 1 ]; then
+mount_debugfs()
+{
 	if [ ! -e /sys/kernel/debug/sched_features ]; then
 		# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
 		mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
 	fi
-	if [ -e /sys/kernel/debug/ibrs_enabled ]; then
-		# if the file is there, we have IBRS compiled-in
-		pstatus green YES
-		ibrs_supported=1
-		ibrs_enabled=$(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=$(cat /sys/kernel/debug/x86/ibrs_enabled 2>/dev/null)
+}
+
+umount_debugfs()
+{
+	if [ "$mounted_debugfs" = 1 ]; then
+		# umount debugfs if we did mount it ourselves
+		umount /sys/kernel/debug
 	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
+}
 
-_info_nol "*   IBRS enabled for Kernel space: "
-if [ "$opt_live" = 1 ]; then
-	# 0 means disabled
-	# 1 is enabled only for kernel space
-	# 2 is enabled for kernel and user space
-	case "$ibrs_enabled" in
-		"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
-		0)     pstatus red NO;;
-		1 | 2) pstatus green YES;;
-		*)     pstatus yellow UNKNOWN;;
-	esac
-else
-	pstatus blue N/A "not testable in offline mode"
-fi
+###################
+# 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: "
 
-_info_nol "*   IBRS enabled for User space: "
-if [ "$opt_live" = 1 ]; then
-	case "$ibrs_enabled" in
-		"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
-		0 | 1) pstatus red NO;;
-		2) pstatus green YES;;
-		*) pstatus yellow UNKNOWN;;
-	esac
-else
-	pstatus blue N/A "not testable in offline mode"
-fi
-
-_info "* Mitigation 2"
-_info_nol "*   Kernel compiled with retpoline option: "
-# We check the RETPOLINE kernel options
-if [ -r "$opt_config" ]; then
-	if grep -q '^CONFIG_RETPOLINE=y' "$opt_config"; then
-		pstatus green YES
-		retpoline=1
+	status=0
+	if [ -n "$vmlinux_err" ]; then
+		pstatus yellow UNKNOWN "$vmlinux_err"
 	else
-		pstatus red NO
+		if ! which objdump >/dev/null 2>&1; then
+			pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
+		else
+			# here we disassemble the kernel and count the number of occurences of the LFENCE opcode
+			# in non-patched kernels, this has been empirically determined as being around 40-50
+			# in patched kernels, this is more around 70-80, sometimes way higher (100+)
+			# v0.13: 68 found in a 3.10.23-xxxx-std-ipv6-64 (with lots of modules compiled-in directly), which doesn't have the LFENCE patches,
+			# so let's push the threshold to 70.
+			# TODO LKML patch is starting to dump LFENCE in favor of the PAUSE opcode, we might need to check that (patch not stabilized yet)
+			nb_lfence=$(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
-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"
+	if ! is_cpu_vulnerable 1; then
+		pvulnstatus CVE-2017-5753 OK "your CPU vendor reported your CPU model as not vulnerable"
 	else
-		pstatus red NO
+		case "$status" in
+			0) pvulnstatus CVE-2017-5753 UNK "impossible to check ${vmlinux}";;
+			1) pvulnstatus CVE-2017-5753 VULN 'heuristic to be improved when official patches become available';;
+			2) pvulnstatus CVE-2017-5753 OK 'heuristic to be improved when official patches become available';;
+		esac
 	fi
-elif [ -n "$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"
+}
+
+###################
+# 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 [ $? -eq 0 ]; then
+			pstatus green YES
 		else
 			pstatus red NO
 		fi
-	elif grep -q noretpoline_setup "$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
+	fi
+
+	if [ "$insmod_msr" = 1 ]; then
+		# if we used modprobe ourselves, rmmod the module
+		rmmod msr 2>/dev/null
+	fi
+
+	_info_nol "*   Kernel support for IBRS: "
+	if [ "$opt_live" = 1 ]; then
+		mount_debugfs
+		if [ -e /sys/kernel/debug/ibrs_enabled ]; then
+			# if the file is there, we have IBRS compiled-in
+			pstatus green YES
+			ibrs_supported=1
+			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
-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 "$ibrs_enabled" = 2 ]; then
-		pvulnstatus CVE-2017-5715 OK "IBRS mitigates the vulnerability"
+	_info_nol "*   IBRS enabled for Kernel space: "
+	if [ "$opt_live" = 1 ]; then
+		# 0 means disabled
+		# 1 is enabled only for kernel space
+		# 2 is enabled for kernel and user space
+		case "$ibrs_enabled" in
+			"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
+			0)     pstatus red NO;;
+			1 | 2) pstatus green YES;;
+			*)     pstatus yellow UNKNOWN;;
+		esac
 	else
-		pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+		pstatus blue N/A "not testable in offline mode"
 	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
-_info
-_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 "$vmlinux" ]; then
-	# same as above but in case we don't have System.map and only vmlinux, look for the
-	# nopti option that is part of the patch (kernel command line option)
-	kpti_can_tell=1
-	if ! which strings >/dev/null 2>&1; then
-		pstatus yellow UNKNOWN "missing 'strings' tool, please install it, usually it's in the binutils package"
+	_info_nol "*   IBRS enabled for User space: "
+	if [ "$opt_live" = 1 ]; then
+		case "$ibrs_enabled" in
+			"") [ "$ibrs_supported" = 1 ] && pstatus yellow UNKNOWN || pstatus red NO;;
+			0 | 1) pstatus red NO;;
+			2) pstatus green YES;;
+			*) pstatus yellow UNKNOWN;;
+		esac
 	else
-		if strings "$vmlinux" | grep -qw nopti; then
+		pstatus blue N/A "not testable in offline mode"
+	fi
+
+	_info "* Mitigation 2"
+	_info_nol "*   Kernel compiled with retpoline option: "
+	# We check the RETPOLINE kernel options
+	if [ -r "$opt_config" ]; then
+		if grep -q '^CONFIG_RETPOLINE=y' "$opt_config"; then
+			pstatus green YES
+			retpoline=1
+		else
+			pstatus red NO
+		fi
+	else
+		pstatus yellow UNKNOWN "couldn't read your kernel configuration"
+	fi
+
+	_info_nol "*   Kernel compiled with a retpoline-aware compiler: "
+	# Now check if the compiler used to compile the kernel knows how to insert retpolines in generated asm
+	# For gcc, this is -mindirect-branch=thunk-extern (detected by the kernel makefiles)
+	# See gcc commit https://github.com/hjl-tools/gcc/commit/23b517d4a67c02d3ef80b6109218f2aadad7bd79
+	# In latest retpoline LKML patches, the noretpoline_setup symbol exists only if CONFIG_RETPOLINE is set
+	# *AND* if the compiler is retpoline-compliant, so look for that symbol
+	if [ -n "$opt_map" ]; then
+		# look for the symbol
+		if grep -qw noretpoline_setup "$opt_map"; then
+			retpoline_compiler=1
+			pstatus green YES "noretpoline_setup symbol found in System.map"
+		else
+			pstatus red NO
+		fi
+	elif [ -n "$vmlinux" ]; then
+		# look for the symbol
+		if which nm >/dev/null 2>&1; then
+			# the proper way: use nm and look for the symbol
+			if nm "$vmlinux" 2>/dev/null | grep -qw 'noretpoline_setup'; then
+				retpoline_compiler=1
+				pstatus green YES "noretpoline_setup found in vmlinux symbols"
+			else
+				pstatus red NO
+			fi
+		elif grep -q noretpoline_setup "$vmlinux"; then
+			# if we don't have nm, nevermind, the symbol name is long enough to not have
+			# any false positive using good old grep directly on the binary
+			retpoline_compiler=1
+			pstatus green YES "noretpoline_setup found in vmlinux"
+		else
+			pstatus red NO
+		fi
+	else
+		pstatus yellow UNKNOWN "couldn't find your kernel image or System.map"
+	fi
+
+	if ! is_cpu_vulnerable 2; then
+		pvulnstatus CVE-2017-5715 OK "your CPU vendor reported your CPU model as not vulnerable"
+	elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
+		pvulnstatus CVE-2017-5715 OK "retpoline mitigate the vulnerability"
+	elif [ "$opt_live" = 1 ]; then
+		if [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
+			pvulnstatus CVE-2017-5715 OK "IBRS mitigates the vulnerability"
+		else
+			pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+		fi
+	else
+		if [ "$ibrs_supported" = 1 ]; then
+			pvulnstatus CVE-2017-5715 OK "offline mode: IBRS will mitigate the vulnerability if enabled at runtime"
+		else
+			pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
+		fi
+	fi
+}
+
+########################
+# MELTDOWN aka VARIANT 3
+check_variant3()
+{
+	_info "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
+	_info_nol "* Kernel supports Page Table Isolation (PTI): "
+	kpti_support=0
+	kpti_can_tell=0
+	if [ -n "$opt_config" ]; then
+		kpti_can_tell=1
+		if grep -Eq '^(CONFIG_PAGE_TABLE_ISOLATION|CONFIG_KAISER)=y' "$opt_config"; then
 			kpti_support=1
 		fi
 	fi
-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
-
-_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 in dmesg
-		kpti_enabled=1
-	else
-		kpti_enabled=0
+	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_enabled" = 1 ]; then
-		pstatus green YES
-	else
-		pstatus red NO
+	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
-else
-	pstatus blue N/A "can't verify if PTI is enabled in offline mode"
-fi
 
-if [ "$mounted_debugfs" = 1 ]; then
-	# umount debugfs if we did mount it ourselves
-	umount /sys/kernel/debug
-fi
-
-if ! is_cpu_vulnerable 3; then
-	pvulnstatus CVE-2017-5754 OK "your CPU vendor reported your CPU model as not vulnerable"
-elif [ "$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"
+		pstatus green YES
+	elif [ "$kpti_can_tell" = 1 ]; then
+		pstatus red NO
 	else
-		pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
+		pstatus yellow UNKNOWN "couldn't read your kernel configuration nor System.map file"
 	fi
+
+	mount_debugfs
+	_info_nol "* PTI enabled and active: "
+	if [ "$opt_live" = 1 ]; then
+		if grep ^flags /proc/cpuinfo | grep -qw pti; then
+			# vanilla PTI patch sets the 'pti' flag in cpuinfo
+			kpti_enabled=1
+		elif grep ^flags /proc/cpuinfo | grep -qw kaiser; then
+			# kernel line 4.9 sets the 'kaiser' flag in cpuinfo
+			kpti_enabled=1
+		elif [ -e /sys/kernel/debug/x86/pti_enabled ]; then
+			# RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301
+			kpti_enabled=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)
+		elif dmesg | grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled'; then
+			# if we can't find the flag, grep dmesg output
+			kpti_enabled=1
+		elif [ -r /var/log/dmesg ] && grep -Eq 'Kernel/User page tables isolation: enabled|Kernel page table isolation enabled' /var/log/dmesg; then
+			# if we can't find the flag in dmesg output, grep in /var/log/dmesg when readable
+			kpti_enabled=1
+		else
+			kpti_enabled=0
+		fi
+		if [ "$kpti_enabled" = 1 ]; then
+			pstatus green YES
+		else
+			pstatus red NO
+		fi
+	else
+		pstatus blue N/A "can't verify if PTI is enabled in offline mode"
+	fi
+
+	if ! is_cpu_vulnerable 3; then
+		pvulnstatus CVE-2017-5754 OK "your CPU vendor reported your CPU model as not vulnerable"
+	elif [ "$opt_live" = 1 ]; then
+		if [ "$kpti_enabled" = 1 ]; then
+			pvulnstatus CVE-2017-5754 OK "PTI mitigates the vulnerability"
+		else
+			pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
+		fi
+	else
+		if [ "$kpti_support" = 1 ]; then
+			pvulnstatus CVE-2017-5754 OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
+		else
+			pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
+		fi
+	fi
+}
+
+# now run the checks the user asked for
+if [ "$opt_variant1" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant1
+	_info
+fi
+if [ "$opt_variant2" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant2
+	_info
+fi
+if [ "$opt_variant3" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant3
+	_info
 fi
 
-_info
+_info "A false sense of security is worse than no security at all, see --disclaimer"
 
-_info "A false sense of security is worst 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