add --variant to specify what check we want to run

spectre-meltdown-checker.sh

@@ -8,7 +8,7 @@
 #
 # Stephane Lesimple
 #
-VERSION=0.21
+VERSION=0.22
 
 # Script configuration
 show_usage()
@@ -34,8 +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.
@@ -79,6 +81,10 @@ 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
@@ -255,6 +261,20 @@ while [ -n "$1" ]; do
 	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
@@ -467,8 +487,31 @@ fi
 
 _info
 
-###########
-# SPECTRE 1
+# end of header stuff
+
+# now we define some util functions and the check_*() funcs, as
+# the user can choose to execute only some of those
+
+mount_debugfs()
+{
+	if [ ! -e /sys/kernel/debug/sched_features ]; then
+		# try to mount the debugfs hierarchy ourselves and remember it to umount afterwards
+		mount -t debugfs debugfs /sys/kernel/debug 2>/dev/null && mounted_debugfs=1
+	fi
+}
+
+umount_debugfs()
+{
+	if [ "$mounted_debugfs" = 1 ]; then
+		# umount debugfs if we did mount it ourselves
+		umount /sys/kernel/debug
+	fi
+}
+
+###################
+# SPECTRE VARIANT 1
+check_variant1()
+{
 	_info "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
 	_info_nol "* Checking count of LFENCE opcodes in kernel: "
 
@@ -505,10 +548,12 @@ else
 			2) pvulnstatus CVE-2017-5753 OK 'heuristic to be improved when official patches become available';;
 		esac
 	fi
+}
 
-###########
-# VARIANT 2
-_info
+###################
+# 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: "
@@ -537,10 +582,7 @@ fi
 
 	_info_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
+		mount_debugfs
 		if [ -e /sys/kernel/debug/ibrs_enabled ]; then
 			# if the file is there, we have IBRS compiled-in
 			pstatus green YES
@@ -657,10 +699,12 @@ else
 			pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
 		fi
 	fi
+}
 
-##########
-# MELTDOWN
-_info
+########################
+# 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
@@ -700,6 +744,7 @@ else
 		pstatus yellow UNKNOWN "couldn't read your kernel configuration nor System.map file"
 	fi
 
+	mount_debugfs
 	_info_nol "* PTI enabled and active: "
 	if [ "$opt_live" = 1 ]; then
 		if grep ^flags /proc/cpuinfo | grep -qw pti; then
@@ -729,11 +774,6 @@ 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
@@ -749,11 +789,28 @@ else
 			pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
 		fi
 	fi
+}
 
+# now run the checks the user asked for
+if [ "$opt_variant1" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant1
 	_info
+fi
+if [ "$opt_variant2" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant2
+	_info
+fi
+if [ "$opt_variant3" = 1 -o "$opt_allvariants" = 1 ]; then
+	check_variant3
+	_info
+fi
 
 _info "A false sense of security is worse than no security at all, see --disclaimer"
 
+# this'll umount only if we mounted debugfs ourselves
+umount_debugfs
+
+# cleanup the temp decompressed config
 [ -n "$dumped_config" ] && rm -f "$dumped_config"
 
 if [ "$opt_batch" = 1 -a "$opt_batch_format" = "nrpe" ]; then