enh: kernel: autodetect customized arch kernels from cmdline

spectre-meltdown-checker.sh

@@ -41,8 +41,9 @@ show_usage()
 	# shellcheck disable=SC2086
 	cat <<EOF
 	Usage:
-		Live mode:    $(basename $0) [options] [--live]
-		Offline mode: $(basename $0) [options] [--kernel <kernel_file>] [--config <kernel_config>] [--map <kernel_map_file>]
+		Live mode (auto):   $(basename $0) [options]
+		Live mode (manual): $(basename $0) [options] <[--kernel <kimage>] [--config <kconfig>] [--map <mapfile>]> --live
+		Offline mode:       $(basename $0) [options] <[--kernel <kimage>] [--config <kconfig>] [--map <mapfile>]>
 
 	Modes:
 		Two modes are available.
@@ -51,12 +52,16 @@ show_usage()
 		To run under this mode, just start the script without any option (you can also use --live explicitly)
 
 		Second mode is the "offline" mode, where you can inspect a non-running kernel.
-		You'll need to specify the location of the kernel file, config and System.map files:
+		This mode is automatically enabled when you specify the location of the kernel file, config and System.map files:
 
 		--kernel kernel_file	specify a (possibly compressed) Linux or BSD kernel file
 		--config kernel_config	specify a kernel config file (Linux only)
 		--map kernel_map_file	specify a kernel System.map file (Linux only)
 
+		If you want to use live mode while specifying the location of the kernel, config or map file yourself,
+		you can add --live to the above options, to tell the script to run in live mode instead of the offline mode,
+		which is enabled by default when at least one file is specified on the command line.
+
 	Options:
 		--no-color		don't use color codes
 		--verbose, -v		increase verbosity level, possibly several times
@@ -134,8 +139,7 @@ os=$(uname -s)
 opt_kernel=''
 opt_config=''
 opt_map=''
-opt_live_explicit=0
-opt_live=1
+opt_live=-1
 opt_no_color=0
 opt_batch=0
 opt_batch_format='text'
@@ -796,22 +800,19 @@ while [ -n "$1" ]; do
 		opt_kernel=$(parse_opt_file kernel "$2"); ret=$?
 		[ $ret -ne 0 ] && exit 255
 		shift 2
-		opt_live=0
 	elif [ "$1" = "--config" ]; then
 		opt_config=$(parse_opt_file config "$2"); ret=$?
 		[ $ret -ne 0 ] && exit 255
 		shift 2
-		opt_live=0
 	elif [ "$1" = "--map" ]; then
 		opt_map=$(parse_opt_file map "$2"); ret=$?
 		[ $ret -ne 0 ] && exit 255
 		shift 2
-		opt_live=0
 	elif [ "$1" = "--arch-prefix" ]; then
 		opt_arch_prefix="$2"
 		shift 2
 	elif [ "$1" = "--live" ]; then
-		opt_live_explicit=1
+		opt_live=1
 		shift
 	elif [ "$1" = "--no-color" ]; then
 		opt_no_color=1
@@ -954,6 +955,15 @@ if [ "$opt_no_hw" = 1 ] && [ "$opt_hw_only" = 1 ]; then
 	exit 255
 fi
 
+if [ "$opt_live" = -1 ]; then
+	if [ -n "$opt_kernel" ] || [ -n "$opt_config" ] || [ -n "$opt_map" ]; then
+		# no --live specified and we have a least one of the kernel/config/map files on the cmdline: offline mode
+		opt_live=0
+	else
+		opt_live=1
+	fi
+fi
+
 # print status function
 pstatus()
 {
@@ -1711,6 +1721,23 @@ is_latest_known_ucode()
 	return 2
 }
 
+get_cmdline()
+{
+	if [ -n "$kernel_cmdline" ]; then
+		return
+	fi
+
+	if [ -n "$SMC_MOCK_CMDLINE" ]; then
+		mocked=1
+		_debug "get_cmdline: using mocked cmdline '$SMC_MOCK_CMDLINE'"
+		kernel_cmdline="$SMC_MOCK_CMDLINE"
+		return
+	else
+		kernel_cmdline=$(cat "$procfs/cmdline")
+		mockme=$(printf "%b\n%b" "$mockme" "SMC_MOCK_CMDLINE='$kernel_cmdline'")
+	fi
+}
+
 # ENTRYPOINT
 
 # we can't do anything useful under WSL
@@ -1722,13 +1749,6 @@ if uname -a | grep -qE -- '-Microsoft #[0-9]+-Microsoft '; then
 fi
 
 # check for mode selection inconsistency
-if [ "$opt_live_explicit" = 1 ]; then
-	if [ -n "$opt_kernel" ] || [ -n "$opt_config" ] || [ -n "$opt_map" ]; then
-		show_usage
-		echo "$0: error: incompatible modes specified, use either --live or --kernel/--config/--map" >&2
-		exit 255
-	fi
-fi
 if [ "$opt_hw_only" = 1 ]; then
 	if [ "$opt_cve_all" = 0 ]; then
 		show_usage
@@ -1782,6 +1802,8 @@ if echo "$os" | grep -q BSD; then
 fi
 
 parse_cpu_details
+get_cmdline
+
 if [ "$opt_live" = 1 ]; then
 	# root check (only for live mode, for offline mode, we already checked if we could read the files)
 	if [ "$(id -u)" -ne 0 ]; then
@@ -1795,9 +1817,12 @@ if [ "$opt_live" = 1 ]; then
 	_info "CPU is \033[35m$cpu_friendly_name\033[0m"
 
 	# try to find the image of the current running kernel
+	if [ -n "$opt_kernel" ]; then
+		# specified by user on cmdline, with --live, don't override
+		:
 	# first, look for the BOOT_IMAGE hint in the kernel cmdline
-	if [ -r "$procfs/cmdline" ] && grep -q 'BOOT_IMAGE=' "$procfs/cmdline"; then
-		opt_kernel=$(grep -Eo 'BOOT_IMAGE=[^ ]+' "$procfs/cmdline" | cut -d= -f2)
+	elif echo "$kernel_cmdline" | grep -q 'BOOT_IMAGE='; then
+		opt_kernel=$(echo "$kernel_cmdline" | grep -Eo 'BOOT_IMAGE=[^ ]+' | cut -d= -f2)
 		_debug "found opt_kernel=$opt_kernel in $procfs/cmdline"
 		# if the boot partition is within a btrfs subvolume, strip the subvolume name
 		# if /boot is a separate subvolume, the remainder of the code in this section should handle it
@@ -1840,10 +1865,19 @@ if [ "$opt_live" = 1 ]; then
 		str_uname=$(uname -r)
 		clear_linux_kernel="/lib/kernel/org.clearlinux.${str_uname##*.}.${str_uname%.*}"
 		[ -e "$clear_linux_kernel" ] && opt_kernel=$clear_linux_kernel
+		# Custom Arch seems to have the kernel path in its cmdline in the form "\directory\kernelimage",
+		# with actual \'s instead of /'s:
+		custom_arch_kernel=$(echo "$kernel_cmdline" | grep -Eo "(^|\s)\\\\[\\\\a-zA-Z0-9_.-]+" | tr "\\\\" "/" | tr -d '[:space:]')
+		if [ -n "$custom_arch_kernel" ] && [ -e "$custom_arch_kernel" ]; then
+			opt_kernel="$custom_arch_kernel"
+		fi
 	fi
 
 	# system.map
-	if [ -e "$procfs/kallsyms" ] ; then
+	if [ -n "$opt_map" ]; then
+		# specified by user on cmdline, with --live, don't override
+		:
+	elif [ -e "$procfs/kallsyms" ] ; then
 		opt_map="$procfs/kallsyms"
 	elif [ -e "/lib/modules/$(uname -r)/System.map" ] ; then
 		opt_map="/lib/modules/$(uname -r)/System.map"
@@ -1854,7 +1888,10 @@ if [ "$opt_live" = 1 ]; then
 	fi
 
 	# config
-	if [ -e "$procfs/config.gz" ] ; then
+	if [ -n "$opt_config" ]; then
+		# specified by user on cmdline, with --live, don't override
+		:
+	elif [ -e "$procfs/config.gz" ] ; then
 		dumped_config="$(mktemp /tmp/config-XXXXXX)"
 		gunzip -c "$procfs/config.gz" > "$dumped_config"
 		# dumped_config will be deleted at the end of the script
@@ -3755,7 +3792,7 @@ check_CVE_2017_5754_linux()
 				if [ -n "$kpti_support" ]; then
 					if [ -e "/sys/kernel/debug/x86/pti_enabled" ]; then
 						explain "Your kernel supports PTI but it's disabled, you can enable it with \`echo 1 > /sys/kernel/debug/x86/pti_enabled\`"
-					elif grep -q -w -e nopti -e pti=off "$procfs/cmdline"; then
+					elif echo "$kernel_cmdline" | grep -q -w -e nopti -e pti=off; then
 						explain "Your kernel supports PTI but it has been disabled on command-line, remove the nopti or pti=off option from your bootloader configuration"
 					else
 						explain "Your kernel supports PTI but it has been disabled, check \`dmesg\` right after boot to find clues why the system disabled it"