spectre-meltdown-checker/spectre-meltdown-checker.sh

#! /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=0.29

# Script configuration
show_usage()
{
    cat <<EOF
    Usage:
        Live mode:    `basename $0` [options] [--live]
        Offline mode: `basename $0` [options] [--kernel <vmlinux_file>] [--config <kernel_config>] [--map <kernel_map_file>]

    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 (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 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
        --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
}

show_disclaimer()
{
    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
explicitly 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
    # explicitly 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 "\033[34m(debug) $@\033[0m"
}

is_cpu_vulnerable()
{
    # param: 1, 2 or 3 (variant)
    # returns 0 if vulnerable, 1 if not vulnerable
    # (note that in shell, a return of 0 is success)
    # 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
        # AMD revised their statement about variant2 => vulnerable
        # https://www.amd.com/en/corporate/speculative-execution
        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
                :
            elif [ "$cpuarch" = 8 ] && echo "$cpupart" | grep -Eq '^0x(d07|d08|d09|d0a)$'; then
                # armv8 vulnerable chips
                :
            else
                variant1=1
                variant2=1
            fi
            # for variant3, only A75 is vulnerable
            if ! [ "$cpuarch" = 8 -a "$cpupart" = 0xd0a ]; then
                variant3=1
            fi
        fi
    fi

    [ "$1" = 1 ] && return $variant1
    [ "$1" = 2 ] && return $variant2
    [ "$1" = 3 ] && return $variant3
    echo "$0: error: invalid variant '$1' passed to is_cpu_vulnerable()" >&2
    exit 1
}

show_header()
{
    _info "\033[1;34mSpectre and Meltdown mitigation detection tool v$VERSION\033[0m"
    _info
}

parse_opt_file()
{
    # parse_opt_file option_name option_value
    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: $option_value is not a file" >&2
        exit 1
    elif [ ! -r "$option_value" ]; then
        show_header
        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" = "--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" = "--version" ]; then
        opt_no_color=1
        show_header
        exit 1
    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
        _warn "Note that you should launch this script with root privileges to get accurate information."
        _warn "We'll proceed but you might see permission denied errors."
        _warn "To run it as root, you can try the following command: sudo $0"
        _warn
    fi
    _info "Checking for vulnerabilities against running kernel \033[35m"$(uname -s) $(uname -r) $(uname -v) $(uname -m)"\033[0m"
    _info "CPU is\033[35m"$(grep '^model name' /proc/cpuinfo | cut -d: -f2 | head -1)"\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
        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
    _info "Checking for vulnerabilities against specified kernel"
fi
if [ -n "$opt_kernel" ]; then
    _verbose "Will use vmlinux image \033[35m$opt_kernel\033[0m"
else
    _verbose "Will use no vmlinux image (accuracy might be reduced)"
fi
if [ -n "$dumped_config" ]; then
    _verbose "Will use kconfig \033[35m/proc/config.gz\033[0m"
elif [ -n "$opt_config" ]; then
    _verbose "Will use kconfig \033[35m$opt_config\033[0m"
else
    _verbose "Will use no kconfig (accuracy might be reduced)"
fi
if [ -n "$opt_map" ]; then
    _verbose "Will use System.map file \033[35m$opt_map\033[0m"
else
    _verbose "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 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

_info

# 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
}

sys_interface_check()
{
    [ "$opt_live" = 1 -a "$opt_no_sysfs" = 0 -a -r "$1" ] || return 1
    _info_nol "* Checking whether 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")
    _debug "sys_interface_check: $1=$msg"
    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 "$vmlinux_err" ]; then
            msg="couldn't check ($vmlinux_err)"
            status=UNK
            pstatus yellow UNKNOWN
        else
            if ! which objdump >/dev/null 2>&1; then
                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 occurrences 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.
                nb_lfence=$(objdump -d "$vmlinux" | grep -wc lfence)
                if [ "$nb_lfence" -lt 70 ]; then
                    msg="only $nb_lfence opcodes found, should be >= 70, heuristic to be improved when official patches become available"
                    status=VULN
                    pstatus red NO
                else
                    msg="$nb_lfence opcodes found, which is >= 70, heuristic to be improved when official patches become available"
                    status=OK
                    pstatus green YES
                fi
            fi
        fi
    fi

    # if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
    if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 1; then
        # override status & msg in case CPU is not vulnerable after all
        msg="your CPU vendor reported your CPU model as not vulnerable"
        status=OK
    fi

    # report status
    pvulnstatus CVE-2017-5753 "$status" "$msg"
}

###################
# 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
            _debug "attempted to load module msr, ret=$insmod_msr"
        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 [ "$insmod_msr" = 1 ]; then
            # if we used modprobe ourselves, rmmod the module
            rmmod msr 2>/dev/null
            _debug "attempted to unload module msr, ret=$?"
        fi

        _info_nol "*   Kernel support for IBRS: "
        if [ "$opt_live" = 1 ]; then
            mount_debugfs
            for ibrs_file in \
                /sys/kernel/debug/ibrs_enabled \
                /sys/kernel/debug/x86/ibrs_enabled \
                /proc/sys/kernel/ibrs_enabled; do
                if [ -e "$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=$(cat "$ibrs_file" 2>/dev/null)
                    _debug "ibrs: found $ibrs_file=$ibrs_enabled"
                    break
                else
                    _debug "ibrs: file $ibrs_file doesn't exist"
                fi
            done
        fi
        if [ "$ibrs_supported" != 1 -a -n "$opt_map" ]; then
            if grep -q spec_ctrl "$opt_map"; then
                pstatus green YES
                ibrs_supported=1
                _debug "ibrs: found '*spec_ctrl*' symbol in $opt_map"
            fi
        fi
        if [ "$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

        _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
                _debug "retpoline: found "$(grep '^CONFIG_RETPOLINE' "$opt_config")" in $opt_config"
            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
    fi

    # if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
    if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 2; then
        # override status & msg in case CPU is not vulnerable after all
        pvulnstatus CVE-2017-5715 OK "your CPU vendor reported your CPU model as not vulnerable"
    elif [ -z "$msg" ]; then
        # if msg is empty, sysfs check didn't fill it, rely on our own test
        if [ "$retpoline" = 1 -a "$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
    else
        pvulnstatus CVE-2017-5715 "$status" "$msg"
    fi
}

########################
# MELTDOWN aka VARIANT 3
check_variant3()
{
    _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
                _debug "kpti_support: found option "$(grep -E '^(CONFIG_PAGE_TABLE_ISOLATION|CONFIG_KAISER)=y' "$opt_config")" in $opt_config"
                kpti_support=1
            fi
        fi
        if [ "$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
                _debug "kpti_support: found kpti_force_enabled in $opt_map"
                kpti_support=1
            fi
        fi
        if [ "$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
                    _debug "kpti_support: found nopti string in $vmlinux"
                    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

        mount_debugfs
        _info_nol "* PTI enabled and active: "
        if [ "$opt_live" = 1 ]; then
            dmesg_grep="Kernel/User page tables isolation: enabled"
            dmesg_grep="$dmesg_grep|Kernel page table isolation enabled"
            dmesg_grep="$dmesg_grep|x86/pti: Unmapping kernel while in userspace"
            if grep ^flags /proc/cpuinfo | grep -qw pti; then
                # vanilla PTI patch sets the 'pti' flag in cpuinfo
                _debug "kpti_enabled: found 'pti' flag in /proc/cpuinfo"
                kpti_enabled=1
            elif grep ^flags /proc/cpuinfo | grep -qw kaiser; then
                # kernel line 4.9 sets the 'kaiser' flag in cpuinfo
                _debug "kpti_enabled: found 'kaiser' flag in /proc/cpuinfo"
                kpti_enabled=1
            elif [ -e /sys/kernel/debug/x86/pti_enabled ]; then
                # RedHat Backport creates a dedicated file, see https://access.redhat.com/articles/3311301
                kpti_enabled=$(cat /sys/kernel/debug/x86/pti_enabled 2>/dev/null)
                _debug "kpti_enabled: file /sys/kernel/debug/x86/pti_enabled exists and says: $kpti_enabled"
            elif dmesg | grep -Eq "$dmesg_grep"; then
                # if we can't find the flag, grep dmesg output
                _debug "kpti_enabled: found hint in dmesg: "$(dmesg | grep -E "$dmesg_grep")
                kpti_enabled=1
            elif [ -r /var/log/dmesg ] && grep -Eq "$dmesg_grep" /var/log/dmesg; then
                # if we can't find the flag in dmesg output, grep in /var/log/dmesg when readable
                _debug "kpti_enabled: found hint in /var/log/dmesg: "$(grep -E "$dmesg_grep" /var/log/dmesg)
                kpti_enabled=1
            else
                _debug "kpti_enabled: couldn't find any hint that PTI is enabled"
                kpti_enabled=0
            fi
            if [ "$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
    fi

    # if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
    cve='CVE-2017-5754'
    if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 3; 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
                pvulnstatus $cve OK "PTI mitigates the vulnerability"
            else
                pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
            fi
        else
            if [ "$kpti_support" = 1 ]; then
                pvulnstatus $cve OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
            else
                pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
            fi
        fi
    else
        pvulnstatus $cve "$status" "$msg"
    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
    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