adding support for new /sys interface (#55)
* adding support for new /sys interface * fix(objdump): prefer -d instead of -D, some kernels crash objdump otherwise
This commit is contained in:
Stéphane Lesimple
GitHub
parent
56b67f8082
commit
62f8ed6f61
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@ -8,7 +8,7 @@
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#
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# Stephane Lesimple
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#
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VERSION=0.25
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VERSION=0.26
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# Script configuration
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show_usage()
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@ -33,7 +33,8 @@ show_usage()
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Options:
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--no-color Don't use color codes
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-v, --verbose Increase verbosity level
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--verbose, -v Increase verbosity level
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--no-sysfs Don't use the /sys interface even if present
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--batch text Produce machine readable output, this is the default if --batch is specified alone
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--batch json Produce JSON output formatted for Puppet, Ansible, Chef...
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--batch nrpe Produce machine readable output formatted for NRPE
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@ -86,6 +87,7 @@ opt_variant1=0
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opt_variant2=0
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opt_variant3=0
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opt_allvariants=1
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opt_no_sysfs=0
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nrpe_critical=0
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nrpe_unknown=0
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@ -95,13 +97,13 @@ __echo()
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{
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opt="$1"
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shift
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msg="$@"
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_msg="$@"
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if [ "$opt_no_color" = 1 ] ; then
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# strip ANSI color codes
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msg=$(/bin/echo -e "$msg" | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g")
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_msg=$(/bin/echo -e "$_msg" | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g")
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fi
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# explicitely call /bin/echo to avoid shell builtins that might not take options
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/bin/echo $opt -e "$msg"
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/bin/echo $opt -e "$_msg"
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}
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_echo()
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@ -250,6 +252,9 @@ while [ -n "$1" ]; do
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elif [ "$1" = "--no-color" ]; then
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opt_no_color=1
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shift
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elif [ "$1" = "--no-sysfs" ]; then
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opt_no_sysfs=1
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shift
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elif [ "$1" = "--batch" ]; then
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opt_batch=1
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opt_verbose=0
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@ -548,46 +553,83 @@ umount_debugfs()
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fi
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}
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sys_interface_check()
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{
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[ "$opt_live" = 1 -a "$opt_no_sysfs" = 0 -a -r "$1" ] || return 1
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_info_nol "* Checking wheter we're safe according to the /sys interface: "
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if grep -qi '^not affected' "$1"; then
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# Not affected
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status=OK
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pstatus green YES "kernel confirms that your CPU is unaffected"
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elif grep -qi '^mitigation' "$1"; then
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# Mitigation: PTI
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status=OK
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pstatus green YES "kernel confirms that the mitigation is active"
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elif grep -qi '^vulnerable' "$1"; then
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# Vulnerable
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status=VULN
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pstatus red NO "kernel confirms your system is vulnerable"
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else
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status=UNK
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pstatus yellow UNKNOWN "unknown value reported by kernel"
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fi
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msg=$(cat "$1")
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return 0
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}
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###################
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# SPECTRE VARIANT 1
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check_variant1()
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{
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_info "\033[1;34mCVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'\033[0m"
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_info_nol "* Checking count of LFENCE opcodes in kernel: "
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status=0
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status=UNK
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sys_interface_available=0
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msg=''
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if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/spectre_v1"; then
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# this kernel has the /sys interface, trust it over everything
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sys_interface_available=1
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else
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# no /sys interface (or offline mode), fallback to our own ways
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_info_nol "* Checking count of LFENCE opcodes in kernel: "
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if [ -n "$vmlinux_err" ]; then
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pstatus yellow UNKNOWN "$vmlinux_err"
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msg="couldn't check ($vmlinux_err)"
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status=UNK
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pstatus yellow UNKNOWN
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else
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if ! which objdump >/dev/null 2>&1; then
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pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
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msg="missing 'objdump' tool, please install it, usually it's in the binutils package"
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status=UNK
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pstatus yellow UNKNOWN
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else
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# here we disassemble the kernel and count the number of occurences of the LFENCE opcode
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# in non-patched kernels, this has been empirically determined as being around 40-50
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# in patched kernels, this is more around 70-80, sometimes way higher (100+)
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# 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,
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# so let's push the threshold to 70.
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# TODO LKML patch is starting to dump LFENCE in favor of the PAUSE opcode, we might need to check that (patch not stabilized yet)
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nb_lfence=$(objdump -D "$vmlinux" | grep -wc lfence)
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nb_lfence=$(objdump -d "$vmlinux" | grep -wc lfence)
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if [ "$nb_lfence" -lt 70 ]; then
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pstatus red NO "only $nb_lfence opcodes found, should be >= 70"
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status=1
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msg="only $nb_lfence opcodes found, should be >= 70, heuristic to be improved when official patches become available"
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status=VULN
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pstatus yellow UNKNOWN
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else
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pstatus green YES "$nb_lfence opcodes found, which is >= 70"
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status=2
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msg="$nb_lfence opcodes found, which is >= 70, heuristic to be improved when official patches become available"
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status=OK
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pstatus green YES
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fi
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fi
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fi
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fi
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if ! is_cpu_vulnerable 1; then
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pvulnstatus CVE-2017-5753 OK "your CPU vendor reported your CPU model as not vulnerable"
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else
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case "$status" in
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0) pvulnstatus CVE-2017-5753 UNK "impossible to check ${vmlinux}";;
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1) pvulnstatus CVE-2017-5753 VULN 'heuristic to be improved when official patches become available';;
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2) pvulnstatus CVE-2017-5753 OK 'heuristic to be improved when official patches become available';;
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esac
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# if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
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if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 1; then
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# override status & msg in case CPU is not vulnerable after all
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msg="your CPU vendor reported your CPU model as not vulnerable"
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status=OK
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fi
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# report status
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pvulnstatus CVE-2017-5753 "$status" "$msg"
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}
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###################
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@ -595,6 +637,14 @@ check_variant1()
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check_variant2()
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{
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_info "\033[1;34mCVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'\033[0m"
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status=UNK
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sys_interface_available=0
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msg=''
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if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
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# this kernel has the /sys interface, trust it over everything
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sys_interface_available=1
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else
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_info "* Mitigation 1"
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_info_nol "* Hardware (CPU microcode) support for mitigation: "
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if [ ! -e /dev/cpu/0/msr ]; then
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@ -725,10 +775,15 @@ check_variant2()
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else
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pstatus yellow UNKNOWN "couldn't find your kernel image or System.map"
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fi
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fi
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if ! is_cpu_vulnerable 2; then
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# if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
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if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 2; then
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# override status & msg in case CPU is not vulnerable after all
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pvulnstatus CVE-2017-5715 OK "your CPU vendor reported your CPU model as not vulnerable"
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elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
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elif [ -z "$msg" ]; then
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# if msg is empty, sysfs check didn't fill it, rely on our own test
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if [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
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pvulnstatus CVE-2017-5715 OK "retpoline mitigate the vulnerability"
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elif [ "$opt_live" = 1 ]; then
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if [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
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@ -743,6 +798,9 @@ check_variant2()
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pvulnstatus CVE-2017-5715 VULN "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
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fi
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fi
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else
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pvulnstatus CVE-2017-5715 "$status" "$msg"
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fi
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}
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########################
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@ -750,6 +808,14 @@ check_variant2()
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check_variant3()
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{
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_info "\033[1;34mCVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'\033[0m"
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status=UNK
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sys_interface_available=0
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msg=''
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if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/meltdown"; then
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# this kernel has the /sys interface, trust it over everything
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sys_interface_available=1
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else
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_info_nol "* Kernel supports Page Table Isolation (PTI): "
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kpti_support=0
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kpti_can_tell=0
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@ -817,22 +883,31 @@ check_variant3()
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else
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pstatus blue N/A "can't verify if PTI is enabled in offline mode"
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fi
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fi
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if ! is_cpu_vulnerable 3; then
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pvulnstatus CVE-2017-5754 OK "your CPU vendor reported your CPU model as not vulnerable"
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elif [ "$opt_live" = 1 ]; then
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# if we have the /sys interface, don't even check is_cpu_vulnerable ourselves, the kernel already does it
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cve='CVE-2017-5754'
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if [ "$sys_interface_available" = 0 ] && ! is_cpu_vulnerable 3; then
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# override status & msg in case CPU is not vulnerable after all
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pvulnstatus $cve OK "your CPU vendor reported your CPU model as not vulnerable"
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elif [ -z "$msg" ]; then
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# if msg is empty, sysfs check didn't fill it, rely on our own test
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if [ "$opt_live" = 1 ]; then
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if [ "$kpti_enabled" = 1 ]; then
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pvulnstatus CVE-2017-5754 OK "PTI mitigates the vulnerability"
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pvulnstatus $cve OK "PTI mitigates the vulnerability"
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else
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pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
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pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
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fi
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else
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if [ "$kpti_support" = 1 ]; then
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pvulnstatus CVE-2017-5754 OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
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pvulnstatus $cve OK "offline mode: PTI will mitigate the vulnerability if enabled at runtime"
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else
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pvulnstatus CVE-2017-5754 VULN "PTI is needed to mitigate the vulnerability"
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pvulnstatus $cve VULN "PTI is needed to mitigate the vulnerability"
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fi
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fi
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else
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pvulnstatus $cve "$status" "$msg"
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fi
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}
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# now run the checks the user asked for
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