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add detection of retpoline-aware compiler

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This commit is contained in:
Stéphane Lesimple 2018-01-08 16:28:00 +01:00
parent 207168e097
commit 206e4b7fbc
1 changed files with 21 additions and 13 deletions
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34
spectre-meltdown-checker.sh
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@ -1,7 +1,7 @@
#! /bin/sh
# Spectre & Meltdown checker
# Stephane Lesimple
VERSION=0.13
VERSION=0.14
# print status function
pstatus()
@ -205,7 +205,7 @@ case "$ibrs_enabled" in
esac
/bin/echo "* Mitigation 2"
/bin/echo -n "* Kernel compiled with retpolines: "
/bin/echo -n "* Kernel compiled with retpoline option: "
# We check the RETPOLINE kernel options
if [ -e /proc/config.gz ]; then
# either the running kernel exports his own config
@ -227,7 +227,7 @@ else
pstatus yellow UNKNOWN "couldn't read your kernel configuration"
fi
/bin/echo -n "* Kernel compiled with a retpolines-aware compiler: "
/bin/echo -n "* Kernel compiled with a retpoline-aware compiler: "
# Now check if the compiler used to compile the kernel knows how to insert retpolines in generated asm
# For gcc, this is -mindirect-branch=thunk-extern (detected by the kernel makefiles)
# See gcc commit https://github.com/hjl-tools/gcc/commit/23b517d4a67c02d3ef80b6109218f2aadad7bd79
@ -238,14 +238,14 @@ if [ -n "$vmlinux" ]; then
# the proper way: use nm and look for the symbol
if nm "$vmlinux" 2>/dev/null | grep -qw retpoline_call_target; then
retpoline_compiler=1
pstatus green YES
pstatus green YES "retpoline_call_target found"
fi
else
# if we don't have nm, nevermind, the symbol name is long enough to not have
# any false positive using good old grep directly on the binary
if grep -q retpoline_call_target "$vmlinux"; then
retpoline_compiler=1
pstatus green YES
pstatus green YES "retpoline_call_target found"
fi
fi
if [ "$retpoline_compiler" != 1 ]; then
@ -261,13 +261,21 @@ if [ -n "$vmlinux" ]; then
# ffffffff8100035a: 48 8d 64 24 08 lea 0x8(%rsp),%rsp
# ffffffff8100035f: c3 retq
#
if ! which objdump >/dev/null 2>&1; then
pstatus yellow UNKNOWN "missing 'objdump' tool, please install it, usually it's in the binutils package"
if ! which perl >/dev/null 2>&1; then
pstatus yellow UNKNOWN "missing 'perl', please install it"
else
# directly look for the opcode sequence in the binary
# 64 bits version
if perl -ne '/\xe8\x05\x00\x00\x00\x0f\xae\xe8\xeb\xfb\x48\x8d\x64\x24\x08\xc3/ and $found=1; END { exit($found ? 0 : 1) }' "$vmlinux"; then
retpoline_compiler=1
pstatus green YES "retpoline 64 bits asm sequence found"
#elif perl -ne ... 32 bits version of retpoline asm seq
# TODO
# objdump -D "$vmlinux"
# pstatus red NO
# pstatus green YES
# retpoline_compiler=1
# pstatus green YES "retpoline 33 bits asm sequence found"
else
pstatus red NO
fi
fi
fi
else
@ -280,10 +288,10 @@ if grep -q AMD /proc/cpuinfo; then
pstatus green "NOT VULNERABLE" "your CPU is not vulnerable as per the vendor"
elif [ "$ibrs_enabled" = 1 -o "$ibrs_enabled" = 2 ]; then
pstatus green "NOT VULNERABLE" "IBRS mitigates the vulnerability"
elif [ "$retpoline" = 1 ]; then
pstatus green "NOT VULNERABLE" "retpolines mitigate the vulnerability"
elif [ "$retpoline" = 1 -a "$retpoline_compiler" = 1 ]; then
pstatus green "NOT VULNERABLE" "retpoline mitigate the vulnerability"
else
pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpolines are needed to mitigate the vulnerability"
pstatus red VULNERABLE "IBRS hardware + kernel support OR kernel with retpoline are needed to mitigate the vulnerability"
fi
##########