This change ensures we check for SMT and advise the user to disable it for maximum security.
Doing this, we'll help users mitigate a whole range of vulnerabilities taking advantage of SMT to attack purely from userland other userland processes, as seen in CVE-2018-5407 (also see #261)
On a (pre-SkyLake) system, where /sys/.../vulnerabilities/spectre_v2 is
"Mitigation: Full generic retpoline, IBPB: conditional, IBRS_FW, RSB filling"
the tool, incorrectly, reports, a couple of lines above:
* IBRS enabled and active: YES (for kernel and firmware code)
Use '\<IBRS\>', as suggested by @jirislaby, in upstream issue #275
(https://github.com/speed47/spectre-meltdown-checker/issues/275) when
checking whether IBRS is enabled/active for the kernel.
With that, the output becomes:
* IBRS enabled and active: YES (for firmware code only)
which is actually the case.
I double checked that, if the same kernel is used on a post-SkyLake
hardware, which on openSUSE uses IBRS as, even with this change, the
tool (this time correctly) reports:
* IBRS enabled and active: YES (for kernel and firmware code)
As we read sysctl values under the vmm hierarchy, the modules needs to be loaded,
so if not already done, we load it before testing for CVE-2018-3620 and CVE-2018-3646
currently, the script tries to use the wrong kernel image on Arch if an
alternative kernel (hardened, zen, or lts) is in use. Fortunately, all
the Arch kernel packages place a symlink to the kernel image as /usr/lib/modules/$(uname -r)/vmlinuz, so simply removing the guess for Arch fixes the issue.
Missing kernel information can cause all sorts of false positives or
negatives. This is worth at least a warning, and repeating immediately
following the status.
As it's seen in unmap_kernel_at_el0 (both the function definition
and its usage in arm64_features[]) from arch/arm64/kernel/cpufeature.c
the kernel reports this string:
CPU features: detected: Kernel page table isolation (KPTI)
or (before commit e0f6429dc1c0 ("arm64: cpufeature: Remove redundant "feature"
in reports")):
CPU features: detected feature: Kernel page table isolation (KPTI)
if KPTI is enabled on the system.
So on let's adjust check_variant3_linux() to make it grep these
strings if executed on an aarch64 platform.
Tested on a Cavium ThunderX2 machine.
Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
Use platomav's MCExtractor DB as the reference to decide whether our CPU microcode is the latest or not.
We have a builtin version of the DB in the script, but an updated version can be fetched and stored locally with --update-mcedb
* Add another location of Arch Linux ARM kernel
* Fix detection of CVE-2018-3615
We change the value of variantl1tf in the line directly before so its
value will never be "immune". Instead we can directly use the value of
variantl1tf to initialize variantl1tf_sgx.
* Fix cases where a CPU ucode version is not found in $procfs/cpuinfo.
When running whithin a virtual machine, it seems like $procfs/cpuinfo doesn't contain
a 'microcode' line, which triggers a script runtime error.
Fall back to '0x0' in this case, as other part of the script seems to already this
as a default value anyway.
* Double quote to prevent globbing and word splitting.
