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L1TF/Linux: Fix "running an hypervisor" detection via sysfs

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If we can look in `/sys/devices/system/cpu/vulnerabilities/l1tf`, and
we find 'VMX' in it, it means we can run KVM guests, and hence we are
running as an hypervisor.

Right now, on a system with VMX enabled, with KVM guests running, and
booted with "l1tf=off", I see this:
`
  CVE-2018-3646 aka 'Foreshadow-NG (VMM), L1 terminal fault'
  * Information from the /sys interface: VMX: vulnerable
  * This system is a host running a hypervisor:  NO
  ... ... ...
    * L1D flush enabled:  NO
  > STATUS:  NOT VULNERABLE  (this system is not running a hypervisor)
`
Which is wrong.

In fact, as said, guests are running, so we are an hypervisor,
and with "l1tf=off" (and hence L1D flush disabled) we are vulnerable.
This commit is contained in:
Dario Faggioli
2019-04-18 17:22:44 +02:00
parent 2cfae92cb0
commit 5e83e2cfa4
1 changed files with 7 additions and 1 deletions
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8
spectre-meltdown-checker.sh
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@@ -3785,9 +3785,15 @@ check_CVE_2018_3646_linux()
msg=''
l1d_mode=-1
has_vmm=$opt_vmm
if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/l1tf" 'VMX:.*' silent; then
# if we can use /sys, and it has 'VMX', we are can run VMs
if [ "$opt_vmm" != 0 ]; then
has_vmm=1;
fi
fi
if [ "$opt_sysfs_only" != 1 ]; then
_info_nol "* This system is a host running a hypervisor: "
has_vmm=$opt_vmm
if [ "$has_vmm" = -1 ]; then
# Assumed to be running on bare metal unless evidence of vm is found.
has_vmm=0