Messages in this thread |  | | Subject | Re: [PATCH v2 1/7] sysfs/cpu: Add "Unknown" vulnerability state | | From | Jeremy Linton <> | | Date | Thu, 3 Jan 2019 10:46:53 -0600 |
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Hi,
On 01/03/2019 10:37 AM, Dave Martin wrote: > On Wed, Jan 02, 2019 at 06:49:15PM -0600, Jeremy Linton wrote: >> There is a lot of variation in the Arm ecosystem. Because of this, >> there exist possible cases where the kernel cannot authoritatively >> determine if a machine is vulnerable. >> >> Rather than guess the vulnerability status in cases where >> the mitigation is disabled or the firmware isn't responding >> correctly, we need to display an "Unknown" state. >> >> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Dave Hansen <dave.hansen@intel.com> >> Cc: Borislav Petkov <bp@alien8.de> >> Cc: David Woodhouse <dwmw@amazon.co.uk> >> --- >> Documentation/ABI/testing/sysfs-devices-system-cpu | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu >> index 9605dbd4b5b5..876103fddfa4 100644 >> --- a/Documentation/ABI/testing/sysfs-devices-system-cpu >> +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu >> @@ -495,6 +495,7 @@ Description: Information about CPU vulnerabilities >> "Not affected" CPU is not affected by the vulnerability >> "Vulnerable" CPU is affected and no mitigation in effect >> "Mitigation: $M" CPU is affected and mitigation $M is in effect >> + "Unknown" The kernel is unable to make a determination > > Do some of the "Unknown" cases arise from the vulnerability detection > code being compiled out of the kernel? >
Yes,
> I wonder whether at least the detection support should be mandatory. > sysfs is not very useful as a standard vulnerability reporting interface > unless we make best efforts to always populate it with real information. > > > Also, does "Unknown" convey anything beyond what is indicated by the > sysfs entry being omitted altogether?
I'm not sure about this one. I tend to think the "unknown" case encourages users that really want an answer to dig deeper and call their hardware/os/whoever to get an answer. I would tend to think that if the entry is missing it would tend to encourage the behavior that Greg KH mentions where the user assumes "hey the system doesn't have a sysfs entry for $VUNLERABILITY, that probably means that its not possible on the architecture".
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