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Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot error region

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  Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot  error region Kees Cook <keescook@google.com> - 2017-08-29 02:20 +0200
    Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to  boot error region "Luck, Tony" <tony.luck@intel.com> - 2017-08-29 18:00 +0200

#1722072 — Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot error region

On Wed, Aug 23, 2017 at 7:56 AM, Luck, Tony <tony.luck@intel.com> wrote:
>>> Should this not also have a capability check. Assuming file permissions
>>> are sufficient for grabbing a chunk of system memory holding error
>>> info doesn't seem too scary but it's at odds with a lot of other cases ?
>>
>> At least one of those other cases (pstore) added a capability check and now regret
>> it.  There's a thread on reverting it. Look for:
>>
>>   Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"
>
> Here's at least part of that thread:
>
> https://marc.info/?l=linux-kernel&m=150301241114262&w=2
>
> Kees: you were OK with removing the capability check from pstore, right?

Yeah, as long as there is comparable protections.

-Kees

-- 
Kees Cook
Pixel Security

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#1722581 — Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot error region

On Mon, Aug 28, 2017 at 05:10:33PM -0700, Kees Cook wrote:
> On Wed, Aug 23, 2017 at 7:56 AM, Luck, Tony <tony.luck@intel.com> wrote:
> >>> Should this not also have a capability check. Assuming file permissions
> >>> are sufficient for grabbing a chunk of system memory holding error
> >>> info doesn't seem too scary but it's at odds with a lot of other cases ?
> >>
> >> At least one of those other cases (pstore) added a capability check and now regret
> >> it.  There's a thread on reverting it. Look for:
> >>
> >>   Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"
> >
> > Here's at least part of that thread:
> >
> > https://marc.info/?l=linux-kernel&m=150301241114262&w=2
> >
> > Kees: you were OK with removing the capability check from pstore, right?
> 
> Yeah, as long as there is comparable protections.

File system permission protection is "0400":

	# ls -al /sys/firmware/acpi/tables/data
	total 0
	drwxr-xr-x. 2 root root     0 Aug 28 14:13 .
	drwxr-xr-x. 4 root root     0 Aug 28 14:10 ..
	-r--------. 1 root root 32768 Aug 28 14:13 BERT

-Tony

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