Re: [PATCH v5 01/10] capabilities: introduce CAP_PERFMON to kernel and user space

Alexey Budankov <[email protected]> Fri, 7 Feb 2020 16:39:12 +0300
Newsgroups gmane.linux.kernel,gmane.linux.kernel.lsm,gmane.comp.freedesktop.xorg.drivers.intel,gmane.linux.ports.parisc,gmane.linux.ports.ppc64.devel,gmane.linux.ports.arm.kernel,gmane.linux.kernel.perf.user,gmane.linux.oprofile
Organization Intel Corp.
Message-ID <[email protected]>
On 07.02.2020 14:38, Thomas Gleixner wrote:
> Alexey Budankov <[email protected]> writes:
>> On 22.01.2020 17:25, Alexey Budankov wrote:
>>> On 22.01.2020 17:07, Stephen Smalley wrote:
>>>>> It keeps the implementation simple and readable. The implementation is more
>>>>> performant in the sense of calling the API - one capable() call for CAP_PERFMON
>>>>> privileged process.
>>>>>
>>>>> Yes, it bloats audit log for CAP_SYS_ADMIN privileged and unprivileged processes,
>>>>> but this bloating also advertises and leverages using more secure CAP_PERFMON
>>>>> based approach to use perf_event_open system call.
>>>>
>>>> I can live with that.  We just need to document that when you see
>>>> both a CAP_PERFMON and a CAP_SYS_ADMIN audit message for a process,
>>>> try only allowing CAP_PERFMON first and see if that resolves the
>>>> issue.  We have a similar issue with CAP_DAC_READ_SEARCH versus
>>>> CAP_DAC_OVERRIDE.
>>>
>>> perf security [1] document can be updated, at least, to align and document 
>>> this audit logging specifics.
>>
>> And I plan to update the document right after this patch set is accepted.
>> Feel free to let me know of the places in the kernel docs that also
>> require update w.r.t CAP_PERFMON extension.
> 
> The documentation update wants be part of the patch set and not planned
> to be done _after_ the patch set is merged.

Well, accepted. It is going to make patches #11 and beyond.

Thanks,
Alexey

> 
> Thanks,
> 
>         tglx
>