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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Alexey Budankov <alexey.budankov@linux.intel.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
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        Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH v5 01/10] capabilities: introduce CAP_PERFMON to kernel and user space
In-Reply-To: <2b608e26-354b-3df9-aea9-58e56dc0c5e5@linux.intel.com>
Date:   Fri, 07 Feb 2020 11:38:11 +0000
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Alexey Budankov <alexey.budankov@linux.intel.com> 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.

Thanks,

        tglx