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Date:   Wed, 19 Feb 2020 06:22:40 +1100 (AEDT)
From:   James Morris <jmorris@namei.org>
To:     Alexey Budankov <alexey.budankov@linux.intel.com>
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Subject: Re: [PATCH v7 03/12] perf/core: open access to probes for CAP_PERFMON
 privileged process
In-Reply-To: <3364fa26-b5d1-1808-aaee-c057f26e0eb4@linux.intel.com>
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References: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com> <3364fa26-b5d1-1808-aaee-c057f26e0eb4@linux.intel.com>
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On Mon, 17 Feb 2020, Alexey Budankov wrote:

> 
> Open access to monitoring via kprobes and uprobes and eBPF tracing for
> CAP_PERFMON privileged process. Providing the access under CAP_PERFMON
> capability singly, without the rest of CAP_SYS_ADMIN credentials,
> excludes chances to misuse the credentials and makes operation more
> secure.
> 
> perf kprobes and uprobes are used by ftrace and eBPF. perf probe uses
> ftrace to define new kprobe events, and those events are treated as
> tracepoint events. eBPF defines new probes via perf_event_open interface
> and then the probes are used in eBPF tracing.
> 
> CAP_PERFMON implements the principal of least privilege for performance
> monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
> principle of least privilege: A security design principle that states
> that a process or program be granted only those privileges (e.g.,
> capabilities) necessary to accomplish its legitimate function, and only
> for the time that such privileges are actually required)
> 
> For backward compatibility reasons access to perf_events subsystem
> remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
> usage for secure perf_events monitoring is discouraged with respect to
> CAP_PERFMON capability.
> 
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>


Reviewed-by: James Morris <jamorris@linux.microsoft.com>


-- 
James Morris
<jmorris@namei.org>