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Date:   Wed, 29 Jan 2020 08:16:40 +1100 (AEDT)
From:   James Morris <jmorris@namei.org>
To:     Alexey Budankov <alexey.budankov@linux.intel.com>
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Subject: Re: [PATCH v6 03/10] perf/core: open access to probes for CAP_PERFMON
 privileged process
In-Reply-To: <6cdc10f2-31e5-6d71-7d71-c6b5250b74f1@linux.intel.com>
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References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> <6cdc10f2-31e5-6d71-7d71-c6b5250b74f1@linux.intel.com>
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On Tue, 28 Jan 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>
> ---
>  kernel/events/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)


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


-- 
James Morris
<jmorris@namei.org>