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Date: Mon, 19 Nov 2018 11:33:37 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Kees Cook <keescook@...omium.org>,
Jann Horn <jannh@...gle.com>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Andi Kleen <ak@...ux.intel.com>, Jonatan Corbet <corbet@....net>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Tvrtko Ursulin <tursulin@...ulin.net>,
linux-kernel <linux-kernel@...r.kernel.org>,
kernel-hardening@...ts.openwall.com, linux-doc@...r.kernel.org
Subject: Re: [PATCH v1 2/2]: Documentation/admin-guide: introduce
perf-security.rst file
On Mon, Nov 19, 2018 at 08:42:52AM +0300, Alexey Budankov wrote:
>
> Implement initial version of perf-security.rst documentation file
> initially covering security concerns related to PCL/Perf performance
> monitoring in multiuser environments.
Ditch the PCL thing. That's not a term used anywhere in the kernel.
Also:
> +PCL/Perf unprivileged users
> +---------------------------
> +
> +PCL/Perf *scope* and *access* control for unprivileged processes is governed by
> +perf_event_paranoid [2]_ setting:
> +
> +**-1**:
> + Impose no *scope* and *access* restrictions on using PCL performance
> + monitoring. Per-user per-cpu perf_event_mlock_kb [2]_ locking limit is
> + ignored when allocating memory buffers for storing performance data.
> + This is the least secure mode since allowed monitored *scope* is
> + maximized and no PCL specific limits are imposed on *resources*
> + allocated for performance monitoring.
> +
> +**>=0**:
> + *scope* includes per-process and system wide performance monitoring
> + but excludes raw tracepoints and ftrace function tracepoints monitoring.
> + CPU and system events happened when executing either in user or
> + in kernel space can be monitored and captured for later analysis.
> + Per-user per-cpu perf_event_mlock_kb locking limit is imposed but
> + ignored for unprivileged processes with CAP_IPC_LOCK [6]_ capability.
> +
> +**>=1**:
> + *scope* includes per-process performance monitoring only and excludes
> + system wide performance monitoring. CPU and system events happened when
> + executing either in user or in kernel space can be monitored and
> + captured for later analysis. Per-user per-cpu perf_event_mlock_kb
> + locking limit is imposed but ignored for unprivileged processes with
> + CAP_IPC_LOCK capability.
> +
> +**>=2**:
> + *scope* includes per-process performance monitoring only. CPU and system
> + events happened when executing in user space only can be monitored and
> + captured for later analysis. Per-user per-cpu perf_event_mlock_kb
> + locking limit is imposed but ignored for unprivileged processes with
> + CAP_IPC_LOCK capability.
> +
> +**>=3**:
> + Restrict *access* to PCL performance monitoring for unprivileged processes.
> + This is the default on Debian and Android [7]_ , [8]_ .
that ** crud is unreadable.
http://lkml.kernel.org/r/094556ca-ea87-9c4a-2115-600d2833fb2a@darmarit.de
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