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 _ setting: > + > +**-1**: > + Impose no *scope* and *access* restrictions on using PCL performance > + monitoring. Per-user per-cpu perf_event_mlock_kb _ 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 _ 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 _ , _ . that ** crud is unreadable. http://email@example.com
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