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@xxxxxxxxxxx
