On Thu, Apr 02, 2020 at 11:47:35AM +0300, Alexey Budankov wrote: > > Extend error messages to mention CAP_PERFMON capability as an option > to substitute CAP_SYS_ADMIN capability for secure system performance > monitoring and observability operations. Make perf_event_paranoid_check() > and __cmd_ftrace() to be aware of CAP_PERFMON capability. > > 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 <[email protected]> > Reviewed-by: James Morris <[email protected]>
Acked-by: Jiri Olsa <[email protected]> thanks, jirka > --- > tools/perf/builtin-ftrace.c | 5 +++-- > tools/perf/design.txt | 3 ++- > tools/perf/util/cap.h | 4 ++++ > tools/perf/util/evsel.c | 10 +++++----- > tools/perf/util/util.c | 1 + > 5 files changed, 15 insertions(+), 8 deletions(-) > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index d5adc417a4ca..55eda54240fb 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -284,10 +284,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int > argc, const char **argv) > .events = POLLIN, > }; > > - if (!perf_cap__capable(CAP_SYS_ADMIN)) { > + if (!(perf_cap__capable(CAP_PERFMON) || > + perf_cap__capable(CAP_SYS_ADMIN))) { > pr_err("ftrace only works for %s!\n", > #ifdef HAVE_LIBCAP_SUPPORT > - "users with the SYS_ADMIN capability" > + "users with the CAP_PERFMON or CAP_SYS_ADMIN capability" > #else > "root" > #endif > diff --git a/tools/perf/design.txt b/tools/perf/design.txt > index 0453ba26cdbd..a42fab308ff6 100644 > --- a/tools/perf/design.txt > +++ b/tools/perf/design.txt > @@ -258,7 +258,8 @@ gets schedule to. Per task counters can be created by any > user, for > their own tasks. > > A 'pid == -1' and 'cpu == x' counter is a per CPU counter that counts > -all events on CPU-x. Per CPU counters need CAP_SYS_ADMIN privilege. > +all events on CPU-x. Per CPU counters need CAP_PERFMON or CAP_SYS_ADMIN > +privilege. > > The 'flags' parameter is currently unused and must be zero. > > diff --git a/tools/perf/util/cap.h b/tools/perf/util/cap.h > index 051dc590ceee..ae52878c0b2e 100644 > --- a/tools/perf/util/cap.h > +++ b/tools/perf/util/cap.h > @@ -29,4 +29,8 @@ static inline bool perf_cap__capable(int cap __maybe_unused) > #define CAP_SYSLOG 34 > #endif > > +#ifndef CAP_PERFMON > +#define CAP_PERFMON 38 > +#endif > + > #endif /* __PERF_CAP_H */ > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index 816d930d774e..2696922f06bc 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -2507,14 +2507,14 @@ int perf_evsel__open_strerror(struct evsel *evsel, > struct target *target, > "You may not have permission to collect %sstats.\n\n" > "Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n" > "which controls use of the performance events system by\n" > - "unprivileged users (without CAP_SYS_ADMIN).\n\n" > + "unprivileged users (without CAP_PERFMON or > CAP_SYS_ADMIN).\n\n" > "The current value is %d:\n\n" > " -1: Allow use of (almost) all events by all users\n" > " Ignore mlock limit after perf_event_mlock_kb without > CAP_IPC_LOCK\n" > - ">= 0: Disallow ftrace function tracepoint by users without > CAP_SYS_ADMIN\n" > - " Disallow raw tracepoint access by users without > CAP_SYS_ADMIN\n" > - ">= 1: Disallow CPU event access by users without > CAP_SYS_ADMIN\n" > - ">= 2: Disallow kernel profiling by users without > CAP_SYS_ADMIN\n\n" > + ">= 0: Disallow ftrace function tracepoint by users without > CAP_PERFMON or CAP_SYS_ADMIN\n" > + " Disallow raw tracepoint access by users without > CAP_SYS_PERFMON or CAP_SYS_ADMIN\n" > + ">= 1: Disallow CPU event access by users without CAP_PERFMON > or CAP_SYS_ADMIN\n" > + ">= 2: Disallow kernel profiling by users without CAP_PERFMON > or CAP_SYS_ADMIN\n\n" > "To make this setting permanent, edit /etc/sysctl.conf too, > e.g.:\n\n" > " kernel.perf_event_paranoid = -1\n" , > target->system_wide ? "system-wide " : "", > diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c > index d707c9624dd9..37a9492edb3e 100644 > --- a/tools/perf/util/util.c > +++ b/tools/perf/util/util.c > @@ -290,6 +290,7 @@ int perf_event_paranoid(void) > bool perf_event_paranoid_check(int max_level) > { > return perf_cap__capable(CAP_SYS_ADMIN) || > + perf_cap__capable(CAP_PERFMON) || > perf_event_paranoid() <= max_level; > } > > -- > 2.24.1 > _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
