[PATCH v7 07/12] powerpc/perf: open access for CAP_PERFMON privileged process

From: Alexey Budankov
Date: Mon Feb 17 2020 - 03:10:24 EST

Open access to monitoring 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.

CAP_PERFMON implements the principal of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e
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 the monitoring remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage
for secure monitoring is discouraged with respect to CAP_PERFMON

Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
arch/powerpc/perf/imc-pmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index cb50a9e1fd2d..e837717492e4 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -898,7 +898,7 @@ static int thread_imc_event_init(struct perf_event *event)
if (event->attr.type != event->pmu->type)
return -ENOENT;

- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;

/* Sampling not supported */
@@ -1307,7 +1307,7 @@ static int trace_imc_event_init(struct perf_event *event)
if (event->attr.type != event->pmu->type)
return -ENOENT;

- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;

/* Return if this is a couting event */