On Tue, 28 Jan 2020, Alexey Budankov wrote: > > 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 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 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 capability. > > Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> > --- > drivers/perf/arm_spe_pmu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > Acked-by: James Morris <jamorris@xxxxxxxxxxxxxxxxxxx> > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 4e4984a55cd1..5dff81bc3324 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -274,7 +274,7 @@ static u64 arm_spe_event_to_pmscr(struct perf_event *event) > if (!attr->exclude_kernel) > reg |= BIT(SYS_PMSCR_EL1_E1SPE_SHIFT); > > - if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && capable(CAP_SYS_ADMIN)) > + if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && perfmon_capable()) > reg |= BIT(SYS_PMSCR_EL1_CX_SHIFT); > > return reg; > @@ -700,7 +700,7 @@ static int arm_spe_pmu_event_init(struct perf_event *event) > return -EOPNOTSUPP; > > reg = arm_spe_event_to_pmscr(event); > - if (!capable(CAP_SYS_ADMIN) && > + if (!perfmon_capable() && > (reg & (BIT(SYS_PMSCR_EL1_PA_SHIFT) | > BIT(SYS_PMSCR_EL1_CX_SHIFT) | > BIT(SYS_PMSCR_EL1_PCT_SHIFT)))) > -- James Morris <jmorris@xxxxxxxxx>
