[PATCH v5 05/10] drm/i915/perf: open access for CAP_PERFMON privileged process

[Alexey Budankov]

Open access to i915_perf monitoring for CAP_PERFMON privileged processes.
For backward compatibility reasons access to i915_perf subsystem remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for
secure i915_perf monitoring is discouraged with respect to CAP_PERFMON
capability. Providing the access under CAP_PERFMON capability singly,
without the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse
the credentials and makes operations more secure.

Signed-off-by: Alexey Budankov <alexey.budan...@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_perf.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 2ae14bc14931..d89347861b7d 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -3375,10 +3375,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf,
        /* Similar to perf's kernel.perf_paranoid_cpu sysctl option
         * we check a dev.i915.perf_stream_paranoid sysctl option
         * to determine if it's ok to access system wide OA counters
-        * without CAP_SYS_ADMIN privileges.
+        * without CAP_PERFMON or CAP_SYS_ADMIN privileges.
         */
        if (privileged_op &&
-           i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+           i915_perf_stream_paranoid && !perfmon_capable()) {
                DRM_DEBUG("Insufficient privileges to open i915 perf stream\n");
                ret = -EACCES;
                goto err_ctx;
@@ -3571,9 +3571,8 @@ static int read_properties_unlocked(struct i915_perf 
*perf,
                        } else
                                oa_freq_hz = 0;
 
-                       if (oa_freq_hz > i915_oa_max_sample_rate &&
-                           !capable(CAP_SYS_ADMIN)) {
-                               DRM_DEBUG("OA exponent would exceed the max 
sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without root 
privileges\n",
+                       if (oa_freq_hz > i915_oa_max_sample_rate && 
!perfmon_capable()) {
+                               DRM_DEBUG("OA exponent would exceed the max 
sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without 
CAP_PERFMON or CAP_SYS_ADMIN privileges\n",
                                          i915_oa_max_sample_rate);
                                return -EACCES;
                        }
@@ -3994,7 +3993,7 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, 
void *data,
                return -EINVAL;
        }
 
-       if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+       if (i915_perf_stream_paranoid && !perfmon_capable()) {
                DRM_DEBUG("Insufficient privileges to add i915 OA config\n");
                return -EACCES;
        }
@@ -4141,7 +4140,7 @@ int i915_perf_remove_config_ioctl(struct drm_device *dev, 
void *data,
                return -ENOTSUPP;
        }
 
-       if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+       if (i915_perf_stream_paranoid && !perfmon_capable()) {
                DRM_DEBUG("Insufficient privileges to remove i915 OA config\n");
                return -EACCES;
        }
-- 
2.20.1