From: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> Open access to i915_perf 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 principle 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 i915_events subsystem remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for secure i915_events monitoring is discouraged with respect to CAP_PERFMON capability. Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> Reviewed-by: James Morris <jamorris@xxxxxxxxxxxxxxxxxxx> Acked-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: Igor Lubashev <ilubashe@xxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Serge Hallyn <serge@xxxxxxxxxx> Cc: Song Liu <songliubraving@xxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx Cc: linux-doc@xxxxxxxxxxxxxxx Cc: linux-man@xxxxxxxxxxxxxxx Cc: linux-security-module@xxxxxxxxxxxxxxx Cc: selinux@xxxxxxxxxxxxxxx Link: http://lore.kernel.org/lkml/e3e3292f-f765-ea98-e59c-fbe2db93fd34@xxxxxxxxxxxxxxx Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> --- 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 3b6b913bd27a..f59265cebe1e 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -3402,10 +3402,10 @@ 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; @@ -3598,9 +3598,8 @@ 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; } @@ -4021,7 +4020,7 @@ 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; } @@ -4168,7 +4167,7 @@ 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; } -- 2.21.1
