Hi Mpe, Thanks for reviewing this patch. My responses below:
Michael Ellerman <m...@ellerman.id.au> writes: > Vaibhav Jain <vaib...@linux.ibm.com> writes: >> The newly introduced 'perf_stats' attribute uses the default access >> mode of 0444 letting non-root users access performance stats of an >> nvdimm and potentially force the kernel into issuing large number of >> expensive HCALLs. Since the information exposed by this attribute >> cannot be cached hence its better to ward of access to this attribute >> from non-root users. >> >> Hence this patch updates the access-mode of 'perf_stats' sysfs >> attribute file to 0400 to make it only readable to root-users. > > Or should we ratelimit it? Ideal consumers of this data will be users with CAP_PERFMON or CAP_SYS_ADMIN. Also they need up-to-date values for these performance stats as these values can be time sensitive. So rate limiting may not be a complete solution since a user running 'perf' might be throttled by another user who is simply reading the sysfs file contents. So instead of setting attribute mode to 0400, will add a check for 'perfmon_capable()' in perf_stats_show() denying read access to users without CAP_PERFMON or CAP_SYS_ADMIN. > Fixes: ?? Right. I will add this in v2. > >> Reported-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> >> Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com> > > cheers > -- Cheers ~ Vaibhav
