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powerpc/papr_scm: Limit the readability of 'perf_stats' sysfs attribute

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The newly introduced 'perf_stats' attribute uses the default access
mode of 0444, allowing non-root users to access performance stats of
an nvdimm and potentially force the kernel into issuing a large number
of expensive hypercalls. Since the information exposed by this
attribute cannot be cached it is better to ward off access to this
attribute from users who don't need to access to these performance
statistics.

Hence update the access mode of 'perf_stats' attribute to be only
readable by root users.

Fixes: 2d02bf835e ("powerpc/papr_scm: Fetch nvdimm performance stats from PHYP")
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200907110540.21349-1-vaibhav@linux.ibm.com
This commit is contained in:
Vaibhav Jain 2020-09-07 16:35:40 +05:30 committed by Michael Ellerman
parent 1d3ee7df00
commit 0460534b53
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/platforms/pseries/papr_scm.c
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@ -822,7 +822,7 @@ static ssize_t perf_stats_show(struct device *dev,
kfree(stats);
return rc ? rc : seq_buf_used(&s);
}
DEVICE_ATTR_RO(perf_stats);
DEVICE_ATTR_ADMIN_RO(perf_stats);
static ssize_t flags_show(struct device *dev,
struct device_attribute *attr, char *buf)