[PATCH 4.9 065/138] libnvdimm, pfn: make resource attribute only readable by root

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@xxxxxxxxx>

commit 26417ae4fc6108f8db436f24108b08f68bdc520e upstream.

For the same reason that /proc/iomem returns 0's for non-root readers
and acpi tables are root-only, make the 'resource' attribute for pfn
devices only readable by root. Otherwise we disclose physical address
information.

Fixes: f6ed58c70d14 ("libnvdimm, pfn: 'resource'-address and 'size'...")
Reported-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/nvdimm/pfn_devs.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -270,8 +270,16 @@ static struct attribute *nd_pfn_attribut
 	NULL,
 };
 
+static umode_t pfn_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	if (a == &dev_attr_resource.attr)
+		return 0400;
+	return a->mode;
+}
+
 struct attribute_group nd_pfn_attribute_group = {
 	.attrs = nd_pfn_attributes,
+	.is_visible = pfn_visible,
 };
 
 static const struct attribute_group *nd_pfn_attribute_groups[] = {