linux-kernel - [PATCH 3/3] libnvdimm, pfn: make 'resource' attribute only readable by root

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Date:   Tue, 26 Sep 2017 15:57:26 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH 3/3] libnvdimm,
 pfn: make 'resource' attribute only readable by root

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'...")
Cc: <stable@...r.kernel.org>
Reported-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/nvdimm/pfn_devs.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 9576c444f0ab..65cc171c721d 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -282,8 +282,16 @@ static struct attribute *nd_pfn_attributes[] = {
 	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[] = {