From: Len Brown <len.brown@intel.com>
Date: Sat, 17 Oct 2020 16:06:48 +0200
Subject: [PATCH] powercap: Restrict energy meter to root access
Git-commit: 949dd0104c496fa7c14991a23c03c62e44637e71
Patch-mainline: v5.10-rc4
References: bsc#1170415 CVE-2020-8694

Remove non-privileged user access to power data contained in
/sys/class/powercap/intel_rapl/*/energy_uj.

Non-privileged users currently have read access to power data
and can use this data to form a security attack. Some privileged
drivers/applications need read access to this data, but don't expose it
to non-privileged users.

For example, thermald uses this data to ensure that power management
works correctly. Thus removing non-privileged access is preferred
over completely disabling this power reporting capability with
CONFIG_INTEL_RAPL=n.

Fixes: 95677a9a3847 ("PowerCap: Fix mode for energy counter")
Signed-off-by: Len Brown <len.brown@intel.com>
Acked-by: Borislav Petkov <bp@suse.de>
---
 drivers/powercap/powercap_sys.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c
index f808c5fa9838..3f0b8e2ef3d4 100644
--- a/drivers/powercap/powercap_sys.c
+++ b/drivers/powercap/powercap_sys.c
@@ -367,9 +367,9 @@ static void create_power_zone_common_attributes(
 					&dev_attr_max_energy_range_uj.attr;
 	if (power_zone->ops->get_energy_uj) {
 		if (power_zone->ops->reset_energy_uj)
-			dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUGO;
+			dev_attr_energy_uj.attr.mode = S_IWUSR | S_IRUSR;
 		else
-			dev_attr_energy_uj.attr.mode = S_IRUGO;
+			dev_attr_energy_uj.attr.mode = S_IRUSR;
 		power_zone->zone_dev_attrs[count++] =
 					&dev_attr_energy_uj.attr;
 	}
-- 
2.21.0