PM / Sleep: Require CAP_BLOCK_SUSPEND to use wake_lock/wake_unlock

Require processes wanting to use the wake_lock/wake_unlock sysfs
files to have the CAP_BLOCK_SUSPEND capability, which also is
required for the eventpoll EPOLLWAKEUP flag to be effective, so that
all interfaces related to blocking autosleep depend on the same
capability.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@vger.kernel.org
Acked-by: Michael Kerrisk <mtk.man-pages@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/power/wakelock.c b/kernel/power/wakelock.c
index c8fba3380076..8f50de394d22 100644
--- a/kernel/power/wakelock.c
+++ b/kernel/power/wakelock.c
@@ -9,6 +9,7 @@
  * manipulate wakelocks on Android.
  */
 
+#include <linux/capability.h>
 #include <linux/ctype.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -188,6 +189,9 @@ int pm_wake_lock(const char *buf)
         size_t len;
         int ret = 0;
 
+        if (!capable(CAP_BLOCK_SUSPEND))
+                return -EPERM;
+
         while (*str && !isspace(*str))
                 str++;
 
@@ -231,6 +235,9 @@ int pm_wake_unlock(const char *buf)
         size_t len;
         int ret = 0;
 
+        if (!capable(CAP_BLOCK_SUSPEND))
+                return -EPERM;
+
         len = strlen(buf);
         if (!len)
                 return -EINVAL;