[PATCH 11/12] asus-wmi: Restrict debugfs interface when securelevel is set

Matthew Garrett
2013-09-09T16:00:56Z

We have no way of validating what all of the Asus WMI methods do on a
given machine, and there's a risk that some will allow hardware state to
be manipulated in such a way that arbitrary code can be executed in the
kernel. Prevent that if securelevel is set.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
---
drivers/platform/x86/asus-wmi.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 19c313b..1a9847b 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -45,6 +45,7 @@
#include <linux/seq_file.h>
#include <linux/platform_device.h>
#include <linux/thermal.h>
+#include <linux/security.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/video.h>
@@ -1618,6 +1619,9 @@ static int show_dsts(struct seq_file *m, void *data)
int err;
u32 retval = -1;

+ if (get_securelevel() > 0)
+ return -EPERM;
+
err = asus_wmi_get_devstate(asus, asus->debug.dev_id, &retval);

if (err < 0)
@@ -1634,6 +1638,9 @@ static int show_devs(struct seq_file *m, void *data)
int err;
u32 retval = -1;

+ if (get_securelevel() > 0)
+ return -EPERM;
+
err = asus_wmi_set_devstate(asus->debug.dev_id, asus->debug.ctrl_param,
&retval);

@@ -1658,6 +1665,9 @@ static int show_call(struct seq_file *m, void *data)
union acpi_object *obj;
acpi_status status;

+ if (get_securelevel() > 0)
+ return -EPERM;
+
status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
1, asus->debug.method_id,
&input, &output);
--
1.8.3.1