[PATCH 11/12] asus-wmi: Restrict debugfs interface when trusted_kernel is true

From: Matthew Garrett
Date: Wed Feb 26 2014 - 15:16:39 EST


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 trusted_kernel is true.

Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
---
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 c5e082f..4c1000b 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -46,6 +46,7 @@
#include <linux/platform_device.h>
#include <linux/thermal.h>
#include <linux/acpi.h>
+#include <linux/security.h>
#include <acpi/video.h>

#include "asus-wmi.h"
@@ -1595,6 +1596,9 @@ static int show_dsts(struct seq_file *m, void *data)
int err;
u32 retval = -1;

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

if (err < 0)
@@ -1611,6 +1615,9 @@ static int show_devs(struct seq_file *m, void *data)
int err;
u32 retval = -1;

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

@@ -1635,6 +1642,9 @@ static int show_call(struct seq_file *m, void *data)
union acpi_object *obj;
acpi_status status;

+ if (get_trusted_kernel())
+ return -EPERM;
+
status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
1, asus->debug.method_id,
&input, &output);
--
1.8.5.3

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