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Subject[PATCH 13/27] asus-wmi: Restrict debugfs interface when the kernel is locked down
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From: Matthew Garrett <matthew.garrett@nebula.com>

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, circumventing module loading restrictions. Prevent that if the
kernel is locked down.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: acpi4asus-user@lists.sourceforge.net
cc: platform-driver-x86@vger.kernel.org
---

drivers/platform/x86/asus-wmi.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 48e1541dc8d4..ef5587469337 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1905,6 +1905,9 @@ static int show_dsts(struct seq_file *m, void *data)
int err;
u32 retval = -1;

+ if (kernel_is_locked_down("Asus WMI"))
+ return -EPERM;
+
err = asus_wmi_get_devstate(asus, asus->debug.dev_id, &retval);

if (err < 0)
@@ -1921,6 +1924,9 @@ static int show_devs(struct seq_file *m, void *data)
int err;
u32 retval = -1;

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

@@ -1945,6 +1951,9 @@ static int show_call(struct seq_file *m, void *data)
union acpi_object *obj;
acpi_status status;

+ if (kernel_is_locked_down("Asus WMI"))
+ return -EPERM;
+
status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
0, asus->debug.method_id,
&input, &output);
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