asus-wmi: Restrict debugfs interface when the kernel is locked down

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>
Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
cc: acpi4asus-user@lists.sourceforge.net
cc: platform-driver-x86@vger.kernel.org

Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0014-asus-wmi-Restrict-debugfs-interface-when-the-kernel-.patch

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index a32c5c00e0e7bdf9868e81c655f30f8fb6cc34be..1f6e68f0b646d213322edd35efb21d1f3132ab0b 100644 (file)
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1968,6 +1968,9 @@ 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)
@@ -1984,6 +1987,9 @@ 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);
 
@@ -2008,6 +2014,9 @@ 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);