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    SubjectRe: [PATCH 15/24] asus-wmi: Restrict debugfs interface when the kernel is locked down
    On Wed, Apr 5, 2017 at 11:16 PM, David Howells <dhowells@redhat.com> wrote:
    > 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.

    > + if (kernel_is_locked_down())
    > + return -EPERM;

    It looks a bit fragile when responsility of whatever reasons kernel
    can't serve become a driver burden.
    Can we fix this in debugfs framework instead?

    > +
    > err = asus_wmi_get_devstate(asus, asus->debug.dev_id, &retval);
    >
    > if (err < 0)
    > @@ -1916,6 +1919,9 @@ static int show_devs(struct seq_file *m, void *data)
    > int err;
    > u32 retval = -1;
    >
    > + if (kernel_is_locked_down())
    > + return -EPERM;
    > +
    > err = asus_wmi_set_devstate(asus->debug.dev_id, asus->debug.ctrl_param,
    > &retval);
    >
    > @@ -1940,6 +1946,9 @@ static int show_call(struct seq_file *m, void *data)
    > union acpi_object *obj;
    > acpi_status status;
    >
    > + if (kernel_is_locked_down())
    > + return -EPERM;
    > +
    > status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
    > 1, asus->debug.method_id,
    > &input, &output);
    >



    --
    With Best Regards,
    Andy Shevchenko

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