Exporting USB device ids from the kernel

Exporting USB device ids from the kernel

[Andrey Konovalov]

Hi Greg and Alan,

For USB fuzzing it would be nice to be able to export usb_device_id
structs from the kernel to facilitate the fuzzer with generating USB
descriptors that match to actual drivers. The same is required for
hid_device_id structs, since those are matched separately by the
usbhid driver (are there other cases like this?).

Currently I have a hacky patch [1] that walks all drivers for USB and
HID buses and then prints all device ids for those drivers into the
kernel log. Those are manually parsed and built into the fuzzer [2]
and then used to generate USB descriptors [3].

I'm thinking of making a proper patch that will add a debugfs entry
like usb/drivers (and usb/hid_drivers?), that can be read to get
USB/HID device ids for all loaded drivers. Would that be acceptable?
Or should I use some other interface to do that?

Thanks!

[1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch
[2] https://github.com/google/syzkaller/blob/master/sys/linux/init_vusb_ids.go
[3] https://github.com/google/syzkaller/blob/master/sys/linux/init_vusb.go

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Fri, Nov 15, 2019 at 03:25:38PM +0100, Andrey Konovalov wrote:
> Hi Greg and Alan,
> 
> For USB fuzzing it would be nice to be able to export usb_device_id
> structs from the kernel to facilitate the fuzzer with generating USB
> descriptors that match to actual drivers. The same is required for
> hid_device_id structs, since those are matched separately by the
> usbhid driver (are there other cases like this?).
> 
> Currently I have a hacky patch [1] that walks all drivers for USB and
> HID buses and then prints all device ids for those drivers into the
> kernel log. Those are manually parsed and built into the fuzzer [2]
> and then used to generate USB descriptors [3].

The kernel will spit out all device ids of all USB devices when found if
you have CONFIG_USB_ANNOUNCE_NEW_DEVICES enabled, if you want to parse
the log.

Otherwise, just walk usbfs or sysfs and get the ids there.  If you use
libusb you can do this with just a few lines of code, or worst case,
just implement the same thing on your own (like lsusb used to do).
Heck, just copy what lsusb does, or again worst case, parse the output
of it.

There's also 'lsusb.py' as part of usbutils that shows how to do this
from within python in userspace, and if you really want it, we also
export the whole raw usb descriptor is in sysfs as well, if you want to
not trust how the kernel parses it.

hope this helps,

greg k-h

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Fri, Nov 15, 2019 at 4:06 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Nov 15, 2019 at 03:25:38PM +0100, Andrey Konovalov wrote:
> > Hi Greg and Alan,
> >
> > For USB fuzzing it would be nice to be able to export usb_device_id
> > structs from the kernel to facilitate the fuzzer with generating USB
> > descriptors that match to actual drivers. The same is required for
> > hid_device_id structs, since those are matched separately by the
> > usbhid driver (are there other cases like this?).
> >
> > Currently I have a hacky patch [1] that walks all drivers for USB and
> > HID buses and then prints all device ids for those drivers into the
> > kernel log. Those are manually parsed and built into the fuzzer [2]
> > and then used to generate USB descriptors [3].
>
> The kernel will spit out all device ids of all USB devices when found if
> you have CONFIG_USB_ANNOUNCE_NEW_DEVICES enabled, if you want to parse
> the log.
>
> Otherwise, just walk usbfs or sysfs and get the ids there.  If you use
> libusb you can do this with just a few lines of code, or worst case,
> just implement the same thing on your own (like lsusb used to do).
> Heck, just copy what lsusb does, or again worst case, parse the output
> of it.
>
> There's also 'lsusb.py' as part of usbutils that shows how to do this
> from within python in userspace, and if you really want it, we also
> export the whole raw usb descriptor is in sysfs as well, if you want to
> not trust how the kernel parses it.
>
> hope this helps,

Either I misunderstand you or you misunderstood me. I don't want to
see IDs of devices that are connected. I want to see all of the IDs
for all of the devices that might be connected and bound to some
driver at some point in the future. Essentially I want to all IDs that
are passed to MODULE_DEVICE_TABLE(usb, ...) and
MODULE_DEVICE_TABLE(hid, ...). Is it possible to obtain those via
usbfs/sysfs?

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Fri, Nov 15, 2019 at 04:13:58PM +0100, Andrey Konovalov wrote:
> On Fri, Nov 15, 2019 at 4:06 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Fri, Nov 15, 2019 at 03:25:38PM +0100, Andrey Konovalov wrote:
> > > Hi Greg and Alan,
> > >
> > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > structs from the kernel to facilitate the fuzzer with generating USB
> > > descriptors that match to actual drivers. The same is required for
> > > hid_device_id structs, since those are matched separately by the
> > > usbhid driver (are there other cases like this?).
> > >
> > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > HID buses and then prints all device ids for those drivers into the
> > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > and then used to generate USB descriptors [3].
> >
> > The kernel will spit out all device ids of all USB devices when found if
> > you have CONFIG_USB_ANNOUNCE_NEW_DEVICES enabled, if you want to parse
> > the log.
> >
> > Otherwise, just walk usbfs or sysfs and get the ids there.  If you use
> > libusb you can do this with just a few lines of code, or worst case,
> > just implement the same thing on your own (like lsusb used to do).
> > Heck, just copy what lsusb does, or again worst case, parse the output
> > of it.
> >
> > There's also 'lsusb.py' as part of usbutils that shows how to do this
> > from within python in userspace, and if you really want it, we also
> > export the whole raw usb descriptor is in sysfs as well, if you want to
> > not trust how the kernel parses it.
> >
> > hope this helps,
> 
> Either I misunderstand you or you misunderstood me. I don't want to
> see IDs of devices that are connected. I want to see all of the IDs
> for all of the devices that might be connected and bound to some
> driver at some point in the future. Essentially I want to all IDs that
> are passed to MODULE_DEVICE_TABLE(usb, ...) and
> MODULE_DEVICE_TABLE(hid, ...). Is it possible to obtain those via
> usbfs/sysfs?

Ah, no, that information is not directly there in sysfs, sorry.

But it is in the modules themselves, look at the output of 'modinfo' at
the "alias:" lines for "usb:" entries.

That is what modprobe uses to find out what module to load when a USB
device is reported by the system.  Same thing goes for any type of
device bus.

hope this helps,

greg k-h

Re: Exporting USB device ids from the kernel

[Alan Stern]

On Fri, 15 Nov 2019, Andrey Konovalov wrote:

> Hi Greg and Alan,
> 
> For USB fuzzing it would be nice to be able to export usb_device_id
> structs from the kernel to facilitate the fuzzer with generating USB
> descriptors that match to actual drivers. The same is required for
> hid_device_id structs, since those are matched separately by the
> usbhid driver (are there other cases like this?).
> 
> Currently I have a hacky patch [1] that walks all drivers for USB and
> HID buses and then prints all device ids for those drivers into the
> kernel log. Those are manually parsed and built into the fuzzer [2]
> and then used to generate USB descriptors [3].

There are so many different flags for those id structures, parsing and 
understanding them must be quite difficult.

> I'm thinking of making a proper patch that will add a debugfs entry
> like usb/drivers (and usb/hid_drivers?), that can be read to get
> USB/HID device ids for all loaded drivers. Would that be acceptable?
> Or should I use some other interface to do that?

I can't think of a better way to get the information from a running 
kernel.

There is another possibility, though.  If the drivers are built as 
modules, the information is already available to userspace tools via
depmod.  You could get it from the modules.dep.bin file.  This has the 
advantage that it will work even for drivers that aren't currently 
loaded.

Alan Stern

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Fri, 15 Nov 2019, Andrey Konovalov wrote:
>
> > Hi Greg and Alan,
> >
> > For USB fuzzing it would be nice to be able to export usb_device_id
> > structs from the kernel to facilitate the fuzzer with generating USB
> > descriptors that match to actual drivers. The same is required for
> > hid_device_id structs, since those are matched separately by the
> > usbhid driver (are there other cases like this?).
> >
> > Currently I have a hacky patch [1] that walks all drivers for USB and
> > HID buses and then prints all device ids for those drivers into the
> > kernel log. Those are manually parsed and built into the fuzzer [2]
> > and then used to generate USB descriptors [3].
>
> There are so many different flags for those id structures, parsing and
> understanding them must be quite difficult.
>
> > I'm thinking of making a proper patch that will add a debugfs entry
> > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > Or should I use some other interface to do that?
>
> I can't think of a better way to get the information from a running
> kernel.
>
> There is another possibility, though.  If the drivers are built as
> modules, the information is already available to userspace tools via
> depmod.  You could get it from the modules.dep.bin file.  This has the
> advantage that it will work even for drivers that aren't currently
> loaded.

This is the same thing Greg mentions above, right? Would this work for
drivers that are built into the kernel (as =y)?

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> >
> > > Hi Greg and Alan,
> > >
> > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > structs from the kernel to facilitate the fuzzer with generating USB
> > > descriptors that match to actual drivers. The same is required for
> > > hid_device_id structs, since those are matched separately by the
> > > usbhid driver (are there other cases like this?).
> > >
> > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > HID buses and then prints all device ids for those drivers into the
> > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > and then used to generate USB descriptors [3].
> >
> > There are so many different flags for those id structures, parsing and
> > understanding them must be quite difficult.
> >
> > > I'm thinking of making a proper patch that will add a debugfs entry
> > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > Or should I use some other interface to do that?
> >
> > I can't think of a better way to get the information from a running
> > kernel.
> >
> > There is another possibility, though.  If the drivers are built as
> > modules, the information is already available to userspace tools via
> > depmod.  You could get it from the modules.dep.bin file.  This has the
> > advantage that it will work even for drivers that aren't currently
> > loaded.
> 
> This is the same thing Greg mentions above, right?

Yes.

> Would this work for drivers that are built into the kernel (as =y)?

No, sorry.  There has not been any need to export that information to
userspace as nothing has ever needed that.

The only reason we exported that at all was to allow modules to
auto-load to handle the device.

thanks,

greg k-h

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > >
> > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > >
> > > > Hi Greg and Alan,
> > > >
> > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > descriptors that match to actual drivers. The same is required for
> > > > hid_device_id structs, since those are matched separately by the
> > > > usbhid driver (are there other cases like this?).
> > > >
> > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > HID buses and then prints all device ids for those drivers into the
> > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > and then used to generate USB descriptors [3].
> > >
> > > There are so many different flags for those id structures, parsing and
> > > understanding them must be quite difficult.
> > >
> > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > Or should I use some other interface to do that?
> > >
> > > I can't think of a better way to get the information from a running
> > > kernel.
> > >
> > > There is another possibility, though.  If the drivers are built as
> > > modules, the information is already available to userspace tools via
> > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > advantage that it will work even for drivers that aren't currently
> > > loaded.
> >
> > This is the same thing Greg mentions above, right?
>
> Yes.
>
> > Would this work for drivers that are built into the kernel (as =y)?
>
> No, sorry.  There has not been any need to export that information to
> userspace as nothing has ever needed that.
>
> The only reason we exported that at all was to allow modules to
> auto-load to handle the device.

OK, I see. Ideally we would want to support both builtin drivers and
modules. I'll then implement the approach with exporting the ids
through debugfs. I'll send a patch once I have it.

Thanks!

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > >
> > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > >
> > > > > Hi Greg and Alan,
> > > > >
> > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > descriptors that match to actual drivers. The same is required for
> > > > > hid_device_id structs, since those are matched separately by the
> > > > > usbhid driver (are there other cases like this?).
> > > > >
> > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > HID buses and then prints all device ids for those drivers into the
> > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > and then used to generate USB descriptors [3].
> > > >
> > > > There are so many different flags for those id structures, parsing and
> > > > understanding them must be quite difficult.
> > > >
> > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > Or should I use some other interface to do that?
> > > >
> > > > I can't think of a better way to get the information from a running
> > > > kernel.
> > > >
> > > > There is another possibility, though.  If the drivers are built as
> > > > modules, the information is already available to userspace tools via
> > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > advantage that it will work even for drivers that aren't currently
> > > > loaded.
> > >
> > > This is the same thing Greg mentions above, right?
> >
> > Yes.
> >
> > > Would this work for drivers that are built into the kernel (as =y)?
> >
> > No, sorry.  There has not been any need to export that information to
> > userspace as nothing has ever needed that.
> >
> > The only reason we exported that at all was to allow modules to
> > auto-load to handle the device.
> 
> OK, I see. Ideally we would want to support both builtin drivers and
> modules. I'll then implement the approach with exporting the ids
> through debugfs. I'll send a patch once I have it.

Note, this is part of the build/link process (see what
MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
it in debugfs very easily.  Why not put it in /sys/module/MODULE_NAME/ ?

thanks,

greg k-h

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > >
> > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > >
> > > > > > Hi Greg and Alan,
> > > > > >
> > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > usbhid driver (are there other cases like this?).
> > > > > >
> > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > and then used to generate USB descriptors [3].
> > > > >
> > > > > There are so many different flags for those id structures, parsing and
> > > > > understanding them must be quite difficult.
> > > > >
> > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > Or should I use some other interface to do that?
> > > > >
> > > > > I can't think of a better way to get the information from a running
> > > > > kernel.
> > > > >
> > > > > There is another possibility, though.  If the drivers are built as
> > > > > modules, the information is already available to userspace tools via
> > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > advantage that it will work even for drivers that aren't currently
> > > > > loaded.
> > > >
> > > > This is the same thing Greg mentions above, right?
> > >
> > > Yes.
> > >
> > > > Would this work for drivers that are built into the kernel (as =y)?
> > >
> > > No, sorry.  There has not been any need to export that information to
> > > userspace as nothing has ever needed that.
> > >
> > > The only reason we exported that at all was to allow modules to
> > > auto-load to handle the device.
> >
> > OK, I see. Ideally we would want to support both builtin drivers and
> > modules. I'll then implement the approach with exporting the ids
> > through debugfs. I'll send a patch once I have it.
>
> Note, this is part of the build/link process (see what
> MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> it in debugfs very easily.

Take a look at the patch I've linked [1]. It iterates all drivers on
the USB bus via bus_for_each_drv and then iterates both builtin ids
(in usb_device_id_dump_static) and the ones that come from modules (in
usb_device_id_dump_dynamic) (at least that's how I understand the code
that I've written :). The patch just does that in a weird place and
prints ids to kernel log. It seems it should be easy to change it to
do the same in a read() handler of a debugfs entry.

[1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch

> Why not put it in /sys/module/MODULE_NAME/ ?

I can look into this, if that's what you prefer. In this case we'll
need to iterate over all dirs in /sys/module to find the ones that
export some USB ids. Seems less convenient than a single debugfs file
approach, but would also work AFAIU.

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Mon, Nov 18, 2019 at 06:42:25PM +0100, Andrey Konovalov wrote:
> On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > >
> > > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > > >
> > > > > > > Hi Greg and Alan,
> > > > > > >
> > > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > > usbhid driver (are there other cases like this?).
> > > > > > >
> > > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > > and then used to generate USB descriptors [3].
> > > > > >
> > > > > > There are so many different flags for those id structures, parsing and
> > > > > > understanding them must be quite difficult.
> > > > > >
> > > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > > Or should I use some other interface to do that?
> > > > > >
> > > > > > I can't think of a better way to get the information from a running
> > > > > > kernel.
> > > > > >
> > > > > > There is another possibility, though.  If the drivers are built as
> > > > > > modules, the information is already available to userspace tools via
> > > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > > advantage that it will work even for drivers that aren't currently
> > > > > > loaded.
> > > > >
> > > > > This is the same thing Greg mentions above, right?
> > > >
> > > > Yes.
> > > >
> > > > > Would this work for drivers that are built into the kernel (as =y)?
> > > >
> > > > No, sorry.  There has not been any need to export that information to
> > > > userspace as nothing has ever needed that.
> > > >
> > > > The only reason we exported that at all was to allow modules to
> > > > auto-load to handle the device.
> > >
> > > OK, I see. Ideally we would want to support both builtin drivers and
> > > modules. I'll then implement the approach with exporting the ids
> > > through debugfs. I'll send a patch once I have it.
> >
> > Note, this is part of the build/link process (see what
> > MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> > it in debugfs very easily.
> 
> Take a look at the patch I've linked [1]. It iterates all drivers on
> the USB bus via bus_for_each_drv and then iterates both builtin ids
> (in usb_device_id_dump_static) and the ones that come from modules (in
> usb_device_id_dump_dynamic) (at least that's how I understand the code
> that I've written :). The patch just does that in a weird place and
> prints ids to kernel log. It seems it should be easy to change it to
> do the same in a read() handler of a debugfs entry.
> 
> [1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch

Iterating over all of that is a mess, why not stick with the stuff we
already are generating for modules to use?

> > Why not put it in /sys/module/MODULE_NAME/ ?
> 
> I can look into this, if that's what you prefer. In this case we'll
> need to iterate over all dirs in /sys/module to find the ones that
> export some USB ids. Seems less convenient than a single debugfs file
> approach, but would also work AFAIU.

It could be done at build time, like the MODULE_DEVICE_TABLE() logic
works, and that way you get it for all bus types, not just USB.  And
this is a module issue really, right?  Yes, the mapping from module name
to driver name is not always the same, but it should be close.

Otherwise, something in the driver core would be good to do, again, that
way you get this for all busses/drivers.

thanks,

greg k-h

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Mon, Nov 18, 2019 at 6:57 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Nov 18, 2019 at 06:42:25PM +0100, Andrey Konovalov wrote:
> > On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > > > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > > >
> > > > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > > > >
> > > > > > > > Hi Greg and Alan,
> > > > > > > >
> > > > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > > > usbhid driver (are there other cases like this?).
> > > > > > > >
> > > > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > > > and then used to generate USB descriptors [3].
> > > > > > >
> > > > > > > There are so many different flags for those id structures, parsing and
> > > > > > > understanding them must be quite difficult.
> > > > > > >
> > > > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > > > Or should I use some other interface to do that?
> > > > > > >
> > > > > > > I can't think of a better way to get the information from a running
> > > > > > > kernel.
> > > > > > >
> > > > > > > There is another possibility, though.  If the drivers are built as
> > > > > > > modules, the information is already available to userspace tools via
> > > > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > > > advantage that it will work even for drivers that aren't currently
> > > > > > > loaded.
> > > > > >
> > > > > > This is the same thing Greg mentions above, right?
> > > > >
> > > > > Yes.
> > > > >
> > > > > > Would this work for drivers that are built into the kernel (as =y)?
> > > > >
> > > > > No, sorry.  There has not been any need to export that information to
> > > > > userspace as nothing has ever needed that.
> > > > >
> > > > > The only reason we exported that at all was to allow modules to
> > > > > auto-load to handle the device.
> > > >
> > > > OK, I see. Ideally we would want to support both builtin drivers and
> > > > modules. I'll then implement the approach with exporting the ids
> > > > through debugfs. I'll send a patch once I have it.
> > >
> > > Note, this is part of the build/link process (see what
> > > MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> > > it in debugfs very easily.
> >
> > Take a look at the patch I've linked [1]. It iterates all drivers on
> > the USB bus via bus_for_each_drv and then iterates both builtin ids
> > (in usb_device_id_dump_static) and the ones that come from modules (in
> > usb_device_id_dump_dynamic) (at least that's how I understand the code
> > that I've written :). The patch just does that in a weird place and
> > prints ids to kernel log. It seems it should be easy to change it to
> > do the same in a read() handler of a debugfs entry.
> >
> > [1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch
>
> Iterating over all of that is a mess, why not stick with the stuff we
> already are generating for modules to use?
>
> > > Why not put it in /sys/module/MODULE_NAME/ ?
> >
> > I can look into this, if that's what you prefer. In this case we'll
> > need to iterate over all dirs in /sys/module to find the ones that
> > export some USB ids. Seems less convenient than a single debugfs file
> > approach, but would also work AFAIU.
>
> It could be done at build time, like the MODULE_DEVICE_TABLE() logic
> works, and that way you get it for all bus types, not just USB.  And
> this is a module issue really, right?  Yes, the mapping from module name
> to driver name is not always the same, but it should be close.

I've tried to change MODULE_DEVICE_TABLE to always emit a device table
regardless of whether a module is being compiled or not. This doesn't
work just like that, because many modules use the same name for the
device table, and I get linking errors. Is this the approach you had
in mind? What would you suggest to do with name clash issue?

>
> Otherwise, something in the driver core would be good to do, again, that
> way you get this for all busses/drivers.

Could you point me to some source files where this would go into?
AFAIU with this we'll still need to implement a pretty printer for
each device table type, right?

Re: Exporting USB device ids from the kernel

[Greg Kroah-Hartman]

On Mon, Dec 02, 2019 at 05:19:55PM +0100, Andrey Konovalov wrote:
> On Mon, Nov 18, 2019 at 6:57 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Mon, Nov 18, 2019 at 06:42:25PM +0100, Andrey Konovalov wrote:
> > > On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > > > > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > > > > <gregkh@linuxfoundation.org> wrote:
> > > > > >
> > > > > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > > > >
> > > > > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > > > > >
> > > > > > > > > Hi Greg and Alan,
> > > > > > > > >
> > > > > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > > > > usbhid driver (are there other cases like this?).
> > > > > > > > >
> > > > > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > > > > and then used to generate USB descriptors [3].
> > > > > > > >
> > > > > > > > There are so many different flags for those id structures, parsing and
> > > > > > > > understanding them must be quite difficult.
> > > > > > > >
> > > > > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > > > > Or should I use some other interface to do that?
> > > > > > > >
> > > > > > > > I can't think of a better way to get the information from a running
> > > > > > > > kernel.
> > > > > > > >
> > > > > > > > There is another possibility, though.  If the drivers are built as
> > > > > > > > modules, the information is already available to userspace tools via
> > > > > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > > > > advantage that it will work even for drivers that aren't currently
> > > > > > > > loaded.
> > > > > > >
> > > > > > > This is the same thing Greg mentions above, right?
> > > > > >
> > > > > > Yes.
> > > > > >
> > > > > > > Would this work for drivers that are built into the kernel (as =y)?
> > > > > >
> > > > > > No, sorry.  There has not been any need to export that information to
> > > > > > userspace as nothing has ever needed that.
> > > > > >
> > > > > > The only reason we exported that at all was to allow modules to
> > > > > > auto-load to handle the device.
> > > > >
> > > > > OK, I see. Ideally we would want to support both builtin drivers and
> > > > > modules. I'll then implement the approach with exporting the ids
> > > > > through debugfs. I'll send a patch once I have it.
> > > >
> > > > Note, this is part of the build/link process (see what
> > > > MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> > > > it in debugfs very easily.
> > >
> > > Take a look at the patch I've linked [1]. It iterates all drivers on
> > > the USB bus via bus_for_each_drv and then iterates both builtin ids
> > > (in usb_device_id_dump_static) and the ones that come from modules (in
> > > usb_device_id_dump_dynamic) (at least that's how I understand the code
> > > that I've written :). The patch just does that in a weird place and
> > > prints ids to kernel log. It seems it should be easy to change it to
> > > do the same in a read() handler of a debugfs entry.
> > >
> > > [1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch
> >
> > Iterating over all of that is a mess, why not stick with the stuff we
> > already are generating for modules to use?
> >
> > > > Why not put it in /sys/module/MODULE_NAME/ ?
> > >
> > > I can look into this, if that's what you prefer. In this case we'll
> > > need to iterate over all dirs in /sys/module to find the ones that
> > > export some USB ids. Seems less convenient than a single debugfs file
> > > approach, but would also work AFAIU.
> >
> > It could be done at build time, like the MODULE_DEVICE_TABLE() logic
> > works, and that way you get it for all bus types, not just USB.  And
> > this is a module issue really, right?  Yes, the mapping from module name
> > to driver name is not always the same, but it should be close.
> 
> I've tried to change MODULE_DEVICE_TABLE to always emit a device table
> regardless of whether a module is being compiled or not. This doesn't
> work just like that, because many modules use the same name for the
> device table, and I get linking errors. Is this the approach you had
> in mind? What would you suggest to do with name clash issue?

It's a static variable, why is there a name clash?  Don't make it global :)

> > Otherwise, something in the driver core would be good to do, again, that
> > way you get this for all busses/drivers.
> 
> Could you point me to some source files where this would go into?
> AFAIU with this we'll still need to implement a pretty printer for
> each device table type, right?

Probably yes, but note that all of the structures are defined in one
place.  Look in scripts/mod/ for some idea of how some of this is done.

Note, I have no idea if any of this is possible, I'm just suggesting
ways it might be done.

thanks,

greg k-h

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Mon, Dec 2, 2019 at 5:49 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Dec 02, 2019 at 05:19:55PM +0100, Andrey Konovalov wrote:
> > On Mon, Nov 18, 2019 at 6:57 PM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Mon, Nov 18, 2019 at 06:42:25PM +0100, Andrey Konovalov wrote:
> > > > On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > > > > > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > > > > > <gregkh@linuxfoundation.org> wrote:
> > > > > > >
> > > > > > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > > > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > > > > >
> > > > > > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > > > > > >
> > > > > > > > > > Hi Greg and Alan,
> > > > > > > > > >
> > > > > > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > > > > > usbhid driver (are there other cases like this?).
> > > > > > > > > >
> > > > > > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > > > > > and then used to generate USB descriptors [3].
> > > > > > > > >
> > > > > > > > > There are so many different flags for those id structures, parsing and
> > > > > > > > > understanding them must be quite difficult.
> > > > > > > > >
> > > > > > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > > > > > Or should I use some other interface to do that?
> > > > > > > > >
> > > > > > > > > I can't think of a better way to get the information from a running
> > > > > > > > > kernel.
> > > > > > > > >
> > > > > > > > > There is another possibility, though.  If the drivers are built as
> > > > > > > > > modules, the information is already available to userspace tools via
> > > > > > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > > > > > advantage that it will work even for drivers that aren't currently
> > > > > > > > > loaded.
> > > > > > > >
> > > > > > > > This is the same thing Greg mentions above, right?
> > > > > > >
> > > > > > > Yes.
> > > > > > >
> > > > > > > > Would this work for drivers that are built into the kernel (as =y)?
> > > > > > >
> > > > > > > No, sorry.  There has not been any need to export that information to
> > > > > > > userspace as nothing has ever needed that.
> > > > > > >
> > > > > > > The only reason we exported that at all was to allow modules to
> > > > > > > auto-load to handle the device.
> > > > > >
> > > > > > OK, I see. Ideally we would want to support both builtin drivers and
> > > > > > modules. I'll then implement the approach with exporting the ids
> > > > > > through debugfs. I'll send a patch once I have it.
> > > > >
> > > > > Note, this is part of the build/link process (see what
> > > > > MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> > > > > it in debugfs very easily.
> > > >
> > > > Take a look at the patch I've linked [1]. It iterates all drivers on
> > > > the USB bus via bus_for_each_drv and then iterates both builtin ids
> > > > (in usb_device_id_dump_static) and the ones that come from modules (in
> > > > usb_device_id_dump_dynamic) (at least that's how I understand the code
> > > > that I've written :). The patch just does that in a weird place and
> > > > prints ids to kernel log. It seems it should be easy to change it to
> > > > do the same in a read() handler of a debugfs entry.
> > > >
> > > > [1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch
> > >
> > > Iterating over all of that is a mess, why not stick with the stuff we
> > > already are generating for modules to use?
> > >
> > > > > Why not put it in /sys/module/MODULE_NAME/ ?
> > > >
> > > > I can look into this, if that's what you prefer. In this case we'll
> > > > need to iterate over all dirs in /sys/module to find the ones that
> > > > export some USB ids. Seems less convenient than a single debugfs file
> > > > approach, but would also work AFAIU.
> > >
> > > It could be done at build time, like the MODULE_DEVICE_TABLE() logic
> > > works, and that way you get it for all bus types, not just USB.  And
> > > this is a module issue really, right?  Yes, the mapping from module name
> > > to driver name is not always the same, but it should be close.
> >
> > I've tried to change MODULE_DEVICE_TABLE to always emit a device table
> > regardless of whether a module is being compiled or not. This doesn't
> > work just like that, because many modules use the same name for the
> > device table, and I get linking errors. Is this the approach you had
> > in mind? What would you suggest to do with name clash issue?
>
> It's a static variable, why is there a name clash?  Don't make it global :)

The device table variable that is passed to MODULE_DEVICE_TABLE() as
the second argument is static, but the alias variable that
MODULE_DEVICE_TABLE() generates is declared as extern, which makes it
global AFAIU.

>
> > > Otherwise, something in the driver core would be good to do, again, that
> > > way you get this for all busses/drivers.
> >
> > Could you point me to some source files where this would go into?
> > AFAIU with this we'll still need to implement a pretty printer for
> > each device table type, right?
>
> Probably yes, but note that all of the structures are defined in one
> place.  Look in scripts/mod/ for some idea of how some of this is done.

That dir I found. AFAIU what you suggested as "something in the driver
core" was some runtime logic that would expose all of the ids. Via the
bus_for_each_drv() logic and some debugfs entry, like what I did in
the patch that I've sent above, but in a more generic way that covers
all bus types. In this case may question is where to put such code.
And we'll still need custom logic for each bus type. Or did you mean
something else?

>
> Note, I have no idea if any of this is possible, I'm just suggesting
> ways it might be done.

Re: Exporting USB device ids from the kernel

[Andrey Konovalov]

On Mon, Nov 18, 2019 at 6:57 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Nov 18, 2019 at 06:42:25PM +0100, Andrey Konovalov wrote:
> > On Mon, Nov 18, 2019 at 5:40 PM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Mon, Nov 18, 2019 at 05:12:34PM +0100, Andrey Konovalov wrote:
> > > > On Sat, Nov 16, 2019 at 9:49 AM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Fri, Nov 15, 2019 at 05:10:26PM +0100, Andrey Konovalov wrote:
> > > > > > On Fri, Nov 15, 2019 at 4:44 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > > >
> > > > > > > On Fri, 15 Nov 2019, Andrey Konovalov wrote:
> > > > > > >
> > > > > > > > Hi Greg and Alan,
> > > > > > > >
> > > > > > > > For USB fuzzing it would be nice to be able to export usb_device_id
> > > > > > > > structs from the kernel to facilitate the fuzzer with generating USB
> > > > > > > > descriptors that match to actual drivers. The same is required for
> > > > > > > > hid_device_id structs, since those are matched separately by the
> > > > > > > > usbhid driver (are there other cases like this?).
> > > > > > > >
> > > > > > > > Currently I have a hacky patch [1] that walks all drivers for USB and
> > > > > > > > HID buses and then prints all device ids for those drivers into the
> > > > > > > > kernel log. Those are manually parsed and built into the fuzzer [2]
> > > > > > > > and then used to generate USB descriptors [3].
> > > > > > >
> > > > > > > There are so many different flags for those id structures, parsing and
> > > > > > > understanding them must be quite difficult.
> > > > > > >
> > > > > > > > I'm thinking of making a proper patch that will add a debugfs entry
> > > > > > > > like usb/drivers (and usb/hid_drivers?), that can be read to get
> > > > > > > > USB/HID device ids for all loaded drivers. Would that be acceptable?
> > > > > > > > Or should I use some other interface to do that?
> > > > > > >
> > > > > > > I can't think of a better way to get the information from a running
> > > > > > > kernel.
> > > > > > >
> > > > > > > There is another possibility, though.  If the drivers are built as
> > > > > > > modules, the information is already available to userspace tools via
> > > > > > > depmod.  You could get it from the modules.dep.bin file.  This has the
> > > > > > > advantage that it will work even for drivers that aren't currently
> > > > > > > loaded.
> > > > > >
> > > > > > This is the same thing Greg mentions above, right?
> > > > >
> > > > > Yes.
> > > > >
> > > > > > Would this work for drivers that are built into the kernel (as =y)?
> > > > >
> > > > > No, sorry.  There has not been any need to export that information to
> > > > > userspace as nothing has ever needed that.
> > > > >
> > > > > The only reason we exported that at all was to allow modules to
> > > > > auto-load to handle the device.
> > > >
> > > > OK, I see. Ideally we would want to support both builtin drivers and
> > > > modules. I'll then implement the approach with exporting the ids
> > > > through debugfs. I'll send a patch once I have it.
> > >
> > > Note, this is part of the build/link process (see what
> > > MODULE_DEVICE_TABLE() does), so I don't know if you will be able to do
> > > it in debugfs very easily.
> >
> > Take a look at the patch I've linked [1]. It iterates all drivers on
> > the USB bus via bus_for_each_drv and then iterates both builtin ids
> > (in usb_device_id_dump_static) and the ones that come from modules (in
> > usb_device_id_dump_dynamic) (at least that's how I understand the code
> > that I've written :). The patch just does that in a weird place and
> > prints ids to kernel log. It seems it should be easy to change it to
> > do the same in a read() handler of a debugfs entry.
> >
> > [1] https://github.com/google/syzkaller/blob/master/tools/syz-usbgen/usb_ids.patch
>
> Iterating over all of that is a mess, why not stick with the stuff we
> already are generating for modules to use?
>
> > > Why not put it in /sys/module/MODULE_NAME/ ?
> >
> > I can look into this, if that's what you prefer. In this case we'll
> > need to iterate over all dirs in /sys/module to find the ones that
> > export some USB ids. Seems less convenient than a single debugfs file
> > approach, but would also work AFAIU.
>
> It could be done at build time, like the MODULE_DEVICE_TABLE() logic
> works, and that way you get it for all bus types, not just USB.  And
> this is a module issue really, right?  Yes, the mapping from module name
> to driver name is not always the same, but it should be close.
>
> Otherwise, something in the driver core would be good to do, again, that
> way you get this for all busses/drivers.

OK, I've looked at this more and what I currently have is a PoC patch
below (gmail-corrupted, sorry).

The issue with having multiple variables with the same name is
resolved by appending the line number to each variable name (as well
as the device table name). I've initially tried to use KBUILD_MODNAME
as a part of variable names, but it doesn't work, since KBUILD_MODNAME
is a string. Since exposing KBUILD_MODNAME is desirable, I've used the
same approach with structs that MODULE_VERSION() uses.

Still, with this approach I get a few section mismatch warnings like:

WARNING: vmlinux.o(.data+0x26210): Section mismatch in reference from
the variable __mod_dt_rh
The variable __mod_dt_rapl_model_match_747 references
the variable __initconst rapl_model_match
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console

since rapl_model_match is declared as __initconst.

I'm not yet sure how to work around that.

Greg, does this look like something that you had in mind?

Patch:

diff --git a/include/linux/module.h b/include/linux/module.h
index bd165ba68617..d78c6f63d2ba 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -72,6 +72,12 @@ extern ssize_t __modver_version_show(struct
module_attribute *,

 extern struct module_attribute module_uevent;

+struct module_device_table_info {
+       const char *module_name;
+       const char *type;
+       const void *addr;
+} __attribute__ ((__aligned__(sizeof(void *))));
+
 /* These are either module local, or the kernel's dummy ones. */
 extern int init_module(void);
 extern void cleanup_module(void);
@@ -229,8 +235,26 @@ extern void cleanup_module(void);
 #define MODULE_DEVICE_TABLE(type, name)
         \
 extern typeof(name) __mod_##type##__##name##_device_table              \
   __attribute__ ((unused, alias(__stringify(name))))
+
 #else  /* !MODULE */
-#define MODULE_DEVICE_TABLE(type, name)
+
+/* TODO: This goes under CONFIG_MODULE_SOMETHING: */
+
+#define MODULE_DEVICE_TABLE_II(t, n, l)
         \
+       static struct module_device_table_info __mod_dt_##n##_##l = {   \
+               .module_name    = KBUILD_MODNAME,                       \
+               .type           = #t,                                   \
+               .addr           = (const void *)&(n),                   \
+       };                                                              \
+       static const struct module_device_table_info                    \
+       __used __attribute__ ((__section__ ("__moddt")))                \
+       * __moduleparam_const __mod_dt_ptr_##n##_##l = &__mod_dt_##n##_##l
+
+#define MODULE_DEVICE_TABLE_I(type, name, line)
         \
+       MODULE_DEVICE_TABLE_II(type, name, line)
+#define MODULE_DEVICE_TABLE(type, name)
         \
+       MODULE_DEVICE_TABLE_I(type, name, __LINE__)                     \
+
 #endif