linux-toradex.git/include/linux/hid.h, branch v6.12-rc4

Merge branch 'for-6.12/constify-rdesc' into for-linus

2024-09-13T13:14:56+00:00

- Constification of report descriptors so drivers can use read-only
  memory when declaring report descriptors fixups (Thomas Weißschuh)

HID: change return type of report_fixup() to const

2024-08-27T14:29:55+00:00

By allowing the drivers to return a "const *" they can constify their
static report arrays.
This makes it clear to driver authors that the HID core will not modify
those reports and they can be reused for multiple devices.
Furthermore security is slightly improved as those reports are protected
against accidental or malicious modifications.

[bentiss: fixup hid-cougar.c and hid-multitouch.c for latest version of
the master branch]

Signed-off-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20240803-hid-const-fixup-v2-6-f53d7a7b29d8@weissschuh.net
Signed-off-by: Benjamin Tissoires

HID: constify hid_device::dev_rdesc

2024-08-27T14:18:51+00:00

Once a report descriptor has been created by the HID core it is not
supposed to be modified anymore.
Enforce this invariant through the type system.

Signed-off-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20240803-hid-const-fixup-v2-5-f53d7a7b29d8@weissschuh.net
Signed-off-by: Benjamin Tissoires

HID: constify params and return value of fetch_item()

2024-08-27T14:18:51+00:00

fetch_item() does not modify the descriptor it operates on.
As a prerequisite for the constification of hid_driver::dev_rdesc,
mark the parameters and return value of fetch_item() as const.

Also adapt the variable types in the callers to match this
constification.

Signed-off-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20240803-hid-const-fixup-v2-4-f53d7a7b29d8@weissschuh.net
Signed-off-by: Benjamin Tissoires

HID: constify hid_device::rdesc

2024-08-27T14:18:51+00:00

Once a report descriptor has been created by the HID core it is not
supposed to be modified anymore.
Enforce this invariant through the type system.

Signed-off-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20240803-hid-const-fixup-v2-3-f53d7a7b29d8@weissschuh.net
Signed-off-by: Benjamin Tissoires

HID: constify parameter rdesc of hid_parse_report()

2024-08-27T14:18:51+00:00

The parameter is never modified, so mark it as const.

This is a prerequisite for constification changes in the HID core.

Signed-off-by: Thomas Weißschuh 
Link: https://patch.msgid.link/20240803-hid-const-fixup-v2-2-f53d7a7b29d8@weissschuh.net
Signed-off-by: Benjamin Tissoires

HID: core: add helper for finding a field with a certain usage

2024-08-02T10:42:23+00:00

This helper will allow HID drivers to easily determine if they should
bind to a hid_device by checking for the prescence of a certain field
when its ID is not enough, which can be the case on USB devices with
multiple interfaces and/or configurations.

Convert google-hammer driver to use it, and remove now superfluous
hammer_has_usage().

[jkosina@suse.com: expand changelog with the information about
 google-hammer being added as user of this API ]
Signed-off-by: Kerem Karabay 
Signed-off-by: Aditya Garg 
Signed-off-by: Jiri Kosina

HID: bpf: add HID-BPF hooks for hid_hw_output_report

2024-06-27T09:00:45+00:00

Same story than hid_hw_raw_requests:

This allows to intercept and prevent or change the behavior of
hid_hw_output_report() from a bpf program.

The intent is to solve a couple of use case:
  - firewalling a HID device: a firewall can monitor who opens the hidraw
    nodes and then prevent or allow access to write operations on that
    hidraw node.
  - change the behavior of a device and emulate a new HID feature request

The hook is allowed to be run as sleepable so it can itself call
hid_hw_output_report(), which allows to "convert" one feature request into
another or even call the feature request on a different HID device on the
same physical device.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-7-cfd60fb6c79f@kernel.org
Acked-by: Jiri Kosina 
Signed-off-by: Benjamin Tissoires

HID: bpf: prevent infinite recursions with hid_hw_raw_requests hooks

2024-06-27T09:00:12+00:00

When we attach a sleepable hook to hid_hw_raw_requests, we can (and in
many cases should) call ourself hid_bpf_raw_request(), to actually fetch
data from the device itself.

However, this means that we might enter an infinite loop between
hid_hw_raw_requests hooks and hid_bpf_hw_request() call.

To prevent that, if a hid_bpf_hw_request() call is emitted, we prevent
any new call of this kfunc by storing the information in the context.
This way we can always trace/monitor/filter the incoming bpf requests,
while preventing those loops to happen.

I don't think exposing "from_bpf" is very interesting because while
writing such a bpf program, you need to match at least the report number
and/or the source of the call. So a blind "if there is a
hid_hw_raw_request() call, I'm emitting another one" makes no real
sense.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-5-cfd60fb6c79f@kernel.org
Acked-by: Jiri Kosina 
Signed-off-by: Benjamin Tissoires

HID: add source argument to HID low level functions

2024-06-27T08:58:19+00:00

This allows to know who actually sent what when we process the request
to the device.
This will be useful for a BPF firewall program to allow or not requests
coming from a dedicated hidraw node client.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-2-cfd60fb6c79f@kernel.org
Acked-by: Jiri Kosina 
Signed-off-by: Benjamin Tissoires