On 10/1/24 08:30, Benjamin Tissoires wrote:
This is a slight change from the fundamentals of HID-BPF.
In theory, HID-BPF is abstract to the kernel itself, and makes
only changes at the HID level (through report descriptors or
events emitted to/from the device).
However, we have seen a few use cases where HID-BPF might interact with
the running kernel when the target device is already handled by a
specific device.
For example, the XP-Pen/Huion/UC-Logic tablets are handled by
hid-uclogic but this driver is also doing a report descriptor fixup
without checking if the device has already been fixed by HID-BPF.
In the same way, another recent example[0] was when a cheap foot pedal is
used and tricks iPhones and Windows machines by presenting itself as a
known Apple wireless keyboard. The problem is that this fake keyboard is
not presenting a compatible report descriptor and hid-core merges all
device nodes together making libinput ignore the keyboard part for
historical reasons.
This series aims at tackling this problem:
- first, we promote hid_bpf_report_descriptor_fixup to be called before
any driver is even matched for the device
- then we allow hdev->quirks to be written during report_fixup and add a
new quirk to force hid-core to ignore any non hid-generic driver.
Basically, it means that when we insert a BPF program to fix a device,
we can force hid-generic to handle the device, and thus preventing
any other kernel driver to tamper with our device.
This branch is on top of the for-6.12/upstream-fixes branch of hid.git.
[0] https://gitlab.freedesktop.org/libinput/libinput/-/issues/1014
Signed-off-by: Benjamin Tissoires <bentiss@xxxxxxxxxx>
---
Changes in v3:
- dropped the last 2 patches with hid-input control, as I'm not 100%
sure of it
- changed the first patch to avoid a double free on cleanup of a device
when a HID-BPF program was attached
- kept Peter's rev-by for all but patches 1 and 6
- Link to v2: https://lore.kernel.org/r/20240910-hid-bpf-hid-generic-v2-0-083dfc189e97@xxxxxxxxxx
HID: bpf: move HID-BPF report descriptor fixup earlier
HID: core: save one kmemdup during .probe()
HID: core: remove one more kmemdup on .probe()
HID: bpf: allow write access to quirks field in struct hid_device
selftests/hid: add dependency on hid_common.h
selftests/hid: cleanup C tests by adding a common struct uhid_device
selftests/hid: allow to parametrize bus/vid/pid/rdesc on the test device
HID: add per device quirk to force bind to hid-generic
selftests/hid: add test for assigning a given device to hid-generic
drivers/hid/bpf/hid_bpf_dispatch.c | 9 +-
drivers/hid/bpf/hid_bpf_struct_ops.c | 1 +
drivers/hid/hid-core.c | 84 +++++++++---
drivers/hid/hid-generic.c | 3 +
include/linux/hid.h | 20 +--
include/linux/hid_bpf.h | 11 +-
tools/testing/selftests/hid/Makefile | 2 +-
tools/testing/selftests/hid/hid_bpf.c | 151 ++++++++++++++-------
tools/testing/selftests/hid/hid_common.h | 112 ++++++++++-----
tools/testing/selftests/hid/hidraw.c | 36 ++---
tools/testing/selftests/hid/progs/hid.c | 12 ++
.../testing/selftests/hid/progs/hid_bpf_helpers.h | 6 +-
12 files changed, 296 insertions(+), 151 deletions(-)
I am assuming selftests go with the driver changes.
For selftests:
Acked-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
thanks,
-- Shuah
