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@kernel.org
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@ker...
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@linuxfoundation.org
thanks, -- Shuah