The purpose of this series is to rethink how HID-BPF is invoked. Currently it implies a jmp table, a prog fd bpf_map, a preloaded tracing bpf program and a lot of manual work for handling the bpf program lifetime and addition/removal.
OTOH, bpf_struct_ops take care of most of the bpf handling leaving us with a simple list of ops pointers, and we can directly call the struct_ops program from the kernel as a regular function.
The net gain right now is in term of code simplicity and lines of code removal (though is an API breakage), but udev-hid-bpf is able to handle such breakages.
In the near future, we will be able to extend the HID-BPF struct_ops with entrypoints for hid_hw_raw_request() and hid_hw_output_report(), allowing for covering all of the initial use cases: - firewalling a HID device - fixing all of the HID device interactions (not just device events as it is right now).
The matching user-space loader (udev-hid-bpf) MR is at https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/86
I'll put it out of draft once this is merged.
Cheers, Benjamin
Signed-off-by: Benjamin Tissoires bentiss@kernel.org --- Changes in v2: - drop HID_BPF_FLAGS enum and use BPF_F_BEFORE instead - fix .init_members to not open code member->offset - allow struct hid_device to be writeable from HID-BPF for its name, uniq and phys - Link to v1: https://lore.kernel.org/r/20240528-hid_bpf_struct_ops-v1-0-8c6663df27d8@kern...
--- Benjamin Tissoires (16): HID: rename struct hid_bpf_ops into hid_ops HID: bpf: add hid_get/put_device() helpers HID: bpf: implement HID-BPF through bpf_struct_ops selftests/hid: convert the hid_bpf selftests with struct_ops HID: samples: convert the 2 HID-BPF samples into struct_ops HID: bpf: add defines for HID-BPF SEC in in-tree bpf fixes HID: bpf: convert in-tree fixes into struct_ops HID: bpf: remove tracing HID-BPF capability selftests/hid: add subprog call test Documentation: HID: amend HID-BPF for struct_ops Documentation: HID: add a small blurb on udev-hid-bpf HID: bpf: Artist24: remove unused variable HID: bpf: error on warnings when compiling bpf objects bpf: allow bpf helpers to be used into HID-BPF struct_ops HID: bpf: rework hid_bpf_ops_btf_struct_access HID: bpf: make part of struct hid_device writable
Documentation/hid/hid-bpf.rst | 173 ++++--- drivers/hid/bpf/Makefile | 2 +- drivers/hid/bpf/entrypoints/Makefile | 93 ---- drivers/hid/bpf/entrypoints/README | 4 - drivers/hid/bpf/entrypoints/entrypoints.bpf.c | 25 - drivers/hid/bpf/entrypoints/entrypoints.lskel.h | 248 --------- drivers/hid/bpf/hid_bpf_dispatch.c | 266 +++------- drivers/hid/bpf/hid_bpf_dispatch.h | 12 +- drivers/hid/bpf/hid_bpf_jmp_table.c | 565 --------------------- drivers/hid/bpf/hid_bpf_struct_ops.c | 298 +++++++++++ drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c | 9 +- drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c | 6 +- drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c | 9 +- .../hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c | 6 +- drivers/hid/bpf/progs/Makefile | 2 +- .../hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c | 6 +- drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c | 6 +- drivers/hid/bpf/progs/XPPen__Artist24.bpf.c | 10 +- drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c | 24 +- drivers/hid/bpf/progs/hid_bpf.h | 5 + drivers/hid/hid-core.c | 6 +- include/linux/hid_bpf.h | 125 ++--- samples/hid/Makefile | 5 +- samples/hid/hid_bpf_attach.bpf.c | 18 - samples/hid/hid_bpf_attach.h | 14 - samples/hid/hid_mouse.bpf.c | 26 +- samples/hid/hid_mouse.c | 39 +- samples/hid/hid_surface_dial.bpf.c | 10 +- samples/hid/hid_surface_dial.c | 53 +- tools/testing/selftests/hid/hid_bpf.c | 100 +++- tools/testing/selftests/hid/progs/hid.c | 100 +++- .../testing/selftests/hid/progs/hid_bpf_helpers.h | 19 +- 32 files changed, 805 insertions(+), 1479 deletions(-) --- base-commit: 70ec81c2e2b4005465ad0d042e90b36087c36104 change-id: 20240513-hid_bpf_struct_ops-e3212a224555
Best regards,