Hi Benjamin,

On 04/03/2022 19:28, Benjamin Tissoires wrote:

Hi,

This is a followup of my v1 at [0].

The short summary of the previous cover letter and discussions is that HID could benefit from BPF for the following use cases:

• simple fixup of report descriptor: benefits are faster development time and testing, with the produced bpf program being shipped in the kernel directly (the shipping part is *not* addressed here).

• Universal Stylus Interface: allows a user-space program to define its own kernel interface

• Surface Dial: somehow similar to the previous one except that userspace can decide to change the shape of the exported device

• firewall: still partly missing there, there is not yet interception of hidraw calls, but it's coming in a followup series, I promise

• tracing: well, tracing.

I tried to address as many comments as I could and here is the short log of changes:

v2:

• split the series by subsystem (bpf, HID, libbpf, selftests and samples)

• Added an extra patch at the beginning to not require CAP_NET_ADMIN for BPF_PROG_TYPE_LIRC_MODE2 (please shout if this is wrong)

• made the bpf context attached to HID program of dynamic size:

  • the first 1 kB will be able to be addressed directly
  • the rest can be retrieved through bpf_hid_{set|get}_data (note that I am definitivey not happy with that API, because there is part of it in bits and other in bytes. ouch)

• added an extra patch to prevent non GPL HID bpf programs to be loaded of type BPF_PROG_TYPE_HID

  • same here, not really happy but I don't know where to put that check in verifier.c

• added a new flag BPF_F_INSERT_HEAD for BPF_LINK_CREATE syscall when in used with HID program types.

  • this flag is used for tracing, to be able to load a program before any others that might already have been inserted and that might change the data stream.

Cheers, Benjamin

I posted a couple of comments to the series, but other than that for the whole series you can use:

Reviewed-by: Tero Kristo tero.kristo@linux.intel.com

Tested-by: Tero Kristo tero.kristo@linux.intel.com

I did test this with my USI-BPF program + userspace code, they work with few minor updates compared to previous version.

-Tero

[0] https://lore.kernel.org/linux-input/20220224110828.2168231-1-benjamin.tissoi...

Benjamin Tissoires (28): bpf: add new is_sys_admin_prog_type() helper bpf: introduce hid program type HID: hook up with bpf libbpf: add HID program type and API selftests/bpf: add tests for the HID-bpf initial implementation samples/bpf: add new hid_mouse example bpf/hid: add a new attach type to change the report descriptor HID: allow to change the report descriptor from an eBPF program libbpf: add new attach type BPF_HID_RDESC_FIXUP selftests/bpf: add report descriptor fixup tests samples/bpf: add a report descriptor fixup bpf/hid: add hid_{get|set}_data helpers HID: bpf: implement hid_bpf_get|set_data selftests/bpf: add tests for hid_{get|set}_data helpers bpf/hid: add new BPF type to trigger commands from userspace libbpf: add new attach type BPF_HID_USER_EVENT selftests/bpf: add test for user call of HID bpf programs selftests/bpf: hid: rely on uhid event to know if a test device is ready bpf/hid: add bpf_hid_raw_request helper function HID: add implementation of bpf_hid_raw_request selftests/bpf: add tests for bpf_hid_hw_request bpf/verifier: prevent non GPL programs to be loaded against HID HID: bpf: compute only the required buffer size for the device HID: bpf: only call hid_bpf_raw_event() if a ctx is available bpf/hid: Add a flag to add the program at the beginning of the list libbpf: add handling for BPF_F_INSERT_HEAD in HID programs selftests/bpf: Add a test for BPF_F_INSERT_HEAD samples/bpf: fix bpf_program__attach_hid() api change

drivers/hid/Makefile | 1 + drivers/hid/hid-bpf.c | 361 +++++++++ drivers/hid/hid-core.c | 34 +- include/linux/bpf-hid.h | 129 +++ include/linux/bpf_types.h | 4 + include/linux/hid.h | 25 + include/uapi/linux/bpf.h | 59 ++ include/uapi/linux/bpf_hid.h | 50 ++ kernel/bpf/Makefile | 3 + kernel/bpf/hid.c | 652 +++++++++++++++ kernel/bpf/syscall.c | 26 +- kernel/bpf/verifier.c | 7 + samples/bpf/.gitignore | 1 + samples/bpf/Makefile | 4 + samples/bpf/hid_mouse_kern.c | 91 +++ samples/bpf/hid_mouse_user.c | 129 +++ tools/include/uapi/linux/bpf.h | 59 ++ tools/lib/bpf/libbpf.c | 22 +- tools/lib/bpf/libbpf.h | 2 + tools/lib/bpf/libbpf.map | 1 + tools/testing/selftests/bpf/prog_tests/hid.c | 788 +++++++++++++++++++ tools/testing/selftests/bpf/progs/hid.c | 216 +++++ 22 files changed, 2649 insertions(+), 15 deletions(-) create mode 100644 drivers/hid/hid-bpf.c create mode 100644 include/linux/bpf-hid.h create mode 100644 include/uapi/linux/bpf_hid.h create mode 100644 kernel/bpf/hid.c create mode 100644 samples/bpf/hid_mouse_kern.c create mode 100644 samples/bpf/hid_mouse_user.c create mode 100644 tools/testing/selftests/bpf/prog_tests/hid.c create mode 100644 tools/testing/selftests/bpf/progs/hid.c