[PATCH bpf-next v2 00/28] Introduce eBPF support for HID devices

[Benjamin Tissoires]

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



[0] https://lore.kernel.org/linux-input/20220224110828.2168231-1-benjamin.tissoires@xxxxxxxxxx/T/#t


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

-- 
2.35.1