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[v2,bpf-next,0/3] bpf: add bpf_progenyof helper

Message ID 20190301180614.4134278-1-javierhonduco@fb.com
Headers show
Series bpf: add bpf_progenyof helper | expand

Message

Javier Honduvilla Coto March 1, 2019, 6:06 p.m. UTC 
Hi all,

This patch add the bpf_progenyof helper which receives a PID and returns
1 if the process currently being executed is in the process hierarchy,
including itself or 0 if not.

This is very useful in tracing programs when we want to filter by a
given PID and all the children it might have. The current workarounds
most people implement for this purpose have issues:

- Attaching to process spawning syscalls and dynamically add those PIDs
  to  some bpf map that would be used to filter is cumbersome and
potentially racy.
- Unrolling some loop to perform what this helper is doing consumes lots
  of instructions. That and the impossibility to jump backwards makes it
really hard to be correct in really large process chains.

Let me know what do you think!

Thanks,

---

Changed in V2:
        - Adding missing docs in include/uapi/linux/bpf.h

Javier Honduvilla Coto (3):
  bpf: add bpf_progenyof helper
  bpf: sync kernel uapi headers
  bpf: add tests for bpf_progenyof

 include/linux/bpf.h                           |   1 +
 include/uapi/linux/bpf.h                      |  11 +-
 kernel/bpf/core.c                             |   1 +
 kernel/bpf/helpers.c                          |  29 ++
 kernel/trace/bpf_trace.c                      |   2 +
 tools/include/uapi/linux/bpf.h                |  11 +-
 tools/testing/selftests/bpf/.gitignore        |   1 +
 tools/testing/selftests/bpf/Makefile          |   2 +-
 tools/testing/selftests/bpf/bpf_helpers.h     |   1 +
 .../selftests/bpf/progs/test_progenyof_kern.c |  46 ++++
 .../selftests/bpf/test_progenyof_user.c       | 249 ++++++++++++++++++
 11 files changed, 351 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_progenyof_kern.c
 create mode 100644 tools/testing/selftests/bpf/test_progenyof_user.c