[PATCHv2 bpf-next 0/8] bpf: Add user memory kfuncs

[Jiri Olsa <jolsa@kernel.org>]

hi,
we have few use cases where having the ability to allocate normal or
executable user space memory would help (like to replace function in
live process or change environment variables).

We also need writes to user memory to handle page faults, while the
existing bpf_probe_write_user() helper disables faults during the copy.

This series adds sleepable kfuncs for BPF programs to copy data into the
current task’s address space and to create or remove private anonymous
mappings with optional execute permissions.

rfc: https://lore.kernel.org/bpf/20261021195759.119421-1-jolsa@kernel.org/
v1:  https://lore.kernel.org/bpf/20261029212551.56964-1-jolsa@kernel.org/


v2 changes:
- infer read-only from constness of a pointer instead of srcptr
  argument suffix [Andrii]
- rename bpf_user_mmap to bpf_user_anon_mmap [Andrii]
- use arch_validate_prot to validate prot argument in mmap
- add the x86 compat mmap workaround
- assorted small changes

v1 changes:
- follow vm_mmap/vm_munmap design suggested by Alexei
- allow user space write only to current process, because we don't
  have remote task use case and it simplifies security checks
- many changes in tests

thanks,
jirka

---
Jiri Olsa (8):
      bpf: Honor const on generic kfunc memory arguments
      bpf: Add user memory kfuncs
      selftests/bpf: Add get_procmap_info helper
      selftests/bpf: Test const kfunc memory arguments
      selftests/bpf: Test user memory mmap kfuncs
      selftests/bpf: Test user memory page exec
      selftests/bpf: Test bpf_copy_to_user kfunc
      selftests/bpf: Test user memory kfunc errors

 Documentation/bpf/kfuncs.rst                               |  17 +++++
 kernel/bpf/helpers.c                                       | 132 +++++++++++++++++++++++++++++++++
 kernel/bpf/syscall.c                                       |  10 +--
 kernel/bpf/verifier.c                                      |  38 +++++++++-
 tools/testing/selftests/bpf/prog_tests/kfunc_call.c        |   2 +
 tools/testing/selftests/bpf/prog_tests/user_mem.c          | 350 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/kfunc_call_fail.c        |  10 +++
 tools/testing/selftests/bpf/progs/kfunc_call_test.c        |  14 ++++
 tools/testing/selftests/bpf/progs/user_mem.c               | 111 ++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/test_kmods/bpf_testmod.c       |  10 +++
 tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h |   2 +
 tools/testing/selftests/bpf/trace_helpers.c                |  38 ++++++++--
 tools/testing/selftests/bpf/trace_helpers.h                |   1 +
 13 files changed, 722 insertions(+), 13 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/user_mem.c
 create mode 100644 tools/testing/selftests/bpf/progs/user_mem.c