[PATCH bpf-next v4 0/3] Check cfi_stubs before registering a struct_ops type.

[thinker.li@gmail.com]

From: Kui-Feng Lee <thinker.li@gmail.com>

Recently, cfi_stubs were introduced. However, existing struct_ops
types that are not in the upstream may not be aware of this, resulting
in kernel crashes. By rejecting struct_ops types that do not provide
cfi_stubs properly during registration, these crashes can be avoided.

---
Changes from v3:

 - Remove CFI stub function for get_info.

 - Allow passing NULL prog arg to check_member of struct
   bpf_struct_ops type.

 - Call check_member to determines if a CFI stub function should be
   defined for an operator.

Changes from v2:

 - Add a stub function for get_info of struct tcp_congestion_ops.

Changes from v1:

 - Check *(void **)(cfi_stubs + moff) to make sure stub functions are
   provided for every operator.

 - Add a test case to ensure that struct_ops rejects incomplete
   cfi_stub.

v3: https://lore.kernel.org/all/20240216193434.735874-1-thinker.li@gmail.com/
v2: https://lore.kernel.org/all/20240216020350.2061373-1-thinker.li@gmail.com/
v1: https://lore.kernel.org/all/20240215022401.1882010-1-thinker.li@gmail.com/

Kui-Feng Lee (3):
  bpf, net: allow passing NULL prog to check_member.
  bpf: Check cfi_stubs before registering a struct_ops type.
  selftests/bpf: Test case for lacking CFI stub functions.

 kernel/bpf/bpf_struct_ops.c                   | 17 ++++
 net/bpf/bpf_dummy_struct_ops.c                |  2 +-
 tools/testing/selftests/bpf/Makefile          | 10 +-
 .../selftests/bpf/bpf_test_no_cfi/Makefile    | 19 ++++
 .../bpf/bpf_test_no_cfi/bpf_test_no_cfi.c     | 93 +++++++++++++++++++
 .../bpf/prog_tests/test_struct_ops_no_cfi.c   | 38 ++++++++
 tools/testing/selftests/bpf/testing_helpers.c |  4 +-
 tools/testing/selftests/bpf/testing_helpers.h |  2 +
 8 files changed, 181 insertions(+), 4 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile
 create mode 100644 tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c

-- 
2.34.1