Commit Graph

2 Commits

Author SHA1 Message Date
Daniel Borkmann
211bf9cf17 selftests/bpf: Add a test case to write mtu result into .rodata
Add a test which attempts to call bpf_check_mtu() and writes the MTU
into .rodata section of the BPF program, and for comparison this adds
test cases also for .bss and .data section again. The bpf_check_mtu()
is a bit more special in that the passed mtu argument is read and
written by the helper (instead of just written to). Assert that writes
into .rodata remain rejected by the verifier.

  # ./vmtest.sh -- ./test_progs -t verifier_const
  [...]
  ./test_progs -t verifier_const
  [    1.657367] bpf_testmod: loading out-of-tree module taints kernel.
  [    1.657773] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  #473/1   verifier_const/rodata/strtol: write rejected:OK
  #473/2   verifier_const/bss/strtol: write accepted:OK
  #473/3   verifier_const/data/strtol: write accepted:OK
  #473/4   verifier_const/rodata/mtu: write rejected:OK
  #473/5   verifier_const/bss/mtu: write accepted:OK
  #473/6   verifier_const/data/mtu: write accepted:OK
  #473     verifier_const:OK
  [...]
  Summary: 2/10 PASSED, 0 SKIPPED, 0 FAILED

For comparison, without the MEM_UNINIT on bpf_check_mtu's proto:

  # ./vmtest.sh -- ./test_progs -t verifier_const
  [...]
  #473/3   verifier_const/data/strtol: write accepted:OK
  run_subtest:PASS:obj_open_mem 0 nsec
  run_subtest:FAIL:unexpected_load_success unexpected success: 0
  #473/4   verifier_const/rodata/mtu: write rejected:FAIL
  #473/5   verifier_const/bss/mtu: write accepted:OK
  #473/6   verifier_const/data/mtu: write accepted:OK
  #473     verifier_const:FAIL
  [...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240913191754.13290-9-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-09-13 13:17:56 -07:00
Daniel Borkmann
2e3f066020 selftests/bpf: Add a test case to write strtol result into .rodata
Add a test case which attempts to write into .rodata section of the
BPF program, and for comparison this adds test cases also for .bss
and .data section.

Before fix:

  # ./vmtest.sh -- ./test_progs -t verifier_const
  [...]
  ./test_progs -t verifier_const
  tester_init:PASS:tester_log_buf 0 nsec
  process_subtest:PASS:obj_open_mem 0 nsec
  process_subtest:PASS:specs_alloc 0 nsec
  run_subtest:PASS:obj_open_mem 0 nsec
  run_subtest:FAIL:unexpected_load_success unexpected success: 0
  #465/1   verifier_const/rodata: write rejected:FAIL
  #465/2   verifier_const/bss: write accepted:OK
  #465/3   verifier_const/data: write accepted:OK
  #465     verifier_const:FAIL
  [...]

After fix:

  # ./vmtest.sh -- ./test_progs -t verifier_const
  [...]
  ./test_progs -t verifier_const
  #465/1   verifier_const/rodata: write rejected:OK
  #465/2   verifier_const/bss: write accepted:OK
  #465/3   verifier_const/data: write accepted:OK
  #465     verifier_const:OK
  [...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240913191754.13290-8-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-09-13 13:17:56 -07:00