[bpf-next,v3,0/4] Fix 32-bit arch and compat support for the kprobe_multi attach type

Message

Eugene Syromiatnikov May 17, 2022, 7:36 a.m. UTC

As suggested in [1], the kprobe_multi interface is to be fixed for 32-bit
architectures and compat, rather then disabled.  As it turned out,
there are a couple of additional problems that are to be addressed:
 - the absence of size overflow checks, leading to possible
   out-of-bounds writes (addressed by the first patch; this one likely has
   to be fixed in 5.18, where the version of the patch from [3]
   may be preferrable, along with [4] to avoid applying the rest
   of the series);
 - the assumption that long has the same size as u64, which would make
   cookies arrays size calculation incorrect on 32-bit architectures
   (addressed by the second patch);
 - the addrs array passing API, that is incompatible with compat and has
   to be changed (addressed in the fourth patch): those are kernel
   addresses and not user ones (as was incorrectly stated in [2]);
   this change is only semantical for 64-bit user/kernelspace,
   so it shouldn't impact ABI there, at least.

[1] https://lore.kernel.org/lkml/[e-mail]/
[2] https://lore.kernel.org/lkml/[e-mail]/
[3] https://lore.kernel.org/lkml/[e-mail]/
[4] https://lore.kernel.org/lkml/[e-mail]/

v3:
 - Rebased on top of bpf-next
 - Removed unnecessary size/cookies_size assignments as suggested
   by Yonghong Sond

v2: https://lore.kernel.org/lkml/[e-mail]/
 - Fixed the isses reported by CI

v1: https://lore.kernel.org/lkml/[e-mail]/

Eugene Syromiatnikov (4):
  bpf_trace: check size for overflow in bpf_kprobe_multi_link_attach
  bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach
  bpf_trace: handle compat in copy_user_syms
  bpf_trace: pass array of u64 values in kprobe_multi.addrs

 kernel/trace/bpf_trace.c                           | 67 ++++++++++++++++------
 tools/lib/bpf/bpf.h                                |  2 +-
 tools/lib/bpf/libbpf.c                             |  8 +--
 tools/lib/bpf/libbpf.h                             |  2 +-
 .../testing/selftests/bpf/prog_tests/bpf_cookie.c  |  2 +-
 .../selftests/bpf/prog_tests/kprobe_multi_test.c   |  8 +--
 6 files changed, 62 insertions(+), 27 deletions(-)