Re: [PATCH bpf 2/2] selftests/bpf: Add tests for allowed helpers

On Mon, Nov 8, 2021 at 10:48 PM Dmitrii Banshchikov [off-list ref] wrote:

On Mon, Nov 08, 2021 at 08:46:20PM +0400, Dmitrii Banshchikov wrote:

quoted

This patch adds tests that bpf_ktime_get_coarse_ns() and bpf_timer_* and
bpf_spin_lock()/bpf_spin_unlock() helpers are forbidden in tracing
progs as it may result in various locking issues.

Signed-off-by: Dmitrii Banshchikov <redacted>
---
 tools/testing/selftests/bpf/test_verifier.c   |  36 +++-
 .../selftests/bpf/verifier/helper_allowed.c   | 196 ++++++++++++++++++
 2 files changed, 231 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/verifier/helper_allowed.c

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 25afe423b3f0..e16eab6fc3a9 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c

@@ -92,6 +92,7 @@ struct bpf_test {
      int fixup_map_event_output[MAX_FIXUPS];
      int fixup_map_reuseport_array[MAX_FIXUPS];
      int fixup_map_ringbuf[MAX_FIXUPS];
+     int fixup_map_timer[MAX_FIXUPS];
      /* Expected verifier log output for result REJECT or VERBOSE_ACCEPT.
       * Can be a tab-separated sequence of expected strings. An empty string
       * means no log verification.

@@ -605,7 +606,7 @@ static int create_cgroup_storage(bool percpu)
  *   struct bpf_spin_lock l;
  * };
  */
-static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l";
+static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l\0bpf_timer\0";

There is extra null byte at the end.

Won't hurt, probably. But I wonder if it will be much easier to add
all those programs as C code and test from test_progs? Instead of all
this assembly.

You can put all of them into a single file and have loop that disabled
all but one program at a time (using bpf_program__set_autoload()) and
loading it and validating that the load failed. WDYT?

--

Dmitrii Banshchikov