selftests/bpf: Add selftest for attaching tracing programs to functions in deny list

The result:

 $ tools/testing/selftests/bpf/test_progs -t tracing_failure/tracing_deny
 #468/3   tracing_failure/tracing_deny:OK
 #468     tracing_failure:OK
 Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250724151454.499040-4-kafai.wan@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
index a222df765bc393743b57efcb9f8294764de66635..39b59276884a117dad5157ef0666e9cbd2bf7bbc 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
@@ -28,10 +28,43 @@ out:
        tracing_failure__destroy(skel);
 }
 
+static void test_tracing_deny(void)
+{
+       struct tracing_failure *skel;
+       char log_buf[256];
+       int btf_id, err;
+
+       /* __rcu_read_lock depends on CONFIG_PREEMPT_RCU */
+       btf_id = libbpf_find_vmlinux_btf_id("__rcu_read_lock", BPF_TRACE_FENTRY);
+       if (btf_id <= 0) {
+               test__skip();
+               return;
+       }
+
+       skel = tracing_failure__open();
+       if (!ASSERT_OK_PTR(skel, "tracing_failure__open"))
+               return;
+
+       bpf_program__set_autoload(skel->progs.tracing_deny, true);
+       bpf_program__set_log_buf(skel->progs.tracing_deny, log_buf, sizeof(log_buf));
+
+       err = tracing_failure__load(skel);
+       if (!ASSERT_ERR(err, "tracing_failure__load"))
+               goto out;
+
+       ASSERT_HAS_SUBSTR(log_buf,
+                         "Attaching tracing programs to function '__rcu_read_lock' is rejected.",
+                         "log_buf");
+out:
+       tracing_failure__destroy(skel);
+}
+
 void test_tracing_failure(void)
 {
        if (test__start_subtest("bpf_spin_lock"))
                test_bpf_spin_lock(true);
        if (test__start_subtest("bpf_spin_unlock"))
                test_bpf_spin_lock(false);
+       if (test__start_subtest("tracing_deny"))
+               test_tracing_deny();
 }

diff --git a/tools/testing/selftests/bpf/progs/tracing_failure.c b/tools/testing/selftests/bpf/progs/tracing_failure.c
index d41665d2ec8c0e4c04529d9245a96bb0a35a2741..58d2777014e18e9354aed92db5dad7fdd07cb2b7 100644 (file)
--- a/tools/testing/selftests/bpf/progs/tracing_failure.c
+++ b/tools/testing/selftests/bpf/progs/tracing_failure.c
@@ -18,3 +18,9 @@ int BPF_PROG(test_spin_unlock, struct bpf_spin_lock *lock)
 {
        return 0;
 }
+
+SEC("?fentry/__rcu_read_lock")
+int BPF_PROG(tracing_deny)
+{
+       return 0;
+}