On Wed, Apr 7, 2021 at 4:22 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding test to verify that once we attach module's trampoline,
> the module can't be unloaded.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
To be fair, to test that you are actually testing what you think you
are testing, you'd have to prove that you *can* detach when no program
is attached to bpf_testmod ;) You'd also need kern_sync_rcu() to wait
for all the async clean up to complete inside the kernel. But that
doesn't interact with other tests well, so I think it's fine.
grumpily due to CHECK() usage (please do consider updating to ASSERT):
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> .../selftests/bpf/prog_tests/module_attach.c | 23 +++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> index 5bc53d53d86e..d180b8c28287 100644
> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> @@ -45,12 +45,18 @@ static int trigger_module_test_write(int write_sz)
> return 0;
> }
>
> +static int delete_module(const char *name, int flags)
> +{
> + return syscall(__NR_delete_module, name, flags);
> +}
> +
> void test_module_attach(void)
> {
> const int READ_SZ = 456;
> const int WRITE_SZ = 457;
> struct test_module_attach* skel;
> struct test_module_attach__bss *bss;
> + struct bpf_link *link;
> int err;
>
> skel = test_module_attach__open();
> @@ -84,6 +90,23 @@ void test_module_attach(void)
> ASSERT_EQ(bss->fexit_ret, -EIO, "fexit_tet");
> ASSERT_EQ(bss->fmod_ret_read_sz, READ_SZ, "fmod_ret");
>
> + test_module_attach__detach(skel);
> +
> + /* attach fentry/fexit and make sure it get's module reference */
> + link = bpf_program__attach(skel->progs.handle_fentry);
> + if (CHECK(IS_ERR(link), "attach_fentry", "err: %ld\n", PTR_ERR(link)))
> + goto cleanup;
> +
> + ASSERT_ERR(delete_module("bpf_testmod", 0), "delete_module");
> + bpf_link__destroy(link);
> +
> + link = bpf_program__attach(skel->progs.handle_fexit);
> + if (CHECK(IS_ERR(link), "attach_fexit", "err: %ld\n", PTR_ERR(link)))
> + goto cleanup;
> +
> + ASSERT_ERR(delete_module("bpf_testmod", 0), "delete_module");
> + bpf_link__destroy(link);
> +
> cleanup:
> test_module_attach__destroy(skel);
> }
> --
> 2.30.2
>
