On Sat, Sep 19, 2020 at 4:50 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>
> From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>
> This adds a selftest that ensures that modify_return tracing programs
> cannot be attached to freplace programs. The security_ prefix is added to
> the freplace program because that would otherwise let it pass the check for
> modify_return.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> ---
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> .../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 68 ++++++++++++++++++++
> .../selftests/bpf/progs/fmod_ret_freplace.c | 14 ++++
> .../selftests/bpf/progs/freplace_get_constant.c | 2 -
> 3 files changed, 83 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/progs/fmod_ret_freplace.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> index 27677e015730..6339d125ef9a 100644
> --- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> @@ -233,6 +233,72 @@ static void test_func_replace_multi(void)
> prog_name, true, test_second_attach);
> }
>
> +static void test_fmod_ret_freplace(void)
> +{
> + const char *tgt_name = "./test_pkt_access.o";
> + const char *freplace_name = "./freplace_get_constant.o";
> + const char *fmod_ret_name = "./fmod_ret_freplace.o";
> + struct bpf_link *freplace_link = NULL, *fmod_link = NULL;
> + struct bpf_object *freplace_obj = NULL, *pkt_obj, *fmod_obj = NULL;
> + struct bpf_program *prog;
> + __u32 duration = 0;
> + int err, pkt_fd;
> +
> + err = bpf_prog_load(tgt_name, BPF_PROG_TYPE_UNSPEC,
> + &pkt_obj, &pkt_fd);
> + /* the target prog should load fine */
> + if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",
> + tgt_name, err, errno))
> + return;
> + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
> + .attach_prog_fd = pkt_fd,
> + );
this is variable declaration, it has to be together with all the variables above
> +
> + freplace_obj = bpf_object__open_file(freplace_name, &opts);
> + if (CHECK(IS_ERR_OR_NULL(freplace_obj), "freplace_obj_open",
> + "failed to open %s: %ld\n", freplace_name,
> + PTR_ERR(freplace_obj)))
> + goto out;
> +
> + err = bpf_object__load(freplace_obj);
> + if (CHECK(err, "freplace_obj_load", "err %d\n", err))
> + goto out;
> +
> + prog = bpf_program__next(NULL, freplace_obj);
> + freplace_link = bpf_program__attach_trace(prog);
> + if (CHECK(IS_ERR(freplace_link), "freplace_attach_trace", "failed to link\n"))
> + goto out;
> +
> + opts.attach_prog_fd = bpf_program__fd(prog);
> + fmod_obj = bpf_object__open_file(fmod_ret_name, &opts);
> + if (CHECK(IS_ERR_OR_NULL(fmod_obj), "fmod_obj_open",
> + "failed to open %s: %ld\n", fmod_ret_name,
> + PTR_ERR(fmod_obj)))
> + goto out;
> +
> + err = bpf_object__load(fmod_obj);
> + if (CHECK(err, "fmod_obj_load", "err %d\n", err))
> + goto out;
> +
> + prog = bpf_program__next(NULL, fmod_obj);
> + fmod_link = bpf_program__attach_trace(prog);
> + if (CHECK(!IS_ERR(fmod_link), "fmod_attach_trace",
> + "linking fmod_ret to freplace should fail\n"))
> + goto out;
> +
> +out:
> + if (!IS_ERR_OR_NULL(freplace_link))
> + bpf_link__destroy(freplace_link);
> + if (!IS_ERR_OR_NULL(fmod_link))
> + bpf_link__destroy(fmod_link);
> + if (!IS_ERR_OR_NULL(freplace_obj))
> + bpf_object__close(freplace_obj);
> + if (!IS_ERR_OR_NULL(fmod_obj))
> + bpf_object__close(fmod_obj);
no need for all IS_ERR_OR_NULL checks
> + bpf_object__close(pkt_obj);
> +}
> +
> +
[...]
