Apparently, no existing selftest covers it. Add a new one where
we load cgroup/bind4 program and attach fentry to it.
Calling bpf_obj_get_info_by_fd on the fentry program
should return non-zero btf_id/btf_obj_id instead of crashing the kernel.
v3:
- move into fexit_bpf2bpf.c (Martin)
- assert on skel->links.bind_v4_prog (Andrii)
- do no close(-1) unconditionally (Andrii)
v2:
- use ret instead of err in find_prog_btf_id (Hao)
- remove verifier log (Hao)
- drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao)
Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 95 +++++++++++++++++++
1 file changed, 95 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
index 02bb8cbf9194..fb62cef35e42 100644
--- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
@@ -3,6 +3,7 @@
#include <test_progs.h>
#include <network_helpers.h>
#include <bpf/btf.h>
+#include "bind4_prog.skel.h"
typedef int (*test_cb)(struct bpf_object *obj);
@@ -407,6 +408,98 @@ static void test_func_replace_global_func(void)
prog_name, false, NULL);
}
+static int find_prog_btf_id(const char *name, __u32 attach_prog_fd)
+{
+ struct bpf_prog_info info = {};
+ __u32 info_len = sizeof(info);
+ struct btf *btf;
+ int ret;
+
+ ret = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len);
+ if (ret)
+ return ret;
+
+ if (!info.btf_id)
+ return -EINVAL;
+
+ btf = btf__load_from_kernel_by_id(info.btf_id);
+ ret = libbpf_get_error(btf);
+ if (ret)
+ return ret;
+
+ ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
+ btf__free(btf);
+ return ret;
+}
+
+static int load_fentry(int attach_prog_fd, int attach_btf_id)
+{
+ LIBBPF_OPTS(bpf_prog_load_opts, opts,
+ .expected_attach_type = BPF_TRACE_FENTRY,
+ .attach_prog_fd = attach_prog_fd,
+ .attach_btf_id = attach_btf_id,
+ );
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+
+ return bpf_prog_load(BPF_PROG_TYPE_TRACING,
+ "bind4_fentry",
+ "GPL",
+ insns,
+ ARRAY_SIZE(insns),
+ &opts);
+}
+
+static void test_fentry_to_cgroup_bpf(void)
+{
+ struct bind4_prog *skel = NULL;
+ struct bpf_prog_info info = {};
+ __u32 info_len = sizeof(info);
+ int cgroup_fd = -1;
+ int fentry_fd = -1;
+ int btf_id;
+
+ cgroup_fd = test__join_cgroup("/fentry_to_cgroup_bpf");
+ if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd"))
+ return;
+
+ skel = bind4_prog__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel"))
+ goto cleanup;
+
+ skel->links.bind_v4_prog = bpf_program__attach_cgroup(skel->progs.bind_v4_prog, cgroup_fd);
+ if (!ASSERT_OK_PTR(skel->links.bind_v4_prog, "bpf_program__attach_cgroup"))
+ goto cleanup;
+
+ btf_id = find_prog_btf_id("bind_v4_prog", bpf_program__fd(skel->progs.bind_v4_prog));
+ if (!ASSERT_GE(btf_id, 0, "find_prog_btf_id"))
+ goto cleanup;
+
+ fentry_fd = load_fentry(bpf_program__fd(skel->progs.bind_v4_prog), btf_id);
+ if (!ASSERT_GE(fentry_fd, 0, "load_fentry"))
+ goto cleanup;
+
+ /* Make sure bpf_obj_get_info_by_fd works correctly when attaching
+ * to another BPF program.
+ */
+
+ ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len),
+ "bpf_obj_get_info_by_fd");
+
+ ASSERT_EQ(info.btf_id, 0, "info.btf_id");
+ ASSERT_GT(info.attach_btf_id, 0, "info.attach_btf_id");
+ ASSERT_GT(info.attach_btf_obj_id, 0, "info.attach_btf_obj_id");
+
+cleanup:
+ if (cgroup_fd >= 0)
+ close(cgroup_fd);
+ if (fentry_fd >= 0)
+ close(fentry_fd);
+ bind4_prog__destroy(skel);
+}
+
/* NOTE: affect other tests, must run in serial mode */
void serial_test_fexit_bpf2bpf(void)
{
@@ -430,4 +523,6 @@ void serial_test_fexit_bpf2bpf(void)
test_fmod_ret_freplace();
if (test__start_subtest("func_replace_global_func"))
test_func_replace_global_func();
+ if (test__start_subtest("fentry_to_cgroup_bpf"))
+ test_fentry_to_cgroup_bpf();
}
--
2.37.1.455.g008518b4e5-goog
