selftests/bpf: Test a BPF CC implementing the unsupported get_info()

Test whether a TCP CC implemented in BPF providing get_info() is
rejected correctly. get_info() is unsupported in a BPF CC. The check for
required functions in a BPF CC has moved, this test ensures unsupported
functions are still rejected correctly.

Signed-off-by: Jörn-Thorben Hinz <jthinz@mailbox.tu-berlin.de>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220622191227.898118-6-jthinz@mailbox.tu-berlin.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
index 194d073..2959a52 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
@@ -11,6 +11,7 @@
 #include "bpf_dctcp_release.skel.h"
 #include "tcp_ca_write_sk_pacing.skel.h"
 #include "tcp_ca_incompl_cong_ops.skel.h"
+#include "tcp_ca_unsupp_cong_op.skel.h"
 
 #ifndef ENOTSUPP
 #define ENOTSUPP 524
@@ -359,6 +360,23 @@ static void test_incompl_cong_ops(void)
        tcp_ca_incompl_cong_ops__destroy(skel);
 }
 
+static void test_unsupp_cong_op(void)
+{
+       libbpf_print_fn_t old_print_fn;
+       struct tcp_ca_unsupp_cong_op *skel;
+
+       err_str = "attach to unsupported member get_info";
+       found = false;
+       old_print_fn = libbpf_set_print(libbpf_debug_print);
+
+       skel = tcp_ca_unsupp_cong_op__open_and_load();
+       ASSERT_NULL(skel, "open_and_load");
+       ASSERT_EQ(found, true, "expected_err_msg");
+
+       tcp_ca_unsupp_cong_op__destroy(skel);
+       libbpf_set_print(old_print_fn);
+}
+
 void test_bpf_tcp_ca(void)
 {
        if (test__start_subtest("dctcp"))
@@ -375,4 +393,6 @@ void test_bpf_tcp_ca(void)
                test_write_sk_pacing();
        if (test__start_subtest("incompl_cong_ops"))
                test_incompl_cong_ops();
+       if (test__start_subtest("unsupp_cong_op"))
+               test_unsupp_cong_op();
 }

diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_unsupp_cong_op.c b/tools/testing/selftests/bpf/progs/tcp_ca_unsupp_cong_op.c
new file mode 100644 (file)
index 0000000..c06f4a4
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tcp_ca_unsupp_cong_op.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/unsupp_cong_op_get_info")
+size_t BPF_PROG(unsupp_cong_op_get_info, struct sock *sk, u32 ext, int *attr,
+               union tcp_cc_info *info)
+{
+       return 0;
+}
+
+SEC(".struct_ops")
+struct tcp_congestion_ops unsupp_cong_op = {
+       .get_info = (void *)unsupp_cong_op_get_info,
+       .name = "bpf_unsupp_op",
+};