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>

1 files changed, 21 insertions, 0 deletions

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
index 000000000000..c06f4a41c21a
--- /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",
+};