1 files changed, 62 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/tc_change_tail.c b/tools/testing/selftests/bpf/prog_tests/tc_change_tail.c
new file mode 100644
index 000000000000..74752233e779
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/tc_change_tail.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <error.h>
+#include <test_progs.h>
+#include <linux/pkt_cls.h>
+
+#include "test_tc_change_tail.skel.h"
+#include "socket_helpers.h"
+
+#define LO_IFINDEX 1
+
+void test_tc_change_tail(void)
+{
+	LIBBPF_OPTS(bpf_tcx_opts, tcx_opts);
+	struct test_tc_change_tail *skel = NULL;
+	struct bpf_link *link;
+	int c1, p1;
+	char buf[2];
+	int ret;
+
+	skel = test_tc_change_tail__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "test_tc_change_tail__open_and_load"))
+		return;
+
+	link = bpf_program__attach_tcx(skel->progs.change_tail, LO_IFINDEX,
+				     &tcx_opts);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_tcx"))
+		goto destroy;
+
+	skel->links.change_tail = link;
+	ret = create_pair(AF_INET, SOCK_DGRAM, &c1, &p1);
+	if (!ASSERT_OK(ret, "create_pair"))
+		goto destroy;
+
+	ret = xsend(p1, "Tr", 2, 0);
+	ASSERT_EQ(ret, 2, "xsend(p1)");
+	ret = recv(c1, buf, 2, 0);
+	ASSERT_EQ(ret, 2, "recv(c1)");
+	ASSERT_EQ(skel->data->change_tail_ret, 0, "change_tail_ret");
+
+	ret = xsend(p1, "G", 1, 0);
+	ASSERT_EQ(ret, 1, "xsend(p1)");
+	ret = recv(c1, buf, 2, 0);
+	ASSERT_EQ(ret, 1, "recv(c1)");
+	ASSERT_EQ(skel->data->change_tail_ret, 0, "change_tail_ret");
+
+	ret = xsend(p1, "E", 1, 0);
+	ASSERT_EQ(ret, 1, "xsend(p1)");
+	ret = recv(c1, buf, 1, 0);
+	ASSERT_EQ(ret, 1, "recv(c1)");
+	ASSERT_EQ(skel->data->change_tail_ret, -EINVAL, "change_tail_ret");
+
+	ret = xsend(p1, "Z", 1, 0);
+	ASSERT_EQ(ret, 1, "xsend(p1)");
+	ret = recv(c1, buf, 1, 0);
+	ASSERT_EQ(ret, 1, "recv(c1)");
+	ASSERT_EQ(skel->data->change_tail_ret, -EINVAL, "change_tail_ret");
+
+	close(c1);
+	close(p1);
+destroy:
+	test_tc_change_tail__destroy(skel);
+}