1 files changed, 174 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
new file mode 100644
index 000000000..d207e968e
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "cgroup_helpers.h"
+#include "network_helpers.h"
+
+struct tcp_rtt_storage {
+	__u32 invoked;
+	__u32 dsack_dups;
+	__u32 delivered;
+	__u32 delivered_ce;
+	__u32 icsk_retransmits;
+};
+
+static void send_byte(int fd)
+{
+	char b = 0x55;
+
+	if (CHECK_FAIL(write(fd, &b, sizeof(b)) != 1))
+		perror("Failed to send single byte");
+}
+
+static int wait_for_ack(int fd, int retries)
+{
+	struct tcp_info info;
+	socklen_t optlen;
+	int i, err;
+
+	for (i = 0; i < retries; i++) {
+		optlen = sizeof(info);
+		err = getsockopt(fd, SOL_TCP, TCP_INFO, &info, &optlen);
+		if (err < 0) {
+			log_err("Failed to lookup TCP stats");
+			return err;
+		}
+
+		if (info.tcpi_unacked == 0)
+			return 0;
+
+		usleep(10);
+	}
+
+	log_err("Did not receive ACK");
+	return -1;
+}
+
+static int verify_sk(int map_fd, int client_fd, const char *msg, __u32 invoked,
+		     __u32 dsack_dups, __u32 delivered, __u32 delivered_ce,
+		     __u32 icsk_retransmits)
+{
+	int err = 0;
+	struct tcp_rtt_storage val;
+
+	if (CHECK_FAIL(bpf_map_lookup_elem(map_fd, &client_fd, &val) < 0)) {
+		perror("Failed to read socket storage");
+		return -1;
+	}
+
+	if (val.invoked != invoked) {
+		log_err("%s: unexpected bpf_tcp_sock.invoked %d != %d",
+			msg, val.invoked, invoked);
+		err++;
+	}
+
+	if (val.dsack_dups != dsack_dups) {
+		log_err("%s: unexpected bpf_tcp_sock.dsack_dups %d != %d",
+			msg, val.dsack_dups, dsack_dups);
+		err++;
+	}
+
+	if (val.delivered != delivered) {
+		log_err("%s: unexpected bpf_tcp_sock.delivered %d != %d",
+			msg, val.delivered, delivered);
+		err++;
+	}
+
+	if (val.delivered_ce != delivered_ce) {
+		log_err("%s: unexpected bpf_tcp_sock.delivered_ce %d != %d",
+			msg, val.delivered_ce, delivered_ce);
+		err++;
+	}
+
+	if (val.icsk_retransmits != icsk_retransmits) {
+		log_err("%s: unexpected bpf_tcp_sock.icsk_retransmits %d != %d",
+			msg, val.icsk_retransmits, icsk_retransmits);
+		err++;
+	}
+
+	return err;
+}
+
+
+static int run_test(int cgroup_fd, int server_fd)
+{
+	struct bpf_prog_load_attr attr = {
+		.prog_type = BPF_PROG_TYPE_SOCK_OPS,
+		.file = "./tcp_rtt.o",
+		.expected_attach_type = BPF_CGROUP_SOCK_OPS,
+	};
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int client_fd;
+	int prog_fd;
+	int map_fd;
+	int err;
+
+	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+	if (err) {
+		log_err("Failed to load BPF object");
+		return -1;
+	}
+
+	map = bpf_map__next(NULL, obj);
+	map_fd = bpf_map__fd(map);
+
+	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
+	if (err) {
+		log_err("Failed to attach BPF program");
+		goto close_bpf_object;
+	}
+
+	client_fd = connect_to_fd(server_fd, 0);
+	if (client_fd < 0) {
+		err = -1;
+		goto close_bpf_object;
+	}
+
+	err += verify_sk(map_fd, client_fd, "syn-ack",
+			 /*invoked=*/1,
+			 /*dsack_dups=*/0,
+			 /*delivered=*/1,
+			 /*delivered_ce=*/0,
+			 /*icsk_retransmits=*/0);
+
+	send_byte(client_fd);
+	if (wait_for_ack(client_fd, 100) < 0) {
+		err = -1;
+		goto close_client_fd;
+	}
+
+
+	err += verify_sk(map_fd, client_fd, "first payload byte",
+			 /*invoked=*/2,
+			 /*dsack_dups=*/0,
+			 /*delivered=*/2,
+			 /*delivered_ce=*/0,
+			 /*icsk_retransmits=*/0);
+
+close_client_fd:
+	close(client_fd);
+
+close_bpf_object:
+	bpf_object__close(obj);
+	return err;
+}
+
+void test_tcp_rtt(void)
+{
+	int server_fd, cgroup_fd;
+
+	cgroup_fd = test__join_cgroup("/tcp_rtt");
+	if (CHECK_FAIL(cgroup_fd < 0))
+		return;
+
+	server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
+	if (CHECK_FAIL(server_fd < 0))
+		goto close_cgroup_fd;
+
+	CHECK_FAIL(run_test(cgroup_fd, server_fd));
+
+	close(server_fd);
+
+close_cgroup_fd:
+	close(cgroup_fd);
+}