selftests/bpf: Test for get_netns_cookie

Add test to use get_netns_cookie() from BPF_PROG_TYPE_SOCK_OPS.
Signed-off-by: Xu Liu <liuxu623@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818105820.91894-3-liuxu623@gmail.com

tools/testing/selftests/bpf/prog_tests/netns_cookie.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "netns_cookie_prog.skel.h"
+#include "network_helpers.h"
+
+#ifndef SO_NETNS_COOKIE
+#define SO_NETNS_COOKIE 71
+#endif
+
+static int duration;
+
+void test_netns_cookie(void)
+{
+	int server_fd = 0, client_fd = 0, cgroup_fd = 0, err = 0, val = 0;
+	struct netns_cookie_prog *skel;
+	uint64_t cookie_expected_value;
+	socklen_t vallen = sizeof(cookie_expected_value);
+
+	skel = netns_cookie_prog__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	cgroup_fd = test__join_cgroup("/netns_cookie");
+	if (CHECK(cgroup_fd < 0, "join_cgroup", "cgroup creation failed\n"))
+		goto out;
+
+	skel->links.get_netns_cookie_sockops = bpf_program__attach_cgroup(
+		skel->progs.get_netns_cookie_sockops, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links.get_netns_cookie_sockops, "prog_attach"))
+		goto close_cgroup_fd;
+
+	server_fd = start_server(AF_INET6, SOCK_STREAM, "::1", 0, 0);
+	if (CHECK(server_fd < 0, "start_server", "errno %d\n", errno))
+		goto close_cgroup_fd;
+
+	client_fd = connect_to_fd(server_fd, 0);
+	if (CHECK(client_fd < 0, "connect_to_fd", "errno %d\n", errno))
+		goto close_server_fd;
+
+	err = bpf_map_lookup_elem(bpf_map__fd(skel->maps.netns_cookies),
+				&client_fd, &val);
+	if (!ASSERT_OK(err, "map_lookup(socket_cookies)"))
+		goto close_client_fd;
+
+	err = getsockopt(client_fd, SOL_SOCKET, SO_NETNS_COOKIE,
+				&cookie_expected_value, &vallen);
+	if (!ASSERT_OK(err, "getsockopt)"))
+		goto close_client_fd;
+
+	ASSERT_EQ(val, cookie_expected_value, "cookie_value");
+
+close_client_fd:
+	close(client_fd);
+close_server_fd:
+	close(server_fd);
+close_cgroup_fd:
+	close(cgroup_fd);
+out:
+	netns_cookie_prog__destroy(skel);
+}

tools/testing/selftests/bpf/progs/netns_cookie_prog.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+
+#define AF_INET6 10
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, int);
+} netns_cookies SEC(".maps");
+
+SEC("sockops")
+int get_netns_cookie_sockops(struct bpf_sock_ops *ctx)
+{
+	struct bpf_sock *sk = ctx->sk;
+	int *cookie;
+
+	if (ctx->family != AF_INET6)
+		return 1;
+
+	if (ctx->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
+		return 1;
+
+	if (!sk)
+		return 1;
+
+	cookie = bpf_sk_storage_get(&netns_cookies, sk, 0,
+				BPF_SK_STORAGE_GET_F_CREATE);
+	if (!cookie)
+		return 1;
+
+	*cookie = bpf_get_netns_cookie(ctx);
+
+	return 1;
+}