bpf, selftests: Add test case for cgroup skb to get net_cls classid h…

…elpers

This patch adds a test for cgroup skb to get classid.

Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>

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

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright 2024 Bytedance.
+ */
+
+#include <test_progs.h>
+
+#include "cg_skb_get_classid.skel.h"
+
+#include "cgroup_helpers.h"
+#include "network_helpers.h"
+
+static int run_test(int cgroup_fd, int server_fd)
+{
+ struct cg_skb_get_classid *skel;
+ int fd, err = 0;
+
+ skel = cg_skb_get_classid__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return -1;
+
+ skel->links.cg_skb_classid =
+ bpf_program__attach_cgroup(skel->progs.cg_skb_classid,
+ cgroup_fd);
+ if (!ASSERT_OK_PTR(skel->links.cg_skb_classid, "prog_attach")) {
+ err = -1;
+ goto out;
+ }
+
+ if (!ASSERT_OK(join_classid(), "join_classid")) {
+ err = -1;
+ goto out;
+ }
+
+ errno = 0;
+ fd = connect_to_fd_opts(server_fd, NULL);
+ if (fd >= 0) {
+ if (skel->bss->classid != getpid()) {
+ log_err("Get unexpected classid");
+ err = -1;
+ }
+
+ close(fd);
+ } else {
+ log_err("Unexpected errno from connect to server");
+ err = -1;
+ }
+out:
+ cg_skb_get_classid__destroy(skel);
+ return err;
+}
+
+void test_cg_skb_get_classid(void)
+{
+ struct network_helper_opts opts = {};
+ int server_fd, client_fd, cgroup_fd;
+ static const int port = 60120;
+
+ /* Step 1: Check base connectivity works without any BPF. */
+ server_fd = start_server(AF_INET, SOCK_STREAM, NULL, port, 0);
+ if (!ASSERT_GE(server_fd, 0, "server_fd"))
+ return;
+ client_fd = connect_to_fd_opts(server_fd, &opts);
+ if (!ASSERT_GE(client_fd, 0, "client_fd")) {
+ close(server_fd);
+ return;
+ }
+ close(client_fd);
+ close(server_fd);
+
+ /* Step 2: Check BPF prog attached to cgroups. */
+ cgroup_fd = test__join_cgroup("/cg_skb_get_classid");
+ if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd"))
+ return;
+ server_fd = start_server(AF_INET, SOCK_STREAM, NULL, port, 0);
+ if (!ASSERT_GE(server_fd, 0, "server_fd")) {
+ close(cgroup_fd);
+ return;
+ }
+ setup_classid_environment();
+ set_classid();
+ ASSERT_OK(run_test(cgroup_fd, server_fd), "cg_skb_get_classid");
+ cleanup_classid_environment();
+ close(server_fd);
+ close(cgroup_fd);
+}

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

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright 2024 Bytedance.
+ */
+
+#include <errno.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+__u32 classid = 0;
+
+SEC("cgroup_skb/egress")
+int cg_skb_classid(struct __sk_buff *ctx)
+{
+ classid = bpf_skb_cgroup_classid(ctx);
+
+ return 1;
+}