netdev - [PATCH bpf v1 2/2] selftests/bpf: Test using cgroup storage in a tail call callee program

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Message-ID: <20251202001822.2769330-2-ameryhung@gmail.com>
Date: Mon,  1 Dec 2025 16:18:22 -0800
From: Amery Hung <ameryhung@...il.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org,
	alexei.starovoitov@...il.com,
	andrii@...nel.org,
	daniel@...earbox.net,
	martin.lau@...nel.org,
	ameryhung@...il.com,
	kernel-team@...a.com
Subject: [PATCH bpf v1 2/2] selftests/bpf: Test using cgroup storage in a tail call callee program

Check that a BPF program that uses cgroup storage cannot be added to
a program array map.

Signed-off-by: Amery Hung <ameryhung@...il.com>
---
 .../selftests/bpf/prog_tests/tailcalls.c      | 25 ++++++++++++
 .../bpf/progs/tailcall_cgrp_storage.c         | 39 +++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/tailcall_cgrp_storage.c

diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index 0ab36503c3b2..e4a5287f10b1 100644
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -8,6 +8,7 @@
 #include "tailcall_freplace.skel.h"
 #include "tc_bpf2bpf.skel.h"
 #include "tailcall_fail.skel.h"
+#include "tailcall_cgrp_storage.skel.h"
 
 /* test_tailcall_1 checks basic functionality by patching multiple locations
  * in a single program for a single tail call slot with nop->jmp, jmp->nop
@@ -1648,6 +1649,28 @@ static void test_tailcall_bpf2bpf_freplace(void)
 	tc_bpf2bpf__destroy(tc_skel);
 }
 
+/*
+ * test_tail_call_cgrp_storage makes sure that callee programs cannot
+ * use cgroup storage
+ */
+static void test_tailcall_cgrp_storage(void)
+{
+	int err, prog_fd, prog_array_fd, key = 0;
+	struct tailcall_cgrp_storage *skel;
+
+	skel = tailcall_cgrp_storage__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "tailcall_cgrp_storage__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.callee_prog);
+	prog_array_fd = bpf_map__fd(skel->maps.prog_array);
+
+	err = bpf_map_update_elem(prog_array_fd, &key, &prog_fd, BPF_ANY);
+	ASSERT_ERR(err, "bpf_map_update_elem");
+
+	tailcall_cgrp_storage__destroy(skel);
+}
+
 static void test_tailcall_failure()
 {
 	RUN_TESTS(tailcall_fail);
@@ -1705,6 +1728,8 @@ void test_tailcalls(void)
 		test_tailcall_freplace();
 	if (test__start_subtest("tailcall_bpf2bpf_freplace"))
 		test_tailcall_bpf2bpf_freplace();
+	if (test__start_subtest("tailcall_cgrp_storage"))
+		test_tailcall_cgrp_storage();
 	if (test__start_subtest("tailcall_failure"))
 		test_tailcall_failure();
 }
diff --git a/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage.c b/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage.c
new file mode 100644
index 000000000000..e4f277d2c4fe
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
+	__type(key, struct bpf_cgroup_storage_key);
+	__type(value, __u64);
+} storage_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+	__uint(max_entries, 1);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u32));
+} prog_array SEC(".maps");
+
+SEC("cgroup_skb/egress")
+int caller_prog(struct __sk_buff *skb)
+{
+	bpf_tail_call(skb, &prog_array, 0);
+
+	return 1;
+}
+
+SEC("cgroup_skb/egress")
+int callee_prog(struct __sk_buff *skb)
+{
+	__u64 *storage;
+
+	storage = bpf_get_local_storage(&storage_map, 0);
+	if (storage)
+		*storage = 1;
+
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.47.3