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Message-ID: <20251202171615.1027536-2-ameryhung@gmail.com>
Date: Tue, 2 Dec 2025 09:16:15 -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,
eddyz87@...il.com,
ameryhung@...il.com,
kernel-team@...a.com
Subject: [PATCH bpf v2 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 | 50 +++++++++++++++++++
.../bpf/progs/tailcall_cgrp_storage.c | 39 +++++++++++++++
.../bpf/progs/tailcall_cgrp_storage_owner.c | 33 ++++++++++++
3 files changed, 122 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_cgrp_storage.c
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_cgrp_storage_owner.c
diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index 0ab36503c3b2..41090a413b09 100644
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -8,6 +8,8 @@
#include "tailcall_freplace.skel.h"
#include "tc_bpf2bpf.skel.h"
#include "tailcall_fail.skel.h"
+#include "tailcall_cgrp_storage_owner.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 +1650,52 @@ 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, storage_map_fd, key = 0;
+ struct tailcall_cgrp_storage_owner *owner_skel;
+ struct tailcall_cgrp_storage *skel;
+
+ /*
+ * The first program loaded tailcalling into prog_array map becomes the
+ * owner. This is needed to allow prog map compatibility check to pass
+ * later during map_update.
+ */
+ owner_skel = tailcall_cgrp_storage_owner__open_and_load();
+ if (!ASSERT_OK_PTR(owner_skel, "tailcall_cgrp_storage_owner__open"))
+ return;
+
+ prog_array_fd = bpf_map__fd(owner_skel->maps.prog_array);
+ storage_map_fd = bpf_map__fd(owner_skel->maps.storage_map);
+
+ skel = tailcall_cgrp_storage__open();
+ if (!ASSERT_OK_PTR(skel, "tailcall_cgrp_storage__open")) {
+ tailcall_cgrp_storage_owner__destroy(owner_skel);
+ return;
+ }
+
+ err = bpf_map__reuse_fd(skel->maps.prog_array, prog_array_fd);
+ ASSERT_OK(err, "bpf_map__reuse_fd(prog_array)");
+
+ err = bpf_map__reuse_fd(skel->maps.storage_map, storage_map_fd);
+ ASSERT_OK(err, "bpf_map__reuse_fd(storage_map)");
+
+ err = bpf_object__load(skel->obj);
+ ASSERT_OK(err, "bpf_object__load");
+
+ 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 +1753,8 @@ 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";
diff --git a/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage_owner.c b/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage_owner.c
new file mode 100644
index 000000000000..6ac195b800cf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_cgrp_storage_owner.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.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 prog_array_owner(struct __sk_buff *skb)
+{
+ __u64 *storage;
+
+ storage = bpf_get_local_storage(&storage_map, 0);
+ if (storage)
+ *storage = 1;
+
+ bpf_tail_call(skb, &prog_array, 0);
+
+ return 1;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.47.3
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