linux-kernel - [PATCH v3 2/2] selftests/bpf: add test for DEVMAP reuse

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250814180113.1245565-4-yuka@yuka.dev>
Date: Thu, 14 Aug 2025 20:01:13 +0200
From: Yureka Lilian <yuka@...a.dev>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>
Cc: Yureka Lilian <yuka@...a.dev>,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/2] selftests/bpf: add test for DEVMAP reuse

The test covers basic re-use of a pinned DEVMAP map,
with both matching and mismatching parameters.

Signed-off-by: Yureka Lilian <yuka@...a.dev>
---
 .../bpf/prog_tests/pinning_devmap_reuse.c     | 50 +++++++++++++++++++
 .../selftests/bpf/progs/test_pinning_devmap.c | 20 ++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/pinning_devmap_reuse.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_pinning_devmap.c

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning_devmap_reuse.c b/tools/testing/selftests/bpf/prog_tests/pinning_devmap_reuse.c
new file mode 100644
index 000000000..9ae49b587
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/pinning_devmap_reuse.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <test_progs.h>
+
+
+#include "test_pinning_devmap.skel.h"
+
+void test_pinning_devmap_reuse(void)
+{
+	const char *pinpath1 = "/sys/fs/bpf/pinmap1";
+	const char *pinpath2 = "/sys/fs/bpf/pinmap2";
+	struct test_pinning_devmap *skel1 = NULL, *skel2 = NULL;
+	int err;
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
+
+	/* load the object a first time */
+	skel1 = test_pinning_devmap__open_and_load();
+	if (!ASSERT_OK_PTR(skel1, "skel_load1"))
+		goto out;
+
+	/* load the object a second time, re-using the pinned map */
+	skel2 = test_pinning_devmap__open_and_load();
+	if (!ASSERT_OK_PTR(skel2, "skel_load2"))
+		goto out;
+
+	/* we can close the reference safely without
+	 * the map's refcount falling to 0
+	 */
+	test_pinning_devmap__destroy(skel1);
+	skel1 = NULL;
+
+	/* now, swap the pins */
+	err = renameat2(0, pinpath1, 0, pinpath2, RENAME_EXCHANGE);
+	if (!ASSERT_OK(err, "swap pins"))
+		goto out;
+
+	/* load the object again, this time the re-use should fail */
+	skel1 = test_pinning_devmap__open_and_load();
+	if (!ASSERT_ERR_PTR(skel1, "skel_load3"))
+		goto out;
+
+out:
+	unlink(pinpath1);
+	unlink(pinpath2);
+	test_pinning_devmap__destroy(skel1);
+	test_pinning_devmap__destroy(skel2);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_pinning_devmap.c b/tools/testing/selftests/bpf/progs/test_pinning_devmap.c
new file mode 100644
index 000000000..c855f8f87
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_pinning_devmap.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_DEVMAP);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+} pinmap1 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_DEVMAP);
+	__uint(max_entries, 2);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+} pinmap2 SEC(".maps");
-- 
2.50.1