[PATCH bpf-next 2/2] selftests/bpf: Add test for resizing data map with struct_ops

[David Vernet <void@manifault.com>]

Tests that if you resize a map after opening a skel, that it doesn't
cause a UAF which causes a struct_ops map to fail to be able to load.

Signed-off-by: David Vernet <void@manifault.com>
---
 .../bpf/prog_tests/struct_ops_resize.c        | 30 +++++++++++++++++++
 .../selftests/bpf/progs/struct_ops_resize.c   | 24 +++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/struct_ops_resize.c
 create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_resize.c

diff --git a/tools/testing/selftests/bpf/prog_tests/struct_ops_resize.c b/tools/testing/selftests/bpf/prog_tests/struct_ops_resize.c
new file mode 100644
index 000000000000..7584f91c2bd1
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/struct_ops_resize.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "struct_ops_resize.skel.h"
+
+static void resize_datasec(void)
+{
+	struct struct_ops_resize *skel;
+	int err;
+
+	skel = struct_ops_resize__open();
+	if (!ASSERT_OK_PTR(skel, "struct_ops_resize__open"))
+		return;
+
+	err  = bpf_map__set_value_size(skel->maps.data_resizable, 1 << 15);
+	if (!ASSERT_OK(err, "bpf_map__set_value_size"))
+		goto cleanup;
+
+	err = struct_ops_resize__load(skel);
+	ASSERT_OK(err, "struct_ops_resize__load");
+
+cleanup:
+	struct_ops_resize__destroy(skel);
+}
+
+void test_struct_ops_resize(void)
+{
+	if (test__start_subtest("resize_datasec"))
+		resize_datasec();
+}
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_resize.c b/tools/testing/selftests/bpf/progs/struct_ops_resize.c
new file mode 100644
index 000000000000..d0b235f4bbaa
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_resize.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+char resizable[1] SEC(".data.resizable");
+
+SEC("struct_ops/test_1")
+int BPF_PROG(test_1)
+{
+	return 0;
+}
+
+struct bpf_testmod_ops {
+	int (*test_1)(void);
+};
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod = {
+	.test_1 = (void *)test_1
+};
-- 
2.45.2