selftests/bpf: Add unit tests for pointers in global functions

test_global_func9  - check valid pointer's scenarios
test_global_func10 - check that a smaller type cannot be passed as a
                     larger one
test_global_func11 - check that CTX pointer cannot be passed
test_global_func12 - check access to a null pointer
test_global_func13 - check access to an arbitrary pointer value
test_global_func14 - check that an opaque pointer cannot be passed
test_global_func15 - check that a variable has an unknown value after
		     it was passed to a global function by pointer
test_global_func16 - check access to uninitialized stack memory

test_global_func_args - check read and write operations through a pointer

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-5-me@ubique.spb.ru

1 files changed, 60 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/global_func_args.c b/tools/testing/selftests/bpf/prog_tests/global_func_args.c
new file mode 100644
index 000000000000..8bcc2869102f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/global_func_args.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "test_progs.h"
+#include "network_helpers.h"
+
+static __u32 duration;
+
+static void test_global_func_args0(struct bpf_object *obj)
+{
+	int err, i, map_fd, actual_value;
+	const char *map_name = "values";
+
+	map_fd = bpf_find_map(__func__, obj, map_name);
+	if (CHECK(map_fd < 0, "bpf_find_map", "cannot find BPF map %s: %s\n",
+		map_name, strerror(errno)))
+		return;
+
+	struct {
+		const char *descr;
+		int expected_value;
+	} tests[] = {
+		{"passing NULL pointer", 0},
+		{"returning value", 1},
+		{"reading local variable", 100 },
+		{"writing local variable", 101 },
+		{"reading global variable", 42 },
+		{"writing global variable", 43 },
+		{"writing to pointer-to-pointer", 1 },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
+		const int expected_value = tests[i].expected_value;
+
+		err = bpf_map_lookup_elem(map_fd, &i, &actual_value);
+
+		CHECK(err || actual_value != expected_value, tests[i].descr,
+			 "err %d result %d expected %d\n", err, actual_value, expected_value);
+	}
+}
+
+void test_global_func_args(void)
+{
+	const char *file = "./test_global_func_args.o";
+	__u32 retval;
+	struct bpf_object *obj;
+	int err, prog_fd;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd);
+	if (CHECK(err, "load program", "error %d loading %s\n", err, file))
+		return;
+
+	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+				NULL, NULL, &retval, &duration);
+	CHECK(err || retval, "pass global func args run",
+	      "err %d errno %d retval %d duration %d\n",
+	      err, errno, retval, duration);
+
+	test_global_func_args0(obj);
+
+	bpf_object__close(obj);
+}