bpf/selftests: Test bpf_d_path on rdonly_mem.

The second parameter of bpf_d_path() can only accept writable
memories. Rdonly_mem obtained from bpf_per_cpu_ptr() can not
be passed into bpf_d_path for modification. This patch adds
a selftest to verify this behavior.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220106205525.2116218-1-haoluo@google.com

1 files changed, 21 insertions, 1 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/d_path.c b/tools/testing/selftests/bpf/prog_tests/d_path.c
index 0a577a248d34..32fc5b3b5cf6 100644
--- a/tools/testing/selftests/bpf/prog_tests/d_path.c
+++ b/tools/testing/selftests/bpf/prog_tests/d_path.c
@@ -9,6 +9,7 @@
 #define MAX_FILES		7
 
 #include "test_d_path.skel.h"
+#include "test_d_path_check_rdonly_mem.skel.h"
 
 static int duration;
 
@@ -99,7 +100,7 @@ out_close:
 	return ret;
 }
 
-void test_d_path(void)
+static void test_d_path_basic(void)
 {
 	struct test_d_path__bss *bss;
 	struct test_d_path *skel;
@@ -155,3 +156,22 @@ void test_d_path(void)
 cleanup:
 	test_d_path__destroy(skel);
 }
+
+static void test_d_path_check_rdonly_mem(void)
+{
+	struct test_d_path_check_rdonly_mem *skel;
+
+	skel = test_d_path_check_rdonly_mem__open_and_load();
+	ASSERT_ERR_PTR(skel, "unexpected_load_overwriting_rdonly_mem");
+
+	test_d_path_check_rdonly_mem__destroy(skel);
+}
+
+void test_d_path(void)
+{
+	if (test__start_subtest("basic"))
+		test_d_path_basic();
+
+	if (test__start_subtest("check_rdonly_mem"))
+		test_d_path_check_rdonly_mem();
+}