[PATCH v8 6/9] selftests/landlock: Test open() and ftruncate() in multiple scenarios

["Günther Noack" <gnoack3000@gmail.com>]

This test uses multiple fixture variants to exercise a broader set of
scnenarios.

Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---
 tools/testing/selftests/landlock/fs_test.c | 96 ++++++++++++++++++++++
 1 file changed, 96 insertions(+)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 718543fd3dfc..308f6f36e8c0 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -3445,6 +3445,102 @@ TEST_F_FORK(layout1, ftruncate)
 	ASSERT_EQ(0, close(fd_layer3));
 }
 
+/* clang-format off */
+FIXTURE(ftruncate) {};
+/* clang-format on */
+
+FIXTURE_SETUP(ftruncate)
+{
+	prepare_layout(_metadata);
+	create_file(_metadata, file1_s1d1);
+}
+
+FIXTURE_TEARDOWN(ftruncate)
+{
+	EXPECT_EQ(0, remove_path(file1_s1d1));
+	cleanup_layout(_metadata);
+}
+
+FIXTURE_VARIANT(ftruncate)
+{
+	const __u64 handled;
+	const __u64 permitted;
+	const int expected_open_result;
+	const int expected_ftruncate_result;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(ftruncate, w_w) {
+	/* clang-format on */
+	.handled = LANDLOCK_ACCESS_FS_WRITE_FILE,
+	.permitted = LANDLOCK_ACCESS_FS_WRITE_FILE,
+	.expected_open_result = 0,
+	.expected_ftruncate_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(ftruncate, t_t) {
+	/* clang-format on */
+	.handled = LANDLOCK_ACCESS_FS_TRUNCATE,
+	.permitted = LANDLOCK_ACCESS_FS_TRUNCATE,
+	.expected_open_result = 0,
+	.expected_ftruncate_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(ftruncate, wt_w) {
+	/* clang-format on */
+	.handled = LANDLOCK_ACCESS_FS_WRITE_FILE | LANDLOCK_ACCESS_FS_TRUNCATE,
+	.permitted = LANDLOCK_ACCESS_FS_WRITE_FILE,
+	.expected_open_result = 0,
+	.expected_ftruncate_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(ftruncate, wt_wt) {
+	/* clang-format on */
+	.handled = LANDLOCK_ACCESS_FS_WRITE_FILE | LANDLOCK_ACCESS_FS_TRUNCATE,
+	.permitted = LANDLOCK_ACCESS_FS_WRITE_FILE |
+		     LANDLOCK_ACCESS_FS_TRUNCATE,
+	.expected_open_result = 0,
+	.expected_ftruncate_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(ftruncate, wt_t) {
+	/* clang-format on */
+	.handled = LANDLOCK_ACCESS_FS_WRITE_FILE | LANDLOCK_ACCESS_FS_TRUNCATE,
+	.permitted = LANDLOCK_ACCESS_FS_TRUNCATE,
+	.expected_open_result = EACCES,
+};
+
+TEST_F_FORK(ftruncate, open_and_ftruncate)
+{
+	const char *const path = file1_s1d1;
+	const struct rule rules[] = {
+		{
+			.path = path,
+			.access = variant->permitted,
+		},
+		{},
+	};
+	int fd, ruleset_fd;
+
+	/* Enable Landlock. */
+	ruleset_fd = create_ruleset(_metadata, variant->handled, rules);
+	ASSERT_LE(0, ruleset_fd);
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	fd = open(path, O_WRONLY);
+	EXPECT_EQ(variant->expected_open_result, (fd < 0 ? errno : 0));
+	if (fd >= 0) {
+		EXPECT_EQ(variant->expected_ftruncate_result,
+			  test_ftruncate(fd));
+		ASSERT_EQ(0, close(fd));
+	}
+}
+
 /* clang-format off */
 FIXTURE(layout1_bind) {};
 /* clang-format on */
-- 
2.37.3