[PATCH v6 4/6] selftests/landlock: Add audit test for whiteout object creation

["Günther Noack" <gnoack@google.com>]

Add audit_layout1.make_whiteout: This test looks similar to
audit_layout1.make_char, but creates a whiteout object through mknod().
Since whiteout object creation is now guarded with
LANDLOCK_ACCESS_FS_MAKE_REG rather than LANDLOCK_ACCESS_FS_MAKE_CHAR, it
also needs to log the matching denial to audit.

Signed-off-by: Günther Noack <gnoack@google.com>
---
 tools/testing/selftests/landlock/fs_test.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 871a5b819b98..a9130ed70af5 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -7622,6 +7622,25 @@ TEST_F(audit_layout1, make_char)
 	EXPECT_EQ(1, records.domain);
 }
 
+TEST_F(audit_layout1, make_whiteout)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	enforce_fs(_metadata, ACCESS_ALL, NULL);
+
+	/* Whiteout creation is denied and logged as fs.make_reg. */
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFCHR | 0644, makedev(0, 0)));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_reg",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
 TEST_F(audit_layout1, make_dir)
 {
 	struct audit_records records;
-- 
2.55.0.699.gb54405d56f-goog