[PATCH v9 09/11] selftests/landlock: Test ftruncate on FDs created by memfd_create(2)

[Günther Noack]

All file descriptors that are truncatable need to have the Landlock
access rights set correctly on the file's Landlock security blob. This
is also the case for files that are opened by other means than
open(2).

Signed-off-by: Günther Noack <gnoack3000 at gmail.com>
---
 tools/testing/selftests/landlock/fs_test.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index f8aae01a2409..d5dab986f612 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -3603,6 +3603,22 @@ TEST_F_FORK(ftruncate, open_and_ftruncate_in_different_processes)
 	ASSERT_EQ(0, close(socket_fds[1]));
 }
 
+TEST(memfd_ftruncate)
+{
+	int fd;
+
+	fd = memfd_create("name", MFD_CLOEXEC);
+	ASSERT_LE(0, fd);
+
+	/*
+	 * Checks that ftruncate is permitted on file descriptors that are
+	 * created in ways other than open(2).
+	 */
+	EXPECT_EQ(0, test_ftruncate(fd));
+
+	ASSERT_EQ(0, close(fd));
+}
+
 /* clang-format off */
 FIXTURE(layout1_bind) {};
 /* clang-format on */
-- 
2.38.0