On 4/1/22 4:08 PM, Daniel Verkamp wrote:
Tests that ensure MFD_NOEXEC memfds have the appropriate mode bits and
cannot be chmod-ed into being executable.
Signed-off-by: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
---
tools/testing/selftests/memfd/memfd_test.c | 34 ++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index fdb0e46e9df9..a79567161cdf 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -32,6 +32,10 @@
#define F_SEAL_EXEC 0x0020
#endif
+#ifndef MFD_NOEXEC
+#define MFD_NOEXEC 0x0008U
+#endif
+
/*
* Default is not to test hugetlbfs
*/
@@ -959,6 +963,35 @@ static void test_seal_exec(void)
close(fd);
}
+/*
+ * Test memfd_create with MFD_NOEXEC flag
+ * Test that MFD_NOEXEC applies F_SEAL_EXEC and prevents change of exec bits
+ */
+static void test_noexec(void)
+{
+ int fd;
+
+ printf("%s NOEXEC\n", memfd_str);
+
+ /* Create with NOEXEC and ALLOW_SEALING */
+ fd = mfd_assert_new("kern_memfd_noexec",
+ mfd_def_size,
+ MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_NOEXEC);
Don't we need to check fd here?
+ mfd_assert_mode(fd, 0666);
+ mfd_assert_has_seals(fd, F_SEAL_EXEC);
+ mfd_fail_chmod(fd, 0777);
+ close(fd);
+
+ /* Create with NOEXEC but without ALLOW_SEALING */
+ fd = mfd_assert_new("kern_memfd_noexec",
+ mfd_def_size,
+ MFD_CLOEXEC | MFD_NOEXEC);
What happens when mfd_assert_new() fails - don't we need to check fd?
+ mfd_assert_mode(fd, 0666);
+ mfd_assert_has_seals(fd, F_SEAL_EXEC | F_SEAL_SEAL);
+ mfd_fail_chmod(fd, 0777);
+ close(fd);
+}
+
/*
* Test sharing via dup()
* Test that seals are shared between dupped FDs and they're all equal.
@@ -1132,6 +1165,7 @@ int main(int argc, char **argv)
test_create();
test_basic();
+ test_noexec();
test_seal_write();
test_seal_future_write();
fd isn't checked in the other test F_SEAL_EXEC in the 3/4 patch.
thanks,
-- Shuah
