Add tests to verify sealing memfds with the F_SEAL_FS_WRITE works as
expected.
Cc: dancol@xxxxxxxxxx
Cc: minchan@xxxxxxxxxx
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/memfd/memfd_test.c | 51 +++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 10baa1652fc2..4bd2b6c87bb4 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -27,7 +27,7 @@
#define MFD_DEF_SIZE 8192
#define STACK_SIZE 65536
-
+#define F_SEAL_FS_WRITE 0x0010
/*
* Default is not to test hugetlbfs
*/
@@ -170,6 +170,24 @@ static void *mfd_assert_mmap_shared(int fd)
return p;
}
+static void *mfd_fail_mmap_shared(int fd)
+{
+ void *p;
+
+ p = mmap(NULL,
+ mfd_def_size,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED,
+ fd,
+ 0);
+ if (p != MAP_FAILED) {
+ printf("mmap() didn't fail as expected\n");
+ abort();
+ }
+
+ return p;
+}
+
static void *mfd_assert_mmap_private(int fd)
{
void *p;
@@ -692,6 +710,36 @@ static void test_seal_write(void)
close(fd);
}
+/*
+ * Test SEAL_WRITE
+ * Test whether SEAL_WRITE actually prevents modifications.
+ */
+static void test_seal_fs_write(void)
+{
+ int fd;
+ void *p;
+
+ printf("%s SEAL-FS-WRITE\n", memfd_str);
+
+ fd = mfd_assert_new("kern_memfd_seal_fs_write",
+ mfd_def_size,
+ MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+ p = mfd_assert_mmap_shared(fd);
+
+ /* FS_WRITE seal can be added even with existing
+ * writeable mappings */
+ mfd_assert_has_seals(fd, 0);
+ mfd_assert_add_seals(fd, F_SEAL_FS_WRITE);
+ mfd_assert_has_seals(fd, F_SEAL_FS_WRITE);
+
+ mfd_assert_read(fd);
+ mfd_fail_write(fd);
+
+ munmap(p, mfd_def_size);
+ close(fd);
+}
+
/*
* Test SEAL_SHRINK
* Test whether SEAL_SHRINK actually prevents shrinking
@@ -945,6 +993,7 @@ int main(int argc, char **argv)
test_basic();
test_seal_write();
+ test_seal_fs_write();
test_seal_shrink();
test_seal_grow();
test_seal_resize();
--
2.19.0.605.g01d371f741-goog
