The patch titled
Subject: selftests/memfd: add tests for F_SEAL_FUTURE_WRITE seal
has been added to the -mm tree. Its filename is
selftests-memfd-add-tests-for-f_seal_future_write-seal.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/selftests-memfd-add-tests-for-f_seal_future_write-seal.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/selftests-memfd-add-tests-for-f_seal_future_write-seal.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Subject: selftests/memfd: add tests for F_SEAL_FUTURE_WRITE seal
Add tests to verify sealing memfds with the F_SEAL_FUTURE_WRITE works as
expected.
Link: http://lkml.kernel.org/r/20181108041537.39694-2-joel@xxxxxxxxxxxxxxxxx
Reviewed-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Daniel Colascione <dancol@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: J. Bruce Fields <bfields@xxxxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Cc: John Reck <jreck@xxxxxxxxxx>
Cc: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
Cc: Lei Yang <Lei.Yang@xxxxxxxxxxxxx>
Cc: Marc-Andr Lureau <marcandre.lureau@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Todd Kjos <tkjos@xxxxxxxxxx>
Cc: Valdis Kletnieks <valdis.kletnieks@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/memfd/memfd_test.c | 74 +++++++++++++++++++
1 file changed, 74 insertions(+)
--- a/tools/testing/selftests/memfd/memfd_test.c~selftests-memfd-add-tests-for-f_seal_future_write-seal
+++ a/tools/testing/selftests/memfd/memfd_test.c
@@ -693,6 +693,79 @@ static void test_seal_write(void)
}
/*
+ * Test SEAL_FUTURE_WRITE
+ * Test whether SEAL_FUTURE_WRITE actually prevents modifications.
+ */
+static void test_seal_future_write(void)
+{
+ int fd;
+ void *p;
+
+ printf("%s SEAL-FUTURE-WRITE\n", memfd_str);
+
+ fd = mfd_assert_new("kern_memfd_seal_future_write",
+ mfd_def_size,
+ MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+ p = mfd_assert_mmap_shared(fd);
+
+ mfd_assert_has_seals(fd, 0);
+ /* Not adding grow/shrink seals makes the future write
+ * seal fail to get added
+ */
+ mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE);
+
+ mfd_assert_add_seals(fd, F_SEAL_GROW);
+ mfd_assert_has_seals(fd, F_SEAL_GROW);
+
+ /* Should still fail since shrink seal has
+ * not yet been added
+ */
+ mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE);
+
+ mfd_assert_add_seals(fd, F_SEAL_SHRINK);
+ mfd_assert_has_seals(fd, F_SEAL_GROW |
+ F_SEAL_SHRINK);
+
+ /* Now should succeed, also verifies that the seal
+ * could be added with an existing writable mmap
+ */
+ mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE);
+ mfd_assert_has_seals(fd, F_SEAL_SHRINK |
+ F_SEAL_GROW |
+ F_SEAL_FUTURE_WRITE);
+
+ /* read should pass, writes should fail */
+ mfd_assert_read(fd);
+ mfd_fail_write(fd);
+
+ munmap(p, mfd_def_size);
+ close(fd);
+
+ /* Test adding all seals (grow, shrink, future write) at once */
+ fd = mfd_assert_new("kern_memfd_seal_future_write2",
+ mfd_def_size,
+ MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+ p = mfd_assert_mmap_shared(fd);
+
+ mfd_assert_has_seals(fd, 0);
+ mfd_assert_add_seals(fd, F_SEAL_SHRINK |
+ F_SEAL_GROW |
+ F_SEAL_FUTURE_WRITE);
+ mfd_assert_has_seals(fd, F_SEAL_SHRINK |
+ F_SEAL_GROW |
+ F_SEAL_FUTURE_WRITE);
+
+ /* read should pass, writes should fail */
+ 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 +1018,7 @@ int main(int argc, char **argv)
test_basic();
test_seal_write();
+ test_seal_future_write();
test_seal_shrink();
test_seal_grow();
test_seal_resize();
_
Patches currently in -mm which might be from joel@xxxxxxxxxxxxxxxxx are
mm-treewide-remove-unused-address-argument-from-pte_alloc-functions-v2.patch
mm-speed-up-mremap-by-20x-on-large-regions-v5.patch
mm-speed-up-mremap-by-20x-on-large-regions-v5-fix.patch
mm-select-have_move_pmd-in-x86-for-faster-mremap.patch
mm-add-an-f_seal_future_write-seal-to-memfd.patch
selftests-memfd-add-tests-for-f_seal_future_write-seal.patch
