From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 308B16B0010 for ; Thu, 18 Oct 2018 02:59:21 -0400 (EDT) Received: by mail-pl1-f200.google.com with SMTP id w12-v6so10572750plp.9 for ; Wed, 17 Oct 2018 23:59:21 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j189-v6sor1410320pgd.42.2018.10.17.23.59.19 for (Google Transport Security); Wed, 17 Oct 2018 23:59:20 -0700 (PDT) From: "Joel Fernandes (Google)" Subject: [PATCH v3 2/2] selftests/memfd: Add tests for F_SEAL_FS_WRITE seal Date: Wed, 17 Oct 2018 23:59:08 -0700 Message-Id: <20181018065908.254389-2-joel@joelfernandes.org> In-Reply-To: <20181018065908.254389-1-joel@joelfernandes.org> References: <20181018065908.254389-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, "Joel Fernandes (Google)" , dancol@google.com, minchan@kernel.org, Al Viro , Andrew Morton , gregkh@linuxfoundation.org, "J. Bruce Fields" , Jeff Layton , John Stultz , jreck@google.com, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, marcandre.lureau@redhat.com, Mike Kravetz , Shuah Khan , Thomas Gleixner , tkjos@google.com Add tests to verify sealing memfds with the F_SEAL_FS_WRITE works as expected. Cc: dancol@google.com Cc: minchan@kernel.org Reviewed-by: John Stultz Signed-off-by: Joel Fernandes (Google) --- tools/testing/selftests/memfd/memfd_test.c | 74 ++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 10baa1652fc2..32b207ca7372 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -692,6 +692,79 @@ static void test_seal_write(void) close(fd); } +/* + * 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(); -- 2.19.1.331.ge82ca0e54c-goog