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Message-ID: <CAEXW_YTDWgY3JAeiY0Ti0BBL=iJMcSkR5V7USJYv6UxHiCpN-g@mail.gmail.com>
Date: Thu, 18 Oct 2018 00:08:58 -0700
From: Joel Fernandes <joel@...lfernandes.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: kernel-team <kernel-team@...roid.com>,
"Joel Fernandes (Google)" <joel@...lfernandes.org>,
Daniel Colascione <dancol@...gle.com>,
Minchan Kim <minchan@...nel.org>,
Al Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"J. Bruce Fields" <bfields@...ldses.org>,
Jeff Layton <jlayton@...nel.org>,
John Stultz <john.stultz@...aro.org>,
John Reck <jreck@...gle.com>, linux-fsdevel@...r.kernel.org,
linux-kselftest <linux-kselftest@...r.kernel.org>,
linux-mm <linux-mm@...ck.org>, marcandre.lureau@...hat.com,
Mike Kravetz <mike.kravetz@...cle.com>,
Shuah Khan <shuah@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Todd Kjos <tkjos@...gle.com>
Subject: Re: [PATCH v3 2/2] selftests/memfd: Add tests for F_SEAL_FS_WRITE seal
On Wed, Oct 17, 2018 at 11:59 PM, Joel Fernandes (Google)
<joel@...lfernandes.org> wrote:
> Add tests to verify sealing memfds with the F_SEAL_FS_WRITE works as
> expected.
I messed the commit message it should be "F_SEAL_FUTURE_WRITE", but
otherwise this
patch itself is good and I'll resend it with the corrected commit
message after further review.
thanks,
- Joel
> Cc: dancol@...gle.com
> Cc: minchan@...nel.org
> Reviewed-by: John Stultz <john.stultz@...aro.org>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> ---
> 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
>
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