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From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	dancol@google.com, minchan@kernel.org,
	"John Stultz" <john.stultz@linaro.org>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	gregkh@linuxfoundation.org, hch@infradead.org,
	"J. Bruce Fields" <bfields@fieldses.org>,
	"Jeff Layton" <jlayton@kernel.org>,
	jreck@google.com, "Khalid Aziz" <khalid.aziz@oracle.com>,
	"Lei Yang" <Lei.Yang@windriver.com>,
	linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-mm@kvack.org,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Shuah Khan" <shuah@kernel.org>,
	tkjos@google.com, valdis.kletnieks@vt.edu
Subject: [PATCH v3 resend 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal
Date: Wed,  7 Nov 2018 20:15:37 -0800
Message-ID: <20181108041537.39694-2-joel@joelfernandes.org> (raw)
In-Reply-To: <20181108041537.39694-1-joel@joelfernandes.org>

Add tests to verify sealing memfds with the F_SEAL_FUTURE_WRITE works as
expected.

Cc: dancol@google.com
Cc: minchan@kernel.org
Reviewed-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.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();
-- 
2.19.1.930.g4563a0d9d0-goog


  reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-08  4:15 [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd Joel Fernandes (Google)
2018-11-08  4:15 ` Joel Fernandes (Google) [this message]
2018-11-09  8:49 ` Joel Fernandes
2018-11-09 20:36 ` Andrew Morton
2018-11-10  3:54   ` Joel Fernandes
2018-11-09 21:06 ` Jann Horn
2018-11-09 21:19   ` Jann Horn
2018-11-10  3:20     ` Joel Fernandes
2018-11-10  6:05       ` Andy Lutomirski
2018-11-10 18:24         ` Joel Fernandes
2018-11-10 18:45           ` Daniel Colascione
2018-11-10 19:11             ` Daniel Colascione
2018-11-10 19:55               ` Andy Lutomirski
2018-11-10 22:09               ` Joel Fernandes
2018-11-10 22:18                 ` Andy Lutomirski
2018-11-11  2:38                   ` Joel Fernandes
2018-11-11  3:40                     ` Andy Lutomirski
2018-11-11  4:01                       ` Joel Fernandes
2018-11-11  8:09                       ` Joel Fernandes
2018-11-11  8:30                         ` Daniel Colascione
2018-11-11 15:14                           ` Andy Lutomirski
2018-11-11 17:36                             ` Joel Fernandes
     [not found]       ` <CAKOZuethC7+YrRyyGciUCfhSSa9cCcAFJ8g_qEw9uh3TBbyOcg@mail.gmail.com>
2018-11-10 17:10         ` Joel Fernandes
2018-11-09 21:40   ` Andy Lutomirski
2018-11-09 20:02     ` Michael Tirado
2018-11-10  1:49       ` Joel Fernandes
2018-11-09 22:20   ` Daniel Colascione
2018-11-09 22:37     ` Andy Lutomirski
2018-11-09 22:42       ` Daniel Colascione
2018-11-09 23:14         ` Andy Lutomirski
2018-11-10  1:36           ` Joel Fernandes
2018-11-09 23:46   ` Joel Fernandes

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