From: Joel Fernandes <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
dancol@google.com, minchan@kernel.org,
"Jann Horn" <jannh@google.com>,
"John Stultz" <john.stultz@linaro.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Hugh Dickins" <hughd@google.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
"Jeff Layton" <jlayton@kernel.org>,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Shuah Khan" <shuah@kernel.org>
Subject: [PATCH v4 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal
Date: Sat, 12 Jan 2019 15:38:16 -0500 [thread overview]
Message-ID: <20190112203816.85534-3-joel@joelfernandes.org> (raw)
In-Reply-To: <20190112203816.85534-1-joel@joelfernandes.org>
From: "Joel Fernandes (Google)" <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
Cc: Jann Horn <jannh@google.com>
Cc: 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..c67d32eeb668 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -54,6 +54,22 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags)
return fd;
}
+static int mfd_assert_reopen_fd(int fd_in)
+{
+ int r, fd;
+ char path[100];
+
+ sprintf(path, "/proc/self/fd/%d", fd_in);
+
+ fd = open(path, O_RDWR);
+ if (fd < 0) {
+ printf("re-open of existing fd %d failed\n", fd_in);
+ abort();
+ }
+
+ return fd;
+}
+
static void mfd_fail_new(const char *name, unsigned int flags)
{
int r;
@@ -255,6 +271,25 @@ static void mfd_assert_read(int fd)
munmap(p, mfd_def_size);
}
+/* Test that PROT_READ + MAP_SHARED mappings work. */
+static void mfd_assert_read_shared(int fd)
+{
+ void *p;
+
+ /* verify PROT_READ and MAP_SHARED *is* allowed */
+ p = mmap(NULL,
+ mfd_def_size,
+ PROT_READ,
+ MAP_SHARED,
+ fd,
+ 0);
+ if (p == MAP_FAILED) {
+ printf("mmap() failed: %m\n");
+ abort();
+ }
+ munmap(p, mfd_def_size);
+}
+
static void mfd_assert_write(int fd)
{
ssize_t l;
@@ -692,6 +727,44 @@ 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, fd2;
+ 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);
+
+ mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE);
+ mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE);
+
+ /* read should pass, writes should fail */
+ mfd_assert_read(fd);
+ mfd_assert_read_shared(fd);
+ mfd_fail_write(fd);
+
+ fd2 = mfd_assert_reopen_fd(fd);
+ /* read should pass, writes should still fail */
+ mfd_assert_read(fd2);
+ mfd_assert_read_shared(fd2);
+ mfd_fail_write(fd2);
+
+ munmap(p, mfd_def_size);
+ close(fd2);
+ 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();
--
2.20.1.97.g81188d93c3-goog
next prev parent reply other threads:[~2019-01-12 20:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-12 20:38 [PATCH v4 0/2] Add a future write seal to memfd Joel Fernandes
2019-01-12 20:38 ` [PATCH v4 1/2] mm/memfd: Add an F_SEAL_FUTURE_WRITE " Joel Fernandes
2019-01-15 17:36 ` John Stultz
2019-01-12 20:38 ` Joel Fernandes [this message]
2019-01-15 1:39 ` [PATCH v4 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal shuah
2019-01-15 14:50 ` Joel Fernandes
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