From: Joel Fernandes <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Jann Horn" <jannh@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Hugh Dickins" <hughd@google.com>,
"Khalid Aziz" <khalid.aziz@oracle.com>,
linux-api@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>,
"Stephen Rothwell" <sfr@canb.auug.org.au>
Subject: Re: [PATCH -next 2/2] selftests/memfd: modify tests for F_SEAL_FUTURE_WRITE seal
Date: Thu, 22 Nov 2018 15:21:52 -0800 [thread overview]
Message-ID: <20181122232152.GA17060@google.com> (raw)
In-Reply-To: <20181120052137.74317-2-joel@joelfernandes.org>
On Mon, Nov 19, 2018 at 09:21:37PM -0800, Joel Fernandes (Google) wrote:
> Modify the tests for F_SEAL_FUTURE_WRITE based on the changes
> introduced in previous patch.
>
> Also add a test to make sure the reopen issue pointed by Jann Horn [1]
> is fixed.
>
> [1] https://lore.kernel.org/lkml/CAG48ez1h=v-JYnDw81HaYJzOfrNhwYksxmc2r=cJvdQVgYM+NA@mail.gmail.com/
>
> Cc: Jann Horn <jannh@google.com>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
> tools/testing/selftests/memfd/memfd_test.c | 88 +++++++++++-----------
> 1 file changed, 44 insertions(+), 44 deletions(-)
Since we squashed [1] the mm/memfd patch modifications suggested by Andy into
the original patch, I also squashed the selftests modifications and appended
the patch inline below if you want to take this instead:
[1] https://lore.kernel.org/lkml/20181122230906.GA198127@google.com/T/#m8ba68f67f3ec24913a977b62bcaeafc4b194b8c8
---8<-----------------------
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Subject: [PATCH v4] 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.
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();
--
2.19.1.1215.g8438c0b245-goog
next prev parent reply other threads:[~2018-11-22 23:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 5:21 [PATCH -next 1/2] mm/memfd: make F_SEAL_FUTURE_WRITE seal more robust Joel Fernandes (Google)
2018-11-20 5:21 ` [PATCH -next 2/2] selftests/memfd: modify tests for F_SEAL_FUTURE_WRITE seal Joel Fernandes (Google)
2018-11-22 23:21 ` Joel Fernandes [this message]
2018-11-20 15:13 ` [PATCH -next 1/2] mm/memfd: make F_SEAL_FUTURE_WRITE seal more robust Andy Lutomirski
2018-11-20 18:39 ` Joel Fernandes
2018-11-20 20:07 ` Stephen Rothwell
2018-11-20 20:33 ` Andy Lutomirski
2018-11-20 20:47 ` Joel Fernandes
2018-11-20 21:02 ` Andy Lutomirski
2018-11-20 21:13 ` Joel Fernandes
2018-11-22 2:27 ` Andrew Morton
2018-11-22 3:25 ` Andy Lutomirski
2018-11-22 23:09 ` Joel Fernandes
2018-11-25 0:42 ` Andrew Morton
2018-11-25 0:47 ` Matthew Wilcox
2018-11-26 13:35 ` Joel Fernandes
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