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authorJoel Fernandes (Google) <joel@joelfernandes.org>2019-03-06 02:47:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-06 08:07:19 +0300
commit544029862cbb1d7903e19f2e58f48d4884e1201b (patch)
treeb6860b6512a4c2f79c5bc75fa2236d5472b313a4 /tools
parentab3948f58ff841e51feb845720624665ef5b7ef3 (diff)
downloadlinux-544029862cbb1d7903e19f2e58f48d4884e1201b.tar.xz
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. Link: http://lkml.kernel.org/r/20190112203816.85534-3-joel@joelfernandes.org Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: Shuah Khan <shuah@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Jann Horn <jannh@google.com> Cc: J. Bruce Fields <bfields@fieldses.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Marc-Andr Lureau <marcandre.lureau@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/memfd/memfd_test.c74
1 files changed, 74 insertions, 0 deletions
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;
@@ -693,6 +728,44 @@ static void test_seal_write(void)
}
/*
+ * 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();