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Subject[PATCH v2 2/3] binderfs_test: switch from /dev to a unique per-test mountpoint
Date
Unprivileged users will be able to create directories in there. The
unprivileged test for /dev wouldn't have worked on most systems.

Cc: Kees Cook <keescook@chromium.org>:
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
- Kees Cook <keescook@chromium.org>:
- Switch to unique mountpoint through mkdtemp().
---
.../filesystems/binderfs/binderfs_test.c | 47 +++++++++----------
1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
index 0cfca65e095a..818eb49f8125 100644
--- a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
+++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
@@ -139,29 +139,25 @@ static int __do_binderfs_test(void)
int fd, ret, saved_errno;
size_t len;
ssize_t wret;
- bool keep = false;
struct binderfs_device device = { 0 };
struct binder_version version = { 0 };
+ char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
+ device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];

change_to_mountns();

- ret = mkdir("/dev/binderfs", 0755);
- if (ret < 0) {
- if (errno != EEXIST)
- ksft_exit_fail_msg(
- "%s - Failed to create binderfs mountpoint\n",
- strerror(errno));
-
- keep = true;
- }
+ if (!mkdtemp(binderfs_mntpt))
+ ksft_exit_fail_msg(
+ "%s - Failed to create binderfs mountpoint\n",
+ strerror(errno));

- ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
+ ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
if (ret < 0) {
if (errno != ENODEV)
ksft_exit_fail_msg("%s - Failed to mount binderfs\n",
strerror(errno));

- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
return 1;
}

@@ -170,7 +166,8 @@ static int __do_binderfs_test(void)

memcpy(device.name, "my-binder", strlen("my-binder"));

- fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);
+ snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
+ fd = open(device_path, O_RDONLY | O_CLOEXEC);
if (fd < 0)
ksft_exit_fail_msg(
"%s - Failed to open binder-control device\n",
@@ -181,7 +178,7 @@ static int __do_binderfs_test(void)
close(fd);
errno = saved_errno;
if (ret < 0) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg(
"%s - Failed to allocate new binder device\n",
strerror(errno));
@@ -194,9 +191,10 @@ static int __do_binderfs_test(void)
/* binder device allocation test passed */
ksft_inc_pass_cnt();

- fd = open("/dev/binderfs/my-binder", O_CLOEXEC | O_RDONLY);
+ snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
+ fd = open(device_path, O_CLOEXEC | O_RDONLY);
if (fd < 0) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg("%s - Failed to open my-binder device\n",
strerror(errno));
}
@@ -206,7 +204,7 @@ static int __do_binderfs_test(void)
close(fd);
errno = saved_errno;
if (ret < 0) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg(
"%s - Failed to open perform BINDER_VERSION request\n",
strerror(errno));
@@ -218,9 +216,9 @@ static int __do_binderfs_test(void)
/* binder transaction with binderfs binder device passed */
ksft_inc_pass_cnt();

- ret = unlink("/dev/binderfs/my-binder");
+ ret = unlink(device_path);
if (ret < 0) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg("%s - Failed to delete binder device\n",
strerror(errno));
}
@@ -228,12 +226,13 @@ static int __do_binderfs_test(void)
/* binder device removal passed */
ksft_inc_pass_cnt();

- ret = unlink("/dev/binderfs/binder-control");
+ snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
+ ret = unlink(device_path);
if (!ret) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg("Managed to delete binder-control device\n");
} else if (errno != EPERM) {
- keep ? : rmdir_protect_errno("/dev/binderfs");
+ rmdir_protect_errno(binderfs_mntpt);
ksft_exit_fail_msg(
"%s - Failed to delete binder-control device but exited with unexpected error code\n",
strerror(errno));
@@ -243,8 +242,8 @@ static int __do_binderfs_test(void)
ksft_inc_xfail_cnt();

on_error:
- ret = umount2("/dev/binderfs", MNT_DETACH);
- keep ?: rmdir_protect_errno("/dev/binderfs");
+ ret = umount2(binderfs_mntpt, MNT_DETACH);
+ rmdir_protect_errno(binderfs_mntpt);
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to unmount binderfs\n",
strerror(errno));
--
2.25.1
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