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// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <linux/android/binder.h>
#include <linux/android/binderfs.h>
#include "../../kselftest.h"
#include "../../kselftest_harness.h"
static ssize_t write_nointr(int fd, const void *buf, size_t count)
{
ssize_t ret;
again:
ret = write(fd, buf, count);
if (ret < 0 && errno == EINTR)
goto again;
return ret;
}
static void write_to_file(const char *filename, const void *buf, size_t count,
int allowed_errno)
{
int fd, saved_errno;
ssize_t ret;
fd = open(filename, O_WRONLY | O_CLOEXEC);
if (fd < 0)
ksft_exit_fail_msg("%s - Failed to open file %s\n",
strerror(errno), filename);
ret = write_nointr(fd, buf, count);
if (ret < 0) {
if (allowed_errno && (errno == allowed_errno)) {
close(fd);
return;
}
goto on_error;
}
if ((size_t)ret != count)
goto on_error;
close(fd);
return;
on_error:
saved_errno = errno;
close(fd);
errno = saved_errno;
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to write to file %s\n",
strerror(errno), filename);
ksft_exit_fail_msg("Failed to write to file %s\n", filename);
}
static void change_to_userns(void)
{
int ret;
uid_t uid;
gid_t gid;
/* {g,u}id_map files only allow a max of 4096 bytes written to them */
char idmap[4096];
uid = getuid();
gid = getgid();
ret = unshare(CLONE_NEWUSER);
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to unshare user namespace\n",
strerror(errno));
write_to_file("/proc/self/setgroups", "deny", strlen("deny"), ENOENT);
ret = snprintf(idmap, sizeof(idmap), "0 %d 1", uid);
if (ret < 0 || (size_t)ret >= sizeof(idmap))
ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n",
strerror(errno));
write_to_file("/proc/self/uid_map", idmap, strlen(idmap), 0);
ret = snprintf(idmap, sizeof(idmap), "0 %d 1", gid);
if (ret < 0 || (size_t)ret >= sizeof(idmap))
ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n",
strerror(errno));
write_to_file("/proc/self/gid_map", idmap, strlen(idmap), 0);
ret = setgid(0);
if (ret)
ksft_exit_fail_msg("%s - Failed to setgid(0)\n",
strerror(errno));
ret = setuid(0);
if (ret)
ksft_exit_fail_msg("%s - Failed to setgid(0)\n",
strerror(errno));
}
static void change_to_mountns(void)
{
int ret;
ret = unshare(CLONE_NEWNS);
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to unshare mount namespace\n",
strerror(errno));
ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to mount / as private\n",
strerror(errno));
}
static void rmdir_protect_errno(const char *dir)
{
int saved_errno = errno;
(void)rmdir(dir);
errno = saved_errno;
}
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 };
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;
}
ret = mount(NULL, "/dev/binderfs", "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");
return 1;
}
/* binderfs mount test passed */
ksft_inc_pass_cnt();
memcpy(device.name, "my-binder", strlen("my-binder"));
fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);
if (fd < 0)
ksft_exit_fail_msg(
"%s - Failed to open binder-control device\n",
strerror(errno));
ret = ioctl(fd, BINDER_CTL_ADD, &device);
saved_errno = errno;
close(fd);
errno = saved_errno;
if (ret < 0) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg(
"%s - Failed to allocate new binder device\n",
strerror(errno));
}
ksft_print_msg(
"Allocated new binder device with major %d, minor %d, and name %s\n",
device.major, device.minor, device.name);
/* binder device allocation test passed */
ksft_inc_pass_cnt();
fd = open("/dev/binderfs/my-binder", O_CLOEXEC | O_RDONLY);
if (fd < 0) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg("%s - Failed to open my-binder device\n",
strerror(errno));
}
ret = ioctl(fd, BINDER_VERSION, &version);
saved_errno = errno;
close(fd);
errno = saved_errno;
if (ret < 0) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg(
"%s - Failed to open perform BINDER_VERSION request\n",
strerror(errno));
}
ksft_print_msg("Detected binder version: %d\n",
version.protocol_version);
/* binder transaction with binderfs binder device passed */
ksft_inc_pass_cnt();
ret = unlink("/dev/binderfs/my-binder");
if (ret < 0) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg("%s - Failed to delete binder device\n",
strerror(errno));
}
/* binder device removal passed */
ksft_inc_pass_cnt();
ret = unlink("/dev/binderfs/binder-control");
if (!ret) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg("Managed to delete binder-control device\n");
} else if (errno != EPERM) {
keep ? : rmdir_protect_errno("/dev/binderfs");
ksft_exit_fail_msg(
"%s - Failed to delete binder-control device but exited with unexpected error code\n",
strerror(errno));
}
/* binder-control device removal failed as expected */
ksft_inc_xfail_cnt();
on_error:
ret = umount2("/dev/binderfs", MNT_DETACH);
keep ?: rmdir_protect_errno("/dev/binderfs");
if (ret < 0)
ksft_exit_fail_msg("%s - Failed to unmount binderfs\n",
strerror(errno));
/* binderfs unmount test passed */
ksft_inc_pass_cnt();
return 0;
}
TEST(binderfs_test_privileged)
{
if (geteuid() != 0)
XFAIL(return, "Tests are not run as root. Skipping privileged tests");
if (__do_binderfs_test() == 1)
XFAIL(return, "The Android binderfs filesystem is not available");
}
TEST(binderfs_test_unprivileged)
{
change_to_userns();
if (__do_binderfs_test() == 1)
XFAIL(return, "The Android binderfs filesystem is not available");
}
TEST_HARNESS_MAIN
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