// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <sched.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/fsuid.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/sysinfo.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <linux/android/binder.h>
#include <linux/android/binderfs.h>
#include "../../kselftest_harness.h"
#define DEFAULT_THREADS 4
#define PTR_TO_INT(p) ((int)((intptr_t)(p)))
#define INT_TO_PTR(u) ((void *)((intptr_t)(u)))
#define close_prot_errno_disarm(fd) \
if (fd >= 0) { \
int _e_ = errno; \
close(fd); \
errno = _e_; \
fd = -EBADF; \
}
static void change_mountns(struct __test_metadata *_metadata)
{
int ret;
ret = unshare(CLONE_NEWNS);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to unshare mount namespace",
strerror(errno));
}
ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to mount / as private",
strerror(errno));
}
}
static int __do_binderfs_test(struct __test_metadata *_metadata)
{
int fd, ret, saved_errno, result = 1;
size_t len;
ssize_t wret;
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];
static const char * const binder_features[] = {
"oneway_spam_detection",
"extended_error",
"freeze_notification",
};
change_mountns(_metadata);
EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
TH_LOG("%s - Failed to create binderfs mountpoint",
strerror(errno));
goto out;
}
ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
EXPECT_EQ(ret, 0) {
if (errno == ENODEV)
SKIP(goto out, "binderfs missing");
TH_LOG("%s - Failed to mount binderfs", strerror(errno));
goto rmdir;
}
/* success: binderfs mounted */
memcpy(device.name, "my-binder", strlen("my-binder"));
snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
fd = open(device_path, O_RDONLY | O_CLOEXEC);
EXPECT_GE(fd, 0) {
TH_LOG("%s - Failed to open binder-control device",
strerror(errno));
goto umount;
}
ret = ioctl(fd, BINDER_CTL_ADD, &device);
saved_errno = errno;
close(fd);
errno = saved_errno;
EXPECT_GE(ret, 0) {
TH_LOG("%s - Failed to allocate new binder device",
strerror(errno));
goto umount;
}
TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
device.major, device.minor, device.name);
/* success: binder device allocation */
snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
fd = open(device_path, O_CLOEXEC | O_RDONLY);
EXPECT_GE(fd, 0) {
TH_LOG("%s - Failed to open my-binder device",
strerror(errno));
goto umount;
}
ret = ioctl(fd, BINDER_VERSION, &version);
saved_errno = errno;
close(fd);
errno = saved_errno;
EXPECT_GE(ret, 0) {
TH_LOG("%s - Failed to open perform BINDER_VERSION request",
strerror(errno));
goto umount;
}
TH_LOG("Detected binder version: %d", version.protocol_version);
/* success: binder transaction with binderfs binder device */
ret = unlink(device_path);
EXPECT_EQ(ret, 0) {
TH_LOG("%s - Failed to delete binder device",
strerror(errno));
goto umount;
}
/* success: binder device removal */
snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
ret = unlink(device_path);
EXPECT_NE(ret, 0) {
TH_LOG("Managed to delete binder-control device");
goto umount;
}
EXPECT_EQ(errno, EPERM) {
TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
strerror(errno));
goto umount;
}
/* success: binder-control device removal failed as expected */
for (int i = 0; i < ARRAY_SIZE(binder_features); i++) {
snprintf(device_path, sizeof(device_path), "%s/features/%s",
binderfs_mntpt, binder_features[i]);
fd = open(device_path, O_CLOEXEC | O_RDONLY);
EXPECT_GE(fd, 0) {
TH_LOG("%s - Failed to open binder feature: %s",
strerror(errno), binder_features[i]);
goto umount;
}
close(fd);
}
/* success: binder feature files found */
result = 0;
umount:
ret = umount2(binderfs_mntpt, MNT_DETACH);
EXPECT_EQ(ret, 0) {
TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
}
rmdir:
ret = rmdir(binderfs_mntpt);
EXPECT_EQ(ret, 0) {
TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
}
out:
return result;
}
static int wait_for_pid(pid_t pid)
{
int status, ret;
again:
ret = waitpid(pid, &status, 0);
if (ret == -1) {
if (errno == EINTR)
goto again;
return -1;
}
if (!WIFEXITED(status))
return -1;
return WEXITSTATUS(status);
}
static int setid_userns_root(void)
{
if (setuid(0))
return -1;
if (setgid(0))
return -1;
setfsuid(0);
setfsgid(0);
return 0;
}
enum idmap_type {
UID_MAP,
GID_MAP,
};
static ssize_t read_nointr(int fd, void *buf, size_t count)
{
ssize_t ret;
again:
ret = read(fd, buf, count);
if (ret < 0 && errno == EINTR)
goto again;
return ret;
}
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 int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
size_t buf_size)
{
int fd;
int ret;
char path[4096];
if (type == GID_MAP) {
int setgroups_fd;
snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
if (setgroups_fd < 0 && errno != ENOENT)
return -1;
if (setgroups_fd >= 0) {
ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
close_prot_errno_disarm(setgroups_fd);
if (ret != sizeof("deny") - 1)
return -1;
}
}
switch (type) {
case UID_MAP:
ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
break;
case GID_MAP:
ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
break;
default:
return -1;
}
if (ret < 0 || ret >= sizeof(path))
return -E2BIG;
fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
if (fd < 0)
return -1;
ret = write_nointr(fd, buf, buf_size);
close_prot_errno_disarm(fd);
if (ret != buf_size)
return -1;
return 0;
}
static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
{
int ret;
char buf;
close_prot_errno_disarm(syncfds[1]);
ret = unshare(CLONE_NEWUSER);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to unshare user namespace",
strerror(errno));
}
ret = write_nointr(syncfds[0], "1", 1);
ASSERT_EQ(ret, 1) {
TH_LOG("write_nointr() failed");
}
ret = read_nointr(syncfds[0], &buf, 1);
ASSERT_EQ(ret, 1) {
TH_LOG("read_nointr() failed");
}
close_prot_errno_disarm(syncfds[0]);
ASSERT_EQ(setid_userns_root(), 0) {
TH_LOG("setid_userns_root() failed");
}
}
static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
{
int ret;
char buf;
char id_map[4096];
close_prot_errno_disarm(syncfds[0]);
ret = read_nointr(syncfds[1], &buf, 1);
ASSERT_EQ(ret, 1) {
TH_LOG("read_nointr() failed");
}
snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
ASSERT_EQ(ret, 0) {
TH_LOG("write_id_mapping(UID_MAP) failed");
}
snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
ASSERT_EQ(ret, 0) {
TH_LOG("write_id_mapping(GID_MAP) failed");
}
ret = write_nointr(syncfds[1], "1", 1);
ASSERT_EQ(ret, 1) {
TH_LOG("write_nointr() failed");
}
close_prot_errno_disarm(syncfds[1]);
}
struct __test_metadata *_thread_metadata;
static void *binder_version_thread(void *data)
{
struct __test_metadata *_metadata = _thread_metadata;
int fd = PTR_TO_INT(data);
struct binder_version version = { 0 };
int ret;
ret = ioctl(fd, BINDER_VERSION, &version);
if (ret < 0)
TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
strerror(errno));
pthread_exit(data);
}
/*
* Regression test:
* 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
* f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
* 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
*/
TEST(binderfs_stress)
{
int fds[1000];
int syncfds[2];
pid_t pid;
int fd, ret;
size_t len;
struct binderfs_device device = { 0 };
char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to create socket pair", strerror(errno));
}
pid = fork();
ASSERT_GE(pid, 0) {
TH_LOG("%s - Failed to fork", strerror(errno));
close_prot_errno_disarm(syncfds[0]);
close_prot_errno_disarm(syncfds[1]);
}
if (pid == 0) {
int i, j, k, nthreads;
pthread_attr_t attr;
pthread_t threads[DEFAULT_THREADS];
change_userns(_metadata, syncfds);
change_mountns(_metadata);
ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
TH_LOG("%s - Failed to create binderfs mountpoint",
strerror(errno));
}
ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel",
strerror(errno));
}
for (int i = 0; i < ARRAY_SIZE(fds); i++) {
snprintf(device_path, sizeof(device_path),
"%s/binder-control", binderfs_mntpt);
fd = open(device_path, O_RDONLY | O_CLOEXEC);
ASSERT_GE(fd, 0) {
TH_LOG("%s - Failed to open binder-control device",
strerror(errno));
}
memset(&device, 0, sizeof(device));
snprintf(device.name, sizeof(device.name), "%d", i);
ret = ioctl(fd, BINDER_CTL_ADD, &device);
close_prot_errno_disarm(fd);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to allocate new binder device",
strerror(errno));
}
snprintf(device_path, sizeof(device_path), "%s/%d",
binderfs_mntpt, i);
fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
ASSERT_GE(fds[i], 0) {
TH_LOG("%s - Failed to open binder device", strerror(errno));
}
}
ret = umount2(binderfs_mntpt, MNT_DETACH);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
rmdir(binderfs_mntpt);
}
nthreads = get_nprocs_conf();
if (nthreads > DEFAULT_THREADS)
nthreads = DEFAULT_THREADS;
_thread_metadata = _metadata;
pthread_attr_init(&attr);
for (k = 0; k < ARRAY_SIZE(fds); k++) {
for (i = 0; i < nthreads; i++) {
ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
if (ret) {
TH_LOG("%s - Failed to create thread %d",
strerror(errno), i);
break;
}
}
for (j = 0; j < i; j++) {
void *fdptr = NULL;
ret = pthread_join(threads[j], &fdptr);
if (ret)
TH_LOG("%s - Failed to join thread %d for fd %d",
strerror(errno), j, PTR_TO_INT(fdptr));
}
}
pthread_attr_destroy(&attr);
for (k = 0; k < ARRAY_SIZE(fds); k++)
close(fds[k]);
exit(EXIT_SUCCESS);
}
change_idmaps(_metadata, syncfds, pid);
ret = wait_for_pid(pid);
ASSERT_EQ(ret, 0) {
TH_LOG("wait_for_pid() failed");
}
}
TEST(binderfs_test_privileged)
{
if (geteuid() != 0)
SKIP(return, "Tests are not run as root. Skipping privileged tests");
if (__do_binderfs_test(_metadata))
SKIP(return, "The Android binderfs filesystem is not available");
}
TEST(binderfs_test_unprivileged)
{
int ret;
int syncfds[2];
pid_t pid;
ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
ASSERT_EQ(ret, 0) {
TH_LOG("%s - Failed to create socket pair", strerror(errno));
}
pid = fork();
ASSERT_GE(pid, 0) {
close_prot_errno_disarm(syncfds[0]);
close_prot_errno_disarm(syncfds[1]);
TH_LOG("%s - Failed to fork", strerror(errno));
}
if (pid == 0) {
change_userns(_metadata, syncfds);
if (__do_binderfs_test(_metadata))
exit(2);
exit(EXIT_SUCCESS);
}
change_idmaps(_metadata, syncfds, pid);
ret = wait_for_pid(pid);
if (ret) {
if (ret == 2)
SKIP(return, "The Android binderfs filesystem is not available");
ASSERT_EQ(ret, 0) {
TH_LOG("wait_for_pid() failed");
}
}
}
TEST_HARNESS_MAIN
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