| // 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.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; \ |
| } |
| |
| #define log_exit(format, ...) \ |
| ({ \ |
| fprintf(stderr, format "\n", ##__VA_ARGS__); \ |
| exit(EXIT_FAILURE); \ |
| }) |
| |
| static void change_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; |
| 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_mountns(); |
| |
| if (!mkdtemp(binderfs_mntpt)) |
| ksft_exit_fail_msg( |
| "%s - Failed to create binderfs mountpoint\n", |
| strerror(errno)); |
| |
| 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)); |
| |
| rmdir_protect_errno(binderfs_mntpt); |
| return 1; |
| } |
| |
| /* binderfs mount test passed */ |
| ksft_inc_pass_cnt(); |
| |
| 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); |
| 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) { |
| rmdir_protect_errno(binderfs_mntpt); |
| 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(); |
| |
| snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt); |
| fd = open(device_path, O_CLOEXEC | O_RDONLY); |
| if (fd < 0) { |
| rmdir_protect_errno(binderfs_mntpt); |
| 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) { |
| rmdir_protect_errno(binderfs_mntpt); |
| 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(device_path); |
| if (ret < 0) { |
| rmdir_protect_errno(binderfs_mntpt); |
| ksft_exit_fail_msg("%s - Failed to delete binder device\n", |
| strerror(errno)); |
| } |
| |
| /* binder device removal passed */ |
| ksft_inc_pass_cnt(); |
| |
| snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt); |
| ret = unlink(device_path); |
| if (!ret) { |
| rmdir_protect_errno(binderfs_mntpt); |
| ksft_exit_fail_msg("Managed to delete binder-control device\n"); |
| } else if (errno != EPERM) { |
| 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)); |
| } |
| |
| /* binder-control device removal failed as expected */ |
| ksft_inc_xfail_cnt(); |
| |
| on_error: |
| 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)); |
| |
| /* binderfs unmount test passed */ |
| ksft_inc_pass_cnt(); |
| return 0; |
| } |
| |
| 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(int syncfds[2]) |
| { |
| int ret; |
| char buf; |
| |
| close_prot_errno_disarm(syncfds[1]); |
| |
| ret = unshare(CLONE_NEWUSER); |
| if (ret < 0) |
| ksft_exit_fail_msg("%s - Failed to unshare user namespace\n", |
| strerror(errno)); |
| |
| ret = write_nointr(syncfds[0], "1", 1); |
| if (ret != 1) |
| ksft_exit_fail_msg("write_nointr() failed\n"); |
| |
| ret = read_nointr(syncfds[0], &buf, 1); |
| if (ret != 1) |
| ksft_exit_fail_msg("read_nointr() failed\n"); |
| |
| close_prot_errno_disarm(syncfds[0]); |
| |
| if (setid_userns_root()) |
| ksft_exit_fail_msg("setid_userns_root() failed"); |
| } |
| |
| static void change_idmaps(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); |
| if (ret != 1) |
| ksft_exit_fail_msg("read_nointr() failed\n"); |
| |
| snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid()); |
| ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map)); |
| if (ret) |
| ksft_exit_fail_msg("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)); |
| if (ret) |
| ksft_exit_fail_msg("write_id_mapping(GID_MAP) failed"); |
| |
| ret = write_nointr(syncfds[1], "1", 1); |
| if (ret != 1) |
| ksft_exit_fail_msg("write_nointr() failed"); |
| |
| close_prot_errno_disarm(syncfds[1]); |
| } |
| |
| static void *binder_version_thread(void *data) |
| { |
| int fd = PTR_TO_INT(data); |
| struct binder_version version = { 0 }; |
| int ret; |
| |
| ret = ioctl(fd, BINDER_VERSION, &version); |
| if (ret < 0) |
| ksft_print_msg("%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); |
| if (ret < 0) |
| ksft_exit_fail_msg("%s - Failed to create socket pair", strerror(errno)); |
| |
| pid = fork(); |
| if (pid < 0) { |
| close_prot_errno_disarm(syncfds[0]); |
| close_prot_errno_disarm(syncfds[1]); |
| ksft_exit_fail_msg("%s - Failed to fork", strerror(errno)); |
| } |
| |
| if (pid == 0) { |
| int i, j, k, nthreads; |
| pthread_attr_t attr; |
| pthread_t threads[DEFAULT_THREADS]; |
| change_userns(syncfds); |
| change_mountns(); |
| |
| if (!mkdtemp(binderfs_mntpt)) |
| log_exit("%s - Failed to create binderfs mountpoint\n", |
| strerror(errno)); |
| |
| ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); |
| if (ret < 0) |
| log_exit("%s - Failed to mount binderfs\n", 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); |
| if (fd < 0) |
| log_exit("%s - Failed to open binder-control device\n", 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); |
| if (ret < 0) |
| log_exit("%s - Failed to allocate new binder device\n", strerror(errno)); |
| |
| snprintf(device_path, sizeof(device_path), "%s/%d", |
| binderfs_mntpt, i); |
| fds[i] = open(device_path, O_RDONLY | O_CLOEXEC); |
| if (fds[i] < 0) |
| log_exit("%s - Failed to open binder device\n", strerror(errno)); |
| } |
| |
| ret = umount2(binderfs_mntpt, MNT_DETACH); |
| rmdir_protect_errno(binderfs_mntpt); |
| if (ret < 0) |
| log_exit("%s - Failed to unmount binderfs\n", strerror(errno)); |
| |
| nthreads = get_nprocs_conf(); |
| if (nthreads > DEFAULT_THREADS) |
| nthreads = DEFAULT_THREADS; |
| |
| 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) { |
| ksft_print_msg("%s - Failed to create thread %d\n", strerror(errno), i); |
| break; |
| } |
| } |
| |
| for (j = 0; j < i; j++) { |
| void *fdptr = NULL; |
| |
| ret = pthread_join(threads[j], &fdptr); |
| if (ret) |
| ksft_print_msg("%s - Failed to join thread %d for fd %d\n", 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(syncfds, pid); |
| |
| ret = wait_for_pid(pid); |
| if (ret) |
| ksft_exit_fail_msg("wait_for_pid() failed"); |
| } |
| |
| 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) |
| { |
| int ret; |
| int syncfds[2]; |
| pid_t pid; |
| |
| ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); |
| if (ret < 0) |
| ksft_exit_fail_msg("%s - Failed to create socket pair", strerror(errno)); |
| |
| pid = fork(); |
| if (pid < 0) { |
| close_prot_errno_disarm(syncfds[0]); |
| close_prot_errno_disarm(syncfds[1]); |
| ksft_exit_fail_msg("%s - Failed to fork", strerror(errno)); |
| } |
| |
| if (pid == 0) { |
| change_userns(syncfds); |
| if (__do_binderfs_test() == 1) |
| exit(2); |
| exit(EXIT_SUCCESS); |
| } |
| |
| change_idmaps(syncfds, pid); |
| |
| ret = wait_for_pid(pid); |
| if (ret) { |
| if (ret == 2) |
| XFAIL(return, "The Android binderfs filesystem is not available"); |
| else |
| ksft_exit_fail_msg("wait_for_pid() failed"); |
| } |
| } |
| |
| TEST_HARNESS_MAIN |