// 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; 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(); 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; } 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