1 // SPDX-License-Identifier: GPL-2.0 2 3 #define _GNU_SOURCE 4 #include <errno.h> 5 #include <fcntl.h> 6 #include <pthread.h> 7 #include <sched.h> 8 #include <stdbool.h> 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <sys/fsuid.h> 13 #include <sys/ioctl.h> 14 #include <sys/mount.h> 15 #include <sys/socket.h> 16 #include <sys/stat.h> 17 #include <sys/sysinfo.h> 18 #include <sys/types.h> 19 #include <sys/wait.h> 20 #include <unistd.h> 21 #include <linux/android/binder.h> 22 #include <linux/android/binderfs.h> 23 24 #include "../../kselftest_harness.h" 25 26 #define DEFAULT_THREADS 4 27 28 #define PTR_TO_INT(p) ((int)((intptr_t)(p))) 29 #define INT_TO_PTR(u) ((void *)((intptr_t)(u))) 30 31 #define close_prot_errno_disarm(fd) \ 32 if (fd >= 0) { \ 33 int _e_ = errno; \ 34 close(fd); \ 35 errno = _e_; \ 36 fd = -EBADF; \ 37 } 38 39 static void change_mountns(struct __test_metadata *_metadata) 40 { 41 int ret; 42 43 ret = unshare(CLONE_NEWNS); 44 ASSERT_EQ(ret, 0) { 45 TH_LOG("%s - Failed to unshare mount namespace", 46 strerror(errno)); 47 } 48 49 ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0); 50 ASSERT_EQ(ret, 0) { 51 TH_LOG("%s - Failed to mount / as private", 52 strerror(errno)); 53 } 54 } 55 56 static int __do_binderfs_test(struct __test_metadata *_metadata) 57 { 58 int fd, ret, saved_errno, result = 1; 59 size_t len; 60 ssize_t wret; 61 struct binderfs_device device = { 0 }; 62 struct binder_version version = { 0 }; 63 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", 64 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; 65 static const char * const binder_features[] = { 66 "oneway_spam_detection", 67 "extended_error", 68 "freeze_notification", 69 }; 70 71 change_mountns(_metadata); 72 73 EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) { 74 TH_LOG("%s - Failed to create binderfs mountpoint", 75 strerror(errno)); 76 goto out; 77 } 78 79 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); 80 EXPECT_EQ(ret, 0) { 81 if (errno == ENODEV) 82 SKIP(goto out, "binderfs missing"); 83 TH_LOG("%s - Failed to mount binderfs", strerror(errno)); 84 goto rmdir; 85 } 86 87 /* success: binderfs mounted */ 88 89 memcpy(device.name, "my-binder", strlen("my-binder")); 90 91 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt); 92 fd = open(device_path, O_RDONLY | O_CLOEXEC); 93 EXPECT_GE(fd, 0) { 94 TH_LOG("%s - Failed to open binder-control device", 95 strerror(errno)); 96 goto umount; 97 } 98 99 ret = ioctl(fd, BINDER_CTL_ADD, &device); 100 saved_errno = errno; 101 close(fd); 102 errno = saved_errno; 103 EXPECT_GE(ret, 0) { 104 TH_LOG("%s - Failed to allocate new binder device", 105 strerror(errno)); 106 goto umount; 107 } 108 109 TH_LOG("Allocated new binder device with major %d, minor %d, and name %s", 110 device.major, device.minor, device.name); 111 112 /* success: binder device allocation */ 113 114 snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt); 115 fd = open(device_path, O_CLOEXEC | O_RDONLY); 116 EXPECT_GE(fd, 0) { 117 TH_LOG("%s - Failed to open my-binder device", 118 strerror(errno)); 119 goto umount; 120 } 121 122 ret = ioctl(fd, BINDER_VERSION, &version); 123 saved_errno = errno; 124 close(fd); 125 errno = saved_errno; 126 EXPECT_GE(ret, 0) { 127 TH_LOG("%s - Failed to open perform BINDER_VERSION request", 128 strerror(errno)); 129 goto umount; 130 } 131 132 TH_LOG("Detected binder version: %d", version.protocol_version); 133 134 /* success: binder transaction with binderfs binder device */ 135 136 ret = unlink(device_path); 137 EXPECT_EQ(ret, 0) { 138 TH_LOG("%s - Failed to delete binder device", 139 strerror(errno)); 140 goto umount; 141 } 142 143 /* success: binder device removal */ 144 145 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt); 146 ret = unlink(device_path); 147 EXPECT_NE(ret, 0) { 148 TH_LOG("Managed to delete binder-control device"); 149 goto umount; 150 } 151 EXPECT_EQ(errno, EPERM) { 152 TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code", 153 strerror(errno)); 154 goto umount; 155 } 156 157 /* success: binder-control device removal failed as expected */ 158 159 for (int i = 0; i < ARRAY_SIZE(binder_features); i++) { 160 snprintf(device_path, sizeof(device_path), "%s/features/%s", 161 binderfs_mntpt, binder_features[i]); 162 fd = open(device_path, O_CLOEXEC | O_RDONLY); 163 EXPECT_GE(fd, 0) { 164 TH_LOG("%s - Failed to open binder feature: %s", 165 strerror(errno), binder_features[i]); 166 goto umount; 167 } 168 close(fd); 169 } 170 171 /* success: binder feature files found */ 172 result = 0; 173 174 umount: 175 ret = umount2(binderfs_mntpt, MNT_DETACH); 176 EXPECT_EQ(ret, 0) { 177 TH_LOG("%s - Failed to unmount binderfs", strerror(errno)); 178 } 179 rmdir: 180 ret = rmdir(binderfs_mntpt); 181 EXPECT_EQ(ret, 0) { 182 TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno)); 183 } 184 out: 185 return result; 186 } 187 188 static int wait_for_pid(pid_t pid) 189 { 190 int status, ret; 191 192 again: 193 ret = waitpid(pid, &status, 0); 194 if (ret == -1) { 195 if (errno == EINTR) 196 goto again; 197 198 return -1; 199 } 200 201 if (!WIFEXITED(status)) 202 return -1; 203 204 return WEXITSTATUS(status); 205 } 206 207 static int setid_userns_root(void) 208 { 209 if (setuid(0)) 210 return -1; 211 if (setgid(0)) 212 return -1; 213 214 setfsuid(0); 215 setfsgid(0); 216 217 return 0; 218 } 219 220 enum idmap_type { 221 UID_MAP, 222 GID_MAP, 223 }; 224 225 static ssize_t read_nointr(int fd, void *buf, size_t count) 226 { 227 ssize_t ret; 228 again: 229 ret = read(fd, buf, count); 230 if (ret < 0 && errno == EINTR) 231 goto again; 232 233 return ret; 234 } 235 236 static ssize_t write_nointr(int fd, const void *buf, size_t count) 237 { 238 ssize_t ret; 239 again: 240 ret = write(fd, buf, count); 241 if (ret < 0 && errno == EINTR) 242 goto again; 243 244 return ret; 245 } 246 247 static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf, 248 size_t buf_size) 249 { 250 int fd; 251 int ret; 252 char path[4096]; 253 254 if (type == GID_MAP) { 255 int setgroups_fd; 256 257 snprintf(path, sizeof(path), "/proc/%d/setgroups", pid); 258 setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); 259 if (setgroups_fd < 0 && errno != ENOENT) 260 return -1; 261 262 if (setgroups_fd >= 0) { 263 ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1); 264 close_prot_errno_disarm(setgroups_fd); 265 if (ret != sizeof("deny") - 1) 266 return -1; 267 } 268 } 269 270 switch (type) { 271 case UID_MAP: 272 ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid); 273 break; 274 case GID_MAP: 275 ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid); 276 break; 277 default: 278 return -1; 279 } 280 if (ret < 0 || ret >= sizeof(path)) 281 return -E2BIG; 282 283 fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); 284 if (fd < 0) 285 return -1; 286 287 ret = write_nointr(fd, buf, buf_size); 288 close_prot_errno_disarm(fd); 289 if (ret != buf_size) 290 return -1; 291 292 return 0; 293 } 294 295 static void change_userns(struct __test_metadata *_metadata, int syncfds[2]) 296 { 297 int ret; 298 char buf; 299 300 close_prot_errno_disarm(syncfds[1]); 301 302 ret = unshare(CLONE_NEWUSER); 303 ASSERT_EQ(ret, 0) { 304 TH_LOG("%s - Failed to unshare user namespace", 305 strerror(errno)); 306 } 307 308 ret = write_nointr(syncfds[0], "1", 1); 309 ASSERT_EQ(ret, 1) { 310 TH_LOG("write_nointr() failed"); 311 } 312 313 ret = read_nointr(syncfds[0], &buf, 1); 314 ASSERT_EQ(ret, 1) { 315 TH_LOG("read_nointr() failed"); 316 } 317 318 close_prot_errno_disarm(syncfds[0]); 319 320 ASSERT_EQ(setid_userns_root(), 0) { 321 TH_LOG("setid_userns_root() failed"); 322 } 323 } 324 325 static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid) 326 { 327 int ret; 328 char buf; 329 char id_map[4096]; 330 331 close_prot_errno_disarm(syncfds[0]); 332 333 ret = read_nointr(syncfds[1], &buf, 1); 334 ASSERT_EQ(ret, 1) { 335 TH_LOG("read_nointr() failed"); 336 } 337 338 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid()); 339 ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map)); 340 ASSERT_EQ(ret, 0) { 341 TH_LOG("write_id_mapping(UID_MAP) failed"); 342 } 343 344 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid()); 345 ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map)); 346 ASSERT_EQ(ret, 0) { 347 TH_LOG("write_id_mapping(GID_MAP) failed"); 348 } 349 350 ret = write_nointr(syncfds[1], "1", 1); 351 ASSERT_EQ(ret, 1) { 352 TH_LOG("write_nointr() failed"); 353 } 354 355 close_prot_errno_disarm(syncfds[1]); 356 } 357 358 struct __test_metadata *_thread_metadata; 359 static void *binder_version_thread(void *data) 360 { 361 struct __test_metadata *_metadata = _thread_metadata; 362 int fd = PTR_TO_INT(data); 363 struct binder_version version = { 0 }; 364 int ret; 365 366 ret = ioctl(fd, BINDER_VERSION, &version); 367 if (ret < 0) 368 TH_LOG("%s - Failed to open perform BINDER_VERSION request\n", 369 strerror(errno)); 370 371 pthread_exit(data); 372 } 373 374 /* 375 * Regression test: 376 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices") 377 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") 378 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too") 379 */ 380 TEST(binderfs_stress) 381 { 382 int fds[1000]; 383 int syncfds[2]; 384 pid_t pid; 385 int fd, ret; 386 size_t len; 387 struct binderfs_device device = { 0 }; 388 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", 389 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; 390 391 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); 392 ASSERT_EQ(ret, 0) { 393 TH_LOG("%s - Failed to create socket pair", strerror(errno)); 394 } 395 396 pid = fork(); 397 ASSERT_GE(pid, 0) { 398 TH_LOG("%s - Failed to fork", strerror(errno)); 399 close_prot_errno_disarm(syncfds[0]); 400 close_prot_errno_disarm(syncfds[1]); 401 } 402 403 if (pid == 0) { 404 int i, j, k, nthreads; 405 pthread_attr_t attr; 406 pthread_t threads[DEFAULT_THREADS]; 407 change_userns(_metadata, syncfds); 408 change_mountns(_metadata); 409 410 ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) { 411 TH_LOG("%s - Failed to create binderfs mountpoint", 412 strerror(errno)); 413 } 414 415 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); 416 ASSERT_EQ(ret, 0) { 417 TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel", 418 strerror(errno)); 419 } 420 421 for (int i = 0; i < ARRAY_SIZE(fds); i++) { 422 423 snprintf(device_path, sizeof(device_path), 424 "%s/binder-control", binderfs_mntpt); 425 fd = open(device_path, O_RDONLY | O_CLOEXEC); 426 ASSERT_GE(fd, 0) { 427 TH_LOG("%s - Failed to open binder-control device", 428 strerror(errno)); 429 } 430 431 memset(&device, 0, sizeof(device)); 432 snprintf(device.name, sizeof(device.name), "%d", i); 433 ret = ioctl(fd, BINDER_CTL_ADD, &device); 434 close_prot_errno_disarm(fd); 435 ASSERT_EQ(ret, 0) { 436 TH_LOG("%s - Failed to allocate new binder device", 437 strerror(errno)); 438 } 439 440 snprintf(device_path, sizeof(device_path), "%s/%d", 441 binderfs_mntpt, i); 442 fds[i] = open(device_path, O_RDONLY | O_CLOEXEC); 443 ASSERT_GE(fds[i], 0) { 444 TH_LOG("%s - Failed to open binder device", strerror(errno)); 445 } 446 } 447 448 ret = umount2(binderfs_mntpt, MNT_DETACH); 449 ASSERT_EQ(ret, 0) { 450 TH_LOG("%s - Failed to unmount binderfs", strerror(errno)); 451 rmdir(binderfs_mntpt); 452 } 453 454 nthreads = get_nprocs_conf(); 455 if (nthreads > DEFAULT_THREADS) 456 nthreads = DEFAULT_THREADS; 457 458 _thread_metadata = _metadata; 459 pthread_attr_init(&attr); 460 for (k = 0; k < ARRAY_SIZE(fds); k++) { 461 for (i = 0; i < nthreads; i++) { 462 ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k])); 463 if (ret) { 464 TH_LOG("%s - Failed to create thread %d", 465 strerror(errno), i); 466 break; 467 } 468 } 469 470 for (j = 0; j < i; j++) { 471 void *fdptr = NULL; 472 473 ret = pthread_join(threads[j], &fdptr); 474 if (ret) 475 TH_LOG("%s - Failed to join thread %d for fd %d", 476 strerror(errno), j, PTR_TO_INT(fdptr)); 477 } 478 } 479 pthread_attr_destroy(&attr); 480 481 for (k = 0; k < ARRAY_SIZE(fds); k++) 482 close(fds[k]); 483 484 exit(EXIT_SUCCESS); 485 } 486 487 change_idmaps(_metadata, syncfds, pid); 488 489 ret = wait_for_pid(pid); 490 ASSERT_EQ(ret, 0) { 491 TH_LOG("wait_for_pid() failed"); 492 } 493 } 494 495 TEST(binderfs_test_privileged) 496 { 497 if (geteuid() != 0) 498 SKIP(return, "Tests are not run as root. Skipping privileged tests"); 499 500 if (__do_binderfs_test(_metadata)) 501 SKIP(return, "The Android binderfs filesystem is not available"); 502 } 503 504 TEST(binderfs_test_unprivileged) 505 { 506 int ret; 507 int syncfds[2]; 508 pid_t pid; 509 510 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); 511 ASSERT_EQ(ret, 0) { 512 TH_LOG("%s - Failed to create socket pair", strerror(errno)); 513 } 514 515 pid = fork(); 516 ASSERT_GE(pid, 0) { 517 close_prot_errno_disarm(syncfds[0]); 518 close_prot_errno_disarm(syncfds[1]); 519 TH_LOG("%s - Failed to fork", strerror(errno)); 520 } 521 522 if (pid == 0) { 523 change_userns(_metadata, syncfds); 524 if (__do_binderfs_test(_metadata)) 525 exit(2); 526 exit(EXIT_SUCCESS); 527 } 528 529 change_idmaps(_metadata, syncfds, pid); 530 531 ret = wait_for_pid(pid); 532 if (ret) { 533 if (ret == 2) 534 SKIP(return, "The Android binderfs filesystem is not available"); 535 ASSERT_EQ(ret, 0) { 536 TH_LOG("wait_for_pid() failed"); 537 } 538 } 539 } 540 541 TEST_HARNESS_MAIN 542