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