tools/testing/selftests/filesystems/binderfs/binderfs_test.c

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