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