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 };
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
541
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.