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, dir: "/" , NULL, MS_REC | MS_PRIVATE, data: 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, dir: binderfs_mntpt, fstype: "binder" , rwflag: 0, data: 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(dest: device.name, src: "my-binder" , n: strlen(s: "my-binder" )); |
89 | |
90 | snprintf(s: device_path, maxlen: sizeof(device_path), format: "%s/binder-control" , binderfs_mntpt); |
91 | fd = open(file: 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: fd, BINDER_CTL_ADD, &device); |
99 | saved_errno = errno; |
100 | close(fd: 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(s: device_path, maxlen: sizeof(device_path), format: "%s/my-binder" , binderfs_mntpt); |
114 | fd = open(file: 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: fd, BINDER_VERSION, &version); |
122 | saved_errno = errno; |
123 | close(fd: 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(name: 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(s: device_path, maxlen: sizeof(device_path), format: "%s/binder-control" , binderfs_mntpt); |
145 | ret = unlink(name: 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(s: device_path, maxlen: sizeof(device_path), format: "%s/features/%s" , |
160 | binderfs_mntpt, binder_features[i]); |
161 | fd = open(file: 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: fd); |
168 | } |
169 | |
170 | /* success: binder feature files found */ |
171 | result = 0; |
172 | |
173 | umount: |
174 | ret = umount2(special_file: 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(path: 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: pid, stat_loc: &status, options: 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: fd, buf: buf, nbytes: 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: fd, buf: buf, n: 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(s: path, maxlen: sizeof(path), format: "/proc/%d/setgroups" , pid); |
257 | setgroups_fd = open(file: 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(fd: setgroups_fd, buf: "deny" , count: 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(s: path, maxlen: sizeof(path), format: "/proc/%d/uid_map" , pid); |
272 | break; |
273 | case GID_MAP: |
274 | ret = snprintf(s: path, maxlen: sizeof(path), format: "/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(file: path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); |
283 | if (fd < 0) |
284 | return -1; |
285 | |
286 | ret = write_nointr(fd, buf, count: 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(fd: syncfds[0], buf: "1" , count: 1); |
308 | ASSERT_EQ(ret, 1) { |
309 | TH_LOG("write_nointr() failed" ); |
310 | } |
311 | |
312 | ret = read_nointr(fd: syncfds[0], buf: &buf, count: 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(fd: syncfds[1], buf: &buf, count: 1); |
333 | ASSERT_EQ(ret, 1) { |
334 | TH_LOG("read_nointr() failed" ); |
335 | } |
336 | |
337 | snprintf(s: id_map, maxlen: sizeof(id_map), format: "0 %d 1\n" , getuid()); |
338 | ret = write_id_mapping(type: UID_MAP, pid, buf: id_map, buf_size: strlen(s: id_map)); |
339 | ASSERT_EQ(ret, 0) { |
340 | TH_LOG("write_id_mapping(UID_MAP) failed" ); |
341 | } |
342 | |
343 | snprintf(s: id_map, maxlen: sizeof(id_map), format: "0 %d 1\n" , getgid()); |
344 | ret = write_id_mapping(type: GID_MAP, pid, buf: id_map, buf_size: strlen(s: id_map)); |
345 | ASSERT_EQ(ret, 0) { |
346 | TH_LOG("write_id_mapping(GID_MAP) failed" ); |
347 | } |
348 | |
349 | ret = write_nointr(fd: syncfds[1], buf: "1" , count: 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: 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(retval: 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, protocol: 0, fds: 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, dir: binderfs_mntpt, fstype: "binder" , rwflag: 0, data: 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(s: device_path, maxlen: sizeof(device_path), |
423 | format: "%s/binder-control" , binderfs_mntpt); |
424 | fd = open(file: 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(s: &device, c: 0, n: sizeof(device)); |
431 | snprintf(s: device.name, maxlen: sizeof(device.name), format: "%d" , i); |
432 | ret = ioctl(fd: 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(s: device_path, maxlen: sizeof(device_path), format: "%s/%d" , |
440 | binderfs_mntpt, i); |
441 | fds[i] = open(file: 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(special_file: binderfs_mntpt, MNT_DETACH); |
448 | ASSERT_EQ(ret, 0) { |
449 | TH_LOG("%s - Failed to unmount binderfs" , strerror(errno)); |
450 | rmdir(path: 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: &attr); |
459 | for (k = 0; k < ARRAY_SIZE(fds); k++) { |
460 | for (i = 0; i < nthreads; i++) { |
461 | ret = pthread_create(newthread: &threads[i], attr: &attr, start_routine: 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(th: threads[j], thread_return: &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: &attr); |
479 | |
480 | for (k = 0; k < ARRAY_SIZE(fds); k++) |
481 | close(fd: 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, protocol: 0, fds: 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(status: 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 | |