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
change_mountns(struct __test_metadata * _metadata)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
__do_binderfs_test(struct __test_metadata * _metadata)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 "freeze_notification",
69 };
70
71 change_mountns(_metadata);
72
73 EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
74 TH_LOG("%s - Failed to create binderfs mountpoint",
75 strerror(errno));
76 goto out;
77 }
78
79 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
80 EXPECT_EQ(ret, 0) {
81 if (errno == ENODEV)
82 SKIP(goto out, "binderfs missing");
83 TH_LOG("%s - Failed to mount binderfs", strerror(errno));
84 goto rmdir;
85 }
86
87 /* success: binderfs mounted */
88
89 memcpy(device.name, "my-binder", strlen("my-binder"));
90
91 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
92 fd = open(device_path, O_RDONLY | O_CLOEXEC);
93 EXPECT_GE(fd, 0) {
94 TH_LOG("%s - Failed to open binder-control device",
95 strerror(errno));
96 goto umount;
97 }
98
99 ret = ioctl(fd, BINDER_CTL_ADD, &device);
100 saved_errno = errno;
101 close(fd);
102 errno = saved_errno;
103 EXPECT_GE(ret, 0) {
104 TH_LOG("%s - Failed to allocate new binder device",
105 strerror(errno));
106 goto umount;
107 }
108
109 TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
110 device.major, device.minor, device.name);
111
112 /* success: binder device allocation */
113
114 snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
115 fd = open(device_path, O_CLOEXEC | O_RDONLY);
116 EXPECT_GE(fd, 0) {
117 TH_LOG("%s - Failed to open my-binder device",
118 strerror(errno));
119 goto umount;
120 }
121
122 ret = ioctl(fd, BINDER_VERSION, &version);
123 saved_errno = errno;
124 close(fd);
125 errno = saved_errno;
126 EXPECT_GE(ret, 0) {
127 TH_LOG("%s - Failed to open perform BINDER_VERSION request",
128 strerror(errno));
129 goto umount;
130 }
131
132 TH_LOG("Detected binder version: %d", version.protocol_version);
133
134 /* success: binder transaction with binderfs binder device */
135
136 ret = unlink(device_path);
137 EXPECT_EQ(ret, 0) {
138 TH_LOG("%s - Failed to delete binder device",
139 strerror(errno));
140 goto umount;
141 }
142
143 /* success: binder device removal */
144
145 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
146 ret = unlink(device_path);
147 EXPECT_NE(ret, 0) {
148 TH_LOG("Managed to delete binder-control device");
149 goto umount;
150 }
151 EXPECT_EQ(errno, EPERM) {
152 TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
153 strerror(errno));
154 goto umount;
155 }
156
157 /* success: binder-control device removal failed as expected */
158
159 for (int i = 0; i < ARRAY_SIZE(binder_features); i++) {
160 snprintf(device_path, sizeof(device_path), "%s/features/%s",
161 binderfs_mntpt, binder_features[i]);
162 fd = open(device_path, O_CLOEXEC | O_RDONLY);
163 EXPECT_GE(fd, 0) {
164 TH_LOG("%s - Failed to open binder feature: %s",
165 strerror(errno), binder_features[i]);
166 goto umount;
167 }
168 close(fd);
169 }
170
171 /* success: binder feature files found */
172 result = 0;
173
174 umount:
175 ret = umount2(binderfs_mntpt, MNT_DETACH);
176 EXPECT_EQ(ret, 0) {
177 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
178 }
179 rmdir:
180 ret = rmdir(binderfs_mntpt);
181 EXPECT_EQ(ret, 0) {
182 TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
183 }
184 out:
185 return result;
186 }
187
wait_for_pid(pid_t pid)188 static int wait_for_pid(pid_t pid)
189 {
190 int status, ret;
191
192 again:
193 ret = waitpid(pid, &status, 0);
194 if (ret == -1) {
195 if (errno == EINTR)
196 goto again;
197
198 return -1;
199 }
200
201 if (!WIFEXITED(status))
202 return -1;
203
204 return WEXITSTATUS(status);
205 }
206
setid_userns_root(void)207 static int setid_userns_root(void)
208 {
209 if (setuid(0))
210 return -1;
211 if (setgid(0))
212 return -1;
213
214 setfsuid(0);
215 setfsgid(0);
216
217 return 0;
218 }
219
220 enum idmap_type {
221 UID_MAP,
222 GID_MAP,
223 };
224
read_nointr(int fd,void * buf,size_t count)225 static ssize_t read_nointr(int fd, void *buf, size_t count)
226 {
227 ssize_t ret;
228 again:
229 ret = read(fd, buf, count);
230 if (ret < 0 && errno == EINTR)
231 goto again;
232
233 return ret;
234 }
235
write_nointr(int fd,const void * buf,size_t count)236 static ssize_t write_nointr(int fd, const void *buf, size_t count)
237 {
238 ssize_t ret;
239 again:
240 ret = write(fd, buf, count);
241 if (ret < 0 && errno == EINTR)
242 goto again;
243
244 return ret;
245 }
246
write_id_mapping(enum idmap_type type,pid_t pid,const char * buf,size_t buf_size)247 static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
248 size_t buf_size)
249 {
250 int fd;
251 int ret;
252 char path[4096];
253
254 if (type == GID_MAP) {
255 int setgroups_fd;
256
257 snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
258 setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
259 if (setgroups_fd < 0 && errno != ENOENT)
260 return -1;
261
262 if (setgroups_fd >= 0) {
263 ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
264 close_prot_errno_disarm(setgroups_fd);
265 if (ret != sizeof("deny") - 1)
266 return -1;
267 }
268 }
269
270 switch (type) {
271 case UID_MAP:
272 ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
273 break;
274 case GID_MAP:
275 ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
276 break;
277 default:
278 return -1;
279 }
280 if (ret < 0 || ret >= sizeof(path))
281 return -E2BIG;
282
283 fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
284 if (fd < 0)
285 return -1;
286
287 ret = write_nointr(fd, buf, buf_size);
288 close_prot_errno_disarm(fd);
289 if (ret != buf_size)
290 return -1;
291
292 return 0;
293 }
294
change_userns(struct __test_metadata * _metadata,int syncfds[2])295 static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
296 {
297 int ret;
298 char buf;
299
300 close_prot_errno_disarm(syncfds[1]);
301
302 ret = unshare(CLONE_NEWUSER);
303 ASSERT_EQ(ret, 0) {
304 TH_LOG("%s - Failed to unshare user namespace",
305 strerror(errno));
306 }
307
308 ret = write_nointr(syncfds[0], "1", 1);
309 ASSERT_EQ(ret, 1) {
310 TH_LOG("write_nointr() failed");
311 }
312
313 ret = read_nointr(syncfds[0], &buf, 1);
314 ASSERT_EQ(ret, 1) {
315 TH_LOG("read_nointr() failed");
316 }
317
318 close_prot_errno_disarm(syncfds[0]);
319
320 ASSERT_EQ(setid_userns_root(), 0) {
321 TH_LOG("setid_userns_root() failed");
322 }
323 }
324
change_idmaps(struct __test_metadata * _metadata,int syncfds[2],pid_t pid)325 static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
326 {
327 int ret;
328 char buf;
329 char id_map[4096];
330
331 close_prot_errno_disarm(syncfds[0]);
332
333 ret = read_nointr(syncfds[1], &buf, 1);
334 ASSERT_EQ(ret, 1) {
335 TH_LOG("read_nointr() failed");
336 }
337
338 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
339 ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
340 ASSERT_EQ(ret, 0) {
341 TH_LOG("write_id_mapping(UID_MAP) failed");
342 }
343
344 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
345 ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
346 ASSERT_EQ(ret, 0) {
347 TH_LOG("write_id_mapping(GID_MAP) failed");
348 }
349
350 ret = write_nointr(syncfds[1], "1", 1);
351 ASSERT_EQ(ret, 1) {
352 TH_LOG("write_nointr() failed");
353 }
354
355 close_prot_errno_disarm(syncfds[1]);
356 }
357
358 struct __test_metadata *_thread_metadata;
binder_version_thread(void * data)359 static void *binder_version_thread(void *data)
360 {
361 struct __test_metadata *_metadata = _thread_metadata;
362 int fd = PTR_TO_INT(data);
363 struct binder_version version = { 0 };
364 int ret;
365
366 ret = ioctl(fd, BINDER_VERSION, &version);
367 if (ret < 0)
368 TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
369 strerror(errno));
370
371 pthread_exit(data);
372 }
373
374 /*
375 * Regression test:
376 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
377 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
378 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
379 */
TEST(binderfs_stress)380 TEST(binderfs_stress)
381 {
382 int fds[1000];
383 int syncfds[2];
384 pid_t pid;
385 int fd, ret;
386 size_t len;
387 struct binderfs_device device = { 0 };
388 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
389 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
390
391 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
392 ASSERT_EQ(ret, 0) {
393 TH_LOG("%s - Failed to create socket pair", strerror(errno));
394 }
395
396 pid = fork();
397 ASSERT_GE(pid, 0) {
398 TH_LOG("%s - Failed to fork", strerror(errno));
399 close_prot_errno_disarm(syncfds[0]);
400 close_prot_errno_disarm(syncfds[1]);
401 }
402
403 if (pid == 0) {
404 int i, j, k, nthreads;
405 pthread_attr_t attr;
406 pthread_t threads[DEFAULT_THREADS];
407 change_userns(_metadata, syncfds);
408 change_mountns(_metadata);
409
410 ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
411 TH_LOG("%s - Failed to create binderfs mountpoint",
412 strerror(errno));
413 }
414
415 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
416 ASSERT_EQ(ret, 0) {
417 TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel",
418 strerror(errno));
419 }
420
421 for (int i = 0; i < ARRAY_SIZE(fds); i++) {
422
423 snprintf(device_path, sizeof(device_path),
424 "%s/binder-control", binderfs_mntpt);
425 fd = open(device_path, O_RDONLY | O_CLOEXEC);
426 ASSERT_GE(fd, 0) {
427 TH_LOG("%s - Failed to open binder-control device",
428 strerror(errno));
429 }
430
431 memset(&device, 0, sizeof(device));
432 snprintf(device.name, sizeof(device.name), "%d", i);
433 ret = ioctl(fd, BINDER_CTL_ADD, &device);
434 close_prot_errno_disarm(fd);
435 ASSERT_EQ(ret, 0) {
436 TH_LOG("%s - Failed to allocate new binder device",
437 strerror(errno));
438 }
439
440 snprintf(device_path, sizeof(device_path), "%s/%d",
441 binderfs_mntpt, i);
442 fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
443 ASSERT_GE(fds[i], 0) {
444 TH_LOG("%s - Failed to open binder device", strerror(errno));
445 }
446 }
447
448 ret = umount2(binderfs_mntpt, MNT_DETACH);
449 ASSERT_EQ(ret, 0) {
450 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
451 rmdir(binderfs_mntpt);
452 }
453
454 nthreads = get_nprocs_conf();
455 if (nthreads > DEFAULT_THREADS)
456 nthreads = DEFAULT_THREADS;
457
458 _thread_metadata = _metadata;
459 pthread_attr_init(&attr);
460 for (k = 0; k < ARRAY_SIZE(fds); k++) {
461 for (i = 0; i < nthreads; i++) {
462 ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
463 if (ret) {
464 TH_LOG("%s - Failed to create thread %d",
465 strerror(errno), i);
466 break;
467 }
468 }
469
470 for (j = 0; j < i; j++) {
471 void *fdptr = NULL;
472
473 ret = pthread_join(threads[j], &fdptr);
474 if (ret)
475 TH_LOG("%s - Failed to join thread %d for fd %d",
476 strerror(errno), j, PTR_TO_INT(fdptr));
477 }
478 }
479 pthread_attr_destroy(&attr);
480
481 for (k = 0; k < ARRAY_SIZE(fds); k++)
482 close(fds[k]);
483
484 exit(EXIT_SUCCESS);
485 }
486
487 change_idmaps(_metadata, syncfds, pid);
488
489 ret = wait_for_pid(pid);
490 ASSERT_EQ(ret, 0) {
491 TH_LOG("wait_for_pid() failed");
492 }
493 }
494
TEST(binderfs_test_privileged)495 TEST(binderfs_test_privileged)
496 {
497 if (geteuid() != 0)
498 SKIP(return, "Tests are not run as root. Skipping privileged tests");
499
500 if (__do_binderfs_test(_metadata))
501 SKIP(return, "The Android binderfs filesystem is not available");
502 }
503
TEST(binderfs_test_unprivileged)504 TEST(binderfs_test_unprivileged)
505 {
506 int ret;
507 int syncfds[2];
508 pid_t pid;
509
510 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
511 ASSERT_EQ(ret, 0) {
512 TH_LOG("%s - Failed to create socket pair", strerror(errno));
513 }
514
515 pid = fork();
516 ASSERT_GE(pid, 0) {
517 close_prot_errno_disarm(syncfds[0]);
518 close_prot_errno_disarm(syncfds[1]);
519 TH_LOG("%s - Failed to fork", strerror(errno));
520 }
521
522 if (pid == 0) {
523 change_userns(_metadata, syncfds);
524 if (__do_binderfs_test(_metadata))
525 exit(2);
526 exit(EXIT_SUCCESS);
527 }
528
529 change_idmaps(_metadata, syncfds, pid);
530
531 ret = wait_for_pid(pid);
532 if (ret) {
533 if (ret == 2)
534 SKIP(return, "The Android binderfs filesystem is not available");
535 ASSERT_EQ(ret, 0) {
536 TH_LOG("wait_for_pid() failed");
537 }
538 }
539 }
540
541 TEST_HARNESS_MAIN
542