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 };
68
69 change_mountns(_metadata);
70
71 EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
72 TH_LOG("%s - Failed to create binderfs mountpoint",
73 strerror(errno));
74 goto out;
75 }
76
77 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
78 EXPECT_EQ(ret, 0) {
79 if (errno == ENODEV)
80 SKIP(goto out, "binderfs missing");
81 TH_LOG("%s - Failed to mount binderfs", strerror(errno));
82 goto rmdir;
83 }
84
85 /* success: binderfs mounted */
86
87 memcpy(device.name, "my-binder", strlen("my-binder"));
88
89 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
90 fd = open(device_path, O_RDONLY | O_CLOEXEC);
91 EXPECT_GE(fd, 0) {
92 TH_LOG("%s - Failed to open binder-control device",
93 strerror(errno));
94 goto umount;
95 }
96
97 ret = ioctl(fd, BINDER_CTL_ADD, &device);
98 saved_errno = errno;
99 close(fd);
100 errno = saved_errno;
101 EXPECT_GE(ret, 0) {
102 TH_LOG("%s - Failed to allocate new binder device",
103 strerror(errno));
104 goto umount;
105 }
106
107 TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
108 device.major, device.minor, device.name);
109
110 /* success: binder device allocation */
111
112 snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
113 fd = open(device_path, O_CLOEXEC | O_RDONLY);
114 EXPECT_GE(fd, 0) {
115 TH_LOG("%s - Failed to open my-binder device",
116 strerror(errno));
117 goto umount;
118 }
119
120 ret = ioctl(fd, BINDER_VERSION, &version);
121 saved_errno = errno;
122 close(fd);
123 errno = saved_errno;
124 EXPECT_GE(ret, 0) {
125 TH_LOG("%s - Failed to open perform BINDER_VERSION request",
126 strerror(errno));
127 goto umount;
128 }
129
130 TH_LOG("Detected binder version: %d", version.protocol_version);
131
132 /* success: binder transaction with binderfs binder device */
133
134 ret = unlink(device_path);
135 EXPECT_EQ(ret, 0) {
136 TH_LOG("%s - Failed to delete binder device",
137 strerror(errno));
138 goto umount;
139 }
140
141 /* success: binder device removal */
142
143 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
144 ret = unlink(device_path);
145 EXPECT_NE(ret, 0) {
146 TH_LOG("Managed to delete binder-control device");
147 goto umount;
148 }
149 EXPECT_EQ(errno, EPERM) {
150 TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
151 strerror(errno));
152 goto umount;
153 }
154
155 /* success: binder-control device removal failed as expected */
156
157 for (int i = 0; i < ARRAY_SIZE(binder_features); i++) {
158 snprintf(device_path, sizeof(device_path), "%s/features/%s",
159 binderfs_mntpt, binder_features[i]);
160 fd = open(device_path, O_CLOEXEC | O_RDONLY);
161 EXPECT_GE(fd, 0) {
162 TH_LOG("%s - Failed to open binder feature: %s",
163 strerror(errno), binder_features[i]);
164 goto umount;
165 }
166 close(fd);
167 }
168
169 /* success: binder feature files found */
170 result = 0;
171
172 umount:
173 ret = umount2(binderfs_mntpt, MNT_DETACH);
174 EXPECT_EQ(ret, 0) {
175 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
176 }
177 rmdir:
178 ret = rmdir(binderfs_mntpt);
179 EXPECT_EQ(ret, 0) {
180 TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
181 }
182 out:
183 return result;
184 }
185
wait_for_pid(pid_t pid)186 static int wait_for_pid(pid_t pid)
187 {
188 int status, ret;
189
190 again:
191 ret = waitpid(pid, &status, 0);
192 if (ret == -1) {
193 if (errno == EINTR)
194 goto again;
195
196 return -1;
197 }
198
199 if (!WIFEXITED(status))
200 return -1;
201
202 return WEXITSTATUS(status);
203 }
204
setid_userns_root(void)205 static int setid_userns_root(void)
206 {
207 if (setuid(0))
208 return -1;
209 if (setgid(0))
210 return -1;
211
212 setfsuid(0);
213 setfsgid(0);
214
215 return 0;
216 }
217
218 enum idmap_type {
219 UID_MAP,
220 GID_MAP,
221 };
222
read_nointr(int fd,void * buf,size_t count)223 static ssize_t read_nointr(int fd, void *buf, size_t count)
224 {
225 ssize_t ret;
226 again:
227 ret = read(fd, buf, count);
228 if (ret < 0 && errno == EINTR)
229 goto again;
230
231 return ret;
232 }
233
write_nointr(int fd,const void * buf,size_t count)234 static ssize_t write_nointr(int fd, const void *buf, size_t count)
235 {
236 ssize_t ret;
237 again:
238 ret = write(fd, buf, count);
239 if (ret < 0 && errno == EINTR)
240 goto again;
241
242 return ret;
243 }
244
write_id_mapping(enum idmap_type type,pid_t pid,const char * buf,size_t buf_size)245 static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
246 size_t buf_size)
247 {
248 int fd;
249 int ret;
250 char path[4096];
251
252 if (type == GID_MAP) {
253 int setgroups_fd;
254
255 snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
256 setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
257 if (setgroups_fd < 0 && errno != ENOENT)
258 return -1;
259
260 if (setgroups_fd >= 0) {
261 ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
262 close_prot_errno_disarm(setgroups_fd);
263 if (ret != sizeof("deny") - 1)
264 return -1;
265 }
266 }
267
268 switch (type) {
269 case UID_MAP:
270 ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
271 break;
272 case GID_MAP:
273 ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
274 break;
275 default:
276 return -1;
277 }
278 if (ret < 0 || ret >= sizeof(path))
279 return -E2BIG;
280
281 fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
282 if (fd < 0)
283 return -1;
284
285 ret = write_nointr(fd, buf, buf_size);
286 close_prot_errno_disarm(fd);
287 if (ret != buf_size)
288 return -1;
289
290 return 0;
291 }
292
has_userns()293 static bool has_userns()
294 {
295 return (access("/proc/self/ns/user", F_OK) == 0);
296 }
297
change_userns(struct __test_metadata * _metadata,int syncfds[2])298 static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
299 {
300 int ret;
301 char buf;
302
303 close_prot_errno_disarm(syncfds[1]);
304
305 ret = unshare(CLONE_NEWUSER);
306 ASSERT_EQ(ret, 0) {
307 TH_LOG("%s - Failed to unshare user namespace",
308 strerror(errno));
309 }
310
311 ret = write_nointr(syncfds[0], "1", 1);
312 ASSERT_EQ(ret, 1) {
313 TH_LOG("write_nointr() failed");
314 }
315
316 ret = read_nointr(syncfds[0], &buf, 1);
317 ASSERT_EQ(ret, 1) {
318 TH_LOG("read_nointr() failed");
319 }
320
321 close_prot_errno_disarm(syncfds[0]);
322
323 ASSERT_EQ(setid_userns_root(), 0) {
324 TH_LOG("setid_userns_root() failed");
325 }
326 }
327
change_idmaps(struct __test_metadata * _metadata,int syncfds[2],pid_t pid)328 static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
329 {
330 int ret;
331 char buf;
332 char id_map[4096];
333
334 close_prot_errno_disarm(syncfds[0]);
335
336 ret = read_nointr(syncfds[1], &buf, 1);
337 ASSERT_EQ(ret, 1) {
338 TH_LOG("read_nointr() failed");
339 }
340
341 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
342 ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
343 ASSERT_EQ(ret, 0) {
344 TH_LOG("write_id_mapping(UID_MAP) failed");
345 }
346
347 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
348 ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
349 ASSERT_EQ(ret, 0) {
350 TH_LOG("write_id_mapping(GID_MAP) failed");
351 }
352
353 ret = write_nointr(syncfds[1], "1", 1);
354 ASSERT_EQ(ret, 1) {
355 TH_LOG("write_nointr() failed");
356 }
357
358 close_prot_errno_disarm(syncfds[1]);
359 }
360
361 struct __test_metadata *_thread_metadata;
binder_version_thread(void * data)362 static void *binder_version_thread(void *data)
363 {
364 struct __test_metadata *_metadata = _thread_metadata;
365 int fd = PTR_TO_INT(data);
366 struct binder_version version = { 0 };
367 int ret;
368
369 ret = ioctl(fd, BINDER_VERSION, &version);
370 if (ret < 0)
371 TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
372 strerror(errno));
373
374 pthread_exit(data);
375 }
376
377 /*
378 * Regression test:
379 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
380 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
381 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
382 */
TEST(binderfs_stress)383 TEST(binderfs_stress)
384 {
385 if (!has_userns())
386 SKIP(return, "%s: user namespace not supported\n", __func__);
387
388 int fds[1000];
389 int syncfds[2];
390 pid_t pid;
391 int fd, ret;
392 size_t len;
393 struct binderfs_device device = { 0 };
394 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
395 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
396
397 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
398 ASSERT_EQ(ret, 0) {
399 TH_LOG("%s - Failed to create socket pair", strerror(errno));
400 }
401
402 pid = fork();
403 ASSERT_GE(pid, 0) {
404 TH_LOG("%s - Failed to fork", strerror(errno));
405 close_prot_errno_disarm(syncfds[0]);
406 close_prot_errno_disarm(syncfds[1]);
407 }
408
409 if (pid == 0) {
410 int i, j, k, nthreads;
411 pthread_attr_t attr;
412 pthread_t threads[DEFAULT_THREADS];
413 change_userns(_metadata, syncfds);
414 change_mountns(_metadata);
415
416 ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
417 TH_LOG("%s - Failed to create binderfs mountpoint",
418 strerror(errno));
419 }
420
421 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
422 ASSERT_EQ(ret, 0) {
423 TH_LOG("%s - Failed to mount binderfs", strerror(errno));
424 }
425
426 for (int i = 0; i < ARRAY_SIZE(fds); i++) {
427
428 snprintf(device_path, sizeof(device_path),
429 "%s/binder-control", binderfs_mntpt);
430 fd = open(device_path, O_RDONLY | O_CLOEXEC);
431 ASSERT_GE(fd, 0) {
432 TH_LOG("%s - Failed to open binder-control device",
433 strerror(errno));
434 }
435
436 memset(&device, 0, sizeof(device));
437 snprintf(device.name, sizeof(device.name), "%d", i);
438 ret = ioctl(fd, BINDER_CTL_ADD, &device);
439 close_prot_errno_disarm(fd);
440 ASSERT_EQ(ret, 0) {
441 TH_LOG("%s - Failed to allocate new binder device",
442 strerror(errno));
443 }
444
445 snprintf(device_path, sizeof(device_path), "%s/%d",
446 binderfs_mntpt, i);
447 fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
448 ASSERT_GE(fds[i], 0) {
449 TH_LOG("%s - Failed to open binder device", strerror(errno));
450 }
451 }
452
453 ret = umount2(binderfs_mntpt, MNT_DETACH);
454 ASSERT_EQ(ret, 0) {
455 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
456 rmdir(binderfs_mntpt);
457 }
458
459 nthreads = get_nprocs_conf();
460 if (nthreads > DEFAULT_THREADS)
461 nthreads = DEFAULT_THREADS;
462
463 _thread_metadata = _metadata;
464 pthread_attr_init(&attr);
465 for (k = 0; k < ARRAY_SIZE(fds); k++) {
466 for (i = 0; i < nthreads; i++) {
467 ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
468 if (ret) {
469 TH_LOG("%s - Failed to create thread %d",
470 strerror(errno), i);
471 break;
472 }
473 }
474
475 for (j = 0; j < i; j++) {
476 void *fdptr = NULL;
477
478 ret = pthread_join(threads[j], &fdptr);
479 if (ret)
480 TH_LOG("%s - Failed to join thread %d for fd %d",
481 strerror(errno), j, PTR_TO_INT(fdptr));
482 }
483 }
484 pthread_attr_destroy(&attr);
485
486 for (k = 0; k < ARRAY_SIZE(fds); k++)
487 close(fds[k]);
488
489 exit(EXIT_SUCCESS);
490 }
491
492 change_idmaps(_metadata, syncfds, pid);
493
494 ret = wait_for_pid(pid);
495 ASSERT_EQ(ret, 0) {
496 TH_LOG("wait_for_pid() failed");
497 }
498 }
499
TEST(binderfs_test_privileged)500 TEST(binderfs_test_privileged)
501 {
502 if (geteuid() != 0)
503 SKIP(return, "Tests are not run as root. Skipping privileged tests");
504
505 if (__do_binderfs_test(_metadata))
506 SKIP(return, "The Android binderfs filesystem is not available");
507 }
508
TEST(binderfs_test_unprivileged)509 TEST(binderfs_test_unprivileged)
510 {
511 if (!has_userns())
512 SKIP(return, "%s: user namespace not supported\n", __func__);
513 int ret;
514 int syncfds[2];
515 pid_t pid;
516
517 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
518 ASSERT_EQ(ret, 0) {
519 TH_LOG("%s - Failed to create socket pair", strerror(errno));
520 }
521
522 pid = fork();
523 ASSERT_GE(pid, 0) {
524 close_prot_errno_disarm(syncfds[0]);
525 close_prot_errno_disarm(syncfds[1]);
526 TH_LOG("%s - Failed to fork", strerror(errno));
527 }
528
529 if (pid == 0) {
530 change_userns(_metadata, syncfds);
531 if (__do_binderfs_test(_metadata))
532 exit(2);
533 exit(EXIT_SUCCESS);
534 }
535
536 change_idmaps(_metadata, syncfds, pid);
537
538 ret = wait_for_pid(pid);
539 if (ret) {
540 if (ret == 2)
541 SKIP(return, "The Android binderfs filesystem is not available");
542 ASSERT_EQ(ret, 0) {
543 TH_LOG("wait_for_pid() failed");
544 }
545 }
546 }
547
548 TEST_HARNESS_MAIN
549