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
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
wait_for_pid(pid_t pid)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
setid_userns_root(void)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
read_nointr(int fd,void * buf,size_t count)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
write_nointr(int fd,const void * buf,size_t count)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
write_id_mapping(enum idmap_type type,pid_t pid,const char * buf,size_t buf_size)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
change_userns(struct __test_metadata * _metadata,int syncfds[2])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
change_idmaps(struct __test_metadata * _metadata,int syncfds[2],pid_t pid)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;
binder_version_thread(void * data)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 */
TEST(binderfs_stress)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
TEST(binderfs_test_privileged)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
TEST(binderfs_test_unprivileged)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
522