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 "transaction_report",
70 };
71
72 change_mountns(_metadata);
73
74 EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
75 TH_LOG("%s - Failed to create binderfs mountpoint",
76 strerror(errno));
77 goto out;
78 }
79
80 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
81 EXPECT_EQ(ret, 0) {
82 if (errno == ENODEV)
83 SKIP(goto out, "binderfs missing");
84 TH_LOG("%s - Failed to mount binderfs", strerror(errno));
85 goto rmdir;
86 }
87
88 /* success: binderfs mounted */
89
90 memcpy(device.name, "my-binder", strlen("my-binder"));
91
92 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
93 fd = open(device_path, O_RDONLY | O_CLOEXEC);
94 EXPECT_GE(fd, 0) {
95 TH_LOG("%s - Failed to open binder-control device",
96 strerror(errno));
97 goto umount;
98 }
99
100 ret = ioctl(fd, BINDER_CTL_ADD, &device);
101 saved_errno = errno;
102 close(fd);
103 errno = saved_errno;
104 EXPECT_GE(ret, 0) {
105 TH_LOG("%s - Failed to allocate new binder device",
106 strerror(errno));
107 goto umount;
108 }
109
110 TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
111 device.major, device.minor, device.name);
112
113 /* success: binder device allocation */
114
115 snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
116 fd = open(device_path, O_CLOEXEC | O_RDONLY);
117 EXPECT_GE(fd, 0) {
118 TH_LOG("%s - Failed to open my-binder device",
119 strerror(errno));
120 goto umount;
121 }
122
123 ret = ioctl(fd, BINDER_VERSION, &version);
124 saved_errno = errno;
125 close(fd);
126 errno = saved_errno;
127 EXPECT_GE(ret, 0) {
128 TH_LOG("%s - Failed to open perform BINDER_VERSION request",
129 strerror(errno));
130 goto umount;
131 }
132
133 TH_LOG("Detected binder version: %d", version.protocol_version);
134
135 /* success: binder transaction with binderfs binder device */
136
137 ret = unlink(device_path);
138 EXPECT_EQ(ret, 0) {
139 TH_LOG("%s - Failed to delete binder device",
140 strerror(errno));
141 goto umount;
142 }
143
144 /* success: binder device removal */
145
146 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
147 ret = unlink(device_path);
148 EXPECT_NE(ret, 0) {
149 TH_LOG("Managed to delete binder-control device");
150 goto umount;
151 }
152 EXPECT_EQ(errno, EPERM) {
153 TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
154 strerror(errno));
155 goto umount;
156 }
157
158 /* success: binder-control device removal failed as expected */
159
160 for (int i = 0; i < ARRAY_SIZE(binder_features); i++) {
161 snprintf(device_path, sizeof(device_path), "%s/features/%s",
162 binderfs_mntpt, binder_features[i]);
163 fd = open(device_path, O_CLOEXEC | O_RDONLY);
164 EXPECT_GE(fd, 0) {
165 TH_LOG("%s - Failed to open binder feature: %s",
166 strerror(errno), binder_features[i]);
167 goto umount;
168 }
169 close(fd);
170 }
171
172 /* success: binder feature files found */
173 result = 0;
174
175 umount:
176 ret = umount2(binderfs_mntpt, MNT_DETACH);
177 EXPECT_EQ(ret, 0) {
178 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
179 }
180 rmdir:
181 ret = rmdir(binderfs_mntpt);
182 EXPECT_EQ(ret, 0) {
183 TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
184 }
185 out:
186 return result;
187 }
188
wait_for_pid(pid_t pid)189 static int wait_for_pid(pid_t pid)
190 {
191 int status, ret;
192
193 again:
194 ret = waitpid(pid, &status, 0);
195 if (ret == -1) {
196 if (errno == EINTR)
197 goto again;
198
199 return -1;
200 }
201
202 if (!WIFEXITED(status))
203 return -1;
204
205 return WEXITSTATUS(status);
206 }
207
setid_userns_root(void)208 static int setid_userns_root(void)
209 {
210 if (setuid(0))
211 return -1;
212 if (setgid(0))
213 return -1;
214
215 setfsuid(0);
216 setfsgid(0);
217
218 return 0;
219 }
220
221 enum idmap_type {
222 UID_MAP,
223 GID_MAP,
224 };
225
read_nointr(int fd,void * buf,size_t count)226 static ssize_t read_nointr(int fd, void *buf, size_t count)
227 {
228 ssize_t ret;
229 again:
230 ret = read(fd, buf, count);
231 if (ret < 0 && errno == EINTR)
232 goto again;
233
234 return ret;
235 }
236
write_nointr(int fd,const void * buf,size_t count)237 static ssize_t write_nointr(int fd, const void *buf, size_t count)
238 {
239 ssize_t ret;
240 again:
241 ret = write(fd, buf, count);
242 if (ret < 0 && errno == EINTR)
243 goto again;
244
245 return ret;
246 }
247
write_id_mapping(enum idmap_type type,pid_t pid,const char * buf,size_t buf_size)248 static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
249 size_t buf_size)
250 {
251 int fd;
252 int ret;
253 char path[4096];
254
255 if (type == GID_MAP) {
256 int setgroups_fd;
257
258 snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
259 setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
260 if (setgroups_fd < 0 && errno != ENOENT)
261 return -1;
262
263 if (setgroups_fd >= 0) {
264 ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
265 close_prot_errno_disarm(setgroups_fd);
266 if (ret != sizeof("deny") - 1)
267 return -1;
268 }
269 }
270
271 switch (type) {
272 case UID_MAP:
273 ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
274 break;
275 case GID_MAP:
276 ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
277 break;
278 default:
279 return -1;
280 }
281 if (ret < 0 || ret >= sizeof(path))
282 return -E2BIG;
283
284 fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
285 if (fd < 0)
286 return -1;
287
288 ret = write_nointr(fd, buf, buf_size);
289 close_prot_errno_disarm(fd);
290 if (ret != buf_size)
291 return -1;
292
293 return 0;
294 }
295
has_userns(void)296 static bool has_userns(void)
297 {
298 return (access("/proc/self/ns/user", F_OK) == 0);
299 }
300
change_userns(struct __test_metadata * _metadata,int syncfds[2])301 static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
302 {
303 int ret;
304 char buf;
305
306 close_prot_errno_disarm(syncfds[1]);
307
308 ret = unshare(CLONE_NEWUSER);
309 ASSERT_EQ(ret, 0) {
310 TH_LOG("%s - Failed to unshare user namespace",
311 strerror(errno));
312 }
313
314 ret = write_nointr(syncfds[0], "1", 1);
315 ASSERT_EQ(ret, 1) {
316 TH_LOG("write_nointr() failed");
317 }
318
319 ret = read_nointr(syncfds[0], &buf, 1);
320 ASSERT_EQ(ret, 1) {
321 TH_LOG("read_nointr() failed");
322 }
323
324 close_prot_errno_disarm(syncfds[0]);
325
326 ASSERT_EQ(setid_userns_root(), 0) {
327 TH_LOG("setid_userns_root() failed");
328 }
329 }
330
change_idmaps(struct __test_metadata * _metadata,int syncfds[2],pid_t pid)331 static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
332 {
333 int ret;
334 char buf;
335 char id_map[4096];
336
337 close_prot_errno_disarm(syncfds[0]);
338
339 ret = read_nointr(syncfds[1], &buf, 1);
340 ASSERT_EQ(ret, 1) {
341 TH_LOG("read_nointr() failed");
342 }
343
344 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
345 ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
346 ASSERT_EQ(ret, 0) {
347 TH_LOG("write_id_mapping(UID_MAP) failed");
348 }
349
350 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
351 ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
352 ASSERT_EQ(ret, 0) {
353 TH_LOG("write_id_mapping(GID_MAP) failed");
354 }
355
356 ret = write_nointr(syncfds[1], "1", 1);
357 ASSERT_EQ(ret, 1) {
358 TH_LOG("write_nointr() failed");
359 }
360
361 close_prot_errno_disarm(syncfds[1]);
362 }
363
364 struct __test_metadata *_thread_metadata;
binder_version_thread(void * data)365 static void *binder_version_thread(void *data)
366 {
367 struct __test_metadata *_metadata = _thread_metadata;
368 int fd = PTR_TO_INT(data);
369 struct binder_version version = { 0 };
370 int ret;
371
372 ret = ioctl(fd, BINDER_VERSION, &version);
373 if (ret < 0)
374 TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
375 strerror(errno));
376
377 pthread_exit(data);
378 }
379
380 /*
381 * Regression test:
382 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
383 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
384 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
385 */
TEST(binderfs_stress)386 TEST(binderfs_stress)
387 {
388 if (!has_userns())
389 SKIP(return, "%s: user namespace not supported\n", __func__);
390
391 int fds[1000];
392 int syncfds[2];
393 pid_t pid;
394 int fd, ret;
395 size_t len;
396 struct binderfs_device device = { 0 };
397 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
398 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
399
400 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
401 ASSERT_EQ(ret, 0) {
402 TH_LOG("%s - Failed to create socket pair", strerror(errno));
403 }
404
405 pid = fork();
406 ASSERT_GE(pid, 0) {
407 TH_LOG("%s - Failed to fork", strerror(errno));
408 close_prot_errno_disarm(syncfds[0]);
409 close_prot_errno_disarm(syncfds[1]);
410 }
411
412 if (pid == 0) {
413 int i, j, k, nthreads;
414 pthread_attr_t attr;
415 pthread_t threads[DEFAULT_THREADS];
416 change_userns(_metadata, syncfds);
417 change_mountns(_metadata);
418
419 ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
420 TH_LOG("%s - Failed to create binderfs mountpoint",
421 strerror(errno));
422 }
423
424 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
425 ASSERT_EQ(ret, 0) {
426 TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel",
427 strerror(errno));
428 }
429
430 for (int i = 0; i < ARRAY_SIZE(fds); i++) {
431
432 snprintf(device_path, sizeof(device_path),
433 "%s/binder-control", binderfs_mntpt);
434 fd = open(device_path, O_RDONLY | O_CLOEXEC);
435 ASSERT_GE(fd, 0) {
436 TH_LOG("%s - Failed to open binder-control device",
437 strerror(errno));
438 }
439
440 memset(&device, 0, sizeof(device));
441 snprintf(device.name, sizeof(device.name), "%d", i);
442 ret = ioctl(fd, BINDER_CTL_ADD, &device);
443 close_prot_errno_disarm(fd);
444 ASSERT_EQ(ret, 0) {
445 TH_LOG("%s - Failed to allocate new binder device",
446 strerror(errno));
447 }
448
449 snprintf(device_path, sizeof(device_path), "%s/%d",
450 binderfs_mntpt, i);
451 fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
452 ASSERT_GE(fds[i], 0) {
453 TH_LOG("%s - Failed to open binder device", strerror(errno));
454 }
455 }
456
457 ret = umount2(binderfs_mntpt, MNT_DETACH);
458 ASSERT_EQ(ret, 0) {
459 TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
460 rmdir(binderfs_mntpt);
461 }
462
463 nthreads = get_nprocs_conf();
464 if (nthreads > DEFAULT_THREADS)
465 nthreads = DEFAULT_THREADS;
466
467 _thread_metadata = _metadata;
468 pthread_attr_init(&attr);
469 for (k = 0; k < ARRAY_SIZE(fds); k++) {
470 for (i = 0; i < nthreads; i++) {
471 ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
472 if (ret) {
473 TH_LOG("%s - Failed to create thread %d",
474 strerror(errno), i);
475 break;
476 }
477 }
478
479 for (j = 0; j < i; j++) {
480 void *fdptr = NULL;
481
482 ret = pthread_join(threads[j], &fdptr);
483 if (ret)
484 TH_LOG("%s - Failed to join thread %d for fd %d",
485 strerror(errno), j, PTR_TO_INT(fdptr));
486 }
487 }
488 pthread_attr_destroy(&attr);
489
490 for (k = 0; k < ARRAY_SIZE(fds); k++)
491 close(fds[k]);
492
493 exit(EXIT_SUCCESS);
494 }
495
496 change_idmaps(_metadata, syncfds, pid);
497
498 ret = wait_for_pid(pid);
499 ASSERT_EQ(ret, 0) {
500 TH_LOG("wait_for_pid() failed");
501 }
502 }
503
TEST(binderfs_test_privileged)504 TEST(binderfs_test_privileged)
505 {
506 if (geteuid() != 0)
507 SKIP(return, "Tests are not run as root. Skipping privileged tests");
508
509 if (__do_binderfs_test(_metadata))
510 SKIP(return, "The Android binderfs filesystem is not available");
511 }
512
TEST(binderfs_test_unprivileged)513 TEST(binderfs_test_unprivileged)
514 {
515 if (!has_userns())
516 SKIP(return, "%s: user namespace not supported\n", __func__);
517 int ret;
518 int syncfds[2];
519 pid_t pid;
520
521 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
522 ASSERT_EQ(ret, 0) {
523 TH_LOG("%s - Failed to create socket pair", strerror(errno));
524 }
525
526 pid = fork();
527 ASSERT_GE(pid, 0) {
528 close_prot_errno_disarm(syncfds[0]);
529 close_prot_errno_disarm(syncfds[1]);
530 TH_LOG("%s - Failed to fork", strerror(errno));
531 }
532
533 if (pid == 0) {
534 change_userns(_metadata, syncfds);
535 if (__do_binderfs_test(_metadata))
536 exit(2);
537 exit(EXIT_SUCCESS);
538 }
539
540 change_idmaps(_metadata, syncfds, pid);
541
542 ret = wait_for_pid(pid);
543 if (ret) {
544 if (ret == 2)
545 SKIP(return, "The Android binderfs filesystem is not available");
546 ASSERT_EQ(ret, 0) {
547 TH_LOG("wait_for_pid() failed");
548 }
549 }
550 }
551
552 TEST_HARNESS_MAIN
553