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
39static 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
56static 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, binderfs_mntpt, "binder", 0, 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(device.name, "my-binder", strlen("my-binder"));
89
90	snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
91	fd = open(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, BINDER_CTL_ADD, &device);
99	saved_errno = errno;
100	close(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(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
114	fd = open(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, BINDER_VERSION, &version);
122	saved_errno = errno;
123	close(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(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(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
145	ret = unlink(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(device_path, sizeof(device_path), "%s/features/%s",
160			 binderfs_mntpt, binder_features[i]);
161		fd = open(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);
168	}
169
170	/* success: binder feature files found */
171	result = 0;
172
173umount:
174	ret = umount2(binderfs_mntpt, MNT_DETACH);
175	EXPECT_EQ(ret, 0) {
176		TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
177	}
178rmdir:
179	ret = rmdir(binderfs_mntpt);
180	EXPECT_EQ(ret, 0) {
181		TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
182	}
183out:
184	return result;
185}
186
187static int wait_for_pid(pid_t pid)
188{
189	int status, ret;
190
191again:
192	ret = waitpid(pid, &status, 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
206static 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
219enum idmap_type {
220	UID_MAP,
221	GID_MAP,
222};
223
224static ssize_t read_nointr(int fd, void *buf, size_t count)
225{
226	ssize_t ret;
227again:
228	ret = read(fd, buf, count);
229	if (ret < 0 && errno == EINTR)
230		goto again;
231
232	return ret;
233}
234
235static ssize_t write_nointr(int fd, const void *buf, size_t count)
236{
237	ssize_t ret;
238again:
239	ret = write(fd, buf, count);
240	if (ret < 0 && errno == EINTR)
241		goto again;
242
243	return ret;
244}
245
246static 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(path, sizeof(path), "/proc/%d/setgroups", pid);
257		setgroups_fd = open(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(setgroups_fd, "deny", 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(path, sizeof(path), "/proc/%d/uid_map", pid);
272		break;
273	case GID_MAP:
274		ret = snprintf(path, sizeof(path), "/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(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
283	if (fd < 0)
284		return -1;
285
286	ret = write_nointr(fd, buf, buf_size);
287	close_prot_errno_disarm(fd);
288	if (ret != buf_size)
289		return -1;
290
291	return 0;
292}
293
294static 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(syncfds[0], "1", 1);
308	ASSERT_EQ(ret, 1) {
309		TH_LOG("write_nointr() failed");
310	}
311
312	ret = read_nointr(syncfds[0], &buf, 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
324static 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(syncfds[1], &buf, 1);
333	ASSERT_EQ(ret, 1) {
334		TH_LOG("read_nointr() failed");
335	}
336
337	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
338	ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
339	ASSERT_EQ(ret, 0) {
340		TH_LOG("write_id_mapping(UID_MAP) failed");
341	}
342
343	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
344	ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
345	ASSERT_EQ(ret, 0) {
346		TH_LOG("write_id_mapping(GID_MAP) failed");
347	}
348
349	ret = write_nointr(syncfds[1], "1", 1);
350	ASSERT_EQ(ret, 1) {
351		TH_LOG("write_nointr() failed");
352	}
353
354	close_prot_errno_disarm(syncfds[1]);
355}
356
357struct __test_metadata *_thread_metadata;
358static 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, 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(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 */
379TEST(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, 0, 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, binderfs_mntpt, "binder", 0, 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(device_path, sizeof(device_path),
423				 "%s/binder-control", binderfs_mntpt);
424			fd = open(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(&device, 0, sizeof(device));
431			snprintf(device.name, sizeof(device.name), "%d", i);
432			ret = ioctl(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(device_path, sizeof(device_path), "%s/%d",
440				 binderfs_mntpt, i);
441			fds[i] = open(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(binderfs_mntpt, MNT_DETACH);
448		ASSERT_EQ(ret, 0) {
449			TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
450			rmdir(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);
459		for (k = 0; k < ARRAY_SIZE(fds); k++) {
460			for (i = 0; i < nthreads; i++) {
461				ret = pthread_create(&threads[i], &attr, 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(threads[j], &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);
479
480		for (k = 0; k < ARRAY_SIZE(fds); k++)
481			close(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
494TEST(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
503TEST(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, 0, 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(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
540TEST_HARNESS_MAIN
541